initial commit

build.sh

@@ -0,0 +1,8 @@
+#!/bin/sh
+
+# works on my system and is a reference for yours
+
+zig 0.15.1 cc -std=c99 -pedantic -Wall -Wextra -Os fmj.c -o fmj
+# this is anyzig, which will run an arbitrary version of the zig compiler, downloading it if necessary.
+# zig ships many versions of libc and wraps clang, so its convenient for me
+# tl;dr you can replace `zig 0.15.1 cc` with something like `clang` or `gcc` or `cc`

fmj.c

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+#include <stdint.h>
+#include <stdbool.h>
+#include <string.h>
+#include <stdio.h>
+#include <ctype.h>
+#include <stdlib.h>
+#include <errno.h>
+
+#include <dirent.h>
+
+
+#define LINE_MAX UINT16_MAX
+
+// appended to the input directory to get the path to the feed's config
+const char* fmjconfp = ".fmjconf";
+
+const char* fmj_extension = ".fmj";
+
+// .fmjconf and .fmj option names
+const char* description = "description";
+const char* title = "title";
+const char* link = "link";
+const char* default_author = "default_author";
+const char* author = "author";
+const char* category = "category";
+const char* comments = "comments";
+const char* pub_date = "pub_date";
+
+// global for the default_author from the .fmjconf
+char* default_author_name = NULL;
+
+void print_usage(void) {
+  puts("usage:\nfmj dir [output file]");
+}
+
+// caller must free returned ptr
+char* join_path(const char* a, const char* b) {
+  char* buf = malloc(strlen(a) + strlen(b) + 2);
+  strcpy(buf, a);
+  strncat(buf, "/", 2);
+  strncat(buf, b, strlen(b) + 1);
+  return buf;
+}
+
+// parses an option from `line` that is formatted like this:
+// "title = contents"
+//
+// it will ignore the whitespace around the "=",
+// and return a pointer to the beginning of "contents",
+// or  return NULL if it didn't match.
+const char* parse_option(const char* line, const char* option) {
+  size_t optlen = strlen(option);
+  // if it doesn't have an "=" and then at least one
+  // char of content then its not valid
+  if (strlen(line) < optlen + 2) {
+    return NULL;
+  }
+
+  if (strncmp(line, option, optlen) != 0) {
+    return NULL;
+  }
+
+  const char* cur = line + optlen;
+
+  bool foundequals = false;
+
+  while (true) {
+    if (isblank(*cur)) {
+      cur++;
+      continue;
+    }
+    if (!foundequals && *cur == '=') {
+      foundequals = true;
+      cur++;
+      continue;
+    }
+    // empty option is invalid
+    if (foundequals && *cur != '\n') {
+      break;
+    }
+    // at this point any valid cases have been exhausted
+    return NULL;
+  }
+
+  return cur;
+}
+
+void write_without_newline(const char* content, FILE* output) {
+  while (*content != '\0' && *content != '\n') {
+    fputc(*content, output);
+    content++;
+  }
+}
+/* broken old version with out of bounds read because of `||` xd
+
+  void write_without_newline(FILE* output, const char* content) {
+  while (*content != '\0' || *content != '\n') {
+    fputc(*content, output);
+    content++;
+  }
+}*/
+
+
+void write_feed_header(FILE* output, FILE* fmjconf) {
+  fputs("<?xml version=\"1.0\" encoding=\"UTF-8\" ?><rss version=\"2.0\"><channel>", output);
+
+  bool found_title = false;
+  bool found_link = false;
+  bool found_description = false;
+  bool found_default_author = false;
+
+  char buf[LINE_MAX];
+  if (fmjconf != NULL) {
+    while (fgets(buf, LINE_MAX, fmjconf) != NULL) {
+      const char* opt;
+      if ((opt = parse_option(buf, title)) != NULL && !found_title) {
+        fputs("<title>", output);
+        write_without_newline(opt, output);
+        fputs("</title>", output);
+        found_title = true;
+        continue;
+      }
+      if ((opt = parse_option(buf, link)) != NULL && !found_link) {
+        fputs("<link>", output);
+        write_without_newline(opt, output);
+        fputs("</link>", output);
+        found_link = true;
+        continue;
+      }
+      if ((opt = parse_option(buf, description)) != NULL && !found_description) {
+        fputs("<description>", output);
+        write_without_newline(opt, output);
+        fputs("</description>", output);
+        found_description = true;
+        continue;
+      }
+      if ((opt = parse_option(buf, default_author)) != NULL && !found_default_author) {
+        default_author_name = malloc(strlen(opt) + 1);
+        strcpy(default_author_name, opt);
+        found_default_author = true;
+        continue;
+      }
+    }
+  }
+
+  if (!found_title) {
+    fputs("<title>fmj generated feed</title>", output);
+  }
+
+  if (!found_link) {
+    fputs("<link>http://example.com/</link>", output);
+  }
+
+  if (!found_description) {
+    fputs("<description>an rss feed generated by fmj</description>", output);
+  }
+
+  fputs("<generator>fmj</generator>", output);
+}
+
+void write_feed_item(FILE* output, const char* dir, const char* entryname) {
+  if (dir == NULL || entryname == NULL) {
+    return;
+  }
+
+  // only consider .fmj files
+  size_t namelen = strlen(entryname);
+  size_t extlen = strlen(fmj_extension);
+  if (namelen < extlen) {
+    return;
+  }
+  if (strncmp(entryname + namelen - extlen, fmj_extension, extlen) != 0) {
+    return;
+  }
+
+  char* path = join_path(dir, entryname);
+  FILE* file = fopen(path, "r");
+  if (file == NULL) {
+    free(path);
+    return;
+  }
+
+  char buf[LINE_MAX];
+
+  // make sure it has either a title or description
+  bool has_requirements = false;
+  while (fgets(buf, LINE_MAX, file) != NULL) {
+    if (parse_option(buf, title) || parse_option(buf, description)) {
+      has_requirements = true;
+      break;
+    }
+  }
+  if (!has_requirements) {
+    return;
+  }
+  rewind(file);
+
+  bool found_title = false;
+  bool found_description = false;
+  bool found_link = false;
+  bool found_pub_date = false;
+  bool found_author = false;
+
+  fputs("<item>", output);
+
+  while (fgets(buf, LINE_MAX, file) != NULL) {
+    const char* opt;
+    if ((opt = parse_option(buf, title)) != NULL && !found_title) {
+      fputs("<title>", output);
+      write_without_newline(opt, output);
+      fputs("</title>", output);
+    }
+    if ((opt = parse_option(buf, link)) != NULL && !found_link) {
+      fputs("<link>", output);
+      write_without_newline(opt, output);
+      fputs("</link>", output);
+    }
+    if ((opt = parse_option(buf, description)) != NULL && !found_description) {
+      fputs("<description>", output);
+      write_without_newline(opt, output);
+      fputs("</description>", output);
+    }
+    if ((opt = parse_option(buf, author)) != NULL && !found_author) {
+      fputs("<author>", output);
+      write_without_newline(opt, output);
+      fputs("</author>", output);
+    }
+    if ((opt = parse_option(buf, pub_date)) != NULL && !found_pub_date) {
+      fputs("<pubDate>", output);
+      write_without_newline(opt, output);
+      fputs("</pubDate>", output);
+    }
+    if ((opt = parse_option(buf, category)) != NULL) {
+      fputs("<category>", output);
+      write_without_newline(opt, output);
+      fputs("</category>", output);
+    }
+  }
+
+  if (!found_author && default_author_name != NULL) {
+    fputs("<author>", output);
+    write_without_newline(default_author_name, output);
+    fputs("</author>", output);
+  }
+
+  fputs("</item>", output);
+
+  free(path);
+}
+
+void write_feed_footer(FILE* output) {
+  fputs("</channel></rss>", output);
+}
+
+
+int main(int argc, char** argv) {
+  if (argc < 2) {
+    print_usage();
+    return 1;
+  }
+
+
+  DIR* dir = opendir(argv[1]);
+  if (dir == NULL) {
+    puts("failed to open the input directory!!!");
+    return 1;
+  }
+
+
+  char* outfilepath = "rss.xml";
+
+  if (argc >= 3) {
+    outfilepath = argv[2];
+  }
+
+  FILE* output;
+
+  if (*outfilepath == '-') {
+    output = stdout;
+  } else {
+    output = fopen(outfilepath, "w");
+    if (output == NULL) {
+      puts("failed to open output file!!!!");
+      return 1;
+    }
+  }
+
+
+  char* fmjconfpath = join_path(argv[1], fmjconfp);
+
+  FILE* fmjconf = fopen(fmjconfpath, "r");
+
+  write_feed_header(output, fmjconf);
+
+  if (fmjconf != NULL) {
+    fclose(fmjconf);
+  }
+
+  free(fmjconfpath);
+
+
+  struct dirent* entry;
+
+  while (true) {
+    errno = 0;
+    entry = readdir(dir);
+    if (entry != NULL) {
+      write_feed_item(output, argv[1], entry->d_name);
+    } else {
+      if (errno == 0) {
+        closedir(dir);
+        break;
+      }
+      // i am going to assume getting here is bad and exit
+      puts("assertion failed, readdir errored.");
+      return 1;
+    }
+  }
+
+
+  write_feed_footer(output);
+
+
+  if (output != stdout) {
+    fclose(output);
+  }
+}

readme.md

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+# fmj
+fmj is an rss feed generator. it takes a directory of config files that describe the posts and outputs xml.
+
+the file format is more concise than handwriting xml:
+```fmj
+title = s/discord/???
+description = on replacing discord
+link = https://bear.o7moon.dev/sdiscord/
+
+anything that isnt one of the defined options is a comment
+```
+
+it does not yet properly handle utf-8 input but should eventually.
+## usage examples:
+- `fmj tests/examples -` will output to stdout
+- `fmj tests/noconf filename.xml` will output to `filename.xml`
+- `fmj tests/defaultauthor` will output to `rss.xml`
+## building / platform support:
+`fmj.c` is the only source file. if you have libc, and a `dirent.h` on your system then it should work.
+
+`build.sh` is what i use on my desktop to compile it, as an example.
+## miscellaneous:
+the name fmj comes from [my favorite band](https://feedmejack.bandcamp.com/), but i will lie and say its stands for "Feed m Jenerator" or something.

tests/defaultauthor/.fmjconf

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+title = default author test case
+description = contains a post with an author option and one without, to test the default author option from the .fmjconf file
+default_author = alice

tests/defaultauthor/alices_post.fmj

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+title = alice's post
+description = this post implicitly has alice as the author due to the .fmjconf

tests/defaultauthor/bobs_post.fmj

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+title = bob's post
+author = bob
+description = bob wrote this post.

tests/example/.fmjconf

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+title = example rss feed !!!!!!!!!
+description = this is an example generated by fmj as a test case

tests/example/test1.fmj

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+title = TEST TITLE !!!!!!
+
+this is a comment

tests/noconf/test1.fmj

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+title = this is a test where the config file doesnt exist