apply.c:update_pre_post_images(): the preimage can be truncated

diff --git a/builtin/apply.c b/builtin/apply.c
index d2180b03744e093c51ffe61168391d4c4f814212..f8202e3b68c06a4a483cfbe6debd83d23e4777f5 100644 (file)
--- a/builtin/apply.c
+++ b/builtin/apply.c
@@ -2086,7 +2086,7 @@ static void update_pre_post_images(struct image *preimage,
                                   char *buf,
                                   size_t len, size_t postlen)
 {
-       int i, ctx;
+       int i, ctx, reduced;
        char *new, *old, *fixed;
        struct image fixed_preimage;
 
@@ -2096,8 +2096,10 @@ static void update_pre_post_images(struct image *preimage,
         * free "oldlines".
         */
        prepare_image(&fixed_preimage, buf, len, 1);
-       assert(fixed_preimage.nr == preimage->nr);
-       for (i = 0; i < preimage->nr; i++)
+       assert(postlen
+              ? fixed_preimage.nr == preimage->nr
+              : fixed_preimage.nr <= preimage->nr);
+       for (i = 0; i < fixed_preimage.nr; i++)
                fixed_preimage.line[i].flag = preimage->line[i].flag;
        free(preimage->line_allocated);
        *preimage = fixed_preimage;
@@ -2117,7 +2119,8 @@ static void update_pre_post_images(struct image *preimage,
        else
                new = old;
        fixed = preimage->buf;
-       for (i = ctx = 0; i < postimage->nr; i++) {
+
+       for (i = reduced = ctx = 0; i < postimage->nr; i++) {
                size_t len = postimage->line[i].len;
                if (!(postimage->line[i].flag & LINE_COMMON)) {
                        /* an added line -- no counterparts in preimage */
@@ -2136,8 +2139,15 @@ static void update_pre_post_images(struct image *preimage,
                        fixed += preimage->line[ctx].len;
                        ctx++;
                }
-               if (preimage->nr <= ctx)
-                       die(_("oops"));
+
+               /*
+                * preimage is expected to run out, if the caller
+                * fixed addition of trailing blank lines.
+                */
+               if (preimage->nr <= ctx) {
+                       reduced++;
+                       continue;
+               }
 
                /* and copy it in, while fixing the line length */
                len = preimage->line[ctx].len;
@@ -2150,6 +2160,7 @@ static void update_pre_post_images(struct image *preimage,
 
        /* Fix the length of the whole thing */
        postimage->len = new - postimage->buf;
+       postimage->nr -= reduced;
 }
 
 static int match_fragment(struct image *img,