init: initHEADmaster

25 files changed, 2111 insertions, 0 deletions

diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..a406b61
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,89 @@
+Copyright (C) 1989, 1991 Free Software Foundation, Inc.
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+
+Everyone is permitted to copy and distribute verbatim copies
+of this license document, but changing it is not allowed.
+
+Preamble
+
+The licenses for most software are designed to take away your freedom to share and change it. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change free software–to make sure the software is free for all its users. This General Public License applies to most of the Free Software Foundation’s software and to any other program whose authors commit to using it. (Some other Free Software Foundation software is covered by the GNU Library General Public License instead.) You can apply it to your programs, too.
+
+When we speak of free software, we are referring to freedom, not price. Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software (and charge for this service if you wish), that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs; and that you know you can do these things.
+
+To protect your rights, we need to make restrictions that forbid anyone to deny you these rights or to ask you to surrender the rights. These restrictions translate to certain responsibilities for you if you distribute copies of the software, or if you modify it.
+
+For example, if you distribute copies of such a program, whether gratis or for a fee, you must give the recipients all the rights that you have. You must make sure that they, too, receive or can get the source code. And you must show them these terms so they know their rights.
+
+We protect your rights with two steps: (1) copyright the software, and (2) offer you this license which gives you legal permission to copy, distribute and/or modify the software.
+
+Also, for each author’s protection and ours, we want to make certain that everyone understands that there is no warranty for this free software. If the software is modified by someone else and passed on, we want its recipients to know that what they have is not the original, so that any problems introduced by others will not reflect on the original authors’ reputations.
+
+Finally, any free program is threatened constantly by software patents. We wish to avoid the danger that redistributors of a free program will individually obtain patent licenses, in effect making the program proprietary. To prevent this, we have made it clear that any patent must be licensed for everyone’s free use or not licensed at all.
+
+The precise terms and conditions for copying, distribution and modification follow.
+
+TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+
+0. This License applies to any program or other work which contains a notice placed by the copyright holder saying it may be distributed under the terms of this General Public License. The “Program”, below, refers to any such program or work, and a “work based on the Program” means either the Program or any derivative work under copyright law: that is to say, a work containing the Program or a portion of it, either verbatim or with modifications and/or translated into another language. (Hereinafter, translation is included without limitation in the term “modification”.) Each licensee is addressed as “you”.
+
+Activities other than copying, distribution and modification are not covered by this License; they are outside its scope. The act of running the Program is not restricted, and the output from the Program is covered only if its contents constitute a work based on the Program (independent of having been made by running the Program). Whether that is true depends on what the Program does.
+
+1. You may copy and distribute verbatim copies of the Program’s source code as you receive it, in any medium, provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice and disclaimer of warranty; keep intact all the notices that refer to this License and to the absence of any warranty; and give any other recipients of the Program a copy of this License along with the Program.
+
+You may charge a fee for the physical act of transferring a copy, and you may at your option offer warranty protection in exchange for a fee.
+
+2. You may modify your copy or copies of the Program or any portion of it, thus forming a work based on the Program, and copy and distribute such modifications or work under the terms of Section 1 above, provided that you also meet all of these conditions:
+
+a) You must cause the modified files to carry prominent notices stating that you changed the files and the date of any change.
+
+b) You must cause any work that you distribute or publish, that in whole or in part contains or is derived from the Program or any part thereof, to be licensed as a whole at no charge to all third parties under the terms of this License.
+
+c) If the modified program normally reads commands interactively when run, you must cause it, when started running for such interactive use in the most ordinary way, to print or display an announcement including an appropriate copyright notice and a notice that there is no warranty (or else, saying that you provide a warranty) and that users may redistribute the program under these conditions, and telling the user how to view a copy of this License. (Exception: if the Program itself is interactive but does not normally print such an announcement, your work based on the Program is not required to print an announcement.)
+
+These requirements apply to the modified work as a whole. If identifiable sections of that work are not derived from the Program, and can be reasonably considered independent and separate works in themselves, then this License, and its terms, do not apply to those sections when you distribute them as separate works. But when you distribute the same sections as part of a whole which is a work based on the Program, the distribution of the whole must be on the terms of this License, whose permissions for other licensees extend to the entire whole, and thus to each and every part regardless of who wrote it.
+
+Thus, it is not the intent of this section to claim rights or contest your rights to work written entirely by you; rather, the intent is to exercise the right to control the distribution of derivative or collective works based on the Program.
+
+In addition, mere aggregation of another work not based on the Program with the Program (or with a work based on the Program) on a volume of a storage or distribution medium does not bring the other work under the scope of this License.
+
+3. You may copy and distribute the Program (or a work based on it, under Section 2) in object code or executable form under the terms of Sections 1 and 2 above provided that you also do one of the following:
+
+a) Accompany it with the complete corresponding machine-readable source code, which must be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or,
+
+b) Accompany it with a written offer, valid for at least three years, to give any third party, for a charge no more than your cost of physically performing source distribution, a complete machine-readable copy of the corresponding source code, to be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or,
+
+c) Accompany it with the information you received as to the offer to distribute corresponding source code. (This alternative is allowed only for noncommercial distribution and only if you received the program in object code or executable form with such an offer, in accord with Subsection b above.)
+
+The source code for a work means the preferred form of the work for making modifications to it. For an executable work, complete source code means all the source code for all modules it contains, plus any associated interface definition files, plus the scripts used to control compilation and installation of the executable. However, as a special exception, the source code distributed need not include anything that is normally distributed (in either source or binary form) with the major components (compiler, kernel, and so on) of the operating system on which the executable runs, unless that component itself accompanies the executable.
+
+If distribution of executable or object code is made by offering access to copy from a designated place, then offering equivalent access to copy the source code from the same place counts as distribution of the source code, even though third parties are not compelled to copy the source along with the object code.
+
+4. You may not copy, modify, sublicense, or distribute the Program except as expressly provided under this License. Any attempt otherwise to copy, modify, sublicense or distribute the Program is void, and will automatically terminate your rights under this License. However, parties who have received copies, or rights, from you under this License will not have their licenses terminated so long as such parties remain in full compliance.
+
+5. You are not required to accept this License, since you have not signed it. However, nothing else grants you permission to modify or distribute the Program or its derivative works. These actions are prohibited by law if you do not accept this License. Therefore, by modifying or distributing the Program (or any work based on the Program), you indicate your acceptance of this License to do so, and all its terms and conditions for copying, distributing or modifying the Program or works based on it.
+
+6. Each time you redistribute the Program (or any work based on the Program), the recipient automatically receives a license from the original licensor to copy, distribute or modify the Program subject to these terms and conditions. You may not impose any further restrictions on the recipients’ exercise of the rights granted herein. You are not responsible for enforcing compliance by third parties to this License.
+
+7. If, as a consequence of a court judgment or allegation of patent infringement or for any other reason (not limited to patent issues), conditions are imposed on you (whether by court order, agreement or otherwise) that contradict the conditions of this License, they do not excuse you from the conditions of this License. If you cannot distribute so as to satisfy simultaneously your obligations under this License and any other pertinent obligations, then as a consequence you may not distribute the Program at all. For example, if a patent license would not permit royalty-free redistribution of the Program by all those who receive copies directly or indirectly through you, then the only way you could satisfy both it and this License would be to refrain entirely from distribution of the Program.
+
+If any portion of this section is held invalid or unenforceable under any particular circumstance, the balance of the section is intended to apply and the section as a whole is intended to apply in other circumstances.
+
+It is not the purpose of this section to induce you to infringe any patents or other property right claims or to contest validity of any such claims; this section has the sole purpose of protecting the integrity of the free software distribution system, which is implemented by public license practices. Many people have made generous contributions to the wide range of software distributed through that system in reliance on consistent application of that system; it is up to the author/donor to decide if he or she is willing to distribute software through any other system and a licensee cannot impose that choice.
+
+This section is intended to make thoroughly clear what is believed to be a consequence of the rest of this License.
+
+8. If the distribution and/or use of the Program is restricted in certain countries either by patents or by copyrighted interfaces, the original copyright holder who places the Program under this License may add an explicit geographical distribution limitation excluding those countries, so that distribution is permitted only in or among countries not thus excluded. In such case, this License incorporates the limitation as if written in the body of this License.
+
+9. The Free Software Foundation may publish revised and/or new versions of the General Public License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns.
+
+Each version is given a distinguishing version number. If the Program specifies a version number of this License which applies to it and “any later version”, you have the option of following the terms and conditions either of that version or of any later version published by the Free Software Foundation. If the Program does not specify a version number of this License, you may choose any version ever published by the Free Software Foundation.
+
+10. If you wish to incorporate parts of the Program into other free programs whose distribution conditions are different, write to the author to ask for permission. For software which is copyrighted by the Free Software Foundation, write to the Free Software Foundation; we sometimes make exceptions for this. Our decision will be guided by the two goals of preserving the free status of all derivatives of our free software and of promoting the sharing and reuse of software generally.
+
+NO WARRANTY
+
+11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM “AS IS” WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
+
+12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
+
+END OF TERMS AND CONDITIONS
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..b63fc83
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,35 @@
+CC ?= cc
+PKG_CONFIG ?= pkg-config
+PREFIX ?= /usr/local
+BINDIR ?= $(PREFIX)/bin
+DESTDIR ?=
+
+TARGET := bin/yapssg
+SOURCES := src/Main.c $(wildcard src/*/*.c)
+OBJECTS := $(patsubst src/%.c,obj/%.o,$(SOURCES))
+
+CPPFLAGS += -Isrc $(shell $(PKG_CONFIG) --cflags libxml-2.0 luajit)
+CFLAGS ?= -O2 -Wall -Wextra -Werror -std=c99
+LDLIBS += $(shell $(PKG_CONFIG) --libs libxml-2.0 luajit)
+
+.PHONY: all clean install
+
+all: $(TARGET)
+
+$(TARGET): $(OBJECTS) | bin
+	$(CC) $(LDFLAGS) $(OBJECTS) $(LDLIBS) -o $@
+
+obj/%.o: src/%.c
+	mkdir -p $(@D)
+	$(CC) $(CPPFLAGS) $(CFLAGS) -MMD -MP -c $< -o $@
+
+bin:
+	mkdir -p $@
+
+clean:
+	rm -rf obj bin
+
+install: $(TARGET)
+	install -Dm755 $(TARGET) $(DESTDIR)$(BINDIR)/yapssg
+
+-include $(OBJECTS:.o=.d)
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..382de49
--- /dev/null
+++ b/README.md
@@ -0,0 +1,31 @@
+# yapssg
+*yet another pointless static site generator*
+
+A static site generator for embedding Lua in your HTML.
+
+## Usage
+Basic CLI Usage:
+```
+yapssg FILE [-o OUTPUT]
+yapssg -d DIRECTORY [-o OUTPUT] [-f]
+```
+
+See examples for other usage.
+
+## Requirements
+- make
+- pkg-config
+- libxml2
+- luajit
+
+## Installation
+```
+$ git clone https://git.bwaaa.monster/yapssg
+$ cd yapssg
+# make install
+```
+
+## Contribution
+Generate a patch with ```git format-patch HEAD~1``` and email to [gabriel@bwaaa.monster](mailto:gabriel@bwaaa.monster), beginning the subject line with [PATCH yapssg] 
+
+*If you are sending a revised version of a previous patch, please use [PATCH yapssg v2, v3, etc].*
diff --git a/examples/site/build.lua b/examples/site/build.lua
new file mode 100644
index 0000000..0b9e67a
--- /dev/null
+++ b/examples/site/build.lua
@@ -0,0 +1,69 @@
+-- External scripts are resolved relative to the HTML file that includes them :)
+
+local function element(tag, attributes, children)
+  return { tag = tag, attributes = attributes or {}, children = children or {} }
+end
+
+local function find_by_class(node, wanted)
+  if type(node) ~= "table" then return nil end
+  local classes = node.attributes and node.attributes.class or ""
+  if (" " .. classes .. " "):find(" " .. wanted .. " ", 1, true) then
+    return node
+  end
+  for _, child in ipairs(node.children or {}) do
+    local match = find_by_class(child, wanted)
+    if match then return match end
+  end
+end
+
+local features = {
+  "inline Lua",
+  "external Lua",
+  "DOM updates",
+  "directory walking",
+  "logging",
+  "mixed content"
+}
+
+local feature_list = assert(find_by_class(page, "feature-list"))
+for _, feature in ipairs(features) do
+  table.insert(feature_list.children, element("li", {}, { feature }))
+end
+
+local entries = {}
+for entry in fs.walk(".") do
+  table.insert(entries, entry)
+end
+table.sort(entries, function(left, right) return left.path < right.path end)
+
+local summary = assert(find_by_class(page, "file-summary"))
+summary.text = tostring(#entries) .. " entries"
+
+local file_list = assert(find_by_class(page, "file-list"))
+for _, entry in ipairs(entries) do
+  table.insert(file_list.children, element("li", {}, {
+    element("code", {}, { entry.path }),
+    " (", entry.type, ")"
+  }))
+end
+
+local build_summary = assert(find_by_class(page, "build-summary"))
+build_summary.text = "Built with " .. site.name .. " " .. site.version
+
+local mixed = assert(find_by_class(page, "mixed-content"))
+mixed.children = {
+  { kind = "comment", text = "generated by Lua" },
+  "Text with ",
+  element("strong", {}, { "an element" }),
+  "."
+}
+
+table.insert(page.head.children, 1, {
+  kind = "processing_instruction",
+  target = "yapssg",
+  text = "generated"
+})
+
+page.attributes["data-entry-count"] = tostring(#entries)
+log.info("generated", #features, "feature items")
+log.debug("walked", #entries, "entries")
diff --git a/examples/site/index.html b/examples/site/index.html
new file mode 100644
index 0000000..39dd21f
--- /dev/null
+++ b/examples/site/index.html
@@ -0,0 +1,42 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1">
+    <title>yapssg feature tour</title>
+  </head>
+  <body>
+    <header>
+      <h1>yapssg feature tour</h1>
+      <p class="build-summary">Building…</p>
+    </header>
+
+    <main>
+      <section>
+        <h2>Features</h2>
+        <ul class="feature-list"></ul>
+      </section>
+
+      <section>
+        <h2>Files</h2>
+        <p class="file-summary"></p>
+        <ul class="file-list"></ul>
+      </section>
+
+      <section>
+        <h2>Mixed content</h2>
+        <p class="mixed-content"></p>
+      </section>
+    </main>
+
+    <footer>
+      <p>Generated with yapssg.</p>
+    </footer>
+
+    <lua>
+      site = { name = "yapssg", version = yapssg.version }
+      page.attributes["data-generated"] = "true"
+    </lua>
+    <lua src="build.lua"></lua>
+  </body>
+</html>
diff --git a/examples/site/nested/child.txt b/examples/site/nested/child.txt
new file mode 100644
index 0000000..b14df64
--- /dev/null
+++ b/examples/site/nested/child.txt
@@ -0,0 +1 @@
+Hi
diff --git a/src/Cli/Cli.c b/src/Cli/Cli.c
new file mode 100644
index 0000000..3648493
--- /dev/null
+++ b/src/Cli/Cli.c
@@ -0,0 +1,102 @@
+#include "Cli/Cli.h"
+
+#include "Logger/Logger.h"
+#include "Version/Version.h"
+
+#include <getopt.h>
+#include <stdio.h>
+
+void cli_print_usage(const char *program_name) {
+  fprintf(
+      stderr,
+      "Usage:\n"
+      "  %s FILE [-o OUTPUT]\n"
+      "  %s -d DIRECTORY [-o OUTPUT] [-f]\n\n"
+      "Options:\n"
+      "  -d, --directory DIRECTORY   Process a directory recursively\n"
+      "  -o, --output OUTPUT         Set the output path\n"
+      "  -f, --overwrite             Overwrite an existing output directory\n"
+      "  -l, --log-level LEVEL       error, warning, info, debug, or silent\n"
+      "  -v, --version               Show the program version\n"
+      "  -h, --help                  Show this help\n",
+      program_name, program_name);
+}
+
+static void cli_print_version(void) { printf("yapssg %s\n", yapssg_version); }
+
+static const char *strip_optional_equals(const char *value) {
+  return value != NULL && value[0] == '=' ? value + 1 : value;
+}
+
+CliParseResult cli_parse(int argc, char **argv, CliOptions *options) {
+  static const struct option long_options[] = {
+      {"directory", required_argument, NULL, 'd'},
+      {"output", required_argument, NULL, 'o'},
+      {"overwrite", no_argument, NULL, 'f'},
+      {"force", no_argument, NULL, 'f'},
+      {"log-level", required_argument, NULL, 'l'},
+      {"version", no_argument, NULL, 'v'},
+      {"help", no_argument, NULL, 'h'},
+      {NULL, 0, NULL, 0}};
+  const char *directory = NULL;
+  int option;
+
+  options->input_type = INPUT_TYPE_NONE;
+  options->input_path = NULL;
+  options->output_path = NULL;
+  options->overwrite_output = 0;
+  options->log_level = LOG_LEVEL_INFO;
+
+  while ((option = getopt_long(argc, argv, "d:o:fl:vh", long_options, NULL)) !=
+         -1) {
+    switch (option) {
+    case 'd':
+      directory = strip_optional_equals(optarg);
+      break;
+    case 'o':
+      options->output_path = strip_optional_equals(optarg);
+      break;
+    case 'f':
+      options->overwrite_output = 1;
+      break;
+    case 'l':
+      if (logger_parse_level(optarg, &options->log_level) != 0) {
+        logger_error("unknown log level '%s'", optarg);
+        return CLI_PARSE_ERROR;
+      }
+      break;
+    case 'v':
+      cli_print_version();
+      return CLI_PARSE_VERSION;
+    case 'h':
+      cli_print_usage(argv[0]);
+      return CLI_PARSE_HELP;
+    default:
+      cli_print_usage(argv[0]);
+      return CLI_PARSE_ERROR;
+    }
+  }
+
+  if (directory != NULL) {
+    if (optind != argc || directory[0] == '\0') {
+      logger_error("a directory cannot be combined with a file");
+      return CLI_PARSE_ERROR;
+    }
+    options->input_type = INPUT_TYPE_DIRECTORY;
+    options->input_path = directory;
+  } else {
+    if (optind + 1 != argc) {
+      cli_print_usage(argv[0]);
+      return CLI_PARSE_ERROR;
+    }
+    options->input_type = INPUT_TYPE_FILE;
+    options->input_path = argv[optind];
+  }
+
+  if (options->output_path != NULL && options->output_path[0] == '\0') {
+    logger_error("output path cannot be empty");
+    return CLI_PARSE_ERROR;
+  }
+
+  return CLI_PARSE_OK;
+}
diff --git a/src/Cli/Cli.h b/src/Cli/Cli.h
new file mode 100644
index 0000000..9695fd4
--- /dev/null
+++ b/src/Cli/Cli.h
@@ -0,0 +1,30 @@
+#ifndef YAPSSG_CLI_H
+#define YAPSSG_CLI_H
+
+#include "Logger/Logger.h"
+
+typedef enum {
+  INPUT_TYPE_NONE,
+  INPUT_TYPE_FILE,
+  INPUT_TYPE_DIRECTORY
+} InputType;
+
+typedef enum {
+  CLI_PARSE_ERROR = -1,
+  CLI_PARSE_OK,
+  CLI_PARSE_HELP,
+  CLI_PARSE_VERSION
+} CliParseResult;
+
+typedef struct {
+  InputType input_type;
+  const char *input_path;
+  const char *output_path;
+  int overwrite_output;
+  LogLevel log_level;
+} CliOptions;
+
+CliParseResult cli_parse(int argc, char **argv, CliOptions *options);
+void cli_print_usage(const char *program_name);
+
+#endif
diff --git a/src/DirectoryWalker/DirectoryWalker.c b/src/DirectoryWalker/DirectoryWalker.c
new file mode 100644
index 0000000..dc3729a
--- /dev/null
+++ b/src/DirectoryWalker/DirectoryWalker.c
@@ -0,0 +1,249 @@
+#define _POSIX_C_SOURCE 200809L
+
+#include "DirectoryWalker/DirectoryWalker.h"
+
+#include "Path/Path.h"
+
+#include <dirent.h>
+#include <errno.h>
+#include <lauxlib.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+
+#define WALKER_METATABLE "yapssg.directory_walker"
+
+typedef struct {
+  DIR *directory;
+  char *absolute_path;
+  char *display_path;
+  size_t depth;
+} WalkFrame;
+
+typedef struct {
+  WalkFrame *frames;
+  size_t length;
+  size_t capacity;
+} DirectoryWalker;
+
+static void close_frame(WalkFrame *frame) {
+  if (frame->directory != NULL) {
+    closedir(frame->directory);
+  }
+  free(frame->absolute_path);
+  free(frame->display_path);
+}
+
+static void clear_walker(DirectoryWalker *walker) {
+  while (walker->length > 0) {
+    close_frame(&walker->frames[--walker->length]);
+  }
+  free(walker->frames);
+  walker->frames = NULL;
+  walker->capacity = 0;
+}
+
+static int walker_gc(lua_State *lua) {
+  DirectoryWalker *walker = lua_touserdata(lua, 1);
+
+  clear_walker(walker);
+  return 0;
+}
+
+static int grow_walker(DirectoryWalker *walker) {
+  size_t larger_capacity;
+  WalkFrame *larger_frames;
+
+  if (walker->capacity > SIZE_MAX / (2 * sizeof(*walker->frames))) {
+    errno = ENOMEM;
+    return -1;
+  }
+
+  larger_capacity = walker->capacity == 0 ? 8 : walker->capacity * 2;
+  larger_frames =
+      realloc(walker->frames, larger_capacity * sizeof(*walker->frames));
+  if (larger_frames == NULL) {
+    errno = ENOMEM;
+    return -1;
+  }
+
+  walker->frames = larger_frames;
+  walker->capacity = larger_capacity;
+  return 0;
+}
+
+static int push_frame(DirectoryWalker *walker, char *absolute_path,
+                      char *display_path, size_t depth) {
+  DIR *directory = opendir(absolute_path);
+  WalkFrame *frame;
+
+  if (directory == NULL) {
+    return -1;
+  }
+  if (walker->length == walker->capacity && grow_walker(walker) != 0) {
+    int error_number = errno;
+
+    closedir(directory);
+    errno = error_number;
+    return -1;
+  }
+
+  frame = &walker->frames[walker->length++];
+  frame->directory = directory;
+  frame->absolute_path = absolute_path;
+  frame->display_path = display_path;
+  frame->depth = depth;
+  return 0;
+}
+
+static const char *entry_type(mode_t mode) {
+  if (S_ISREG(mode)) {
+    return "file";
+  }
+  if (S_ISDIR(mode)) {
+    return "directory";
+  }
+  if (S_ISLNK(mode)) {
+    return "symlink";
+  }
+  return "other";
+}
+
+static void push_entry(lua_State *lua, const char *path, const char *name,
+                       const struct stat *status, size_t depth) {
+  lua_newtable(lua);
+
+  lua_pushstring(lua, path);
+  lua_setfield(lua, -2, "path");
+
+  lua_pushstring(lua, name);
+  lua_setfield(lua, -2, "name");
+
+  lua_pushstring(lua, entry_type(status->st_mode));
+  lua_setfield(lua, -2, "type");
+
+  lua_pushnumber(lua, (lua_Number)depth);
+  lua_setfield(lua, -2, "depth");
+
+  if (S_ISREG(status->st_mode)) {
+    lua_pushnumber(lua, (lua_Number)status->st_size);
+    lua_setfield(lua, -2, "size");
+  }
+}
+
+static int walker_next(lua_State *lua) {
+  DirectoryWalker *walker = lua_touserdata(lua, lua_upvalueindex(1));
+
+  while (walker->length > 0) {
+    WalkFrame *frame = &walker->frames[walker->length - 1];
+    struct dirent *entry;
+    char *absolute_path;
+    char *display_path;
+    struct stat status;
+    size_t depth;
+
+    errno = 0;
+    entry = readdir(frame->directory);
+    if (entry == NULL) {
+      int error_number = errno;
+
+      close_frame(frame);
+      --walker->length;
+      if (error_number != 0) {
+        clear_walker(walker);
+        return luaL_error(lua, "cannot read directory while walking: %s",
+                          strerror(error_number));
+      }
+      continue;
+    }
+    if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0) {
+      continue;
+    }
+
+    absolute_path = path_join(frame->absolute_path, entry->d_name);
+    display_path = path_join(frame->display_path, entry->d_name);
+    if (absolute_path == NULL || display_path == NULL) {
+      free(absolute_path);
+      free(display_path);
+      clear_walker(walker);
+      return luaL_error(lua, "unable to allocate directory-walk path");
+    }
+    if (lstat(absolute_path, &status) != 0) {
+      int error_number = errno;
+
+      free(absolute_path);
+      free(display_path);
+      clear_walker(walker);
+      return luaL_error(lua, "cannot inspect directory entry: %s",
+                        strerror(error_number));
+    }
+
+    depth = frame->depth + 1;
+    push_entry(lua, display_path, entry->d_name, &status, depth);
+
+    if (S_ISDIR(status.st_mode)) {
+      if (push_frame(walker, absolute_path, display_path, depth) != 0) {
+        int error_number = errno;
+
+        free(absolute_path);
+        free(display_path);
+        clear_walker(walker);
+        return luaL_error(lua, "cannot open directory while walking: %s",
+                          strerror(error_number));
+      }
+    } else {
+      free(absolute_path);
+      free(display_path);
+    }
+    return 1;
+  }
+  clear_walker(walker);
+  return 0;
+}
+
+static int walk(lua_State *lua) {
+  const char *input_path = lua_tostring(lua, lua_upvalueindex(1));
+  const char *requested_path = luaL_checkstring(lua, 1);
+  char *absolute_path = path_resolve_from_file(input_path, requested_path);
+  char *display_path = path_join("", requested_path);
+  DirectoryWalker *walker;
+
+  if (absolute_path == NULL || display_path == NULL) {
+    free(absolute_path);
+    free(display_path);
+    return luaL_error(lua, "unable to allocate directory-walk root");
+  }
+
+  walker = lua_newuserdata(lua, sizeof(*walker));
+  memset(walker, 0, sizeof(*walker));
+  luaL_getmetatable(lua, WALKER_METATABLE);
+  lua_setmetatable(lua, -2);
+
+  if (push_frame(walker, absolute_path, display_path, 0) != 0) {
+    int error_number = errno;
+
+    free(absolute_path);
+    free(display_path);
+    return luaL_error(lua, "cannot open directory '%s': %s", requested_path,
+                      strerror(error_number));
+  }
+
+  lua_pushcclosure(lua, walker_next, 1);
+  return 1;
+}
+
+void directory_walker_register(lua_State *lua, const char *input_path) {
+  if (luaL_newmetatable(lua, WALKER_METATABLE)) {
+    lua_pushcfunction(lua, walker_gc);
+    lua_setfield(lua, -2, "__gc");
+  }
+  lua_pop(lua, 1);
+
+  lua_newtable(lua);
+  lua_pushstring(lua, input_path);
+  lua_pushcclosure(lua, walk, 1);
+  lua_setfield(lua, -2, "walk");
+  lua_setglobal(lua, "fs");
+}
diff --git a/src/DirectoryWalker/DirectoryWalker.h b/src/DirectoryWalker/DirectoryWalker.h
new file mode 100644
index 0000000..94dcbf6
--- /dev/null
+++ b/src/DirectoryWalker/DirectoryWalker.h
@@ -0,0 +1,8 @@
+#ifndef YAPSSG_DIRECTORY_WALKER_H
+#define YAPSSG_DIRECTORY_WALKER_H
+
+#include <lua.h>
+
+void directory_walker_register(lua_State *lua, const char *input_path);
+
+#endif
diff --git a/src/Dom/Dom.c b/src/Dom/Dom.c
new file mode 100644
index 0000000..ede7ddd
--- /dev/null
+++ b/src/Dom/Dom.c
@@ -0,0 +1,303 @@
+#include "Dom/Dom.h"
+
+#include <lauxlib.h>
+#include <limits.h>
+#include <stddef.h>
+#include <string.h>
+#include <strings.h>
+
+static int absolute_index(lua_State *lua, int index) {
+  return index < 0 ? lua_gettop(lua) + index + 1 : index;
+}
+
+static int is_lua_element(const xmlNode *node) {
+  return node->type == XML_ELEMENT_NODE &&
+         strcasecmp((const char *)node->name, "lua") == 0;
+}
+
+static void set_string_field(lua_State *lua, int table_index, const char *name,
+                             const char *value) {
+  lua_pushstring(lua, value);
+  lua_setfield(lua, table_index, name);
+}
+
+static int has_structured_children(const xmlNode *node) {
+  const xmlNode *child;
+
+  for (child = node->children; child != NULL; child = child->next) {
+    if (is_lua_element(child)) {
+      continue;
+    }
+    if (child->type != XML_TEXT_NODE && child->type != XML_CDATA_SECTION_NODE) {
+      return 1;
+    }
+  }
+  return 0;
+}
+
+static void push_element(lua_State *lua, const xmlNode *node);
+
+static void push_special_node(lua_State *lua, const xmlNode *node) {
+  lua_newtable(lua);
+  if (node->type == XML_COMMENT_NODE) {
+    set_string_field(lua, -2, "kind", "comment");
+  } else {
+    set_string_field(lua, -2, "kind", "processing_instruction");
+    set_string_field(lua, -2, "target", (const char *)node->name);
+  }
+  set_string_field(lua, -2, "text",
+                   node->content == NULL ? "" : (const char *)node->content);
+}
+
+static void add_child_alias(lua_State *lua, int element_index,
+                            const xmlNode *child, int child_index) {
+  const char *name = (const char *)child->name;
+
+  lua_getfield(lua, element_index, name);
+  if (lua_isnil(lua, -1)) {
+    lua_pop(lua, 1);
+    lua_pushvalue(lua, child_index);
+    lua_setfield(lua, element_index, name);
+    return;
+  }
+  lua_pop(lua, 1);
+}
+
+static void push_children(lua_State *lua, const xmlNode *node,
+                          int element_index, int include_text) {
+  const xmlNode *child;
+  int children_index;
+  int array_index = 1;
+
+  lua_newtable(lua);
+  children_index = lua_gettop(lua);
+
+  for (child = node->children; child != NULL; child = child->next) {
+    if (is_lua_element(child)) {
+      continue;
+    }
+
+    if (child->type == XML_ELEMENT_NODE) {
+      int child_index;
+
+      push_element(lua, child);
+      child_index = lua_gettop(lua);
+      lua_pushvalue(lua, child_index);
+      lua_rawseti(lua, children_index, array_index++);
+      add_child_alias(lua, element_index, child, child_index);
+      lua_pop(lua, 1);
+    } else if (include_text && (child->type == XML_TEXT_NODE ||
+                                child->type == XML_CDATA_SECTION_NODE)) {
+      lua_pushstring(
+          lua, child->content == NULL ? "" : (const char *)child->content);
+      lua_rawseti(lua, children_index, array_index++);
+    } else if (child->type == XML_COMMENT_NODE || child->type == XML_PI_NODE) {
+      push_special_node(lua, child);
+      lua_rawseti(lua, children_index, array_index++);
+    }
+  }
+
+  lua_setfield(lua, element_index, "children");
+}
+
+static void push_attributes(lua_State *lua, const xmlNode *node,
+                            int element_index) {
+  const xmlAttr *attribute;
+
+  lua_newtable(lua);
+  for (attribute = node->properties; attribute != NULL;
+       attribute = attribute->next) {
+    xmlChar *value = xmlNodeListGetString(node->doc, attribute->children, 1);
+
+    lua_pushstring(lua, value == NULL ? "" : (const char *)value);
+    lua_setfield(lua, -2, (const char *)attribute->name);
+    xmlFree(value);
+  }
+  lua_setfield(lua, element_index, "attributes");
+}
+
+static void push_text(lua_State *lua, const xmlNode *node, int element_index) {
+  const xmlNode *child;
+  luaL_Buffer buffer;
+
+  luaL_buffinit(lua, &buffer);
+  for (child = node->children; child != NULL; child = child->next) {
+    if (child->type == XML_TEXT_NODE || child->type == XML_CDATA_SECTION_NODE) {
+      luaL_addstring(
+          &buffer, child->content == NULL ? "" : (const char *)child->content);
+    }
+  }
+  luaL_pushresult(&buffer);
+  lua_setfield(lua, element_index, "text");
+}
+
+static void push_element(lua_State *lua, const xmlNode *node) {
+  int element_index;
+  int structured_children = has_structured_children(node);
+
+  lua_newtable(lua);
+  element_index = lua_gettop(lua);
+  set_string_field(lua, element_index, "tag", (const char *)node->name);
+  push_attributes(lua, node, element_index);
+  push_children(lua, node, element_index, structured_children);
+  if (!structured_children) {
+    push_text(lua, node, element_index);
+  }
+}
+
+void dom_push_page(lua_State *lua, const xmlNode *root) {
+  push_element(lua, root);
+}
+
+static xmlNodePtr node_from_table(lua_State *lua, int table_index, int *valid);
+
+static int add_attributes(lua_State *lua, int table_index, xmlNodePtr node) {
+  int attributes_index;
+  int valid = 1;
+
+  lua_getfield(lua, table_index, "attributes");
+  attributes_index = lua_gettop(lua);
+  if (lua_istable(lua, -1)) {
+    lua_pushnil(lua);
+    while (valid && lua_next(lua, -2) != 0) {
+      if (lua_type(lua, -2) != LUA_TSTRING ||
+          lua_type(lua, -1) != LUA_TSTRING ||
+          xmlNewProp(node, BAD_CAST lua_tostring(lua, -2),
+                     BAD_CAST lua_tostring(lua, -1)) == NULL) {
+        valid = 0;
+      }
+      lua_pop(lua, 1);
+    }
+  }
+  lua_settop(lua, attributes_index - 1);
+  return valid ? 0 : -1;
+}
+
+static int append_lua_child(lua_State *lua, xmlNodePtr parent,
+                            int child_index) {
+  xmlNodePtr child = NULL;
+  int valid = 1;
+
+  if (lua_type(lua, child_index) == LUA_TSTRING) {
+    child = xmlNewText(BAD_CAST lua_tostring(lua, child_index));
+  } else if (lua_istable(lua, child_index)) {
+    child = node_from_table(lua, child_index, &valid);
+  } else {
+    valid = 0;
+  }
+
+  if (!valid || child == NULL) {
+    xmlFreeNode(child);
+    return -1;
+  }
+  if (xmlAddChild(parent, child) == NULL) {
+    xmlFreeNode(child);
+    return -1;
+  }
+  return 0;
+}
+
+static int add_children(lua_State *lua, int table_index, xmlNodePtr node) {
+  size_t index;
+  size_t length;
+  int result = 0;
+
+  lua_getfield(lua, table_index, "children");
+  length = lua_istable(lua, -1) ? lua_objlen(lua, -1) : 0;
+
+  if (length > INT_MAX) {
+    lua_pop(lua, 1);
+    return -1;
+  }
+
+  for (index = 1; result == 0 && index <= length; ++index) {
+    lua_rawgeti(lua, -1, (int)index);
+    result = append_lua_child(lua, node, lua_gettop(lua));
+    lua_pop(lua, 1);
+  }
+  lua_pop(lua, 1);
+
+  if (result == 0 && length == 0) {
+    lua_getfield(lua, table_index, "text");
+    if (lua_type(lua, -1) == LUA_TSTRING) {
+      xmlNodePtr text = xmlNewText(BAD_CAST lua_tostring(lua, -1));
+
+      if (text == NULL || xmlAddChild(node, text) == NULL) {
+        xmlFreeNode(text);
+        result = -1;
+      }
+    }
+    lua_pop(lua, 1);
+  }
+  return result;
+}
+
+static xmlNodePtr special_node_from_table(lua_State *lua, int table_index,
+                                          const char *kind, int *valid) {
+  xmlNodePtr node;
+  const char *text;
+
+  lua_getfield(lua, table_index, "text");
+  text = lua_tostring(lua, -1);
+
+  if (strcmp(kind, "comment") == 0) {
+    node = xmlNewComment(BAD_CAST(text == NULL ? "" : text));
+  } else if (strcmp(kind, "processing_instruction") == 0) {
+    const char *target;
+
+    lua_getfield(lua, table_index, "target");
+    target = lua_tostring(lua, -1);
+    node = target == NULL || target[0] == '\0'
+               ? NULL
+               : xmlNewPI(BAD_CAST target, BAD_CAST(text == NULL ? "" : text));
+    lua_pop(lua, 1);
+  } else {
+    node = NULL;
+  }
+
+  lua_pop(lua, 1);
+  if (node == NULL) {
+    *valid = 0;
+  }
+  return node;
+}
+
+static xmlNodePtr node_from_table(lua_State *lua, int table_index, int *valid) {
+  const char *kind;
+  const char *tag;
+  xmlNodePtr node;
+
+  table_index = absolute_index(lua, table_index);
+  lua_getfield(lua, table_index, "kind");
+  kind = lua_tostring(lua, -1);
+  if (kind != NULL) {
+    node = special_node_from_table(lua, table_index, kind, valid);
+    lua_pop(lua, 1);
+    return node;
+  }
+  lua_pop(lua, 1);
+
+  lua_getfield(lua, table_index, "tag");
+  tag = lua_tostring(lua, -1);
+  node = tag == NULL || tag[0] == '\0' ? NULL : xmlNewNode(NULL, BAD_CAST tag);
+  lua_pop(lua, 1);
+
+  if (node == NULL || add_attributes(lua, table_index, node) != 0 ||
+      add_children(lua, table_index, node) != 0) {
+    xmlFreeNode(node);
+    *valid = 0;
+    return NULL;
+  }
+  return node;
+}
+
+xmlNodePtr dom_page_from_lua(lua_State *lua, int table_index) {
+  int valid = 1;
+  xmlNodePtr root = node_from_table(lua, table_index, &valid);
+
+  if (!valid) {
+    xmlFreeNode(root);
+    return NULL;
+  }
+  return root;
+}
diff --git a/src/Dom/Dom.h b/src/Dom/Dom.h
new file mode 100644
index 0000000..06bd1ff
--- /dev/null
+++ b/src/Dom/Dom.h
@@ -0,0 +1,10 @@
+#ifndef YAPSSG_DOM_H
+#define YAPSSG_DOM_H
+
+#include <libxml/tree.h>
+#include <lua.h>
+
+void dom_push_page(lua_State *lua, const xmlNode *root);
+xmlNodePtr dom_page_from_lua(lua_State *lua, int table_index);
+
+#endif
diff --git a/src/FileProcessor/FileProcessor.c b/src/FileProcessor/FileProcessor.c
new file mode 100644
index 0000000..d856fb4
--- /dev/null
+++ b/src/FileProcessor/FileProcessor.c
@@ -0,0 +1,396 @@
+#define _POSIX_C_SOURCE 200809L
+#define _XOPEN_SOURCE 700
+
+#include "FileProcessor/FileProcessor.h"
+
+#include "Logger/Logger.h"
+#include "LuaEngine/LuaEngine.h"
+#include "Path/Path.h"
+
+#include <dirent.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <libxml/HTMLparser.h>
+#include <libxml/HTMLtree.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <strings.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#define COPY_BUFFER_SIZE 16384
+
+static int has_html_extension(const char *path) {
+  const char *extension = strrchr(path, '.');
+
+  return extension != NULL && (strcasecmp(extension, ".html") == 0 ||
+                               strcasecmp(extension, ".htm") == 0);
+}
+
+static void report_copy_error(const char *input_path, const char *output_path,
+                              int error_number) {
+  logger_error("cannot copy %s to %s: %s", input_path, output_path,
+               strerror(error_number));
+}
+
+static int write_all(int file, const char *buffer, size_t length) {
+  size_t offset = 0;
+
+  while (offset < length) {
+    ssize_t written = write(file, buffer + offset, length - offset);
+
+    if (written > 0) {
+      offset += (size_t)written;
+    } else if (written == 0) {
+      errno = EIO;
+      return -1;
+    } else if (errno != EINTR) {
+      return -1;
+    }
+  }
+  return 0;
+}
+
+static int copy_file_data(int input, int output) {
+  char buffer[COPY_BUFFER_SIZE];
+
+  for (;;) {
+    ssize_t count = read(input, buffer, sizeof(buffer));
+
+    if (count > 0 && write_all(output, buffer, (size_t)count) != 0) {
+      return -1;
+    }
+    if (count == 0) {
+      return 0;
+    }
+    if (count < 0 && errno != EINTR) {
+      return -1;
+    }
+  }
+}
+
+static int copy_regular_file(const char *input_path, const char *output_path,
+                             mode_t mode) {
+  int input = open(input_path, O_RDONLY);
+  int output;
+  int result;
+  int error_number;
+
+  logger_debug("copying file %s -> %s", input_path, output_path);
+
+  if (input < 0) {
+    report_copy_error(input_path, output_path, errno);
+    return -1;
+  }
+
+  output = open(output_path, O_WRONLY | O_CREAT | O_TRUNC, mode & 0777);
+  if (output < 0) {
+    error_number = errno;
+    close(input);
+    report_copy_error(input_path, output_path, error_number);
+    return -1;
+  }
+
+  result = copy_file_data(input, output);
+  error_number = result == 0 ? 0 : errno;
+
+  if (close(output) != 0 && result == 0) {
+    result = -1;
+    error_number = errno;
+  }
+  if (close(input) != 0 && result == 0) {
+    result = -1;
+    error_number = errno;
+  }
+
+  if (result != 0) {
+    report_copy_error(input_path, output_path, error_number);
+  }
+  return result;
+}
+
+int process_file(const char *input_path, const char *output_path) {
+  const int parse_options = HTML_PARSE_RECOVER | HTML_PARSE_NONET |
+                            HTML_PARSE_NOERROR | HTML_PARSE_NOWARNING;
+  struct stat status;
+  htmlDocPtr document;
+  int saved;
+
+  if (stat(input_path, &status) != 0) {
+    logger_error("cannot inspect %s: %s", input_path, strerror(errno));
+    return -1;
+  }
+  if (!S_ISREG(status.st_mode)) {
+    logger_error("input is not a regular file: %s", input_path);
+    return -1;
+  }
+
+  logger_info("processing HTML %s -> %s", input_path, output_path);
+  document = htmlReadFile(input_path, NULL, parse_options);
+  if (document == NULL) {
+    logger_error("unable to parse HTML file: %s", input_path);
+    return -1;
+  }
+
+  if (process_html_document(document, input_path) != 0) {
+    xmlFreeDoc(document);
+    return -1;
+  }
+
+  saved = htmlSaveFileFormat(output_path, document, "UTF-8", 1);
+  xmlFreeDoc(document);
+  if (saved < 0) {
+    logger_error("unable to write HTML file: %s", output_path);
+    return -1;
+  }
+  return 0;
+}
+
+static int copy_symlink(const char *input_path, const char *output_path,
+                        const struct stat *status) {
+  size_t capacity = status->st_size > 0 ? (size_t)status->st_size + 1 : 256;
+  char *target = malloc(capacity + 1);
+  ssize_t length = -1;
+
+  logger_debug("copying symbolic link %s -> %s", input_path, output_path);
+
+  if (target == NULL) {
+    logger_error("unable to allocate symbolic-link buffer");
+    return -1;
+  }
+
+  while (length < 0) {
+    ssize_t read_length = readlink(input_path, target, capacity);
+
+    if (read_length < 0) {
+      logger_error("cannot read symbolic link %s: %s", input_path,
+                   strerror(errno));
+      free(target);
+      return -1;
+    }
+    if ((size_t)read_length < capacity) {
+      length = read_length;
+    } else {
+      size_t larger_capacity;
+      char *larger_target;
+
+      if (capacity > (SIZE_MAX - 1) / 2) {
+        logger_error("unable to allocate symbolic-link buffer");
+        free(target);
+        return -1;
+      }
+      larger_capacity = capacity * 2;
+      larger_target = realloc(target, larger_capacity + 1);
+      if (larger_target == NULL) {
+        logger_error("unable to allocate symbolic-link buffer");
+        free(target);
+        return -1;
+      }
+      target = larger_target;
+      capacity = larger_capacity;
+    }
+  }
+
+  target[length] = '\0';
+  if (symlink(target, output_path) != 0) {
+    logger_error("cannot copy symbolic link %s: %s", input_path,
+                 strerror(errno));
+    free(target);
+    return -1;
+  }
+
+  free(target);
+  return 0;
+}
+
+static int copy_tree(const char *input_path, const char *output_path) {
+  struct stat status;
+  DIR *directory;
+  int result = 0;
+
+  if (lstat(input_path, &status) != 0) {
+    logger_error("cannot inspect %s: %s", input_path, strerror(errno));
+    return -1;
+  }
+  if (S_ISLNK(status.st_mode)) {
+    return copy_symlink(input_path, output_path, &status);
+  }
+  if (S_ISREG(status.st_mode)) {
+    return has_html_extension(input_path)
+               ? process_file(input_path, output_path)
+               : copy_regular_file(input_path, output_path, status.st_mode);
+  }
+  if (!S_ISDIR(status.st_mode)) {
+    logger_error("unsupported file type: %s", input_path);
+    return -1;
+  }
+
+  if (mkdir(output_path, status.st_mode & 0777) != 0) {
+    logger_error("cannot create directory %s: %s", output_path,
+                 strerror(errno));
+    return -1;
+  }
+
+  directory = opendir(input_path);
+  if (directory == NULL) {
+    logger_error("cannot open directory %s: %s", input_path, strerror(errno));
+    return -1;
+  }
+
+  while (result == 0) {
+    struct dirent *entry;
+    char *input_child;
+    char *output_child;
+
+    errno = 0;
+    entry = readdir(directory);
+    if (entry == NULL) {
+      if (errno != 0) {
+        logger_error("cannot read directory %s: %s", input_path,
+                     strerror(errno));
+        result = -1;
+      }
+      break;
+    }
+    if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0) {
+      continue;
+    }
+
+    input_child = path_join(input_path, entry->d_name);
+    output_child = path_join(output_path, entry->d_name);
+    if (input_child == NULL || output_child == NULL) {
+      logger_error("unable to allocate child path");
+      result = -1;
+    } else {
+      result = copy_tree(input_child, output_child);
+    }
+    free(input_child);
+    free(output_child);
+  }
+
+  if (closedir(directory) != 0 && result == 0) {
+    logger_error("cannot close directory %s: %s", input_path, strerror(errno));
+    result = -1;
+  }
+  return result;
+}
+
+static int remove_tree(const char *path) {
+  struct stat status;
+  DIR *directory;
+  int result = 0;
+
+  if (lstat(path, &status) != 0) {
+    if (errno == ENOENT) {
+      return 0;
+    }
+    logger_error("cannot inspect output %s: %s", path, strerror(errno));
+    return -1;
+  }
+
+  if (!S_ISDIR(status.st_mode) || S_ISLNK(status.st_mode)) {
+    if (unlink(path) != 0) {
+      logger_error("cannot remove output %s: %s", path, strerror(errno));
+      return -1;
+    }
+    return 0;
+  }
+
+  directory = opendir(path);
+  if (directory == NULL) {
+    logger_error("cannot open output directory %s: %s", path, strerror(errno));
+    return -1;
+  }
+
+  while (result == 0) {
+    struct dirent *entry;
+    char *child;
+
+    errno = 0;
+    entry = readdir(directory);
+    if (entry == NULL) {
+      if (errno != 0) {
+        logger_error("cannot read output directory %s: %s", path,
+                     strerror(errno));
+        result = -1;
+      }
+      break;
+    }
+    if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0) {
+      continue;
+    }
+
+    child = path_join(path, entry->d_name);
+    if (child == NULL) {
+      logger_error("unable to allocate output child path");
+      result = -1;
+    } else {
+      result = remove_tree(child);
+    }
+    free(child);
+  }
+
+  if (closedir(directory) != 0 && result == 0) {
+    logger_error("cannot close output directory %s: %s", path, strerror(errno));
+    result = -1;
+  }
+  if (result == 0 && rmdir(path) != 0) {
+    logger_error("cannot remove output directory %s: %s", path,
+                 strerror(errno));
+    result = -1;
+  }
+  return result;
+}
+
+int process_directory(const char *input_path, const char *output_path,
+                      int overwrite_output) {
+  struct stat status;
+  struct stat output_status;
+  char *resolved_input;
+  char *resolved_output;
+  int result;
+
+  if (stat(input_path, &status) != 0) {
+    logger_error("cannot inspect %s: %s", input_path, strerror(errno));
+    return -1;
+  }
+  if (!S_ISDIR(status.st_mode)) {
+    logger_error("input is not a directory: %s", input_path);
+    return -1;
+  }
+
+  resolved_input = realpath(input_path, NULL);
+  if (lstat(output_path, &output_status) == 0 &&
+      !S_ISLNK(output_status.st_mode)) {
+    resolved_output = realpath(output_path, NULL);
+  } else {
+    resolved_output = path_resolve_new(output_path);
+  }
+  if (resolved_input == NULL || resolved_output == NULL) {
+    logger_error("cannot resolve input or output path");
+    free(resolved_input);
+    free(resolved_output);
+    return -1;
+  }
+
+  if (path_is_within(resolved_input, resolved_output)) {
+    logger_error("output directory cannot be inside input: %s", output_path);
+    result = -1;
+  } else if (overwrite_output &&
+             path_is_within(resolved_output, resolved_input)) {
+    logger_error("output directory cannot contain input: %s", output_path);
+    result = -1;
+  } else if (overwrite_output && remove_tree(output_path) != 0) {
+    result = -1;
+  } else {
+    logger_info("processing directory %s -> %s", input_path, output_path);
+    result = copy_tree(input_path, output_path);
+  }
+
+  free(resolved_input);
+  free(resolved_output);
+  return result;
+}
diff --git a/src/FileProcessor/FileProcessor.h b/src/FileProcessor/FileProcessor.h
new file mode 100644
index 0000000..90027d7
--- /dev/null
+++ b/src/FileProcessor/FileProcessor.h
@@ -0,0 +1,8 @@
+#ifndef YAPSSG_FILE_PROCESSOR_H
+#define YAPSSG_FILE_PROCESSOR_H
+
+int process_file(const char *input_path, const char *output_path);
+int process_directory(const char *input_path, const char *output_path,
+                      int overwrite_output);
+
+#endif
diff --git a/src/Logger/Logger.c b/src/Logger/Logger.c
new file mode 100644
index 0000000..c43b24b
--- /dev/null
+++ b/src/Logger/Logger.c
@@ -0,0 +1,102 @@
+#include "Logger/Logger.h"
+
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+
+static LogLevel current_level = LOG_LEVEL_INFO;
+
+static const char *level_name(LogLevel level) {
+  switch (level) {
+  case LOG_LEVEL_ERROR:
+    return "error";
+  case LOG_LEVEL_WARNING:
+    return "warning";
+  case LOG_LEVEL_INFO:
+    return "info";
+  case LOG_LEVEL_DEBUG:
+    return "debug";
+  case LOG_LEVEL_SILENT:
+    return "silent";
+  }
+  return "unknown";
+}
+
+int logger_is_enabled(LogLevel level) {
+  return current_level != LOG_LEVEL_SILENT && level <= current_level;
+}
+
+static void log_message(LogLevel level, const char *format, va_list arguments)
+    YAPSSG_FORMAT_PRINTF(2, 0);
+
+static void log_message(LogLevel level, const char *format, va_list arguments) {
+  if (!logger_is_enabled(level)) {
+    return;
+  }
+
+  fprintf(stderr, "yapssg: %s: ", level_name(level));
+  vfprintf(stderr, format, arguments);
+  fputc('\n', stderr);
+  fflush(stderr);
+}
+
+void logger_set_level(LogLevel level) { current_level = level; }
+
+LogLevel logger_get_level(void) { return current_level; }
+
+int logger_parse_level(const char *name, LogLevel *level) {
+  if (strcmp(name, "error") == 0) {
+    *level = LOG_LEVEL_ERROR;
+  } else if (strcmp(name, "warning") == 0 || strcmp(name, "warn") == 0) {
+    *level = LOG_LEVEL_WARNING;
+  } else if (strcmp(name, "info") == 0) {
+    *level = LOG_LEVEL_INFO;
+  } else if (strcmp(name, "debug") == 0) {
+    *level = LOG_LEVEL_DEBUG;
+  } else if (strcmp(name, "silent") == 0 || strcmp(name, "quiet") == 0) {
+    *level = LOG_LEVEL_SILENT;
+  } else {
+    return -1;
+  }
+  return 0;
+}
+
+void logger_log(LogLevel level, const char *format, ...) {
+  va_list arguments;
+
+  va_start(arguments, format);
+  log_message(level, format, arguments);
+  va_end(arguments);
+}
+
+void logger_error(const char *format, ...) {
+  va_list arguments;
+
+  va_start(arguments, format);
+  log_message(LOG_LEVEL_ERROR, format, arguments);
+  va_end(arguments);
+}
+
+void logger_warning(const char *format, ...) {
+  va_list arguments;
+
+  va_start(arguments, format);
+  log_message(LOG_LEVEL_WARNING, format, arguments);
+  va_end(arguments);
+}
+
+void logger_info(const char *format, ...) {
+  va_list arguments;
+
+  va_start(arguments, format);
+  log_message(LOG_LEVEL_INFO, format, arguments);
+  va_end(arguments);
+}
+
+void logger_debug(const char *format, ...) {
+  va_list arguments;
+
+  va_start(arguments, format);
+  log_message(LOG_LEVEL_DEBUG, format, arguments);
+  va_end(arguments);
+}
diff --git a/src/Logger/Logger.h b/src/Logger/Logger.h
new file mode 100644
index 0000000..f0bef12
--- /dev/null
+++ b/src/Logger/Logger.h
@@ -0,0 +1,31 @@
+#ifndef YAPSSG_LOGGER_H
+#define YAPSSG_LOGGER_H
+
+#if defined(__GNUC__) || defined(__clang__)
+#define YAPSSG_FORMAT_PRINTF(format_index, arguments_index)                    \
+  __attribute__((format(printf, format_index, arguments_index)))
+#else
+#define YAPSSG_FORMAT_PRINTF(format_index, arguments_index)
+#endif
+
+typedef enum {
+  LOG_LEVEL_SILENT = -1,
+  LOG_LEVEL_ERROR,
+  LOG_LEVEL_WARNING,
+  LOG_LEVEL_INFO,
+  LOG_LEVEL_DEBUG
+} LogLevel;
+
+void logger_set_level(LogLevel level);
+LogLevel logger_get_level(void);
+int logger_is_enabled(LogLevel level);
+int logger_parse_level(const char *name, LogLevel *level);
+
+void logger_log(LogLevel level, const char *format, ...)
+    YAPSSG_FORMAT_PRINTF(2, 3);
+void logger_error(const char *format, ...) YAPSSG_FORMAT_PRINTF(1, 2);
+void logger_warning(const char *format, ...) YAPSSG_FORMAT_PRINTF(1, 2);
+void logger_info(const char *format, ...) YAPSSG_FORMAT_PRINTF(1, 2);
+void logger_debug(const char *format, ...) YAPSSG_FORMAT_PRINTF(1, 2);
+
+#endif
diff --git a/src/Logger/LuaLogger.c b/src/Logger/LuaLogger.c
new file mode 100644
index 0000000..5739791
--- /dev/null
+++ b/src/Logger/LuaLogger.c
@@ -0,0 +1,60 @@
+#include "Logger/LuaLogger.h"
+
+#include "Logger/Logger.h"
+
+#include <lauxlib.h>
+#include <lua.h>
+
+static void add_value(lua_State *lua, luaL_Buffer *buffer, int index) {
+  int type = lua_type(lua, index);
+
+  if (type == LUA_TSTRING || type == LUA_TNUMBER) {
+    luaL_addstring(buffer, lua_tostring(lua, index));
+  } else if (type == LUA_TBOOLEAN) {
+    luaL_addstring(buffer, lua_toboolean(lua, index) ? "true" : "false");
+  } else if (type == LUA_TNIL) {
+    luaL_addstring(buffer, "nil");
+  } else {
+    luaL_addchar(buffer, '<');
+    luaL_addstring(buffer, lua_typename(lua, type));
+    luaL_addchar(buffer, '>');
+  }
+}
+
+static int log_from_lua(lua_State *lua) {
+  LogLevel level = (LogLevel)lua_tointeger(lua, lua_upvalueindex(1));
+  int argument_count = lua_gettop(lua);
+  int index;
+  luaL_Buffer buffer;
+
+  if (!logger_is_enabled(level)) {
+    return 0;
+  }
+
+  luaL_buffinit(lua, &buffer);
+  for (index = 1; index <= argument_count; ++index) {
+    if (index > 1) {
+      luaL_addchar(&buffer, '\t');
+    }
+    add_value(lua, &buffer, index);
+  }
+  luaL_pushresult(&buffer);
+  logger_log(level, "%s", lua_tostring(lua, -1));
+  lua_pop(lua, 1);
+  return 0;
+}
+
+static void set_log_function(lua_State *lua, const char *name, LogLevel level) {
+  lua_pushinteger(lua, (lua_Integer)level);
+  lua_pushcclosure(lua, log_from_lua, 1);
+  lua_setfield(lua, -2, name);
+}
+
+void lua_logger_register(lua_State *lua) {
+  lua_newtable(lua);
+  set_log_function(lua, "error", LOG_LEVEL_ERROR);
+  set_log_function(lua, "warn", LOG_LEVEL_WARNING);
+  set_log_function(lua, "info", LOG_LEVEL_INFO);
+  set_log_function(lua, "debug", LOG_LEVEL_DEBUG);
+  lua_setglobal(lua, "log");
+}
diff --git a/src/Logger/LuaLogger.h b/src/Logger/LuaLogger.h
new file mode 100644
index 0000000..98c9a8f
--- /dev/null
+++ b/src/Logger/LuaLogger.h
@@ -0,0 +1,8 @@
+#ifndef YAPSSG_LUA_LOGGER_H
+#define YAPSSG_LUA_LOGGER_H
+
+#include <lua.h>
+
+void lua_logger_register(lua_State *lua);
+
+#endif
diff --git a/src/LuaEngine/LuaEngine.c b/src/LuaEngine/LuaEngine.c
new file mode 100644
index 0000000..319f408
--- /dev/null
+++ b/src/LuaEngine/LuaEngine.c
@@ -0,0 +1,273 @@
+#include "LuaEngine/LuaEngine.h"
+
+#include "DirectoryWalker/DirectoryWalker.h"
+#include "Dom/Dom.h"
+#include "Logger/Logger.h"
+#include "Logger/LuaLogger.h"
+#include "Path/Path.h"
+#include "Version/Version.h"
+
+#include <lauxlib.h>
+#include <lua.h>
+#include <lualib.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <strings.h>
+
+typedef enum { SCRIPT_INLINE, SCRIPT_EXTERNAL } ScriptType;
+
+typedef struct {
+  char *source;
+  ScriptType type;
+  unsigned long line;
+} LuaScript;
+
+typedef struct {
+  LuaScript *items;
+  size_t length;
+  size_t capacity;
+} ScriptList;
+
+static int is_lua_element(const xmlNode *node) {
+  return node->type == XML_ELEMENT_NODE &&
+         strcasecmp((const char *)node->name, "lua") == 0;
+}
+
+static char *duplicate_string(const char *value) {
+  size_t length = strlen(value);
+  char *copy = malloc(length + 1);
+
+  if (copy != NULL) {
+    memcpy(copy, value, length + 1);
+  }
+  return copy;
+}
+
+static int grow_script_list(ScriptList *scripts) {
+  size_t larger_capacity;
+  LuaScript *larger_items;
+
+  if (scripts->capacity > SIZE_MAX / (2 * sizeof(*scripts->items))) {
+    return -1;
+  }
+
+  larger_capacity = scripts->capacity == 0 ? 4 : scripts->capacity * 2;
+  larger_items =
+      realloc(scripts->items, larger_capacity * sizeof(*scripts->items));
+  if (larger_items == NULL) {
+    return -1;
+  }
+
+  scripts->items = larger_items;
+  scripts->capacity = larger_capacity;
+  return 0;
+}
+
+static int append_script(ScriptList *scripts, const char *source,
+                         ScriptType type, unsigned long line) {
+  LuaScript *script;
+
+  if (scripts->length == scripts->capacity && grow_script_list(scripts) != 0) {
+    return -1;
+  }
+
+  script = &scripts->items[scripts->length];
+  script->source = duplicate_string(source);
+  if (script->source == NULL) {
+    return -1;
+  }
+
+  script->type = type;
+  script->line = line;
+  ++scripts->length;
+  return 0;
+}
+
+static int collect_script(xmlNode *node, ScriptList *scripts) {
+  xmlChar *source_path = xmlGetProp(node, BAD_CAST "src");
+  xmlChar *code;
+  int result;
+
+  if (source_path != NULL) {
+    result = append_script(scripts, (const char *)source_path, SCRIPT_EXTERNAL,
+                           node->line);
+    xmlFree(source_path);
+    return result;
+  }
+
+  code = xmlNodeGetContent(node);
+  result = append_script(scripts, code == NULL ? "" : (const char *)code,
+                         SCRIPT_INLINE, node->line);
+  xmlFree(code);
+  return result;
+}
+
+static int collect_scripts(xmlNode *node, ScriptList *scripts) {
+  for (; node != NULL; node = node->next) {
+    if (is_lua_element(node)) {
+      if (collect_script(node, scripts) != 0) {
+        return -1;
+      }
+    } else if (collect_scripts(node->children, scripts) != 0) {
+      return -1;
+    }
+  }
+  return 0;
+}
+
+static void free_scripts(ScriptList *scripts) {
+  size_t index;
+
+  for (index = 0; index < scripts->length; ++index) {
+    free(scripts->items[index].source);
+  }
+  free(scripts->items);
+}
+
+static char *make_chunk_name(const char *input_path, unsigned long line) {
+  size_t input_length = strlen(input_path);
+  size_t capacity;
+  char *chunk_name;
+
+  if (input_length > SIZE_MAX - 32) {
+    return NULL;
+  }
+  capacity = input_length + 32;
+  chunk_name = malloc(capacity);
+
+  if (chunk_name != NULL) {
+    snprintf(chunk_name, capacity, "@%s:%lu", input_path, line);
+  }
+  return chunk_name;
+}
+
+static int run_script(lua_State *lua, const LuaScript *script,
+                      const char *input_path) {
+  char *source_path = NULL;
+  char *chunk_name = NULL;
+  const char *display_path;
+  int load_result;
+  int result;
+
+  if (script->type == SCRIPT_EXTERNAL) {
+    source_path = path_resolve_from_file(input_path, script->source);
+    if (source_path == NULL) {
+      logger_error("unable to allocate Lua source path");
+      return -1;
+    }
+    display_path = source_path;
+    load_result = luaL_loadfile(lua, source_path);
+  } else {
+    chunk_name = make_chunk_name(input_path, script->line);
+    if (chunk_name == NULL) {
+      logger_error("unable to allocate Lua chunk name");
+      return -1;
+    }
+    display_path = input_path;
+    load_result = luaL_loadbuffer(lua, script->source, strlen(script->source),
+                                  chunk_name);
+  }
+
+  result = load_result == 0 ? lua_pcall(lua, 0, 0, 0) : load_result;
+  if (result != 0) {
+    const char *message = lua_tostring(lua, -1);
+
+    logger_error("Lua error in %s: %s", display_path,
+                 message == NULL ? "unknown error" : message);
+    lua_pop(lua, 1);
+  }
+
+  free(chunk_name);
+  free(source_path);
+  return result == 0 ? 0 : -1;
+}
+
+static int run_scripts(lua_State *lua, const ScriptList *scripts,
+                       const char *input_path) {
+  size_t index;
+
+  for (index = 0; index < scripts->length; ++index) {
+    if (run_script(lua, &scripts->items[index], input_path) != 0) {
+      return -1;
+    }
+  }
+  return 0;
+}
+
+static void register_yapssg(lua_State *lua) {
+  lua_newtable(lua);
+  lua_pushstring(lua, yapssg_version);
+  lua_setfield(lua, -2, "version");
+  lua_setglobal(lua, "yapssg");
+}
+
+static int replace_document_root(lua_State *lua, htmlDocPtr document,
+                                 const char *input_path) {
+  xmlNodePtr replacement;
+  xmlNodePtr old_root;
+
+  lua_getglobal(lua, "page");
+  if (!lua_istable(lua, -1)) {
+    logger_error("Lua global 'page' must remain a table: %s", input_path);
+    lua_pop(lua, 1);
+    return -1;
+  }
+
+  replacement = dom_page_from_lua(lua, lua_gettop(lua));
+  lua_pop(lua, 1);
+  if (replacement == NULL || replacement->type != XML_ELEMENT_NODE) {
+    logger_error("Lua produced an invalid page root: %s", input_path);
+    xmlFreeNode(replacement);
+    return -1;
+  }
+
+  old_root = xmlDocSetRootElement(document, replacement);
+  xmlFreeNode(old_root);
+  return 0;
+}
+
+int process_html_document(htmlDocPtr document, const char *input_path) {
+  xmlNodePtr root = xmlDocGetRootElement(document);
+  ScriptList scripts = {0};
+  lua_State *lua;
+  int result;
+
+  if (root == NULL) {
+    logger_error("HTML document has no root element: %s", input_path);
+    return -1;
+  }
+  if (collect_scripts(root, &scripts) != 0) {
+    logger_error("unable to collect Lua scripts: %s", input_path);
+    free_scripts(&scripts);
+    return -1;
+  }
+  if (scripts.length == 0) {
+    free_scripts(&scripts);
+    return 0;
+  }
+
+  lua = luaL_newstate();
+  if (lua == NULL) {
+    logger_error("unable to create Lua state");
+    free_scripts(&scripts);
+    return -1;
+  }
+
+  luaL_openlibs(lua);
+  register_yapssg(lua);
+  lua_logger_register(lua);
+  directory_walker_register(lua, input_path);
+  dom_push_page(lua, root);
+  lua_setglobal(lua, "page");
+
+  result = run_scripts(lua, &scripts, input_path);
+  if (result == 0) {
+    result = replace_document_root(lua, document, input_path);
+  }
+
+  lua_close(lua);
+  free_scripts(&scripts);
+  return result;
+}
diff --git a/src/LuaEngine/LuaEngine.h b/src/LuaEngine/LuaEngine.h
new file mode 100644
index 0000000..bd035b9
--- /dev/null
+++ b/src/LuaEngine/LuaEngine.h
@@ -0,0 +1,8 @@
+#ifndef YAPSSG_LUA_ENGINE_H
+#define YAPSSG_LUA_ENGINE_H
+
+#include <libxml/HTMLparser.h>
+
+int process_html_document(htmlDocPtr document, const char *input_path);
+
+#endif
diff --git a/src/Main.c b/src/Main.c
new file mode 100644
index 0000000..b7c77f1
--- /dev/null
+++ b/src/Main.c
@@ -0,0 +1,52 @@
+#include "Cli/Cli.h"
+#include "FileProcessor/FileProcessor.h"
+#include "Logger/Logger.h"
+#include "Path/Path.h"
+
+#include <libxml/parser.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+static int run(int argc, char **argv) {
+  CliOptions options;
+  CliParseResult parse_result;
+  char *automatic_output = NULL;
+  const char *output_path;
+  int result;
+
+  parse_result = cli_parse(argc, argv, &options);
+  if (parse_result != CLI_PARSE_OK) {
+    return parse_result == CLI_PARSE_ERROR ? EXIT_FAILURE : EXIT_SUCCESS;
+  }
+
+  logger_set_level(options.log_level);
+
+  output_path = options.output_path;
+  if (output_path == NULL) {
+    automatic_output = path_make_default_output(options.input_path);
+    if (automatic_output == NULL) {
+      logger_error("unable to allocate output path");
+      return EXIT_FAILURE;
+    }
+    output_path = automatic_output;
+  }
+
+  if (options.input_type == INPUT_TYPE_DIRECTORY) {
+    result = process_directory(options.input_path, output_path,
+                               options.overwrite_output);
+  } else {
+    result = process_file(options.input_path, output_path);
+  }
+
+  free(automatic_output);
+  return result == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
+}
+
+int main(int argc, char **argv) {
+  int result;
+
+  xmlInitParser();
+  result = run(argc, argv);
+  xmlCleanupParser();
+  return result;
+}
diff --git a/src/Path/Path.c b/src/Path/Path.c
new file mode 100644
index 0000000..8a0ab2b
--- /dev/null
+++ b/src/Path/Path.c
@@ -0,0 +1,185 @@
+#define _POSIX_C_SOURCE 200809L
+#define _XOPEN_SOURCE 700
+
+#include "Path/Path.h"
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+static const char output_prefix[] = "yapssg_";
+
+static int checked_add(size_t left, size_t right, size_t *sum) {
+  if (left > SIZE_MAX - right) {
+    return -1;
+  }
+  *sum = left + right;
+  return 0;
+}
+
+static char *duplicate_string(const char *value) {
+  size_t length = strlen(value);
+  char *copy = malloc(length + 1);
+
+  if (copy != NULL) {
+    memcpy(copy, value, length + 1);
+  }
+  return copy;
+}
+
+char *path_join(const char *left, const char *right) {
+  size_t left_length = strlen(left);
+  size_t right_length = strlen(right);
+  int needs_separator = left_length > 0 && left[left_length - 1] != '/';
+  size_t path_length;
+  size_t allocation_size;
+  char *path;
+
+  if (checked_add(left_length, (size_t)needs_separator, &path_length) != 0 ||
+      checked_add(path_length, right_length, &path_length) != 0 ||
+      checked_add(path_length, 1, &allocation_size) != 0) {
+    return NULL;
+  }
+
+  path = malloc(allocation_size);
+  if (path == NULL) {
+    return NULL;
+  }
+  memcpy(path, left, left_length);
+  if (needs_separator) {
+    path[left_length++] = '/';
+  }
+  memcpy(path + left_length, right, right_length + 1);
+  return path;
+}
+
+char *path_make_default_output(const char *input_path) {
+  const char *end = input_path + strlen(input_path);
+  const char *base;
+  size_t parent_length;
+  size_t base_length;
+  size_t prefix_length = sizeof(output_prefix) - 1;
+  size_t output_length;
+  size_t allocation_size;
+  char *output_path;
+
+  while (end > input_path + 1 && end[-1] == '/') {
+    --end;
+  }
+  base = end;
+  while (base > input_path && base[-1] != '/') {
+    --base;
+  }
+
+  parent_length = (size_t)(base - input_path);
+  base_length = (size_t)(end - base);
+  if (base_length == 0) {
+    return NULL;
+  }
+
+  if (checked_add(parent_length, prefix_length, &output_length) != 0 ||
+      checked_add(output_length, base_length, &output_length) != 0 ||
+      checked_add(output_length, 1, &allocation_size) != 0) {
+    return NULL;
+  }
+
+  output_path = malloc(allocation_size);
+  if (output_path == NULL) {
+    return NULL;
+  }
+  memcpy(output_path, input_path, parent_length);
+  memcpy(output_path + parent_length, output_prefix, prefix_length);
+  memcpy(output_path + parent_length + prefix_length, base, base_length);
+  output_path[parent_length + prefix_length + base_length] = '\0';
+  return output_path;
+}
+
+char *path_resolve_new(const char *path) {
+  char *path_copy = duplicate_string(path);
+  char *slash;
+  char *parent;
+  char *resolved_parent;
+  char *resolved_path;
+  const char *base;
+  size_t length;
+
+  if (path_copy == NULL) {
+    return NULL;
+  }
+
+  length = strlen(path_copy);
+  while (length > 1 && path_copy[length - 1] == '/') {
+    path_copy[--length] = '\0';
+  }
+
+  slash = strrchr(path_copy, '/');
+  if (slash == NULL) {
+    parent = duplicate_string(".");
+    base = path_copy;
+  } else if (slash == path_copy) {
+    parent = duplicate_string("/");
+    base = slash + 1;
+  } else {
+    *slash = '\0';
+    parent = duplicate_string(path_copy);
+    base = slash + 1;
+  }
+
+  if (parent == NULL || base[0] == '\0') {
+    free(parent);
+    free(path_copy);
+    return NULL;
+  }
+
+  resolved_parent = realpath(parent, NULL);
+  free(parent);
+  if (resolved_parent == NULL) {
+    free(path_copy);
+    return NULL;
+  }
+
+  resolved_path = path_join(resolved_parent, base);
+  free(resolved_parent);
+  free(path_copy);
+  return resolved_path;
+}
+
+char *path_resolve_from_file(const char *file_path, const char *relative_path) {
+  const char *slash;
+  size_t directory_length;
+  size_t relative_length;
+  size_t path_length;
+  size_t allocation_size;
+  char *path;
+
+  if (relative_path[0] == '/') {
+    return duplicate_string(relative_path);
+  }
+
+  slash = strrchr(file_path, '/');
+  directory_length = slash == NULL ? 0 : (size_t)(slash - file_path + 1);
+  relative_length = strlen(relative_path);
+  if (checked_add(directory_length, relative_length, &path_length) != 0 ||
+      checked_add(path_length, 1, &allocation_size) != 0) {
+    return NULL;
+  }
+
+  path = malloc(allocation_size);
+  if (path == NULL) {
+    return NULL;
+  }
+
+  memcpy(path, file_path, directory_length);
+  memcpy(path + directory_length, relative_path, relative_length + 1);
+  return path;
+}
+
+int path_is_within(const char *parent, const char *candidate) {
+  size_t parent_length = strlen(parent);
+
+  if (parent_length == 1 && parent[0] == '/') {
+    return candidate[0] == '/';
+  }
+  return strncmp(parent, candidate, parent_length) == 0 &&
+         (candidate[parent_length] == '\0' || candidate[parent_length] == '/');
+}
diff --git a/src/Path/Path.h b/src/Path/Path.h
new file mode 100644
index 0000000..a4ac530
--- /dev/null
+++ b/src/Path/Path.h
@@ -0,0 +1,10 @@
+#ifndef YAPSSG_PATH_H
+#define YAPSSG_PATH_H
+
+char *path_join(const char *left, const char *right);
+char *path_make_default_output(const char *input_path);
+char *path_resolve_new(const char *path);
+char *path_resolve_from_file(const char *file_path, const char *relative_path);
+int path_is_within(const char *parent, const char *candidate);
+
+#endif
diff --git a/src/Version/Version.c b/src/Version/Version.c
new file mode 100644
index 0000000..4f4a1ea
--- /dev/null
+++ b/src/Version/Version.c
@@ -0,0 +1,3 @@
+#include "Version/Version.h"
+
+const char yapssg_version[] = "0.1.0";
diff --git a/src/Version/Version.h b/src/Version/Version.h
new file mode 100644
index 0000000..f17b243
--- /dev/null
+++ b/src/Version/Version.h
@@ -0,0 +1,6 @@
+#ifndef YAPSSG_VERSION_H
+#define YAPSSG_VERSION_H
+
+extern const char yapssg_version[];
+
+#endif