| /* |
| * patch-delta.c: |
| * recreate a buffer from a source and the delta produced by diff-delta.c |
| * |
| * (C) 2005 Nicolas Pitre <nico@fluxnic.net> |
| * |
| * This code is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License version 2 as |
| * published by the Free Software Foundation. |
| */ |
| |
| #include "git-compat-util.h" |
| #include "delta.h" |
| |
| 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; |
| unsigned char *dst_buf, *out, cmd; |
| unsigned long size; |
| |
| if (delta_size < DELTA_SIZE_MIN) |
| return NULL; |
| |
| data = delta_buf; |
| top = (const unsigned char *) delta_buf + delta_size; |
| |
| /* make sure the orig file size matches what we expect */ |
| size = get_delta_hdr_size(&data, top); |
| if (size != src_size) |
| return NULL; |
| |
| /* now the result size */ |
| size = get_delta_hdr_size(&data, top); |
| dst_buf = xmallocz(size); |
| |
| out = dst_buf; |
| while (data < top) { |
| cmd = *data++; |
| if (cmd & 0x80) { |
| unsigned long cp_off = 0, cp_size = 0; |
| if (cmd & 0x01) cp_off = *data++; |
| if (cmd & 0x02) cp_off |= (*data++ << 8); |
| if (cmd & 0x04) cp_off |= (*data++ << 16); |
| if (cmd & 0x08) cp_off |= ((unsigned) *data++ << 24); |
| if (cmd & 0x10) cp_size = *data++; |
| if (cmd & 0x20) cp_size |= (*data++ << 8); |
| if (cmd & 0x40) cp_size |= (*data++ << 16); |
| if (cp_size == 0) cp_size = 0x10000; |
| if (unsigned_add_overflows(cp_off, cp_size) || |
| cp_off + cp_size > src_size || |
| cp_size > size) |
| break; |
| memcpy(out, (char *) src_buf + cp_off, cp_size); |
| out += cp_size; |
| 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 || size != 0) { |
| error("delta replay has gone wild"); |
| bad: |
| free(dst_buf); |
| return NULL; |
| } |
| |
| *dst_size = out - dst_buf; |
| return dst_buf; |
| } |