Use git_buf for path storage instead of stack-based buffers

This converts virtually all of the places that allocate GIT_PATH_MAX
buffers on the stack for manipulating paths to use git_buf objects
instead.  The patch is pretty careful not to touch the public API
for libgit2, so there are a few places that still use GIT_PATH_MAX.

This extends and changes some details of the git_buf implementation
to add a couple of extra functions and to make error handling easier.

This includes serious alterations to all the path.c functions, and
several of the fileops.c ones, too.  Also, there are a number of new
functions that parallel existing ones except that use a git_buf
instead of a stack-based buffer (such as git_config_find_global_r
that exists alongsize git_config_find_global).

This also modifies the win32 version of p_realpath to allocate whatever
buffer size is needed to accommodate the realpath instead of hardcoding
a GIT_PATH_MAX limit, but that change needs to be tested still.

1 files changed, 4 insertions, 3 deletions

diff --git a/src/filebuf.c b/src/filebuf.c
index 6600bfa4b..aa47d5eb0 100644
--- a/src/filebuf.c
+++ b/src/filebuf.c
@@ -196,18 +196,19 @@ int git_filebuf_open(git_filebuf *file, const char *path, int flags)
 
 	/* If we are writing to a temp file */
 	if (flags & GIT_FILEBUF_TEMPORARY) {
-		char tmp_path[GIT_PATH_MAX];
+		git_buf tmp_path = GIT_BUF_INIT;
 
 		/* Open the file as temporary for locking */
-		file->fd = git_futils_mktmp(tmp_path, path);
+		file->fd = git_futils_mktmp(&tmp_path, path);
 		if (file->fd < 0) {
+			git_buf_free(&tmp_path);
 			error = GIT_EOSERR;
 			goto cleanup;
 		}
 
 		/* No original path */
 		file->path_original = NULL;
-		file->path_lock = git__strdup(tmp_path);
+		file->path_lock = git_buf_detach(&tmp_path);
 
 		if (file->path_lock == NULL) {
 			error = GIT_ENOMEM;