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, 18 insertions, 0 deletions

diff --git a/src/refspec.c b/src/refspec.c
index 62683e7b7..7ce32ba14 100644
--- a/src/refspec.c
+++ b/src/refspec.c
@@ -93,3 +93,21 @@ int git_refspec_transform(char *out, size_t outlen, const git_refspec *spec, con
 
 	return GIT_SUCCESS;
 }
+
+int git_refspec_transform_r(git_buf *out, const git_refspec *spec, const char *name)
+{
+	if (git_buf_sets(out, spec->dst) < GIT_SUCCESS)
+		return git_buf_lasterror(out);
+
+	/*
+	 * No '*' at the end means that it's mapped to one specific local
+	 * branch, so no actual transformation is needed.
+	 */
+	if (out->size > 0 && out->ptr[out->size - 1] != '*')
+		return GIT_SUCCESS;
+
+	git_buf_truncate(out, out->size - 1); /* remove trailing '*' */
+	git_buf_puts(out, name);
+
+	return git_buf_lasterror(out);
+}