Re: [PATCH v2] git-merge: ignore space support

[Jonathan Nieder <jrnieder@gmail.com>]

Justin Frankel wrote:

> Fine by me... (ok if I were to nitpick I would probably make most of
> the internal static functions check that opts was non-NULL before
> dereferencing, in case the calling code ever changed

Not a bad idea.  I'll squash in something like this.

A real BUG_ON macro would make this less ugly.

-- 8< --
Subject: ll-merge: BUG_ON(!opts) in internal functions

If one of the functions used to implement ll_merge() gets exposed,
callers would be likely to pass a NULL options argument, resulting in
segfaults.  Die with a more meaningful message in that case.

Suggested-by: Justin Frankel <justin@cockos.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
---
 ll-merge.c |   18 ++++++++++++++++--
 1 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/ll-merge.c b/ll-merge.c
index 98f353a..8ff0b27 100644
--- a/ll-merge.c
+++ b/ll-merge.c
@@ -42,12 +42,17 @@ static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
 			   const struct ll_merge_options *opts,
 			   int marker_size)
 {
+	mmfile_t *stolen;
+
+	if (!opts)
+		die("BUG: !opts in binary merge driver");
+
 	/*
 	 * The tentative merge result is "ours" for the final round,
 	 * or common ancestor for an internal merge.  Still return
 	 * "conflicted merge" status.
 	 */
-	mmfile_t *stolen = opts->virtual_ancestor ? orig : src1;
+	stolen = opts->virtual_ancestor ? orig : src1;
 
 	result->ptr = stolen->ptr;
 	result->size = stolen->size;
@@ -66,6 +71,9 @@ static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
 {
 	xmparam_t xmp;
 
+	if (!opts)
+		die("BUG: !opts in xdiff merge driver");
+
 	if (buffer_is_binary(orig->ptr, orig->size) ||
 	    buffer_is_binary(src1->ptr, src1->size) ||
 	    buffer_is_binary(src2->ptr, src2->size)) {
@@ -102,7 +110,10 @@ static int ll_union_merge(const struct ll_merge_driver *drv_unused,
 			  int marker_size)
 {
 	/* Use union favor */
-	struct ll_merge_options o = *opts;
+	struct ll_merge_options o;
+	if (!opts)
+		die("BUG: !opts in union merge driver");
+	o = *opts;
 	o.variant = XDL_MERGE_FAVOR_UNION;
 	return ll_xdl_merge(drv_unused, result, path_unused,
 			    orig, NULL, src1, NULL, src2, NULL,
@@ -149,6 +160,9 @@ static int ll_ext_merge(const struct ll_merge_driver *fn,
 	int status, fd, i;
 	struct stat st;
 
+	if (!opts)
+		die("BUG: !opts in custom merge driver");
+
 	dict[0].placeholder = "O"; dict[0].value = temp[0];
 	dict[1].placeholder = "A"; dict[1].value = temp[1];
 	dict[2].placeholder = "B"; dict[2].value = temp[2];
-- 
1.7.2.2