From: Phillip Wood <phillip.wood@xxxxxxxxxxxxx>
In some shells, such as bash and zsh, it's possible to use a command
substitution to provide the output of a command as a file argument to
another process, like so:
diff -u <(printf "a\nb\n") <(printf "a\nc\n")
However, this syntax does not produce useful results with "git diff
--no-index". On macOS, the arguments to the command are named pipes
under /dev/fd, and git diff doesn't know how to handle a named pipe. On
Linux, the arguments are symlinks to pipes, so git diff "helpfully"
diffs these symlinks, comparing their targets like "pipe:[1234]" and
"pipe:[5678]".
To address this "diff --no-index" is changed so that if a path given on
the commandline is a named pipe or a symbolic link that resolves to a
named pipe then we read the data to diff from that pipe. This is
implemented by generalizing the code that already exists to handle
reading from stdin when the user passes the path "-".
As process substitution is not support by POSIX this change is tested by
using a pipe and a symbolic link to a pipe.
Signed-off-by: Phillip Wood <phillip.wood@xxxxxxxxxxxxx>
---
diff-no-index.c | 80 ++++++++++++++++++++++++----------------
t/t4053-diff-no-index.sh | 25 +++++++++++++
2 files changed, 73 insertions(+), 32 deletions(-)
diff --git a/diff-no-index.c b/diff-no-index.c
index 7b9327f8f3..45fbd7cdbe 100644
--- a/diff-no-index.c
+++ b/diff-no-index.c
@@ -41,7 +41,7 @@ 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)
+static int get_mode(const char *path, int is_pipe, int *mode)
{
struct stat st;
@@ -51,7 +51,7 @@ static int get_mode(const char *path, int *mode)
else if (!strcasecmp(path, "nul"))
*mode = 0;
#endif
- else if (path == file_from_standard_input)
+ else if (is_pipe)
*mode = create_ce_mode(0666);
else if (lstat(path, &st))
return error("Could not access '%s'", path);
@@ -60,13 +60,18 @@ static int get_mode(const char *path, int *mode)
return 0;
}
-static void populate_from_stdin(struct diff_filespec *s)
+static void populate_from_pipe(struct diff_filespec *s, int is_stdin)
{
struct strbuf buf = STRBUF_INIT;
size_t size = 0;
+ int fd = 0;
- if (strbuf_read(&buf, 0, 0) < 0)
+ if (!is_stdin)
+ fd = xopen(s->path, O_RDONLY);
+ if (strbuf_read(&buf, fd, 0) < 0)
die_errno("error while reading from stdin");
+ if (!is_stdin)
+ close(fd);
s->should_munmap = 0;
s->data = strbuf_detach(&buf, &size);
@@ -75,40 +80,43 @@ static void populate_from_stdin(struct diff_filespec *s)
s->is_stdin = 1;
}
-static struct diff_filespec *noindex_filespec(const char *name, int mode)
+static struct diff_filespec *noindex_filespec(const char *name, int is_pipe,
+ int mode)
{
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)
- populate_from_stdin(s);
+ if (is_pipe)
+ populate_from_pipe(s, name == file_from_standard_input);
return s;
}
static int queue_diff(struct diff_options *o,
- const char *name1, const char *name2)
+ const char *name1, int is_pipe1,
+ const char *name2, int is_pipe2)
{
int mode1 = 0, mode2 = 0;
- if (get_mode(name1, &mode1) || get_mode(name2, &mode2))
+ if (get_mode(name1, is_pipe1, &mode1) ||
+ get_mode(name2, is_pipe2, &mode2))
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, 0);
+ d2 = noindex_filespec(name2, is_pipe2, mode2);
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, is_pipe1, mode1);
+ d2 = noindex_filespec(NULL, 0, 0);
name1 = NULL;
mode1 = 0;
}
@@ -173,7 +181,7 @@ static int queue_diff(struct diff_options *o,
n2 = buffer2.buf;
}
- ret = queue_diff(o, n1, n2);
+ ret = queue_diff(o, n1, 0, n2, 0);
}
string_list_clear(&p1, 0);
string_list_clear(&p2, 0);
@@ -189,8 +197,8 @@ 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, is_pipe1, mode1);
+ d2 = noindex_filespec(name2, is_pipe2, mode2);
diff_queue(&diff_queued_diff, d1, d2);
return 0;
}
@@ -213,18 +221,11 @@ static void append_basename(struct strbuf *path, const char *dir, const char *fi
* Note that we append the basename of F to D/, so "diff a/b/file D"
* becomes "diff a/b/file D/file", not "diff a/b/file D/a/b/file".
*/
-static void fixup_paths(const char **path, struct strbuf *replacement)
+static void fixup_paths(const char **path, int *is_dir, struct strbuf *replacement)
{
- unsigned int isdir0, isdir1;
-
- 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) {
+ if (is_dir[0] == is_dir[1])
+ return;
+ if (is_dir[0]) {
append_basename(replacement, path[0], path[1]);
path[0] = replacement->buf;
} else {
@@ -246,6 +247,8 @@ int diff_no_index(struct rev_info *revs,
int ret = 1;
const char *paths[2];
char *to_free[ARRAY_SIZE(paths)] = { 0 };
+ int is_dir[ARRAY_SIZE(paths)] = { 0 };
+ int is_pipe[ARRAY_SIZE(paths)] = { 0 };
struct strbuf replacement = STRBUF_INIT;
const char *prefix = revs->prefix;
struct option no_index_options[] = {
@@ -267,18 +270,30 @@ int diff_no_index(struct rev_info *revs,
FREE_AND_NULL(options);
for (i = 0; i < 2; i++) {
const char *p = argv[i];
- if (!strcmp(p, "-"))
+ if (!strcmp(p, "-")) {
/*
* stdin should be spelled as "-"; if you have
* path that is "-", spell it as "./-".
*/
p = file_from_standard_input;
- else if (prefix)
- p = to_free[i] = prefix_filename(prefix, p);
+ is_pipe[i] = 1;
+ } else {
+ struct stat st;
+
+ if (prefix)
+ p = to_free[i] = prefix_filename(prefix, p);
+ if (stat(p, &st))
+ ;
+ else if (S_ISDIR(st.st_mode))
+ is_dir[i] = 1;
+ else if (S_ISFIFO(st.st_mode))
+ is_pipe[i] = 1;
+ }
paths[i] = p;
}
- fixup_paths(paths, &replacement);
+ if (!is_pipe[0] && !is_pipe[1])
+ fixup_paths(paths, is_dir, &replacement);
revs->diffopt.skip_stat_unmatch = 1;
if (!revs->diffopt.output_format)
@@ -295,7 +310,8 @@ 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], is_pipe[0], paths[1], is_pipe[1]))
goto out;
diff_set_mnemonic_prefix(&revs->diffopt, "1/", "2/");
diffcore_std(&revs->diffopt);
diff --git a/t/t4053-diff-no-index.sh b/t/t4053-diff-no-index.sh
index d14b194ea2..30b9e2c2f0 100755
--- a/t/t4053-diff-no-index.sh
+++ b/t/t4053-diff-no-index.sh
@@ -223,4 +223,29 @@ test_expect_success "diff --no-index treats '-' as stdin" '
test_write_lines 1 | git diff --no-index -- a/1 - >actual &&
test_must_be_empty actual
'
+
+test_expect_success PIPE,SYMLINKS 'diff --no-index reads from pipes' '
+ mkfifo old &&
+ mkfifo new &&
+ ln -s new new-link &&
+ {
+ (test_write_lines a b c >old) &
+ (test_write_lines a x c >new) &
+ } &&
+
+ 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
--
2.40.1.852.g22d29fd9ba
