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[PATCH] Diff-tree-helper take two.
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This reworks the diff-tree-helper and show-diff to further make external
diff command interface simpler.

These commands now honor GIT_EXTERNAL_DIFF environment variable which
can point at an arbitrary program that takes 7 parameters:

  name file1 file1-sha1 file1-mode file2 file2-sha1 file2-mode

The parameters for an external diff command are as follows:

  name        this invocation of the command is to emit diff
	      for the named cache/tree entry.

  file1       pathname that holds the contents of the first
	      file.  This can be a file inside the working
	      tree, or a temporary file created from the blob
	      object, or /dev/null.  The command should not
	      attempt to unlink it -- the temporary is
	      unlinked by the caller.

  file1-sha1  sha1 hash if file1 is a blob object, or "."
	      otherwise.

  file1-mode  mode bits for file1, or "." for a deleted file.

If GIT_EXTERNAL_DIFF environment variable is not set, the
default is to invoke diff with the set of parameters old
show-diff used to use.  This built-in implementation honors the
GIT_DIFF_CMD and GIT_DIFF_OPTS environment variables as before.

Signed-off-by: Junio C Hamano <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Junio C Hamano authored and Linus Torvalds committed Apr 26, 2005
1 parent d1df574 commit be3cfa8
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Showing 4 changed files with 271 additions and 270 deletions.
242 changes: 39 additions & 203 deletions diff-tree-helper.c
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Original file line number Diff line number Diff line change
@@ -1,3 +1,6 @@
/*
* Copyright (C) 2005 Junio C Hamano
*/
#include "cache.h"
#include "strbuf.h"
#include "diff.h"
Expand All @@ -17,15 +20,22 @@ static int matches_pathspec(const char *name, char **spec, int cnt)
return 0;
}

static int parse_oneside_change(const char *cp, unsigned char *sha1,
char *path) {
static int parse_oneside_change(const char *cp, struct diff_spec *one,
char *path)
{
int ch;
while ((ch = *cp) && '0' <= ch && ch <= '7')
cp++; /* skip mode bits */

one->file_valid = one->sha1_valid = 1;
one->mode = 0;
while ((ch = *cp) && '0' <= ch && ch <= '7') {
one->mode = (one->mode << 3) | (ch - '0');
cp++;
}

if (strncmp(cp, "\tblob\t", 6))
return -1;
cp += 6;
if (get_sha1_hex(cp, sha1))
if (get_sha1_hex(cp, one->u.sha1))
return -1;
cp += 40;
if (*cp++ != '\t')
Expand All @@ -34,223 +44,57 @@ static int parse_oneside_change(const char *cp, unsigned char *sha1,
return 0;
}

#define STATUS_CACHED 0 /* cached and sha1 valid */
#define STATUS_ABSENT 1 /* diff-tree says old removed or new added */
#define STATUS_UNCACHED 2 /* diff-cache output: read from working tree */

static int parse_diff_tree_output(const char *buf,
unsigned char *old_sha1,
int *old_status,
unsigned char *new_sha1,
int *new_status,
struct diff_spec *old,
struct diff_spec *new,
char *path) {
const char *cp = buf;
int ch;
static unsigned char null_sha[20] = { 0, };

switch (*cp++) {
case '+':
*old_status = STATUS_ABSENT;
*new_status = (memcmp(new_sha1, null_sha, sizeof(null_sha)) ?
STATUS_CACHED : STATUS_UNCACHED);
return parse_oneside_change(cp, new_sha1, path);
old->file_valid = 0;
return parse_oneside_change(cp, new, path);
case '-':
*new_status = STATUS_ABSENT;
*old_status = (memcmp(old_sha1, null_sha, sizeof(null_sha)) ?
STATUS_CACHED : STATUS_UNCACHED);
return parse_oneside_change(cp, old_sha1, path);
new->file_valid = 0;
return parse_oneside_change(cp, old, path);
case '*':
break;
default:
return -1;
}

/* This is for '*' entries */
while ((ch = *cp) && ('0' <= ch && ch <= '7'))
cp++; /* skip mode bits */
old->file_valid = old->sha1_valid = 1;
new->file_valid = new->sha1_valid = 1;

old->mode = new->mode = 0;
while ((ch = *cp) && ('0' <= ch && ch <= '7')) {
old->mode = (old->mode << 3) | (ch - '0');
cp++;
}
if (strncmp(cp, "->", 2))
return -1;
cp += 2;
while ((ch = *cp) && ('0' <= ch && ch <= '7'))
cp++; /* skip mode bits */
while ((ch = *cp) && ('0' <= ch && ch <= '7')) {
new->mode = (new->mode << 3) | (ch - '0');
cp++;
}
if (strncmp(cp, "\tblob\t", 6))
return -1;
cp += 6;
if (get_sha1_hex(cp, old_sha1))
if (get_sha1_hex(cp, old->u.sha1))
return -1;
cp += 40;
if (strncmp(cp, "->", 2))
return -1;
cp += 2;
if (get_sha1_hex(cp, new_sha1))
if (get_sha1_hex(cp, new->u.sha1))
return -1;
cp += 40;
if (*cp++ != '\t')
return -1;
strcpy(path, cp);
*old_status = (memcmp(old_sha1, null_sha, sizeof(null_sha)) ?
STATUS_CACHED : STATUS_UNCACHED);
*new_status = (memcmp(new_sha1, null_sha, sizeof(null_sha)) ?
STATUS_CACHED : STATUS_UNCACHED);
return 0;
}

static int sha1err(const char *path, const unsigned char *sha1)
{
return error("diff-tree-helper: unable to read sha1 file of %s (%s)",
path, sha1_to_hex(sha1));
}

static int fserr(const char *path)
{
return error("diff-tree-helper: unable to read file %s", path);
}

static char *map_whole_file(const char *path, unsigned long *size) {
int fd;
struct stat st;
void *buf;

if ((fd = open(path, O_RDONLY)) < 0) {
error("diff-tree-helper: unable to read file %s", path);
return 0;
}
if (fstat(fd, &st) < 0) {
close(fd);
error("diff-tree-helper: unable to stat file %s", path);
return 0;
}
*size = st.st_size;
buf = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
close(fd);
return buf;
}

static int show_diff(const unsigned char *old_sha1, int old_status,
const unsigned char *new_sha1, int new_status,
const char *path, int reverse_diff)
{
char other[PATH_MAX];
unsigned long size;
char type[20];
int fd;
int reverse;
void *blob = 0;
const char *fs = 0;
int need_unmap = 0;
int need_unlink = 0;


switch (old_status) {
case STATUS_CACHED:
blob = read_sha1_file(old_sha1, type, &size);
if (! blob)
return sha1err(path, old_sha1);

switch (new_status) {
case STATUS_CACHED:
strcpy(other, ".diff_tree_helper_XXXXXX");
fd = mkstemp(other);
if (fd < 0)
die("unable to create temp-file");
if (write(fd, blob, size) != size)
die("unable to write temp-file");
close(fd);
free(blob);

blob = read_sha1_file(new_sha1, type, &size);
if (! blob)
return sha1err(path, new_sha1);

need_unlink = 1;
/* new = blob, old = fs */
reverse = !reverse_diff;
fs = other;
break;

case STATUS_ABSENT:
case STATUS_UNCACHED:
fs = ((new_status == STATUS_ABSENT) ?
"/dev/null" : path);
reverse = reverse_diff;
break;

default:
reverse = reverse_diff;
}
break;

case STATUS_ABSENT:
switch (new_status) {
case STATUS_CACHED:
blob = read_sha1_file(new_sha1, type, &size);
if (! blob)
return sha1err(path, new_sha1);
/* old = fs, new = blob */
fs = "/dev/null";
reverse = !reverse_diff;
break;

case STATUS_ABSENT:
return error("diff-tree-helper: absent from both old and new?");
case STATUS_UNCACHED:
fs = path;
blob = strdup("");
size = 0;
/* old = blob, new = fs */
reverse = reverse_diff;
break;
default:
reverse = reverse_diff;
}
break;

case STATUS_UNCACHED:
fs = path; /* old = fs, new = blob */
reverse = !reverse_diff;

switch (new_status) {
case STATUS_CACHED:
blob = read_sha1_file(new_sha1, type, &size);
if (! blob)
return sha1err(path, new_sha1);
break;

case STATUS_ABSENT:
blob = strdup("");
size = 0;
break;

case STATUS_UNCACHED:
/* old = fs */
blob = map_whole_file(path, &size);
if (! blob)
return fserr(path);
need_unmap = 1;
break;
default:
reverse = reverse_diff;
}
break;

default:
reverse = reverse_diff;
}

if (fs)
show_differences(fs,
path, /* label */
blob,
size,
reverse /* 0: diff blob fs
1: diff fs blob */);

if (need_unlink)
unlink(other);
if (need_unmap && blob)
munmap(blob, size);
else
free(blob);
return 0;
}

Expand All @@ -275,28 +119,20 @@ int main(int ac, char **av) {
}
/* the remaining parameters are paths patterns */

prepare_diff_cmd();

while (1) {
int old_status, new_status;
unsigned char old_sha1[20], new_sha1[20];
struct diff_spec old, new;
char path[PATH_MAX];
read_line(&sb, stdin, line_termination);
if (sb.eof)
break;
if (parse_diff_tree_output(sb.buf,
old_sha1, &old_status,
new_sha1, &new_status,
path)) {
if (parse_diff_tree_output(sb.buf, &old, &new, path)) {
fprintf(stderr, "cannot parse %s\n", sb.buf);
continue;
}
if (1 < ac && ! matches_pathspec(path, av+1, ac-1))
if (1 < ac && !matches_pathspec(path, av+1, ac-1))
continue;

show_diff(old_sha1, old_status,
new_sha1, new_status,
path, reverse_diff);
run_external_diff(path, &old, &new);
}
return 0;
}
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