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.

2 files changed, 11 insertions, 10 deletions

diff --git a/src/transports/git.c b/src/transports/git.c
index bdb94d090..ece4d40a8 100644
--- a/src/transports/git.c
+++ b/src/transports/git.c
@@ -68,7 +68,7 @@ static int gen_proto(git_buf *request, const char *cmd, const char *url)
 	git_buf_put(request, url, delim - url);
 	git_buf_putc(request, '\0');
 
-	return git_buf_oom(request);
+	return git_buf_lasterror(request);
 }
 
 static int send_request(GIT_SOCKET s, const char *cmd, const char *url)
diff --git a/src/transports/http.c b/src/transports/http.c
index e463a0f59..48ea78dce 100644
--- a/src/transports/http.c
+++ b/src/transports/http.c
@@ -77,10 +77,7 @@ static int gen_request(git_buf *buf, const char *url, const char *host, const ch
 	}
 	git_buf_puts(buf, "\r\n");
 
-	if (git_buf_oom(buf))
-		return GIT_ENOMEM;
-
-	return GIT_SUCCESS;
+	return git_buf_lasterror(buf);
 }
 
 static int do_connect(transport_http *t, const char *host, const char *port)
@@ -608,8 +605,9 @@ static int http_download_pack(char **out, git_transport *transport, git_reposito
 	char buffer[1024];
 	gitno_buffer buf;
 	download_pack_cbdata data;
-	git_filebuf file;
-	char path[GIT_PATH_MAX], suff[] = "/objects/pack/pack-received\0";
+	git_filebuf file = GIT_FILEBUF_INIT;
+	git_buf path = GIT_BUF_INIT;
+	char suff[] = "/objects/pack/pack-received\0";
 
 	/*
 	 * This is part of the previous response, so we don't want to
@@ -625,13 +623,15 @@ static int http_download_pack(char **out, git_transport *transport, git_reposito
 
 	gitno_buffer_setup(&buf, buffer, sizeof(buffer), t->socket);
 
-	git_path_join(path, repo->path_repository, suff);
-
 	if (memcmp(oldbuf->ptr, "PACK", strlen("PACK"))) {
 		return git__throw(GIT_ERROR, "The pack doesn't start with the signature");
 	}
 
-	error = git_filebuf_open(&file, path, GIT_FILEBUF_TEMPORARY);
+	error = git_buf_joinpath(&path, repo->path_repository, suff);
+	if (error < GIT_SUCCESS)
+		goto cleanup;
+
+	error = git_filebuf_open(&file, path.ptr, GIT_FILEBUF_TEMPORARY);
 	if (error < GIT_SUCCESS)
 		goto cleanup;
 
@@ -671,6 +671,7 @@ static int http_download_pack(char **out, git_transport *transport, git_reposito
 cleanup:
 	if (error < GIT_SUCCESS)
 		git_filebuf_cleanup(&file);
+	git_buf_free(&path);
 
 	return error;
 }