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![Linus Torvalds](/assets/img/avatar_default.png)
The tar-ball and the git archive itself is fine, but yes, the diff from 2.6.23 to 2.6.24-rc6 is bad. It's the "trim_common_tail()" optimization that has caused way too much pain. Very interesting breakage. The patch was actually "correct" in a (rather limited) technical sense, but the context at the end was missing because while the trim_common_tail() code made sure to keep enough common context to allow a valid diff to be generated, the diff machinery itself could decide that it could generate the diff differently than the "obvious" solution. Thee sad fact is that the git optimization (which is very important for "git blame", which needs no context), is only really valid for that one case where we really don't need any context. [jc: since this is shared with "git diff -U0" codepath, context recovery to the end of line needs to be done even for zero context case.] Signed-off-by: Junio C Hamano <gitster@pobox.com>
241 lines
5.3 KiB
C
241 lines
5.3 KiB
C
#include "cache.h"
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#include "xdiff-interface.h"
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static int parse_num(char **cp_p, int *num_p)
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{
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char *cp = *cp_p;
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int num = 0;
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int read_some;
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while ('0' <= *cp && *cp <= '9')
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num = num * 10 + *cp++ - '0';
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if (!(read_some = cp - *cp_p))
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return -1;
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*cp_p = cp;
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*num_p = num;
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return 0;
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}
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int parse_hunk_header(char *line, int len,
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int *ob, int *on,
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int *nb, int *nn)
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{
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char *cp;
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cp = line + 4;
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if (parse_num(&cp, ob)) {
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bad_line:
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return error("malformed diff output: %s", line);
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}
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if (*cp == ',') {
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cp++;
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if (parse_num(&cp, on))
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goto bad_line;
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}
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else
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*on = 1;
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if (*cp++ != ' ' || *cp++ != '+')
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goto bad_line;
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if (parse_num(&cp, nb))
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goto bad_line;
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if (*cp == ',') {
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cp++;
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if (parse_num(&cp, nn))
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goto bad_line;
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}
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else
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*nn = 1;
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return -!!memcmp(cp, " @@", 3);
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}
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static void consume_one(void *priv_, char *s, unsigned long size)
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{
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struct xdiff_emit_state *priv = priv_;
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char *ep;
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while (size) {
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unsigned long this_size;
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ep = memchr(s, '\n', size);
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this_size = (ep == NULL) ? size : (ep - s + 1);
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priv->consume(priv, s, this_size);
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size -= this_size;
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s += this_size;
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}
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}
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int xdiff_outf(void *priv_, mmbuffer_t *mb, int nbuf)
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{
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struct xdiff_emit_state *priv = priv_;
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int i;
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for (i = 0; i < nbuf; i++) {
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if (mb[i].ptr[mb[i].size-1] != '\n') {
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/* Incomplete line */
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priv->remainder = xrealloc(priv->remainder,
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priv->remainder_size +
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mb[i].size);
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memcpy(priv->remainder + priv->remainder_size,
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mb[i].ptr, mb[i].size);
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priv->remainder_size += mb[i].size;
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continue;
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}
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/* we have a complete line */
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if (!priv->remainder) {
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consume_one(priv, mb[i].ptr, mb[i].size);
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continue;
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}
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priv->remainder = xrealloc(priv->remainder,
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priv->remainder_size +
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mb[i].size);
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memcpy(priv->remainder + priv->remainder_size,
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mb[i].ptr, mb[i].size);
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consume_one(priv, priv->remainder,
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priv->remainder_size + mb[i].size);
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free(priv->remainder);
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priv->remainder = NULL;
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priv->remainder_size = 0;
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}
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if (priv->remainder) {
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consume_one(priv, priv->remainder, priv->remainder_size);
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free(priv->remainder);
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priv->remainder = NULL;
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priv->remainder_size = 0;
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}
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return 0;
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}
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/*
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* Trim down common substring at the end of the buffers,
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* but leave at least ctx lines at the end.
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*/
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static void trim_common_tail(mmfile_t *a, mmfile_t *b, long ctx)
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{
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const int blk = 1024;
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long trimmed = 0, recovered = 0;
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char *ap = a->ptr + a->size;
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char *bp = b->ptr + b->size;
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long smaller = (a->size < b->size) ? a->size : b->size;
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if (ctx)
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return;
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while (blk + trimmed <= smaller && !memcmp(ap - blk, bp - blk, blk)) {
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trimmed += blk;
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ap -= blk;
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bp -= blk;
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}
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while (recovered < trimmed)
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if (ap[recovered++] == '\n')
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break;
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a->size -= trimmed - recovered;
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b->size -= trimmed - recovered;
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}
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int xdi_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp, xdemitconf_t const *xecfg, xdemitcb_t *xecb)
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{
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mmfile_t a = *mf1;
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mmfile_t b = *mf2;
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trim_common_tail(&a, &b, xecfg->ctxlen);
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return xdl_diff(&a, &b, xpp, xecfg, xecb);
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}
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int read_mmfile(mmfile_t *ptr, const char *filename)
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{
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struct stat st;
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FILE *f;
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size_t sz;
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if (stat(filename, &st))
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return error("Could not stat %s", filename);
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if ((f = fopen(filename, "rb")) == NULL)
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return error("Could not open %s", filename);
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sz = xsize_t(st.st_size);
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ptr->ptr = xmalloc(sz);
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if (fread(ptr->ptr, sz, 1, f) != 1)
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return error("Could not read %s", filename);
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fclose(f);
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ptr->size = sz;
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return 0;
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}
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#define FIRST_FEW_BYTES 8000
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int buffer_is_binary(const char *ptr, unsigned long size)
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{
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if (FIRST_FEW_BYTES < size)
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size = FIRST_FEW_BYTES;
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return !!memchr(ptr, 0, size);
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}
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struct ff_regs {
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int nr;
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struct ff_reg {
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regex_t re;
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int negate;
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} *array;
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};
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static long ff_regexp(const char *line, long len,
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char *buffer, long buffer_size, void *priv)
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{
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char *line_buffer = xstrndup(line, len); /* make NUL terminated */
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struct ff_regs *regs = priv;
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regmatch_t pmatch[2];
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int result = 0, i;
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for (i = 0; i < regs->nr; i++) {
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struct ff_reg *reg = regs->array + i;
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if (reg->negate ^ !!regexec(®->re,
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line_buffer, 2, pmatch, 0)) {
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free(line_buffer);
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return -1;
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}
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}
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i = pmatch[1].rm_so >= 0 ? 1 : 0;
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line += pmatch[i].rm_so;
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result = pmatch[i].rm_eo - pmatch[i].rm_so;
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if (result > buffer_size)
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result = buffer_size;
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else
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while (result > 0 && (isspace(line[result - 1]) ||
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line[result - 1] == '\n'))
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result--;
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memcpy(buffer, line, result);
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free(line_buffer);
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return result;
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}
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void xdiff_set_find_func(xdemitconf_t *xecfg, const char *value)
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{
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int i;
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struct ff_regs *regs;
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xecfg->find_func = ff_regexp;
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regs = xecfg->find_func_priv = xmalloc(sizeof(struct ff_regs));
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for (i = 0, regs->nr = 1; value[i]; i++)
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if (value[i] == '\n')
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regs->nr++;
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regs->array = xmalloc(regs->nr * sizeof(struct ff_reg));
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for (i = 0; i < regs->nr; i++) {
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struct ff_reg *reg = regs->array + i;
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const char *ep = strchr(value, '\n'), *expression;
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char *buffer = NULL;
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reg->negate = (*value == '!');
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if (reg->negate && i == regs->nr - 1)
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die("Last expression must not be negated: %s", value);
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if (*value == '!')
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value++;
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if (ep)
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expression = buffer = xstrndup(value, ep - value);
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else
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expression = value;
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if (regcomp(®->re, expression, 0))
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die("Invalid regexp to look for hunk header: %s", expression);
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if (buffer)
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free(buffer);
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value = ep + 1;
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}
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}
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