git/diff.c
Junio C Hamano 915838c3cb [PATCH] Diff-helper update
This patch adds a framework and a stub implementation of rename
detection to diff-helper program.

The current stub code is just enough to detect pure renames in
diff-tree output and not fancier.  The plan is perhaps to use
the same delta code when Nico's delta storage patch is merged
for similarity evaluation purposes.

Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-05-18 11:16:24 -07:00

419 lines
10 KiB
C

/*
* Copyright (C) 2005 Junio C Hamano
*/
#include <sys/types.h>
#include <sys/wait.h>
#include <signal.h>
#include <limits.h>
#include "cache.h"
#include "diff.h"
static const char *diff_opts = "-pu";
static const char *external_diff(void)
{
static const char *external_diff_cmd = NULL;
static int done_preparing = 0;
if (done_preparing)
return external_diff_cmd;
/*
* Default values above are meant to match the
* Linux kernel development style. Examples of
* alternative styles you can specify via environment
* variables are:
*
* GIT_DIFF_OPTS="-c";
*/
if (gitenv("GIT_EXTERNAL_DIFF"))
external_diff_cmd = gitenv("GIT_EXTERNAL_DIFF");
/* In case external diff fails... */
diff_opts = gitenv("GIT_DIFF_OPTS") ? : diff_opts;
done_preparing = 1;
return external_diff_cmd;
}
/* Help to copy the thing properly quoted for the shell safety.
* any single quote is replaced with '\'', and the caller is
* expected to enclose the result within a single quote pair.
*
* E.g.
* original sq_expand result
* name ==> name ==> 'name'
* a b ==> a b ==> 'a b'
* a'b ==> a'\''b ==> 'a'\''b'
*/
static char *sq_expand(const char *src)
{
static char *buf = NULL;
int cnt, c;
const char *cp;
char *bp;
/* count bytes needed to store the quoted string. */
for (cnt = 1, cp = src; *cp; cnt++, cp++)
if (*cp == '\'')
cnt += 3;
buf = xmalloc(cnt);
bp = buf;
while ((c = *src++)) {
if (c != '\'')
*bp++ = c;
else {
bp = strcpy(bp, "'\\''");
bp += 4;
}
}
*bp = 0;
return buf;
}
static struct diff_tempfile {
const char *name;
char hex[41];
char mode[10];
char tmp_path[50];
} diff_temp[2];
static void builtin_diff(const char *name_a,
const char *name_b,
struct diff_tempfile *temp)
{
int i, next_at;
const char *diff_cmd = "diff -L'%s%s' -L'%s%s'";
const char *diff_arg = "'%s' '%s'||:"; /* "||:" is to return 0 */
const char *input_name_sq[2];
const char *path0[2];
const char *path1[2];
const char *name_sq[2];
char *cmd;
name_sq[0] = sq_expand(name_a);
name_sq[1] = sq_expand(name_b);
/* diff_cmd and diff_arg have 6 %s in total which makes
* the sum of these strings 12 bytes larger than required.
* we use 2 spaces around diff-opts, and we need to count
* terminating NUL, so we subtract 9 here.
*/
int cmd_size = (strlen(diff_cmd) + strlen(diff_opts) +
strlen(diff_arg) - 9);
for (i = 0; i < 2; i++) {
input_name_sq[i] = sq_expand(temp[i].name);
if (!strcmp(temp[i].name, "/dev/null")) {
path0[i] = "/dev/null";
path1[i] = "";
} else {
path0[i] = i ? "b/" : "a/";
path1[i] = name_sq[i];
}
cmd_size += (strlen(path0[i]) + strlen(path1[i]) +
strlen(input_name_sq[i]));
}
cmd = xmalloc(cmd_size);
next_at = 0;
next_at += snprintf(cmd+next_at, cmd_size-next_at,
diff_cmd,
path0[0], path1[0], path0[1], path1[1]);
next_at += snprintf(cmd+next_at, cmd_size-next_at,
" %s ", diff_opts);
next_at += snprintf(cmd+next_at, cmd_size-next_at,
diff_arg, input_name_sq[0], input_name_sq[1]);
printf("diff --git a/%s b/%s\n", name_a, name_b);
if (!path1[0][0])
printf("new file mode %s\n", temp[1].mode);
else if (!path1[1][0])
printf("deleted file mode %s\n", temp[0].mode);
else {
if (strcmp(temp[0].mode, temp[1].mode)) {
printf("old mode %s\n", temp[0].mode);
printf("new mode %s\n", temp[1].mode);
}
if (strcmp(name_a, name_b)) {
printf("rename old %s\n", name_a);
printf("rename new %s\n", name_b);
}
if (strncmp(temp[0].mode, temp[1].mode, 3))
/* we do not run diff between different kind
* of objects.
*/
exit(0);
}
fflush(NULL);
execlp("/bin/sh","sh", "-c", cmd, NULL);
}
/*
* Given a name and sha1 pair, if the dircache tells us the file in
* the work tree has that object contents, return true, so that
* prepare_temp_file() does not have to inflate and extract.
*/
static int work_tree_matches(const char *name, const unsigned char *sha1)
{
struct cache_entry *ce;
struct stat st;
int pos, len;
/* We do not read the cache ourselves here, because the
* benchmark with my previous version that always reads cache
* shows that it makes things worse for diff-tree comparing
* two linux-2.6 kernel trees in an already checked out work
* tree. This is because most diff-tree comparisons deal with
* only a small number of files, while reading the cache is
* expensive for a large project, and its cost outweighs the
* savings we get by not inflating the object to a temporary
* file. Practically, this code only helps when we are used
* by diff-cache --cached, which does read the cache before
* calling us.
*/
if (!active_cache)
return 0;
len = strlen(name);
pos = cache_name_pos(name, len);
if (pos < 0)
return 0;
ce = active_cache[pos];
if ((lstat(name, &st) < 0) ||
!S_ISREG(st.st_mode) ||
ce_match_stat(ce, &st) ||
memcmp(sha1, ce->sha1, 20))
return 0;
return 1;
}
static void prep_temp_blob(struct diff_tempfile *temp,
void *blob,
unsigned long size,
unsigned char *sha1,
int mode)
{
int fd;
strcpy(temp->tmp_path, ".diff_XXXXXX");
fd = mkstemp(temp->tmp_path);
if (fd < 0)
die("unable to create temp-file");
if (write(fd, blob, size) != size)
die("unable to write temp-file");
close(fd);
temp->name = temp->tmp_path;
strcpy(temp->hex, sha1_to_hex(sha1));
temp->hex[40] = 0;
sprintf(temp->mode, "%06o", mode);
}
static void prepare_temp_file(const char *name,
struct diff_tempfile *temp,
struct diff_spec *one)
{
static unsigned char null_sha1[20] = { 0, };
int use_work_tree = 0;
if (!one->file_valid) {
not_a_valid_file:
/* A '-' entry produces this for file-2, and
* a '+' entry produces this for file-1.
*/
temp->name = "/dev/null";
strcpy(temp->hex, ".");
strcpy(temp->mode, ".");
return;
}
if (one->sha1_valid &&
(!memcmp(one->blob_sha1, null_sha1, sizeof(null_sha1)) ||
work_tree_matches(name, one->blob_sha1)))
use_work_tree = 1;
if (!one->sha1_valid || use_work_tree) {
struct stat st;
temp->name = name;
if (lstat(temp->name, &st) < 0) {
if (errno == ENOENT)
goto not_a_valid_file;
die("stat(%s): %s", temp->name, strerror(errno));
}
if (S_ISLNK(st.st_mode)) {
int ret;
char *buf, buf_[1024];
buf = ((sizeof(buf_) < st.st_size) ?
xmalloc(st.st_size) : buf_);
ret = readlink(name, buf, st.st_size);
if (ret < 0)
die("readlink(%s)", name);
prep_temp_blob(temp, buf, st.st_size,
(one->sha1_valid ?
one->blob_sha1 : null_sha1),
(one->sha1_valid ?
one->mode : S_IFLNK));
}
else {
if (!one->sha1_valid)
strcpy(temp->hex, sha1_to_hex(null_sha1));
else
strcpy(temp->hex, sha1_to_hex(one->blob_sha1));
sprintf(temp->mode, "%06o",
S_IFREG |ce_permissions(st.st_mode));
}
return;
}
else {
void *blob;
char type[20];
unsigned long size;
blob = read_sha1_file(one->blob_sha1, type, &size);
if (!blob || strcmp(type, "blob"))
die("unable to read blob object for %s (%s)",
name, sha1_to_hex(one->blob_sha1));
prep_temp_blob(temp, blob, size, one->blob_sha1, one->mode);
free(blob);
}
}
static void remove_tempfile(void)
{
int i;
for (i = 0; i < 2; i++)
if (diff_temp[i].name == diff_temp[i].tmp_path) {
unlink(diff_temp[i].name);
diff_temp[i].name = NULL;
}
}
static void remove_tempfile_on_signal(int signo)
{
remove_tempfile();
}
/* An external diff command takes:
*
* diff-cmd name infile1 infile1-sha1 infile1-mode \
* infile2 infile2-sha1 infile2-mode.
*
*/
void run_external_diff(const char *name,
const char *other,
struct diff_spec *one,
struct diff_spec *two)
{
struct diff_tempfile *temp = diff_temp;
pid_t pid;
int status;
static int atexit_asked = 0;
if (one && two) {
prepare_temp_file(name, &temp[0], one);
prepare_temp_file(other ? : name, &temp[1], two);
if (! atexit_asked &&
(temp[0].name == temp[0].tmp_path ||
temp[1].name == temp[1].tmp_path)) {
atexit_asked = 1;
atexit(remove_tempfile);
}
signal(SIGINT, remove_tempfile_on_signal);
}
fflush(NULL);
pid = fork();
if (pid < 0)
die("unable to fork");
if (!pid) {
const char *pgm = external_diff();
/* not passing rename patch to external ones */
if (!other && pgm) {
if (one && two)
execlp(pgm, pgm,
name,
temp[0].name, temp[0].hex, temp[0].mode,
temp[1].name, temp[1].hex, temp[1].mode,
NULL);
else
execlp(pgm, pgm, name, NULL);
}
/*
* otherwise we use the built-in one.
*/
if (one && two)
builtin_diff(name, other ? : name, temp);
else
printf("* Unmerged path %s\n", name);
exit(0);
}
if (waitpid(pid, &status, 0) < 0 ||
!WIFEXITED(status) || WEXITSTATUS(status)) {
/* Earlier we did not check the exit status because
* diff exits non-zero if files are different, and
* we are not interested in knowing that. It was a
* mistake which made it harder to quit a diff-*
* session that uses the git-apply-patch-script as
* the GIT_EXTERNAL_DIFF. A custom GIT_EXTERNAL_DIFF
* should also exit non-zero only when it wants to
* abort the entire diff-* session.
*/
remove_tempfile();
fprintf(stderr, "external diff died, stopping at %s.\n", name);
exit(1);
}
remove_tempfile();
}
void diff_addremove(int addremove, unsigned mode,
const unsigned char *sha1,
const char *base, const char *path)
{
char concatpath[PATH_MAX];
struct diff_spec spec[2], *one, *two;
memcpy(spec[0].blob_sha1, sha1, 20);
spec[0].mode = mode;
spec[0].sha1_valid = spec[0].file_valid = 1;
spec[1].file_valid = 0;
if (addremove == '+') {
one = spec + 1; two = spec;
} else {
one = spec; two = one + 1;
}
if (path) {
strcpy(concatpath, base);
strcat(concatpath, path);
}
run_external_diff(path ? concatpath : base, NULL, one, two);
}
void diff_change(unsigned old_mode, unsigned new_mode,
const unsigned char *old_sha1,
const unsigned char *new_sha1,
const char *base, const char *path) {
char concatpath[PATH_MAX];
struct diff_spec spec[2];
memcpy(spec[0].blob_sha1, old_sha1, 20);
spec[0].mode = old_mode;
memcpy(spec[1].blob_sha1, new_sha1, 20);
spec[1].mode = new_mode;
spec[0].sha1_valid = spec[0].file_valid = 1;
spec[1].sha1_valid = spec[1].file_valid = 1;
if (path) {
strcpy(concatpath, base);
strcat(concatpath, path);
}
run_external_diff(path ? concatpath : base, NULL, &spec[0], &spec[1]);
}
void diff_unmerge(const char *path)
{
run_external_diff(path, NULL, NULL, NULL);
}