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Merge branch 'pw/diff-no-index-from-named-pipes'
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"git diff --no-index" learned to read from named pipes as if they
were regular files, to allow "git diff <(process) <(substitution)"
some shells support.

* pw/diff-no-index-from-named-pipes:
  diff --no-index: support reading from named pipes
  t4054: test diff --no-index with stdin
  diff --no-index: die on error reading stdin
  diff --no-index: refuse to compare stdin to a directory
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@gitster
gitster committed Jul 17, 2023
2 parents 830b4a0 + 1e3f265 commit 9187b27
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Showing 2 changed files with 153 additions and 31 deletions.
120 changes: 89 additions & 31 deletions diff-no-index.c
View file
Expand Up @@ -41,75 +41,119 @@ static int read_directory_contents(const char *path, struct string_list *list)
*/
static const char file_from_standard_input[] = "-";

static int get_mode(const char *path, int *mode)
/*
* For paths given on the command-line we treat "-" as stdin and named
* pipes and symbolic links to named pipes specially.
*/
enum special {
SPECIAL_NONE,
SPECIAL_STDIN,
SPECIAL_PIPE,
};

static int get_mode(const char *path, int *mode, enum special *special)
{
struct stat st;

if (!path || !strcmp(path, "/dev/null"))
if (!path || !strcmp(path, "/dev/null")) {
*mode = 0;
#ifdef GIT_WINDOWS_NATIVE
else if (!strcasecmp(path, "nul"))
} else if (!strcasecmp(path, "nul")) {
*mode = 0;
#endif
else if (path == file_from_standard_input)
} else if (path == file_from_standard_input) {
*mode = create_ce_mode(0666);
else if (lstat(path, &st))
*special = SPECIAL_STDIN;
} else if (lstat(path, &st)) {
return error("Could not access '%s'", path);
else
} else {
*mode = st.st_mode;
}
/*
* For paths on the command-line treat named pipes and symbolic
* links that resolve to a named pipe specially.
*/
if (special &&
(S_ISFIFO(*mode) ||
(S_ISLNK(*mode) && !stat(path, &st) && S_ISFIFO(st.st_mode)))) {
*mode = create_ce_mode(0666);
*special = SPECIAL_PIPE;
}

return 0;
}

static int populate_from_stdin(struct diff_filespec *s)
static void populate_common(struct diff_filespec *s, struct strbuf *buf)
{
struct strbuf buf = STRBUF_INIT;
size_t size = 0;

if (strbuf_read(&buf, 0, 0) < 0)
return error_errno("error while reading from stdin");

s->should_munmap = 0;
s->data = strbuf_detach(&buf, &size);
s->data = strbuf_detach(buf, &size);
s->size = size;
s->should_free = 1;
s->is_stdin = 1;
return 0;
}

static struct diff_filespec *noindex_filespec(const char *name, int mode)
static void populate_from_pipe(struct diff_filespec *s)
{
struct strbuf buf = STRBUF_INIT;
int fd = xopen(s->path, O_RDONLY);

if (strbuf_read(&buf, fd, 0) < 0)
die_errno("error while reading from '%s'", s->path);
close(fd);
populate_common(s, &buf);
}

static void populate_from_stdin(struct diff_filespec *s)
{
struct strbuf buf = STRBUF_INIT;

if (strbuf_read(&buf, 0, 0) < 0)
die_errno("error while reading from stdin");
populate_common(s, &buf);
}

static struct diff_filespec *noindex_filespec(const char *name, int mode,
enum special special)
{
struct diff_filespec *s;

if (!name)
name = "/dev/null";
s = alloc_filespec(name);
fill_filespec(s, null_oid(), 0, mode);
if (name == file_from_standard_input)
if (special == SPECIAL_STDIN)
populate_from_stdin(s);
else if (special == SPECIAL_PIPE)
populate_from_pipe(s);
return s;
}

static int queue_diff(struct diff_options *o,
const char *name1, const char *name2)
const char *name1, const char *name2, int recursing)
{
int mode1 = 0, mode2 = 0;
enum special special1 = SPECIAL_NONE, special2 = SPECIAL_NONE;

if (get_mode(name1, &mode1) || get_mode(name2, &mode2))
/* Paths can only be special if we're not recursing. */
if (get_mode(name1, &mode1, recursing ? NULL : &special1) ||
get_mode(name2, &mode2, recursing ? NULL : &special2))
return -1;

if (mode1 && mode2 && S_ISDIR(mode1) != S_ISDIR(mode2)) {
struct diff_filespec *d1, *d2;

if (S_ISDIR(mode1)) {
/* 2 is file that is created */
d1 = noindex_filespec(NULL, 0);
d2 = noindex_filespec(name2, mode2);
d1 = noindex_filespec(NULL, 0, SPECIAL_NONE);
d2 = noindex_filespec(name2, mode2, special2);
name2 = NULL;
mode2 = 0;
} else {
/* 1 is file that is deleted */
d1 = noindex_filespec(name1, mode1);
d2 = noindex_filespec(NULL, 0);
d1 = noindex_filespec(name1, mode1, special1);
d2 = noindex_filespec(NULL, 0, SPECIAL_NONE);
name1 = NULL;
mode1 = 0;
}
Expand Down Expand Up @@ -174,7 +218,7 @@ static int queue_diff(struct diff_options *o,
n2 = buffer2.buf;
}

ret = queue_diff(o, n1, n2);
ret = queue_diff(o, n1, n2, 1);
}
string_list_clear(&p1, 0);
string_list_clear(&p2, 0);
Expand All @@ -190,8 +234,8 @@ static int queue_diff(struct diff_options *o,
SWAP(name1, name2);
}

d1 = noindex_filespec(name1, mode1);
d2 = noindex_filespec(name2, mode2);
d1 = noindex_filespec(name1, mode1, special1);
d2 = noindex_filespec(name2, mode2, special2);
diff_queue(&diff_queued_diff, d1, d2);
return 0;
}
Expand All @@ -216,13 +260,27 @@ static void append_basename(struct strbuf *path, const char *dir, const char *fi
*/
static void fixup_paths(const char **path, struct strbuf *replacement)
{
unsigned int isdir0, isdir1;
struct stat st;
unsigned int isdir0 = 0, isdir1 = 0;
unsigned int ispipe0 = 0, ispipe1 = 0;

if (path[0] != file_from_standard_input && !stat(path[0], &st)) {
isdir0 = S_ISDIR(st.st_mode);
ispipe0 = S_ISFIFO(st.st_mode);
}

if (path[1] != file_from_standard_input && !stat(path[1], &st)) {
isdir1 = S_ISDIR(st.st_mode);
ispipe1 = S_ISFIFO(st.st_mode);
}

if ((path[0] == file_from_standard_input && isdir1) ||
(isdir0 && path[1] == file_from_standard_input))
die(_("cannot compare stdin to a directory"));

if ((isdir0 && ispipe1) || (ispipe0 && isdir1))
die(_("cannot compare a named pipe to a directory"));

if (path[0] == file_from_standard_input ||
path[1] == file_from_standard_input)
return;
isdir0 = is_directory(path[0]);
isdir1 = is_directory(path[1]);
if (isdir0 == isdir1)
return;
if (isdir0) {
Expand Down Expand Up @@ -296,7 +354,7 @@ int diff_no_index(struct rev_info *revs,
setup_diff_pager(&revs->diffopt);
revs->diffopt.flags.exit_with_status = 1;

if (queue_diff(&revs->diffopt, paths[0], paths[1]))
if (queue_diff(&revs->diffopt, paths[0], paths[1], 0))
goto out;
diff_set_mnemonic_prefix(&revs->diffopt, "1/", "2/");
diffcore_std(&revs->diffopt);
Expand Down
64 changes: 64 additions & 0 deletions t/t4053-diff-no-index.sh
View file
Expand Up @@ -205,4 +205,68 @@ test_expect_success POSIXPERM,SYMLINKS 'diff --no-index normalizes: mode not lik
test_cmp expected actual
'

test_expect_success "diff --no-index treats '-' as stdin" '
cat >expect <<-EOF &&
diff --git a/- b/a/1
index $ZERO_OID..$(git hash-object --stdin <a/1) 100644
--- a/-
+++ b/a/1
@@ -1 +1 @@
-x
+1
EOF
test_write_lines x | test_expect_code 1 \
git -c core.abbrev=no diff --no-index -- - a/1 >actual &&
test_cmp expect actual &&
test_write_lines 1 | git diff --no-index -- a/1 - >actual &&
test_must_be_empty actual
'

test_expect_success 'diff --no-index refuses to diff stdin and a directory' '
test_must_fail git diff --no-index -- - a </dev/null 2>err &&
grep "fatal: cannot compare stdin to a directory" err
'

test_expect_success PIPE 'diff --no-index refuses to diff a named pipe and a directory' '
test_when_finished "rm -f pipe" &&
mkfifo pipe &&
{
(>pipe) &
} &&
test_when_finished "kill $!" &&
test_must_fail git diff --no-index -- pipe a 2>err &&
grep "fatal: cannot compare a named pipe to a directory" err
'

test_expect_success PIPE,SYMLINKS 'diff --no-index reads from pipes' '
test_when_finished "rm -f old new new-link" &&
mkfifo old &&
mkfifo new &&
ln -s new new-link &&
{
(test_write_lines a b c >old) &
} &&
test_when_finished "! kill $!" &&
{
(test_write_lines a x c >new) &
} &&
test_when_finished "! kill $!" &&
cat >expect <<-EOF &&
diff --git a/old b/new-link
--- a/old
+++ b/new-link
@@ -1,3 +1,3 @@
a
-b
+x
c
EOF
test_expect_code 1 git diff --no-index old new-link >actual &&
test_cmp expect actual
'

test_done

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