You can ask the diff machinery to let the exit code indicate whether
there are changes, e.g. with --exit-code. It as two ways to calculate
that bit: The quick one assumes blobs with different hashes have
different content, and the more elaborate way actually compares the
contents, possibly applying transformations like ignoring whitespace.
Always use the slower path by setting the flag diff_from_contents,
because any of the files could have an external diff driver set via an
attribute, which might consider binary differences irrelevant, like e.g.
diff -b.
And don't stop walking that path in diff_flush() just because
output_format is unset. Instead run diff_flush_patch() with output
redirected to /dev/null to get the exit status, like we already do for
DIFF_FORMAT_NO_OUTPUT. That's consistent with the comments in diff.h:
/* Same as output_format = 0 but we know that -s flag was given
* and we should not give default value to output_format.
*/
#define DIFF_FORMAT_NO_OUTPUT 0x0800
An unset output_format is given e.g. by repo_index_has_changes(). We
could set it right there, but there may be other places, so simply let
diff_flush() handle it for all of them consistently.
Finally, capture the output of the external diff and only register a
change by setting found_changes if the program wrote anything.
Reported-by: German Lashevich <german.lashevich@xxxxxxxxx>
Signed-off-by: René Scharfe <l.s.r@xxxxxx>
---
diff.c | 33 ++++++++++++++++++++++++++++++---
t/t4020-diff-external.sh | 8 ++++++++
2 files changed, 38 insertions(+), 3 deletions(-)
diff --git a/diff.c b/diff.c
index ded9ac70df..cd3c8a3978 100644
--- a/diff.c
+++ b/diff.c
@@ -40,6 +40,7 @@
#include "setup.h"
#include "strmap.h"
#include "ws.h"
+#include "write-or-die.h"
#ifdef NO_FAST_WORKING_DIRECTORY
#define FAST_WORKING_DIRECTORY 0
@@ -4404,8 +4405,33 @@ static void run_external_diff(const char *pgm,
diff_free_filespec_data(one);
diff_free_filespec_data(two);
cmd.use_shell = 1;
- if (run_command(&cmd))
- die(_("external diff died, stopping at %s"), name);
+ if (o->flags.diff_from_contents) {
+ int got_output = 0;
+ cmd.out = -1;
+ if (start_command(&cmd))
+ die(_("external diff died, stopping at %s"), name);
+ for (;;) {
+ char buffer[8192];
+ ssize_t len = xread(cmd.out, buffer, sizeof(buffer));
+ if (!len)
+ break;
+ if (len < 0)
+ die(_("unable to read from external diff,"
+ " stopping at %s"), name);
+ got_output = 1;
+ if (write_in_full(1, buffer, len) < 0)
+ die(_("unable to write output of external diff,"
+ " stopping at %s"), name);
+ }
+ close(cmd.out);
+ if (finish_command(&cmd))
+ die(_("external diff died, stopping at %s"), name);
+ if (got_output)
+ o->found_changes = 1;
+ } else {
+ if (run_command(&cmd))
+ die(_("external diff died, stopping at %s"), name);
+ }
remove_tempfile();
}
@@ -4852,6 +4878,7 @@ void diff_setup_done(struct diff_options *options)
*/
if ((options->xdl_opts & XDF_WHITESPACE_FLAGS) ||
+ options->flags.exit_with_status ||
options->ignore_regex_nr)
options->flags.diff_from_contents = 1;
else
@@ -6742,7 +6769,7 @@ void diff_flush(struct diff_options *options)
if (output_format & DIFF_FORMAT_CALLBACK)
options->format_callback(q, options, options->format_callback_data);
- if (output_format & DIFF_FORMAT_NO_OUTPUT &&
+ if ((!output_format || output_format & DIFF_FORMAT_NO_OUTPUT) &&
options->flags.exit_with_status &&
options->flags.diff_from_contents) {
/*
diff --git a/t/t4020-diff-external.sh b/t/t4020-diff-external.sh
index fdd865f7c3..26430ca66b 100755
--- a/t/t4020-diff-external.sh
+++ b/t/t4020-diff-external.sh
@@ -172,6 +172,14 @@ test_expect_success 'no diff with -diff' '
grep Binary out
'
+test_expect_success 'diff.external and --exit-code with output' '
+ test_expect_code 1 git -c diff.external=echo diff --exit-code
+'
+
+test_expect_success 'diff.external and --exit-code without output' '
+ git -c diff.external=true diff --exit-code
+'
+
echo NULZbetweenZwords | perl -pe 'y/Z/\000/' > file
test_expect_success 'force diff with "diff"' '
--
2.45.0
