git/diffcore-pickaxe.c
Jeff King e1b161161d diffcore-pickaxe: fix infinite loop on zero-length needle
The "contains" algorithm runs into an infinite loop if the needle string
has zero length. The loop could be modified to handle this, but it makes
more sense to simply have an empty needle return no matches. Thus, a
command like
  git log -S
produces no output.

We place the check at the top of the function so that we get the same
results with or without --pickaxe-regex. Note that until now,
  git log -S --pickaxe-regex
would match everything, not nothing.

Arguably, an empty pickaxe string should simply produce an error
message; however, this is still a useful assertion to add to the
algorithm at this layer of the code.

Noticed by Bill Lear.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2007-01-25 21:17:19 -08:00

139 lines
3.2 KiB
C

/*
* Copyright (C) 2005 Junio C Hamano
*/
#include "cache.h"
#include "diff.h"
#include "diffcore.h"
static unsigned int contains(struct diff_filespec *one,
const char *needle, unsigned long len,
regex_t *regexp)
{
unsigned int cnt;
unsigned long offset, sz;
const char *data;
if (diff_populate_filespec(one, 0))
return 0;
if (!len)
return 0;
sz = one->size;
data = one->data;
cnt = 0;
if (regexp) {
regmatch_t regmatch;
int flags = 0;
while (*data && !regexec(regexp, data, 1, &regmatch, flags)) {
flags |= REG_NOTBOL;
data += regmatch.rm_so;
if (*data) data++;
cnt++;
}
} else { /* Classic exact string match */
/* Yes, I've heard of strstr(), but the thing is *data may
* not be NUL terminated. Sue me.
*/
for (offset = 0; offset + len <= sz; offset++) {
/* we count non-overlapping occurrences of needle */
if (!memcmp(needle, data + offset, len)) {
offset += len - 1;
cnt++;
}
}
}
return cnt;
}
void diffcore_pickaxe(const char *needle, int opts)
{
struct diff_queue_struct *q = &diff_queued_diff;
unsigned long len = strlen(needle);
int i, has_changes;
regex_t regex, *regexp = NULL;
struct diff_queue_struct outq;
outq.queue = NULL;
outq.nr = outq.alloc = 0;
if (opts & DIFF_PICKAXE_REGEX) {
int err;
err = regcomp(&regex, needle, REG_EXTENDED | REG_NEWLINE);
if (err) {
/* The POSIX.2 people are surely sick */
char errbuf[1024];
regerror(err, &regex, errbuf, 1024);
regfree(&regex);
die("invalid pickaxe regex: %s", errbuf);
}
regexp = &regex;
}
if (opts & DIFF_PICKAXE_ALL) {
/* Showing the whole changeset if needle exists */
for (i = has_changes = 0; !has_changes && i < q->nr; i++) {
struct diff_filepair *p = q->queue[i];
if (!DIFF_FILE_VALID(p->one)) {
if (!DIFF_FILE_VALID(p->two))
continue; /* ignore unmerged */
/* created */
if (contains(p->two, needle, len, regexp))
has_changes++;
}
else if (!DIFF_FILE_VALID(p->two)) {
if (contains(p->one, needle, len, regexp))
has_changes++;
}
else if (!diff_unmodified_pair(p) &&
contains(p->one, needle, len, regexp) !=
contains(p->two, needle, len, regexp))
has_changes++;
}
if (has_changes)
return; /* not munge the queue */
/* otherwise we will clear the whole queue
* by copying the empty outq at the end of this
* function, but first clear the current entries
* in the queue.
*/
for (i = 0; i < q->nr; i++)
diff_free_filepair(q->queue[i]);
}
else
/* Showing only the filepairs that has the needle */
for (i = 0; i < q->nr; i++) {
struct diff_filepair *p = q->queue[i];
has_changes = 0;
if (!DIFF_FILE_VALID(p->one)) {
if (!DIFF_FILE_VALID(p->two))
; /* ignore unmerged */
/* created */
else if (contains(p->two, needle, len, regexp))
has_changes = 1;
}
else if (!DIFF_FILE_VALID(p->two)) {
if (contains(p->one, needle, len, regexp))
has_changes = 1;
}
else if (!diff_unmodified_pair(p) &&
contains(p->one, needle, len, regexp) !=
contains(p->two, needle, len, regexp))
has_changes = 1;
if (has_changes)
diff_q(&outq, p);
else
diff_free_filepair(p);
}
if (opts & DIFF_PICKAXE_REGEX) {
regfree(&regex);
}
free(q->queue);
*q = outq;
return;
}