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, 29 insertions, 22 deletions

diff --git a/src/blob.c b/src/blob.c
index 87f5686af..7497ba7bf 100644
--- a/src/blob.c
+++ b/src/blob.c
@@ -67,12 +67,13 @@ int git_blob_create_frombuffer(git_oid *oid, git_repository *repo, const void *b
 
 int git_blob_create_fromfile(git_oid *oid, git_repository *repo, const char *path)
 {
-	int error, islnk;
+	int error = GIT_SUCCESS;
+	int islnk = 0;
 	int fd = 0;
-	char full_path[GIT_PATH_MAX];
+	git_buf full_path = GIT_BUF_INIT;
 	char buffer[2048];
 	git_off_t size;
-	git_odb_stream *stream;
+	git_odb_stream *stream = NULL;
 	struct stat st;
 	const char *workdir;
 	git_odb *odb;
@@ -81,11 +82,14 @@ int git_blob_create_fromfile(git_oid *oid, git_repository *repo, const char *pat
 	if (workdir == NULL)
 		return git__throw(GIT_ENOTFOUND, "Failed to create blob. (No working directory found)");
 
-	git_path_join(full_path, workdir, path);
+	error = git_buf_joinpath(&full_path, workdir, path);
+	if (error < GIT_SUCCESS)
+		return error;
 
-	error = p_lstat(full_path, &st);
+	error = p_lstat(full_path.ptr, &st);
 	if (error < 0) {
-		return git__throw(GIT_EOSERR, "Failed to stat blob. %s", strerror(errno));
+		error = git__throw(GIT_EOSERR, "Failed to stat blob. %s", strerror(errno));
+		goto cleanup;
 	}
 
 	islnk = S_ISLNK(st.st_mode);
@@ -93,18 +97,18 @@ int git_blob_create_fromfile(git_oid *oid, git_repository *repo, const char *pat
 
 	error = git_repository_odb__weakptr(&odb, repo);
 	if (error < GIT_SUCCESS)
-		return error;
+		goto cleanup;
 
 	if (!islnk) {
-		if ((fd = p_open(full_path, O_RDONLY)) < 0)
-			return git__throw(GIT_ENOTFOUND, "Failed to create blob. Could not open '%s'", full_path);
+		if ((fd = p_open(full_path.ptr, O_RDONLY)) < 0) {
+			error = git__throw(GIT_ENOTFOUND, "Failed to create blob. Could not open '%s'", full_path.ptr
+);
+			goto cleanup;
+		}
 	}
 
-	if ((error = git_odb_open_wstream(&stream, odb, (size_t)size, GIT_OBJ_BLOB)) < GIT_SUCCESS) {
-		if (!islnk)
-			p_close(fd);
-		return git__rethrow(error, "Failed to create blob");
-	}
+	if ((error = git_odb_open_wstream(&stream, odb, (size_t)size, GIT_OBJ_BLOB)) < GIT_SUCCESS)
+		goto cleanup;
 
 	while (size > 0) {
 		ssize_t read_len;
@@ -112,13 +116,11 @@ int git_blob_create_fromfile(git_oid *oid, git_repository *repo, const char *pat
 		if (!islnk)
 			read_len = p_read(fd, buffer, sizeof(buffer));
 		else
-			read_len = p_readlink(full_path, buffer, sizeof(buffer));
+			read_len = p_readlink(full_path.ptr, buffer, sizeof(buffer));
 
 		if (read_len < 0) {
-			if (!islnk)
-				p_close(fd);
-			stream->free(stream);
-			return git__throw(GIT_EOSERR, "Failed to create blob. Can't read full file");
+			error = git__throw(GIT_EOSERR, "Failed to create blob. Can't read full file");
+			goto cleanup;
 		}
 
 		stream->write(stream, buffer, read_len);
@@ -126,10 +128,15 @@ int git_blob_create_fromfile(git_oid *oid, git_repository *repo, const char *pat
 	}
 
 	error = stream->finalize_write(oid, stream);
-	stream->free(stream);
-	if (!islnk)
+
+cleanup:
+	if (stream)
+		stream->free(stream);
+	if (!islnk && fd)
 		p_close(fd);
+	git_buf_free(&full_path);
 
-	return error == GIT_SUCCESS ? GIT_SUCCESS : git__rethrow(error, "Failed to create blob");
+	return error == GIT_SUCCESS ? GIT_SUCCESS :
+		git__rethrow(error, "Failed to create blob");
 }