Initial commit: plan, Makefile and skeleton code in place.

Makefile

@@ -0,0 +1,14 @@
+CC=gcc
+FLAGS=-Wall -pedantic -g
+
+all: tigger
+
+clean:
+	rm -f tigger
+	rm -f *.o
+
+tigger: tigger.o
+	${CC} -o tigger ${FLAGS} tigger.o
+
+tigger.o: tigger.c
+	${CC} -o tigger.o ${FLAGS} -c tigger.c

plan

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+What should be trivial:
+    * Finding tags for a given file.
+    * Finding files for a given tag.
+    * Adding a tag to a given file.
+    * Removing a tag from a given file.
+
+What should be possible but unimportant:
+    * Finding files for a combination of tags.
+    * Giving tags descriptions.
+    * Marking tags as related.
+
+Structure:
+    .tigger dir in any tagged folder.
+    'tags' dir in there, with each file in it being named for one tag
+      - maybe also split into subdirs by first two chars of tag, so as to
+      avoid having many files all in a single dir
+    each tag file begins with a description, then a blank line, then one filename per line
+    'index' file also in .tigger, alternates between filename lines and taglist lines
+    'tags' used for quickly listing files by tag, 'index' used for quickly listing tags by file
+    'index' automatically regenerated after any command that modifies a tags file
+
+Commands:
+    tigger reindex            // force a reindex
+    tigger tag $file $tag [$tag ..]
+    tigger untag $file $tag [$tag ..]
+    tigger files $tag
+    tigger tags $file
+    tigger mv $file $newfile  // does an mv, and preserves tags
+    tigger cp $file $newfile  // does a cp, and duplicates tags
+    tigger rm $file           // does an rm, and removes tags
+
+Pseudocode:
+    reindex:
+        if index is nonexistent, create it, and set new_index=true
+        for each tagfile in tags:
+            if last modified date is more recent than index's l.m.d, or new_index==true, add $tag to the hashmap for each filename it contains, creating a new entry for file if needed
+        iterate over the hashmap, dumping out in the index format specified above
+
+    tag $file $tag [$tag ..]:
+        if $file is not in current directory, move to $file's directory
+        for each $tag:
+            check existence of tags file for $tag, create if nonexistent
+            append $file name to it
+        do reindex
+
+    untag $file $tag [$tag ..]:
+        if $file is not in current directory, move to $file's directory
+        for each $tag:
+            check existence of tags file for $tag, skip $tag if nonexistent
+            remove $file name from it
+        do reindex
+
+    files $tag:
+        start with a list
+        walk the tree from here, gathering a list of all subdirs plus .
+        iterating over the dir list, for each dir:
+            if $tag is in tags for dir, add files to the list, with path relative to starting dir
+        dump the list to STDOUT, one file per line
+
+    tags $file:
+        if $file is not in current directory, move to $file's directory
+        do reindex
+        search index for $file, print out its taglist if found, otherwise "untagged"
+
+    mv, cp, rm:
+        mimic OS behavior for these, modifying tags afterwards as needed
+        do reindex

tigger.c

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+#include <string.h>
+#include <stdio.h>
+
+#define CMD_TAG 0x01
+#define CMD_UNTAG 0x02
+#define CMD_FILES 0x04
+#define CMD_TAGS 0x08
+#define CMD_MV 0x10
+#define CMD_CP 0x20
+#define CMD_RM 0x40
+#define CMD_ALL 0x7f
+
+void print_usage (char*, int);
+
+
+int main (int argc, char* argv []) {
+    if (argc == 1) {
+        print_usage(argv[0], CMD_ALL);
+        return 0;
+    }
+
+    if (!strcmp("tag", argv[1])) {
+        if (argc < 4) {
+            printf("tag: too few arguments\n\n");
+            print_usage(argv[0], CMD_TAG);
+            return 1;
+        }
+        printf("tag()\n");
+    } else if (!strcmp("untag", argv[1])) {
+        if (argc < 4) {
+            printf("untag: too few arguments\n\n");
+            print_usage(argv[0], CMD_UNTAG);
+            return 1;
+        }
+        printf("untag()\n");
+    } else if (!strcmp("files", argv[1])) {
+        if (argc != 3) {
+            printf("files: wrong number of arguments\n\n");
+            print_usage(argv[0], CMD_FILES);
+            return 1;
+        }
+        printf("files()\n");
+    } else if (!strcmp("tags", argv[1])) {
+        if (argc != 3) {
+            printf("tags: wrong number of arguments\n\n");
+            print_usage(argv[0], CMD_TAGS);
+            return 1;
+        }
+        printf("tags()\n");
+    } else if (!strcmp("mv", argv[1])) {
+        if (argc < 4) {
+            printf("mv: too few arguments\n\n");
+            print_usage(argv[0], CMD_MV);
+            return 1;
+        }
+        printf("mv()\n");
+    } else if (!strcmp("cp", argv[1])) {
+        if (argc < 4) {
+            printf("cp: too few arguments\n\n");
+            print_usage(argv[0], CMD_CP);
+            return 1;
+        }
+        printf("cp()\n");
+    } else if (!strcmp("rm", argv[1])) {
+        if (argc < 3) {
+            printf("rm: too few arguments\n\n");
+            print_usage(argv[0], CMD_RM);
+            return 1;
+        }
+        printf("rm()\n");
+    } else {
+        printf("%s: unrecognized command\n\n", argv[1]);
+        print_usage(argv[0], CMD_ALL);
+        return 1;
+    }
+
+    return 0;
+}
+
+void print_usage (char* cmd_name, int cmds_mask) {
+    if (cmds_mask == CMD_ALL) {
+        printf("Usage: %s [COMMAND [OPTIONS]]\n\n", cmd_name);
+
+        printf("Commands:");
+    } else {
+        printf("Usage:");
+    }
+
+    if (cmds_mask & CMD_TAG) {
+        printf("\n\ttag FILE TAG [TAG ..]\n");
+        printf("\t\tAdds all TAGs to FILE's tag list.\n");
+    }
+
+    if (cmds_mask & CMD_UNTAG) {
+        printf("\n\tuntag FILE TAG [TAG ..]\n");
+        printf("\t\tRemoves all TAGs from FILE's tag list.\n");
+    }
+
+    if (cmds_mask & CMD_FILES) {
+        printf("\n\tfiles TAG\n");
+        printf("\t\tLists all files with tag TAG.\n");
+    }
+
+    if (cmds_mask & CMD_TAGS) {
+        printf("\n\ttags FILE\n");
+        printf("\t\tLists all of FILE's tags.\n");
+    }
+
+    if (cmds_mask & CMD_MV) {
+        printf("\n\tmv FILE [FILE ..] TARGET\n");
+        printf("\t\tMove one or more FILEs to TARGET, renaming if only one FILE is given and TARGET is not a directory. Update tag lists to reflect the change(s).\n");
+    }
+
+    if (cmds_mask & CMD_CP) {
+        printf("\n\tcp FILE [FILE ..] TARGET\n");
+        printf("\t\tCopy one or more FILEs to TARGET, copying to a new filename if only one FILE is given and TARGET is not a directory. Update tag lists to reflect the change(s).\n");
+    }
+
+    if (cmds_mask & CMD_RM) {
+        printf("\n\trm FILE [FILE ..]\n");
+        printf("\t\tRemove all FILEs. Update tag lists to reflect the change(s).\n");
+    }
+}