http-push: push <remote> :<branch> deletes remote branch

[git.git] / xdiff-interface.c

diff --git a/xdiff-interface.c b/xdiff-interface.c
index be866d12d38f6f1328f5fae8c7108176d4ecba70..4b8e5cca804198b0e227454a585fa025281bbe2d 100644 (file)
--- a/xdiff-interface.c
+++ b/xdiff-interface.c
@@ -103,6 +103,44 @@ int xdiff_outf(void *priv_, mmbuffer_t *mb, int nbuf)
        return 0;
 }
 
+/*
+ * Trim down common substring at the end of the buffers,
+ * but leave at least ctx lines at the end.
+ */
+static void trim_common_tail(mmfile_t *a, mmfile_t *b, long ctx)
+{
+       const int blk = 1024;
+       long trimmed = 0, recovered = 0;
+       char *ap = a->ptr + a->size;
+       char *bp = b->ptr + b->size;
+       long smaller = (a->size < b->size) ? a->size : b->size;
+
+       if (ctx)
+               return;
+
+       while (blk + trimmed <= smaller && !memcmp(ap - blk, bp - blk, blk)) {
+               trimmed += blk;
+               ap -= blk;
+               bp -= blk;
+       }
+
+       while (recovered < trimmed)
+               if (ap[recovered++] == '\n')
+                       break;
+       a->size -= trimmed - recovered;
+       b->size -= trimmed - recovered;
+}
+
+int xdi_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp, xdemitconf_t const *xecfg, xdemitcb_t *xecb)
+{
+       mmfile_t a = *mf1;
+       mmfile_t b = *mf2;
+
+       trim_common_tail(&a, &b, xecfg->ctxlen);
+
+       return xdl_diff(&a, &b, xpp, xecfg, xecb);
+}
+
 int read_mmfile(mmfile_t *ptr, const char *filename)
 {
        struct stat st;