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87 lines
2.2 KiB
87 lines
2.2 KiB
/* |
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* patch-delta.c: |
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* recreate a buffer from a source and the delta produced by diff-delta.c |
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* |
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* (C) 2005 Nicolas Pitre <nico@fluxnic.net> |
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* |
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* This code is free software; you can redistribute it and/or modify |
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* it under the terms of the GNU General Public License version 2 as |
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* published by the Free Software Foundation. |
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*/ |
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#include "git-compat-util.h" |
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#include "delta.h" |
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void *patch_delta(const void *src_buf, unsigned long src_size, |
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const void *delta_buf, unsigned long delta_size, |
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unsigned long *dst_size) |
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{ |
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const unsigned char *data, *top; |
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unsigned char *dst_buf, *out, cmd; |
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unsigned long size; |
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if (delta_size < DELTA_SIZE_MIN) |
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return NULL; |
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data = delta_buf; |
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top = (const unsigned char *) delta_buf + delta_size; |
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/* make sure the orig file size matches what we expect */ |
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size = get_delta_hdr_size(&data, top); |
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if (size != src_size) |
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return NULL; |
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/* now the result size */ |
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size = get_delta_hdr_size(&data, top); |
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dst_buf = xmalloc(size + 1); |
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dst_buf[size] = 0; |
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out = dst_buf; |
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while (data < top) { |
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cmd = *data++; |
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if (cmd & 0x80) { |
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unsigned long cp_off = 0, cp_size = 0; |
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if (cmd & 0x01) cp_off = *data++; |
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if (cmd & 0x02) cp_off |= (*data++ << 8); |
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if (cmd & 0x04) cp_off |= (*data++ << 16); |
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if (cmd & 0x08) cp_off |= ((unsigned) *data++ << 24); |
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if (cmd & 0x10) cp_size = *data++; |
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if (cmd & 0x20) cp_size |= (*data++ << 8); |
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if (cmd & 0x40) cp_size |= (*data++ << 16); |
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if (cp_size == 0) cp_size = 0x10000; |
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if (cp_off + cp_size < cp_size || |
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cp_off + cp_size > src_size || |
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cp_size > size) |
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break; |
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memcpy(out, (char *) src_buf + cp_off, cp_size); |
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out += cp_size; |
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size -= cp_size; |
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} else if (cmd) { |
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if (cmd > size) |
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break; |
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memcpy(out, data, cmd); |
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out += cmd; |
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data += cmd; |
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size -= cmd; |
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} else { |
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/* |
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* cmd == 0 is reserved for future encoding |
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* extensions. In the mean time we must fail when |
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* encountering them (might be data corruption). |
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*/ |
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error("unexpected delta opcode 0"); |
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goto bad; |
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} |
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} |
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/* sanity check */ |
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if (data != top || size != 0) { |
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error("delta replay has gone wild"); |
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bad: |
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free(dst_buf); |
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return NULL; |
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} |
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*dst_size = out - dst_buf; |
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return dst_buf; |
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}
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