git: ensure 0/1/2 are open in main()

diff --git a/setup.c b/setup.c
index f108c4b990c0e4f6a98c1fe34d3031040c84195a..12a85d16138f1500d8e86c4c5f80273b615e657a 100644 (file)
--- 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);
        }
@@ -860,3 +872,15 @@ const char *resolve_gitdir(const char *suspect)
                return suspect;
        return read_gitfile(suspect);
 }
+
+/* if any standard file descriptor is missing open it to /dev/null */
+void sanitize_stdfds(void)
+{
+       int fd = open("/dev/null", O_RDWR, 0);
+       while (fd != -1 && fd < 2)
+               fd = dup(fd);
+       if (fd == -1)
+               die_errno("open /dev/null or dup failed");
+       if (fd > 2)
+               close(fd);
+}