for-each-reflog: fix case for empty log directory

diff --git a/patch-delta.c b/patch-delta.c
index c0e13114351c4ea427ddfe4d9e9c20a541201ad6..ed9db81fa82c812c9ffa07f5a40540dbb15da0d3 100644 (file)
--- a/patch-delta.c
+++ b/patch-delta.c
@@ -9,12 +9,11 @@
  * published by the Free Software Foundation.
  */
 
-#include <stdlib.h>
-#include <string.h>
+#include "git-compat-util.h"
 #include "delta.h"
 
-void *patch_delta(void *src_buf, unsigned long src_size,
-                 void *delta_buf, unsigned long delta_size,
+void *patch_delta(const void *src_buf, unsigned long src_size,
+                 const void *delta_buf, unsigned long delta_size,
                  unsigned long *dst_size)
 {
        const unsigned char *data, *top;
@@ -25,18 +24,16 @@ void *patch_delta(void *src_buf, unsigned long src_size,
                return NULL;
 
        data = delta_buf;
-       top = delta_buf + delta_size;
+       top = (const unsigned char *) delta_buf + delta_size;
 
        /* make sure the orig file size matches what we expect */
-       size = get_delta_hdr_size(&data);
+       size = get_delta_hdr_size(&data, top);
        if (size != src_size)
                return NULL;
 
        /* now the result size */
-       size = get_delta_hdr_size(&data);
-       dst_buf = malloc(size + 1);
-       if (!dst_buf)
-               return NULL;
+       size = get_delta_hdr_size(&data, top);
+       dst_buf = xmalloc(size + 1);
        dst_buf[size] = 0;
 
        out = dst_buf;
@@ -52,21 +49,39 @@ void *patch_delta(void *src_buf, unsigned long src_size,
                        if (cmd & 0x20) cp_size |= (*data++ << 8);
                        if (cmd & 0x40) cp_size |= (*data++ << 16);
                        if (cp_size == 0) cp_size = 0x10000;
-                       memcpy(out, src_buf + cp_off, cp_size);
+                       if (cp_off + cp_size < cp_size ||
+                           cp_off + cp_size > src_size ||
+                           cp_size > size)
+                               break;
+                       memcpy(out, (char *) src_buf + cp_off, cp_size);
                        out += cp_size;
-               } else {
+                       size -= cp_size;
+               } else if (cmd) {
+                       if (cmd > size)
+                               break;
                        memcpy(out, data, cmd);
                        out += cmd;
                        data += cmd;
+                       size -= cmd;
+               } else {
+                       /*
+                        * cmd == 0 is reserved for future encoding
+                        * extensions. In the mean time we must fail when
+                        * encountering them (might be data corruption).
+                        */
+                       error("unexpected delta opcode 0");
+                       goto bad;
                }
        }
 
        /* sanity check */
-       if (data != top || out - dst_buf != size) {
+       if (data != top || size != 0) {
+               error("delta replay has gone wild");
+               bad:
                free(dst_buf);
                return NULL;
        }
 
-       *dst_size = size;
+       *dst_size = out - dst_buf;
        return dst_buf;
 }