Merge branch 'mh/ceiling'

An element on GIT_CEILING_DIRECTORIES list that does not name the
real path to a directory (i.e. a symbolic link) could have caused
the GIT_DIR discovery logic to escape the ceiling.

* mh/ceiling:
  string_list_longest_prefix(): remove function
  setup_git_directory_gently_1(): resolve symlinks in ceiling paths
  longest_ancestor_length(): require prefix list entries to be normalized
  longest_ancestor_length(): take a string_list argument for prefixes
  longest_ancestor_length(): use string_list_split()
  Introduce new function real_path_if_valid()
  real_path_internal(): add comment explaining use of cwd
  Introduce new static function real_path_internal()

1 files changed, 32 insertions, 2 deletions

diff --git a/setup.c b/setup.c
index 3a1b2fd455..f108c4b990 100644
--- a/setup.c
+++ b/setup.c
@@ -1,5 +1,6 @@
 #include "cache.h"
 #include "dir.h"
+#include "string-list.h"
 
 static int inside_git_dir = -1;
 static int inside_work_tree = -1;
@@ -621,16 +622,38 @@ 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.
+ */
+static int canonicalize_ceiling_entry(struct string_list_item *item,
+				      void *unused)
+{
+	char *ceil = item->string;
+	const char *real_path;
+
+	if (!*ceil || !is_absolute_path(ceil))
+		return 0;
+	real_path = real_path_if_valid(ceil);
+	if (!real_path)
+		return 0;
+	free(item->string);
+	item->string = xstrdup(real_path);
+	return 1;
+}
+
+/*
  * We cannot decide in this function whether we are in the work tree or
  * not, since the config can only be read _after_ this function was called.
  */
 static const char *setup_git_directory_gently_1(int *nongit_ok)
 {
 	const char *env_ceiling_dirs = getenv(CEILING_DIRECTORIES_ENVIRONMENT);
+	struct string_list ceiling_dirs = STRING_LIST_INIT_DUP;
 	static char cwd[PATH_MAX+1];
 	const char *gitdirenv, *ret;
 	char *gitfile;
-	int len, offset, offset_parent, ceil_offset;
+	int len, offset, offset_parent, ceil_offset = -1;
 	dev_t current_device = 0;
 	int one_filesystem = 1;
 
@@ -655,7 +678,14 @@ static const char *setup_git_directory_gently_1(int *nongit_ok)
 	if (gitdirenv)
 		return setup_explicit_git_dir(gitdirenv, cwd, len, nongit_ok);
 
-	ceil_offset = longest_ancestor_length(cwd, env_ceiling_dirs);
+	if (env_ceiling_dirs) {
+		string_list_split(&ceiling_dirs, env_ceiling_dirs, PATH_SEP, -1);
+		filter_string_list(&ceiling_dirs, 0,
+				   canonicalize_ceiling_entry, NULL);
+		ceil_offset = longest_ancestor_length(cwd, &ceiling_dirs);
+		string_list_clear(&ceiling_dirs, 0);
+	}
+
 	if (ceil_offset < 0 && has_dos_drive_prefix(cwd))
 		ceil_offset = 1;