setup_git_directory_1(): avoid changing global state
For historical reasons, Git searches for the .git/ directory (or the .git file) by changing the working directory successively to the parent directory of the current directory, until either anything was found or until a ceiling or a mount point is hit. Further global state may be changed in case a .git/ directory was found. We do have a use case, though, where we would like to find the .git/ directory without having any global state touched, though: when we read the early config e.g. for the pager or for alias expansion. Let's just move all of code that changes any global state out of the function `setup_git_directory_gently_1()` into `setup_git_directory_gently()`. In subsequent patches, we will use the _1() function in a new `discover_git_directory()` function that we will then use for the early config code. Note: the new loop is a *little* tricky, as we have to handle the root directory specially: we cannot simply strip away the last component including the slash, as the root directory only has that slash. To remedy that, we introduce the `min_offset` variable that holds the minimal length of an absolute path, and using that to special-case the root directory, including an early exit before trying to find the parent of the root directory. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Johannes Schindelin committed
Mar 13, 2017 at 21:10 UTC
ce9b8aab5d9a40a84b4868fa890654900ab2d4cc
1 file changed
+118
-75
setup.c
+118
-75
@@ -818,50 +818,49 @@ static int canonicalize_ceiling_entry(struct string_list_item *item,
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}
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}
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+enum discovery_result {
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+ GIT_DIR_NONE = 0,
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+ GIT_DIR_EXPLICIT,
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+ GIT_DIR_DISCOVERED,
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+ GIT_DIR_BARE,
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+ /* these are errors */
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+ GIT_DIR_HIT_CEILING = -1,
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+ GIT_DIR_HIT_MOUNT_POINT = -2
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+};
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+
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/*
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* We cannot decide in this function whether we are in the work tree or
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* not, since the config can only be read _after_ this function was called.
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+ *
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+ * Also, we avoid changing any global state (such as the current working
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+ * directory) to allow early callers.
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+ *
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+ * The directory where the search should start needs to be passed in via the
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+ * `dir` parameter; upon return, the `dir` buffer will contain the path of
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+ * the directory where the search ended, and `gitdir` will contain the path of
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+ * the discovered .git/ directory, if any. If `gitdir` is not absolute, it
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+ * is relative to `dir` (i.e. *not* necessarily the cwd).
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*/
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-static const char *setup_git_directory_gently_1(int *nongit_ok)
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+static enum discovery_result setup_git_directory_gently_1(struct strbuf *dir,
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+ struct strbuf *gitdir)
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{
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const char *env_ceiling_dirs = getenv(CEILING_DIRECTORIES_ENVIRONMENT);
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struct string_list ceiling_dirs = STRING_LIST_INIT_DUP;
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- static struct strbuf cwd = STRBUF_INIT;
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- const char *gitdirenv, *ret;
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- char *gitfile;
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- int offset, offset_parent, ceil_offset = -1;
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+ const char *gitdirenv;
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+ int ceil_offset = -1, min_offset = has_dos_drive_prefix(dir->buf) ? 3 : 1;
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dev_t current_device = 0;
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int one_filesystem = 1;
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- /*
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- * We may have read an incomplete configuration before
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- * setting-up the git directory. If so, clear the cache so
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- * that the next queries to the configuration reload complete
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- * configuration (including the per-repo config file that we
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- * ignored previously).
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- */
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- git_config_clear();
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-
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- /*
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- * Let's assume that we are in a git repository.
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- * If it turns out later that we are somewhere else, the value will be
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- * updated accordingly.
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- */
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- if (nongit_ok)
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- *nongit_ok = 0;
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-
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- if (strbuf_getcwd(&cwd))
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- die_errno(_("Unable to read current working directory"));
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- offset = cwd.len;
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-
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/*
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* If GIT_DIR is set explicitly, we're not going
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* to do any discovery, but we still do repository
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* validation.
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*/
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gitdirenv = getenv(GIT_DIR_ENVIRONMENT);
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- if (gitdirenv)
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- return setup_explicit_git_dir(gitdirenv, &cwd, nongit_ok);
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+ if (gitdirenv) {
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+ strbuf_addstr(gitdir, gitdirenv);
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+ return GIT_DIR_EXPLICIT;
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+ }
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if (env_ceiling_dirs) {
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int empty_entry_found = 0;
@@ -869,15 +868,15 @@ static const char *setup_git_directory_gently_1(int *nongit_ok)
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string_list_split(&ceiling_dirs, env_ceiling_dirs, PATH_SEP, -1);
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filter_string_list(&ceiling_dirs, 0,
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canonicalize_ceiling_entry, &empty_entry_found);
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- ceil_offset = longest_ancestor_length(cwd.buf, &ceiling_dirs);
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+ ceil_offset = longest_ancestor_length(dir->buf, &ceiling_dirs);
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string_list_clear(&ceiling_dirs, 0);
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}
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- if (ceil_offset < 0 && has_dos_drive_prefix(cwd.buf))
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- ceil_offset = 1;
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+ if (ceil_offset < 0)
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+ ceil_offset = min_offset - 2;
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/*
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- * Test in the following order (relative to the cwd):
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+ * Test in the following order (relative to the dir):
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* - .git (file containing "gitdir: <path>")
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* - .git/
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* - ./ (bare)
@@ -889,63 +888,104 @@ static const char *setup_git_directory_gently_1(int *nongit_ok)
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*/
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one_filesystem = !git_env_bool("GIT_DISCOVERY_ACROSS_FILESYSTEM", 0);
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if (one_filesystem)
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- current_device = get_device_or_die(".", NULL, 0);
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+ current_device = get_device_or_die(dir->buf, NULL, 0);
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for (;;) {
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- gitfile = (char*)read_gitfile(DEFAULT_GIT_DIR_ENVIRONMENT);
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- if (gitfile)
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- gitdirenv = gitfile = xstrdup(gitfile);
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- else {
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- if (is_git_directory(DEFAULT_GIT_DIR_ENVIRONMENT))
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- gitdirenv = DEFAULT_GIT_DIR_ENVIRONMENT;
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+ int offset = dir->len;
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+
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+ if (offset > min_offset)
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+ strbuf_addch(dir, '/');
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+ strbuf_addstr(dir, DEFAULT_GIT_DIR_ENVIRONMENT);
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+ gitdirenv = read_gitfile(dir->buf);
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+ if (!gitdirenv && is_git_directory(dir->buf))
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+ gitdirenv = DEFAULT_GIT_DIR_ENVIRONMENT;
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+ strbuf_setlen(dir, offset);
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+ if (gitdirenv) {
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+ strbuf_addstr(gitdir, gitdirenv);
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+ return GIT_DIR_DISCOVERED;
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}
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- if (gitdirenv) {
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- ret = setup_discovered_git_dir(gitdirenv,
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- &cwd, offset,
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- nongit_ok);
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- free(gitfile);
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- return ret;
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+ if (is_git_directory(dir->buf)) {
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+ strbuf_addstr(gitdir, ".");
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+ return GIT_DIR_BARE;
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}
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- free(gitfile);
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- if (is_git_directory("."))
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- return setup_bare_git_dir(&cwd, offset, nongit_ok);
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+ if (offset <= min_offset)
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+ return GIT_DIR_HIT_CEILING;
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- offset_parent = offset;
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- while (--offset_parent > ceil_offset &&
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- !is_dir_sep(cwd.buf[offset_parent]))
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+ while (--offset > ceil_offset && !is_dir_sep(dir->buf[offset]))
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; /* continue */
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- if (offset_parent <= ceil_offset)
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- return setup_nongit(cwd.buf, nongit_ok);
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- if (one_filesystem) {
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- dev_t parent_device = get_device_or_die("..", cwd.buf,
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- offset);
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- if (parent_device != current_device) {
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- if (nongit_ok) {
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- if (chdir(cwd.buf))
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- die_errno(_("Cannot come back to cwd"));
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- *nongit_ok = 1;
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- return NULL;
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- }
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- strbuf_setlen(&cwd, offset);
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- die(_("Not a git repository (or any parent up to mount point %s)\n"
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- "Stopping at filesystem boundary (GIT_DISCOVERY_ACROSS_FILESYSTEM not set)."),
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- cwd.buf);
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- }
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- }
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- if (chdir("..")) {
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- strbuf_setlen(&cwd, offset);
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- die_errno(_("Cannot change to '%s/..'"), cwd.buf);
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- }
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- offset = offset_parent;
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+ if (offset <= ceil_offset)
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+ return GIT_DIR_HIT_CEILING;
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+
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+ strbuf_setlen(dir, offset > min_offset ? offset : min_offset);
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+ if (one_filesystem &&
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+ current_device != get_device_or_die(dir->buf, NULL, offset))
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+ return GIT_DIR_HIT_MOUNT_POINT;
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}
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}
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const char *setup_git_directory_gently(int *nongit_ok)
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{
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+ static struct strbuf cwd = STRBUF_INIT;
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+ struct strbuf dir = STRBUF_INIT, gitdir = STRBUF_INIT;
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const char *prefix;
932
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- prefix = setup_git_directory_gently_1(nongit_ok);
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+ /*
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+ * We may have read an incomplete configuration before
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+ * setting-up the git directory. If so, clear the cache so
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+ * that the next queries to the configuration reload complete
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+ * configuration (including the per-repo config file that we
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+ * ignored previously).
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+ */
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+ git_config_clear();
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+
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+ /*
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+ * Let's assume that we are in a git repository.
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+ * If it turns out later that we are somewhere else, the value will be
945
+ * updated accordingly.
946
+ */
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+ if (nongit_ok)
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+ *nongit_ok = 0;
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+
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+ if (strbuf_getcwd(&cwd))
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+ die_errno(_("Unable to read current working directory"));
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+ strbuf_addbuf(&dir, &cwd);
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+
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+ switch (setup_git_directory_gently_1(&dir, &gitdir)) {
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+ case GIT_DIR_NONE:
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+ prefix = NULL;
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+ break;
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+ case GIT_DIR_EXPLICIT:
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+ prefix = setup_explicit_git_dir(gitdir.buf, &cwd, nongit_ok);
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+ break;
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+ case GIT_DIR_DISCOVERED:
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+ if (dir.len < cwd.len && chdir(dir.buf))
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+ die(_("Cannot change to '%s'"), dir.buf);
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+ prefix = setup_discovered_git_dir(gitdir.buf, &cwd, dir.len,
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+ nongit_ok);
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+ break;
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+ case GIT_DIR_BARE:
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+ if (dir.len < cwd.len && chdir(dir.buf))
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+ die(_("Cannot change to '%s'"), dir.buf);
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+ prefix = setup_bare_git_dir(&cwd, dir.len, nongit_ok);
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+ break;
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+ case GIT_DIR_HIT_CEILING:
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+ prefix = setup_nongit(cwd.buf, nongit_ok);
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+ break;
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+ case GIT_DIR_HIT_MOUNT_POINT:
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+ if (nongit_ok) {
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+ *nongit_ok = 1;
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+ strbuf_release(&cwd);
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+ strbuf_release(&dir);
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+ return NULL;
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+ }
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+ die(_("Not a git repository (or any parent up to mount point %s)\n"
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+ "Stopping at filesystem boundary (GIT_DISCOVERY_ACROSS_FILESYSTEM not set)."),
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+ dir.buf);
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+ default:
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+ die("BUG: unhandled setup_git_directory_1() result");
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+ }
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+
989
if (prefix)
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setenv(GIT_PREFIX_ENVIRONMENT, prefix, 1);
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else
@@ -954,6 +994,9 @@ const char *setup_git_directory_gently(int *nongit_ok)
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startup_info->have_repository = !nongit_ok || !*nongit_ok;
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startup_info->prefix = prefix;
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997
+ strbuf_release(&dir);
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+ strbuf_release(&gitdir);
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+
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return prefix;
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}
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