git/builtin/rerere.c
Jeff King 3efb988098 react to errors in xdi_diff
When we call into xdiff to perform a diff, we generally lose
the return code completely. Typically by ignoring the return
of our xdi_diff wrapper, but sometimes we even propagate
that return value up and then ignore it later.  This can
lead to us silently producing incorrect diffs (e.g., "git
log" might produce no output at all, not even a diff header,
for a content-level diff).

In practice this does not happen very often, because the
typical reason for xdiff to report failure is that it
malloc() failed (it uses straight malloc, and not our
xmalloc wrapper).  But it could also happen when xdiff
triggers one our callbacks, which returns an error (e.g.,
outf() in builtin/rerere.c tries to report a write failure
in this way). And the next patch also plans to add more
failure modes.

Let's notice an error return from xdiff and react
appropriately. In most of the diff.c code, we can simply
die(), which matches the surrounding code (e.g., that is
what we do if we fail to load a file for diffing in the
first place). This is not that elegant, but we are probably
better off dying to let the user know there was a problem,
rather than simply generating bogus output.

We could also just die() directly in xdi_diff, but the
callers typically have a bit more context, and can provide a
better message (and if we do later decide to pass errors up,
we're one step closer to doing so).

There is one interesting case, which is in diff_grep(). Here
if we cannot generate the diff, there is nothing to match,
and we silently return "no hits". This is actually what the
existing code does already, but we make it a little more
explicit.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-09-28 14:57:10 -07:00

117 lines
2.9 KiB
C

#include "builtin.h"
#include "cache.h"
#include "dir.h"
#include "parse-options.h"
#include "string-list.h"
#include "rerere.h"
#include "xdiff/xdiff.h"
#include "xdiff-interface.h"
#include "pathspec.h"
static const char * const rerere_usage[] = {
N_("git rerere [clear | forget path... | status | remaining | diff | gc]"),
NULL,
};
static int outf(void *dummy, mmbuffer_t *ptr, int nbuf)
{
int i;
for (i = 0; i < nbuf; i++)
if (write_in_full(1, ptr[i].ptr, ptr[i].size) != ptr[i].size)
return -1;
return 0;
}
static int diff_two(const char *file1, const char *label1,
const char *file2, const char *label2)
{
xpparam_t xpp;
xdemitconf_t xecfg;
xdemitcb_t ecb;
mmfile_t minus, plus;
int ret;
if (read_mmfile(&minus, file1) || read_mmfile(&plus, file2))
return -1;
printf("--- a/%s\n+++ b/%s\n", label1, label2);
fflush(stdout);
memset(&xpp, 0, sizeof(xpp));
xpp.flags = 0;
memset(&xecfg, 0, sizeof(xecfg));
xecfg.ctxlen = 3;
ecb.outf = outf;
ret = xdi_diff(&minus, &plus, &xpp, &xecfg, &ecb);
free(minus.ptr);
free(plus.ptr);
return ret;
}
int cmd_rerere(int argc, const char **argv, const char *prefix)
{
struct string_list merge_rr = STRING_LIST_INIT_DUP;
int i, fd, autoupdate = -1, flags = 0;
struct option options[] = {
OPT_SET_INT(0, "rerere-autoupdate", &autoupdate,
N_("register clean resolutions in index"), 1),
OPT_END(),
};
argc = parse_options(argc, argv, prefix, options, rerere_usage, 0);
git_config(git_xmerge_config, NULL);
if (autoupdate == 1)
flags = RERERE_AUTOUPDATE;
if (autoupdate == 0)
flags = RERERE_NOAUTOUPDATE;
if (argc < 1)
return rerere(flags);
if (!strcmp(argv[0], "forget")) {
struct pathspec pathspec;
if (argc < 2)
warning("'git rerere forget' without paths is deprecated");
parse_pathspec(&pathspec, 0, PATHSPEC_PREFER_CWD,
prefix, argv + 1);
return rerere_forget(&pathspec);
}
fd = setup_rerere(&merge_rr, flags);
if (fd < 0)
return 0;
if (!strcmp(argv[0], "clear")) {
rerere_clear(&merge_rr);
} else if (!strcmp(argv[0], "gc"))
rerere_gc(&merge_rr);
else if (!strcmp(argv[0], "status"))
for (i = 0; i < merge_rr.nr; i++)
printf("%s\n", merge_rr.items[i].string);
else if (!strcmp(argv[0], "remaining")) {
rerere_remaining(&merge_rr);
for (i = 0; i < merge_rr.nr; i++) {
if (merge_rr.items[i].util != RERERE_RESOLVED)
printf("%s\n", merge_rr.items[i].string);
else
/* prepare for later call to
* string_list_clear() */
merge_rr.items[i].util = NULL;
}
} else if (!strcmp(argv[0], "diff"))
for (i = 0; i < merge_rr.nr; i++) {
const char *path = merge_rr.items[i].string;
const char *name = (const char *)merge_rr.items[i].util;
if (diff_two(rerere_path(name, "preimage"), path, path, path))
die("unable to generate diff for %s", name);
}
else
usage_with_options(rerere_usage, options);
string_list_clear(&merge_rr, 1);
return 0;
}