setup: introduce the discover_git_directory() function

We modified the setup_git_directory_gently_1() function earlier to make
it possible to discover the GIT_DIR without changing global state.

However, it is still a bit cumbersome to use if you only need to figure
out the (possibly absolute) path of the .git/ directory. Let's just
provide a convenient wrapper function with an easier signature that
*just* discovers the .git/ directory.

We will use it in a subsequent patch to fix the early config.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/cache.h b/cache.h
index 61fc86e6d7199518555632a0b0b584471b9083a8..3cba58e219ba58834b83881715b3b699d3bc4af5 100644 (file)
--- a/cache.h
+++ b/cache.h
@@ -518,6 +518,13 @@ extern void set_git_work_tree(const char *tree);
 #define ALTERNATE_DB_ENVIRONMENT "GIT_ALTERNATE_OBJECT_DIRECTORIES"
 
 extern void setup_work_tree(void);
+/*
+ * Find GIT_DIR of the repository that contains the current working directory,
+ * without changing the working directory or other global state. The result is
+ * appended to gitdir. The return value is either NULL if no repository was
+ * found, or pointing to the path inside gitdir's buffer.
+ */
+extern const char *discover_git_directory(struct strbuf *gitdir);
 extern const char *setup_git_directory_gently(int *);
 extern const char *setup_git_directory(void);
 extern char *prefix_path(const char *prefix, int len, const char *path);

diff --git a/setup.c b/setup.c
index 27a31de33fd84fd4b6d3a3adbd071e573c759f9f..d08730d94d488af6e4a631dac88cc222807878d6 100644 (file)
--- a/setup.c
+++ b/setup.c
@@ -924,6 +924,49 @@ static enum discovery_result setup_git_directory_gently_1(struct strbuf *dir,
        }
 }
 
+const char *discover_git_directory(struct strbuf *gitdir)
+{
+       struct strbuf dir = STRBUF_INIT, err = STRBUF_INIT;
+       size_t gitdir_offset = gitdir->len, cwd_len;
+       struct repository_format candidate;
+
+       if (strbuf_getcwd(&dir))
+               return NULL;
+
+       cwd_len = dir.len;
+       if (setup_git_directory_gently_1(&dir, gitdir) <= 0) {
+               strbuf_release(&dir);
+               return NULL;
+       }
+
+       /*
+        * The returned gitdir is relative to dir, and if dir does not reflect
+        * the current working directory, we simply make the gitdir absolute.
+        */
+       if (dir.len < cwd_len && !is_absolute_path(gitdir->buf + gitdir_offset)) {
+               /* Avoid a trailing "/." */
+               if (!strcmp(".", gitdir->buf + gitdir_offset))
+                       strbuf_setlen(gitdir, gitdir_offset);
+               else
+                       strbuf_addch(&dir, '/');
+               strbuf_insert(gitdir, gitdir_offset, dir.buf, dir.len);
+       }
+
+       strbuf_reset(&dir);
+       strbuf_addf(&dir, "%s/config", gitdir->buf + gitdir_offset);
+       read_repository_format(&candidate, dir.buf);
+       strbuf_release(&dir);
+
+       if (verify_repository_format(&candidate, &err) < 0) {
+               warning("ignoring git dir '%s': %s",
+                       gitdir->buf + gitdir_offset, err.buf);
+               strbuf_release(&err);
+               return NULL;
+       }
+
+       return gitdir->buf + gitdir_offset;
+}
+
 const char *setup_git_directory_gently(int *nongit_ok)
 {
        static struct strbuf cwd = STRBUF_INIT;