summaryrefslogtreecommitdiff
path: root/setup.c
diff options
context:
space:
mode:
authorMichael Haggerty <mhagger@alum.mit.edu>2013-02-20 10:09:24 +0100
committerJunio C Hamano <gitster@pobox.com>2013-02-22 11:37:34 -0800
commit7ec30aaa5ba2a71287879d7bd9a5c55363ea1bbe (patch)
tree8ac9c173f11c48b12298fc7f13064905718efbb8 /setup.c
parent1b77d83cab798668d8a54a05b3fa0262486f7dfc (diff)
downloadgit-7ec30aaa5ba2a71287879d7bd9a5c55363ea1bbe.tar.gz
Provide a mechanism to turn off symlink resolution in ceiling paths
Commit 1b77d83cab 'setup_git_directory_gently_1(): resolve symlinks in ceiling paths' changed the setup code to resolve symlinks in the entries in GIT_CEILING_DIRECTORIES. Because those entries are compared textually to the symlink-resolved current directory, an entry in GIT_CEILING_DIRECTORIES that contained a symlink would have no effect. It was known that this could cause performance problems if the symlink resolution *itself* touched slow filesystems, but it was thought that such use cases would be unlikely. The intention of the earlier change was to deal with a case when the user has this: GIT_CEILING_DIRECTORIES=/home/gitster but in reality, /home/gitster is a symbolic link to somewhere else, e.g. /net/machine/home4/gitster. A textual comparison between the specified value /home/gitster and the location getcwd(3) returns would not help us, but readlink("/home/gitster") would still be fast. After this change was released, Anders Kaseorg <andersk@mit.edu> reported: > [...] my computer has been acting so slow when I’m not connected to > the network. I put various network filesystem paths in > $GIT_CEILING_DIRECTORIES, such as > /afs/athena.mit.edu/user/a/n/andersk (to avoid hitting its parents > /afs/athena.mit.edu, /afs/athena.mit.edu/user/a, and > /afs/athena.mit.edu/user/a/n which all live in different AFS > volumes). Now when I’m not connected to the network, every > invocation of Git, including the __git_ps1 in my shell prompt, waits > for AFS to timeout. To allow users to work around this problem, give them a mechanism to turn off symlink resolution in GIT_CEILING_DIRECTORIES entries. All the entries that follow an empty entry will not be checked for symbolic links and used literally in comparison. E.g. with these: GIT_CEILING_DIRECTORIES=:/foo/bar:/xyzzy or GIT_CEILING_DIRECTORIES=/foo/bar::/xyzzy we will not readlink("/xyzzy") because it comes after an empty entry. With the former (but not with the latter), "/foo/bar" comes after an empty entry, and we will not readlink it, either. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'setup.c')
-rw-r--r--setup.c32
1 files changed, 22 insertions, 10 deletions
diff --git a/setup.c b/setup.c
index f108c4b990..1b120175f2 100644
--- a/setup.c
+++ b/setup.c
@@ -624,22 +624,32 @@ static dev_t get_device_or_die(const char *path, const char *prefix, int prefix_
/*
* A "string_list_each_func_t" function that canonicalizes an entry
* from GIT_CEILING_DIRECTORIES using real_path_if_valid(), or
- * discards it if unusable.
+ * discards it if unusable. The presence of an empty entry in
+ * GIT_CEILING_DIRECTORIES turns off canonicalization for all
+ * subsequent entries.
*/
static int canonicalize_ceiling_entry(struct string_list_item *item,
- void *unused)
+ void *cb_data)
{
+ int *empty_entry_found = cb_data;
char *ceil = item->string;
- const char *real_path;
- if (!*ceil || !is_absolute_path(ceil))
+ if (!*ceil) {
+ *empty_entry_found = 1;
return 0;
- real_path = real_path_if_valid(ceil);
- if (!real_path)
+ } else if (!is_absolute_path(ceil)) {
return 0;
- free(item->string);
- item->string = xstrdup(real_path);
- return 1;
+ } else if (*empty_entry_found) {
+ /* Keep entry but do not canonicalize it */
+ return 1;
+ } else {
+ const char *real_path = real_path_if_valid(ceil);
+ if (!real_path)
+ return 0;
+ free(item->string);
+ item->string = xstrdup(real_path);
+ return 1;
+ }
}
/*
@@ -679,9 +689,11 @@ static const char *setup_git_directory_gently_1(int *nongit_ok)
return setup_explicit_git_dir(gitdirenv, cwd, len, nongit_ok);
if (env_ceiling_dirs) {
+ int empty_entry_found = 0;
+
string_list_split(&ceiling_dirs, env_ceiling_dirs, PATH_SEP, -1);
filter_string_list(&ceiling_dirs, 0,
- canonicalize_ceiling_entry, NULL);
+ canonicalize_ceiling_entry, &empty_entry_found);
ceil_offset = longest_ancestor_length(cwd, &ceiling_dirs);
string_list_clear(&ceiling_dirs, 0);
}