examples/describe.c

   1 /*
   2  * libgit2 "describe" example - shows how to describe commits
   3  *
   4  * Written by the libgit2 contributors
   5  *
   6  * To the extent possible under law, the author(s) have dedicated all copyright
   7  * and related and neighboring rights to this software to the public domain
   8  * worldwide. This software is distributed without any warranty.
   9  *
  10  * You should have received a copy of the CC0 Public Domain Dedication along
  11  * with this software. If not, see
  12  * <http://creativecommons.org/publicdomain/zero/1.0/>.
  13  */
  14
  15 #include "common.h"
  16
  17 /**
  18  * The following example partially reimplements the `git describe` command
  19  * and some of its options.
  20  *
  21  * These commands should work:
  22
  23  * - Describe HEAD with default options (`describe`)
  24  * - Describe specified revision (`describe master~2`)
  25  * - Describe specified revisions (`describe master~2 HEAD~3`)
  26  * - Describe HEAD with dirty state suffix (`describe --dirty=*`)
  27  * - Describe consider all refs (`describe --all master`)
  28  * - Describe consider lightweight tags (`describe --tags temp-tag`)
  29  * - Describe show non-default abbreviated size (`describe --abbrev=10`)
  30  * - Describe always output the long format if matches a tag (`describe --long v1.0`)
  31  * - Describe consider only tags of specified pattern (`describe --match v*-release`)
  32  * - Describe show the fallback result (`describe --always`)
  33  * - Describe follow only the first parent commit (`describe --first-parent`)
  34  *
  35  * The command line parsing logic is simplified and doesn't handle
  36  * all of the use cases.
  37  */
  38
  39 /** describe_options represents the parsed command line options */
  40 struct describe_options {
  41         const char **commits;
  42         size_t commit_count;
  43         git_describe_options describe_options;
  44         git_describe_format_options format_options;
  45 };
  46
  47 static void opts_add_commit(struct describe_options *opts, const char *commit)
  48 {
  49         size_t sz;
  50
  51         assert(opts != NULL);
  52
  53         sz = ++opts->commit_count * sizeof(opts->commits[0]);
  54         opts->commits = xrealloc((void *) opts->commits, sz);
  55         opts->commits[opts->commit_count - 1] = commit;
  56 }
  57
  58 static void do_describe_single(git_repository *repo, struct describe_options *opts, const char *rev)
  59 {
  60         git_object *commit;
  61         git_describe_result *describe_result;
  62         git_buf buf = { 0 };
  63
  64         if (rev) {
  65                 check_lg2(git_revparse_single(&commit, repo, rev),
  66                         "Failed to lookup rev", rev);
  67
  68                 check_lg2(git_describe_commit(&describe_result, commit, &opts->describe_options),
  69                         "Failed to describe rev", rev);
  70         }
  71         else
  72                 check_lg2(git_describe_workdir(&describe_result, repo, &opts->describe_options),
  73                         "Failed to describe workdir", NULL);
  74
  75         check_lg2(git_describe_format(&buf, describe_result, &opts->format_options),
  76                         "Failed to format describe rev", rev);
  77
  78         printf("%s\n", buf.ptr);
  79 }
  80
  81 static void do_describe(git_repository *repo, struct describe_options *opts)
  82 {
  83         if (opts->commit_count == 0)
  84                 do_describe_single(repo, opts, NULL);
  85         else
  86         {
  87                 size_t i;
  88                 for (i = 0; i < opts->commit_count; i++)
  89                         do_describe_single(repo, opts, opts->commits[i]);
  90         }
  91 }
  92
  93 static void print_usage(void)
  94 {
  95         fprintf(stderr, "usage: see `git help describe`\n");
  96         exit(1);
  97 }
  98
  99 /** Parse command line arguments */
 100 static void parse_options(struct describe_options *opts, int argc, char **argv)
 101 {
 102         struct args_info args = ARGS_INFO_INIT;
 103
 104         for (args.pos = 1; args.pos < argc; ++args.pos) {
 105                 const char *curr = argv[args.pos];
 106
 107                 if (curr[0] != '-') {
 108                         opts_add_commit(opts, curr);
 109                 } else if (!strcmp(curr, "--all")) {
 110                         opts->describe_options.describe_strategy = GIT_DESCRIBE_ALL;
 111                 } else if (!strcmp(curr, "--tags")) {
 112                         opts->describe_options.describe_strategy = GIT_DESCRIBE_TAGS;
 113                 } else if (!strcmp(curr, "--exact-match")) {
 114                         opts->describe_options.max_candidates_tags = 0;
 115                 } else if (!strcmp(curr, "--long")) {
 116                         opts->format_options.always_use_long_format = 1;
 117                 } else if (!strcmp(curr, "--always")) {
 118                         opts->describe_options.show_commit_oid_as_fallback = 1;
 119                 } else if (!strcmp(curr, "--first-parent")) {
 120                         opts->describe_options.only_follow_first_parent = 1;
 121                 } else if (optional_str_arg(&opts->format_options.dirty_suffix, &args, "--dirty", "-dirty")) {
 122                 } else if (match_int_arg((int *)&opts->format_options.abbreviated_size, &args, "--abbrev", 0)) {
 123                 } else if (match_int_arg((int *)&opts->describe_options.max_candidates_tags, &args, "--candidates", 0)) {
 124                 } else if (match_str_arg(&opts->describe_options.pattern, &args, "--match")) {
 125                 } else {
 126                         print_usage();
 127                 }
 128         }
 129
 130         if (opts->commit_count > 0) {
 131                 if (opts->format_options.dirty_suffix)
 132                         fatal("--dirty is incompatible with commit-ishes", NULL);
 133         }
 134         else {
 135                 if (!opts->format_options.dirty_suffix || !opts->format_options.dirty_suffix[0]) {
 136                         opts_add_commit(opts, "HEAD");
 137                 }
 138         }
 139 }
 140
 141 /** Initialize describe_options struct */
 142 static void describe_options_init(struct describe_options *opts)
 143 {
 144         memset(opts, 0, sizeof(*opts));
 145
 146         opts->commits = NULL;
 147         opts->commit_count = 0;
 148         git_describe_options_init(&opts->describe_options, GIT_DESCRIBE_OPTIONS_VERSION);
 149         git_describe_format_options_init(&opts->format_options, GIT_DESCRIBE_FORMAT_OPTIONS_VERSION);
 150 }
 151
 152 int lg2_describe(git_repository *repo, int argc, char **argv)
 153 {
 154         struct describe_options opts;
 155
 156         describe_options_init(&opts);
 157         parse_options(&opts, argc, argv);
 158
 159         do_describe(repo, &opts);
 160
 161         return 0;
 162 }