config: exit on error accessing any config file

There is convenience in warning and moving on when somebody has a
bogus permissions on /etc/gitconfig and cannot do anything about it.
But the cost in predictability and security is too high --- when
unreadable config files are skipped, it means an I/O error or
permissions problem causes important configuration to be bypassed.

For example, servers may depend on /etc/gitconfig to enforce security
policy (setting transfer.fsckObjects or receive.deny*).  Best to
always error out when encountering trouble accessing a config file.

This may add inconvenience in some cases:

1. You are inspecting somebody else's repo, and you do not have
access to their .git/config file.  Git typically dies in this
case already since we cannot read core.repositoryFormatVersion,
so the change should not be too noticeable.

2. You have used "sudo -u" or a similar tool to switch uid, and your
environment still points Git at your original user's global
config, which is not readable.  In this case people really would
be inconvenienced (they would rather see the harmless warning and
continue the operation) but they can work around it by setting
HOME appropriately after switching uids.

3. You do not have access to /etc/gitconfig due to a broken setup.
In this case, erroring out is a good way to put pressure on the
sysadmin to fix the setup.  While they wait for a reply, users
can set GIT_CONFIG_NOSYSTEM to true to keep Git working without
complaint.

After this patch, errors accessing the repository-local and systemwide
config files and files requested in include directives cause Git to
exit, just like errors accessing ~/.gitconfig.

Explained-by: Jeff King <peff@peff.net>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Acked-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/config.c b/config.c
index e8875b8a57bfe6596370bc297155f3f58e624665..a4d153f631c79fc660220b050ad49a1b2ad24229 100644 (file)
--- a/config.c
+++ b/config.c
@@ -60,7 +60,7 @@ static int handle_path_include(const char *path, struct config_include_data *inc
                path = buf.buf;
        }
 
-       if (!access_or_warn(path, R_OK)) {
+       if (!access_or_die(path, R_OK)) {
                if (++inc->depth > MAX_INCLUDE_DEPTH)
                        die(include_depth_advice, MAX_INCLUDE_DEPTH, path,
                            cf && cf->name ? cf->name : "the command line");
@@ -939,7 +939,7 @@ int git_config_early(config_fn_t fn, void *data, const char *repo_config)
 
        home_config_paths(&user_config, &xdg_config, "config");
 
-       if (git_config_system() && !access_or_warn(git_etc_gitconfig(), R_OK)) {
+       if (git_config_system() && !access_or_die(git_etc_gitconfig(), R_OK)) {
                ret += git_config_from_file(fn, git_etc_gitconfig(),
                                            data);
                found += 1;
@@ -955,7 +955,7 @@ int git_config_early(config_fn_t fn, void *data, const char *repo_config)
                found += 1;
        }
 
-       if (repo_config && !access_or_warn(repo_config, R_OK)) {
+       if (repo_config && !access_or_die(repo_config, R_OK)) {
                ret += git_config_from_file(fn, repo_config, data);
                found += 1;
        }