git/builtin/merge-file.c
Jeff King e34f80278e merge-file: clamp exit code to maximum 127
Git-merge-file is documented to return one of three exit
codes:

  - zero means the merge was successful

  - a negative number means an error occurred

  - a positive number indicates the number of conflicts

Unfortunately, this all gets stuffed into an 8-bit return
code. Which means that if you have 256 conflicts, this wraps
to zero, and the merge appears to succeed (and commits a
blob full of conflict-marker cruft!).

This patch clamps the return value to a maximum of 127,
which we should be able to safely represent everywhere. This
also leaves 128-255 for other values. Shells (and some parts
of git) will typically represent signal death as 128 plus
the signal number. And negative values are typically coerced
to an 8-bit unsigned value (so "return -1" ends up as 255).

Technically negative returns have the same problem (e.g.,
"-256" wraps back to 0), but this is not a problem in
practice, as the only negative value we use is "-1".

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2015-10-29 12:10:23 -07:00

110 lines
3.0 KiB
C

#include "builtin.h"
#include "cache.h"
#include "xdiff/xdiff.h"
#include "xdiff-interface.h"
#include "parse-options.h"
static const char *const merge_file_usage[] = {
N_("git merge-file [options] [-L name1 [-L orig [-L name2]]] file1 orig_file file2"),
NULL
};
static int label_cb(const struct option *opt, const char *arg, int unset)
{
static int label_count = 0;
const char **names = (const char **)opt->value;
if (label_count >= 3)
return error("too many labels on the command line");
names[label_count++] = arg;
return 0;
}
int cmd_merge_file(int argc, const char **argv, const char *prefix)
{
const char *names[3] = { NULL, NULL, NULL };
mmfile_t mmfs[3];
mmbuffer_t result = {NULL, 0};
xmparam_t xmp = {{0}};
int ret = 0, i = 0, to_stdout = 0;
int quiet = 0;
int prefixlen = 0;
struct option options[] = {
OPT_BOOL('p', "stdout", &to_stdout, N_("send results to standard output")),
OPT_SET_INT(0, "diff3", &xmp.style, N_("use a diff3 based merge"), XDL_MERGE_DIFF3),
OPT_SET_INT(0, "ours", &xmp.favor, N_("for conflicts, use our version"),
XDL_MERGE_FAVOR_OURS),
OPT_SET_INT(0, "theirs", &xmp.favor, N_("for conflicts, use their version"),
XDL_MERGE_FAVOR_THEIRS),
OPT_SET_INT(0, "union", &xmp.favor, N_("for conflicts, use a union version"),
XDL_MERGE_FAVOR_UNION),
OPT_INTEGER(0, "marker-size", &xmp.marker_size,
N_("for conflicts, use this marker size")),
OPT__QUIET(&quiet, N_("do not warn about conflicts")),
OPT_CALLBACK('L', NULL, names, N_("name"),
N_("set labels for file1/orig_file/file2"), &label_cb),
OPT_END(),
};
xmp.level = XDL_MERGE_ZEALOUS_ALNUM;
xmp.style = 0;
xmp.favor = 0;
if (startup_info->have_repository) {
/* Read the configuration file */
git_config(git_xmerge_config, NULL);
if (0 <= git_xmerge_style)
xmp.style = git_xmerge_style;
}
argc = parse_options(argc, argv, prefix, options, merge_file_usage, 0);
if (argc != 3)
usage_with_options(merge_file_usage, options);
if (quiet) {
if (!freopen("/dev/null", "w", stderr))
return error("failed to redirect stderr to /dev/null: "
"%s", strerror(errno));
}
if (prefix)
prefixlen = strlen(prefix);
for (i = 0; i < 3; i++) {
const char *fname = prefix_filename(prefix, prefixlen, argv[i]);
if (!names[i])
names[i] = argv[i];
if (read_mmfile(mmfs + i, fname))
return -1;
if (buffer_is_binary(mmfs[i].ptr, mmfs[i].size))
return error("Cannot merge binary files: %s",
argv[i]);
}
xmp.ancestor = names[1];
xmp.file1 = names[0];
xmp.file2 = names[2];
ret = xdl_merge(mmfs + 1, mmfs + 0, mmfs + 2, &xmp, &result);
for (i = 0; i < 3; i++)
free(mmfs[i].ptr);
if (ret >= 0) {
const char *filename = argv[0];
FILE *f = to_stdout ? stdout : fopen(filename, "wb");
if (!f)
ret = error("Could not open %s for writing", filename);
else if (result.size &&
fwrite(result.ptr, result.size, 1, f) != 1)
ret = error("Could not write to %s", filename);
else if (fclose(f))
ret = error("Could not close %s", filename);
free(result.ptr);
}
if (ret > 127)
ret = 127;
return ret;
}