Make our overflow check look more like gcc/clang's

Make our overflow checking look more like gcc and clang's, so that
we can substitute it out with the compiler instrinsics on platforms
that support it.  This means dropping the ability to pass `NULL` as
an out parameter.

As a result, the macros also get updated to reflect this as well.

1 files changed, 22 insertions, 20 deletions

diff --git a/src/odb_loose.c b/src/odb_loose.c
index e43b261fa..bfd95588b 100644
--- a/src/odb_loose.c
+++ b/src/odb_loose.c
@@ -63,10 +63,12 @@ typedef struct {
 static int object_file_name(
 	git_buf *name, const loose_backend *be, const git_oid *id)
 {
+	size_t alloclen;
+
 	/* expand length for object root + 40 hex sha1 chars + 2 * '/' + '\0' */
-	GITERR_CHECK_ALLOC_ADD(be->objects_dirlen, GIT_OID_HEXSZ);
-	GITERR_CHECK_ALLOC_ADD(be->objects_dirlen + GIT_OID_HEXSZ, 3);
-	if (git_buf_grow(name, be->objects_dirlen + GIT_OID_HEXSZ + 3) < 0)
+	GITERR_CHECK_ALLOC_ADD(&alloclen, be->objects_dirlen, GIT_OID_HEXSZ);
+	GITERR_CHECK_ALLOC_ADD(&alloclen, alloclen, 3);
+	if (git_buf_grow(name, alloclen) < 0)
 		return -1;
 
 	git_buf_set(name, be->objects_dir, be->objects_dirlen);
@@ -263,15 +265,15 @@ static int inflate_buffer(void *in, size_t inlen, void *out, size_t outlen)
 static void *inflate_tail(z_stream *s, void *hb, size_t used, obj_hdr *hdr)
 {
 	unsigned char *buf, *head = hb;
-	size_t tail;
+	size_t tail, alloc_size;
 
 	/*
 	 * allocate a buffer to hold the inflated data and copy the
 	 * initial sequence of inflated data from the tail of the
 	 * head buffer, if any.
 	 */
-	if (GIT_ALLOC_OVERFLOW_ADD(hdr->size, 1) ||
-		(buf = git__malloc(hdr->size + 1)) == NULL) {
+	if (GIT_ADD_SIZET_OVERFLOW(&alloc_size, hdr->size, 1) ||
+		(buf = git__malloc(alloc_size)) == NULL) {
 		inflateEnd(s);
 		return NULL;
 	}
@@ -309,7 +311,7 @@ static int inflate_packlike_loose_disk_obj(git_rawobj *out, git_buf *obj)
 {
 	unsigned char *in, *buf;
 	obj_hdr hdr;
-	size_t len, used;
+	size_t len, used, alloclen;
 
 	/*
 	 * read the object header, which is an (uncompressed)
@@ -324,8 +326,8 @@ static int inflate_packlike_loose_disk_obj(git_rawobj *out, git_buf *obj)
 	/*
 	 * allocate a buffer and inflate the data into it
 	 */
-	GITERR_CHECK_ALLOC_ADD(hdr.size, 1);
-	buf = git__malloc(hdr.size + 1);
+	GITERR_CHECK_ALLOC_ADD(&alloclen, hdr.size, 1);
+	buf = git__malloc(alloclen);
 	GITERR_CHECK_ALLOC(buf);
 
 	in = ((unsigned char *)obj->ptr) + used;
@@ -519,14 +521,14 @@ static int locate_object_short_oid(
 	size_t len)
 {
 	char *objects_dir = backend->objects_dir;
-	size_t dir_len = strlen(objects_dir);
+	size_t dir_len = strlen(objects_dir), alloc_len;
 	loose_locate_object_state state;
 	int error;
 
 	/* prealloc memory for OBJ_DIR/xx/xx..38x..xx */
-	GITERR_CHECK_ALLOC_ADD(dir_len, GIT_OID_HEXSZ);
-	GITERR_CHECK_ALLOC_ADD(dir_len + GIT_OID_HEXSZ, 3);
-	if (git_buf_grow(object_location, dir_len + 3 + GIT_OID_HEXSZ) < 0)
+	GITERR_CHECK_ALLOC_ADD(&alloc_len, dir_len, GIT_OID_HEXSZ);
+	GITERR_CHECK_ALLOC_ADD(&alloc_len, alloc_len, 3);
+	if (git_buf_grow(object_location, alloc_len) < 0)
 		return -1;
 
 	git_buf_set(object_location, objects_dir, dir_len);
@@ -569,11 +571,11 @@ static int locate_object_short_oid(
 		return error;
 
 	/* Update the location according to the oid obtained */
-	GITERR_CHECK_ALLOC_ADD(dir_len, GIT_OID_HEXSZ);
-	GITERR_CHECK_ALLOC_ADD(dir_len + GIT_OID_HEXSZ, 2);
+	GITERR_CHECK_ALLOC_ADD(&alloc_len, dir_len, GIT_OID_HEXSZ);
+	GITERR_CHECK_ALLOC_ADD(&alloc_len, alloc_len, 2);
 
 	git_buf_truncate(object_location, dir_len);
-	if (git_buf_grow(object_location, dir_len + GIT_OID_HEXSZ + 2) < 0)
+	if (git_buf_grow(object_location, alloc_len) < 0)
 		return -1;
 
 	git_oid_pathfmt(object_location->ptr + dir_len, res_oid);
@@ -930,15 +932,15 @@ int git_odb_backend_loose(
 	unsigned int file_mode)
 {
 	loose_backend *backend;
-	size_t objects_dirlen;
+	size_t objects_dirlen, alloclen;
 
 	assert(backend_out && objects_dir);
 
 	objects_dirlen = strlen(objects_dir);
 
-	GITERR_CHECK_ALLOC_ADD(sizeof(loose_backend), objects_dirlen);
-	GITERR_CHECK_ALLOC_ADD(sizeof(loose_backend) + objects_dirlen, 2);
-	backend = git__calloc(1, sizeof(loose_backend) + objects_dirlen + 2);
+	GITERR_CHECK_ALLOC_ADD(&alloclen, sizeof(loose_backend), objects_dirlen);
+	GITERR_CHECK_ALLOC_ADD(&alloclen, alloclen, 2);
+	backend = git__calloc(1, alloclen);
 	GITERR_CHECK_ALLOC(backend);
 
 	backend->parent.version = GIT_ODB_BACKEND_VERSION;