0660626caf
This updates the user interface and generated diff data format. * "diff --binary" is used to signal that we want an e-mailable binary patch. It implies --full-index and -p. * "apply --allow-binary-replacement" acquired a short synonym "apply --binary". * After the "GIT binary patch\n" header line there is a token to record which binary patch mechanism was used, so that we can extend it later. Currently there are two mechanisms defined: "literal" and "delta". The former records the deflated postimage and the latter records the deflated delta from the preimage to postimage. For purely implementation convenience, I added the deflated length after these "literal/delta" tokens (otherwise the decoding side needs to guess and reallocate the buffer while inflating). Improvement patches are very welcomed. Signed-off-by: Junio C Hamano <junkio@cox.net>
135 lines
2.8 KiB
C
135 lines
2.8 KiB
C
#include "cache.h"
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#undef DEBUG_85
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#ifdef DEBUG_85
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#define say(a) fprintf(stderr, a)
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#define say1(a,b) fprintf(stderr, a, b)
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#define say2(a,b,c) fprintf(stderr, a, b, c)
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#else
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#define say(a) do {} while(0)
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#define say1(a,b) do {} while(0)
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#define say2(a,b,c) do {} while(0)
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#endif
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static const char en85[] = {
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'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
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'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J',
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'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
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'U', 'V', 'W', 'X', 'Y', 'Z',
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'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',
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'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't',
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'u', 'v', 'w', 'x', 'y', 'z',
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'!', '#', '$', '%', '&', '(', ')', '*', '+', '-',
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';', '<', '=', '>', '?', '@', '^', '_', '`', '{',
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'|', '}', '~'
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};
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static char de85[256];
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static void prep_base85(void)
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{
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int i;
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if (de85['Z'])
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return;
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for (i = 0; i < ARRAY_SIZE(en85); i++) {
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int ch = en85[i];
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de85[ch] = i + 1;
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}
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}
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int decode_85(char *dst, char *buffer, int len)
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{
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prep_base85();
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say2("decode 85 <%.*s>", len/4*5, buffer);
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while (len) {
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unsigned acc = 0;
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int cnt;
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for (cnt = 0; cnt < 5; cnt++, buffer++) {
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int ch = *((unsigned char *)buffer);
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int de = de85[ch];
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if (!de)
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return error("invalid base85 alphabet %c", ch);
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de--;
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if (cnt == 4) {
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/*
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* Detect overflow. The largest
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* 5-letter possible is "|NsC0" to
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* encode 0xffffffff, and "|NsC" gives
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* 0x03030303 at this point (i.e.
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* 0xffffffff = 0x03030303 * 85).
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*/
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if (0x03030303 < acc ||
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(0x03030303 == acc && de))
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error("invalid base85 sequence %.5s",
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buffer-3);
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}
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acc = acc * 85 + de;
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say1(" <%08x>", acc);
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}
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say1(" %08x", acc);
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for (cnt = 0; cnt < 4 && len; cnt++, len--) {
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*dst++ = (acc >> 24) & 0xff;
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acc = acc << 8;
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}
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}
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say("\n");
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return 0;
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}
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void encode_85(char *buf, unsigned char *data, int bytes)
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{
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prep_base85();
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say("encode 85");
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while (bytes) {
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unsigned acc = 0;
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int cnt;
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for (cnt = 0; cnt < 4 && bytes; cnt++, bytes--) {
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int ch = *data++;
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acc |= ch << ((3-cnt)*8);
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}
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say1(" %08x", acc);
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for (cnt = 0; cnt < 5; cnt++) {
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int val = acc % 85;
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acc /= 85;
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buf[4-cnt] = en85[val];
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}
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buf += 5;
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}
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say("\n");
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*buf = 0;
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}
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#ifdef DEBUG_85
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int main(int ac, char **av)
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{
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char buf[1024];
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if (!strcmp(av[1], "-e")) {
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int len = strlen(av[2]);
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encode_85(buf, av[2], len);
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if (len <= 26) len = len + 'A' - 1;
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else len = len + 'a' - 26 + 1;
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printf("encoded: %c%s\n", len, buf);
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return 0;
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}
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if (!strcmp(av[1], "-d")) {
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int len = *av[2];
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if ('A' <= len && len <= 'Z') len = len - 'A' + 1;
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else len = len - 'a' + 26 + 1;
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decode_85(buf, av[2]+1, len);
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printf("decoded: %.*s\n", len, buf);
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return 0;
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}
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if (!strcmp(av[1], "-t")) {
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char t[4] = { -1,-1,-1,-1 };
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encode_85(buf, t, 4);
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printf("encoded: D%s\n", buf);
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return 0;
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}
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}
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#endif
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