+static int parse_binary(char *buffer, unsigned long size, struct patch *patch)
+{
+ /* We have read "GIT binary patch\n"; what follows is a
+ * sequence of 'length-byte' followed by base-85 encoded
+ * delta data.
+ *
+ * Each 5-byte sequence of base-85 encodes up to 4 bytes,
+ * and we would limit the patch line to 66 characters,
+ * so one line can fit up to 13 groups that would decode
+ * to 52 bytes max. The length byte 'A'-'Z' corresponds
+ * to 1-26 bytes, and 'a'-'z' corresponds to 27-52 bytes.
+ * The end of binary is signalled with an empty line.
+ */
+ int llen, used;
+ struct fragment *fragment;
+ char *delta = NULL;
+
+ patch->is_binary = 1;
+ patch->fragments = fragment = xcalloc(1, sizeof(*fragment));
+ used = 0;
+ while (1) {
+ int byte_length, max_byte_length, newsize;
+ llen = linelen(buffer, size);
+ used += llen;
+ linenr++;
+ if (llen == 1)
+ break;
+ /* Minimum line is "A00000\n" which is 7-byte long,
+ * and the line length must be multiple of 5 plus 2.
+ */
+ if ((llen < 7) || (llen-2) % 5)
+ goto corrupt;
+ max_byte_length = (llen - 2) / 5 * 4;
+ byte_length = *buffer;
+ if ('A' <= byte_length && byte_length <= 'Z')
+ byte_length = byte_length - 'A' + 1;
+ else if ('a' <= byte_length && byte_length <= 'z')
+ byte_length = byte_length - 'a' + 27;
+ else
+ goto corrupt;
+ /* if the input length was not multiple of 4, we would
+ * have filler at the end but the filler should never
+ * exceed 3 bytes
+ */
+ if (max_byte_length < byte_length ||
+ byte_length <= max_byte_length - 4)
+ goto corrupt;
+ newsize = fragment->size + byte_length;
+ delta = xrealloc(delta, newsize);
+ if (decode_85(delta + fragment->size,
+ buffer + 1,
+ byte_length))
+ goto corrupt;
+ fragment->size = newsize;
+ buffer += llen;
+ size -= llen;
+ }
+ fragment->patch = delta;
+ return used;
+ corrupt:
+ return error("corrupt binary patch at line %d: %.*s",
+ linenr-1, llen-1, buffer);
+}
+