Git's diff machinery does not follow symlinks, which makes sense as git
itself also does not, but stores the symlink destination.
In --no-index mode however, it is useful for diff to be able to follow
symlinks, matching the behaviour of ordinary diff. A new --dereference
(name copied from diff) option has been added to enable this behaviour.
--no-dereference can be used to disable it again.
Signed-off-by: Dennis Kaarsemaker <dennis@xxxxxxxxxxxxxxx>
---
Documentation/diff-options.txt | 9 +++++++++
builtin/diff.c | 2 ++
diff-no-index.c | 7 ++++---
diff.c | 12 ++++++++++--
diff.h | 2 +-
t/t4011-diff-symlink.sh | 6 ++++++
t/t4053-diff-no-index.sh | 44 ++++++++++++++++++++++++++++++++++++++++++
7 files changed, 76 insertions(+), 6 deletions(-)
diff --git a/Documentation/diff-options.txt b/Documentation/diff-options.txt
index 2d77a19626..5a9d58b701 100644
--- a/Documentation/diff-options.txt
+++ b/Documentation/diff-options.txt
@@ -216,6 +216,15 @@ any of those replacements occurred.
commit range. Defaults to `diff.submodule` or the 'short' format
if the config option is unset.
+ifdef::git-diff[]
+--dereference::
+--no-dereference::
+ Normally, "git diff --no-index" will compare symlinks by comparing what
+ they point to. The `--dereference` option will make it compare the content
+ of the linked files. The `--no-dereference` option disables an earlier
+ `--dereference`.
+endif::git-diff[]
+
--color[=<when>]::
Show colored diff.
`--color` (i.e. without '=<when>') is the same as `--color=always`.
diff --git a/builtin/diff.c b/builtin/diff.c
index 7f91f6d226..09e646060e 100644
--- a/builtin/diff.c
+++ b/builtin/diff.c
@@ -360,6 +360,8 @@ int cmd_diff(int argc, const char **argv, const char *prefix)
if (nongit)
die(_("Not a git repository"));
argc = setup_revisions(argc, argv, &rev, NULL);
+ if (DIFF_OPT_TST(&rev.diffopt, DEREFERENCE))
+ die(_("--dereference can only be used together with --no-index"));
if (!rev.diffopt.output_format) {
rev.diffopt.output_format = DIFF_FORMAT_PATCH;
diff_setup_done(&rev.diffopt);
diff --git a/diff-no-index.c b/diff-no-index.c
index f420786039..fe48f32ddd 100644
--- a/diff-no-index.c
+++ b/diff-no-index.c
@@ -40,7 +40,7 @@ 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 *mode, int dereference)
{
struct stat st;
@@ -52,7 +52,7 @@ static int get_mode(const char *path, int *mode)
#endif
else if (path == file_from_standard_input)
*mode = create_ce_mode(0666);
- else if (lstat(path, &st))
+ else if (dereference ? stat(path, &st) : lstat(path, &st))
return error("Could not access '%s'", path);
else
*mode = st.st_mode;
@@ -93,7 +93,8 @@ static int queue_diff(struct diff_options *o,
{
int mode1 = 0, mode2 = 0;
- if (get_mode(name1, &mode1) || get_mode(name2, &mode2))
+ if (get_mode(name1, &mode1, DIFF_OPT_TST(o, DEREFERENCE)) ||
+ get_mode(name2, &mode2, DIFF_OPT_TST(o, DEREFERENCE)))
return -1;
if (mode1 && mode2 && S_ISDIR(mode1) != S_ISDIR(mode2)) {
diff --git a/diff.c b/diff.c
index be11e4ef2b..2afecfb939 100644
--- a/diff.c
+++ b/diff.c
@@ -2815,7 +2815,7 @@ int diff_populate_filespec(struct diff_filespec *s, unsigned int flags)
s->size = xsize_t(st.st_size);
if (!s->size)
goto empty;
- if (S_ISLNK(st.st_mode)) {
+ if (S_ISLNK(s->mode)) {
struct strbuf sb = STRBUF_INIT;
if (strbuf_readlink(&sb, s->path, s->size))
@@ -2825,6 +2825,10 @@ int diff_populate_filespec(struct diff_filespec *s, unsigned int flags)
s->should_free = 1;
return 0;
}
+ if (S_ISLNK(st.st_mode)) {
+ stat(s->path, &st);
+ s->size = xsize_t(st.st_size);
+ }
if (size_only)
return 0;
if ((flags & CHECK_BINARY) &&
@@ -3884,7 +3888,11 @@ int diff_opt_parse(struct diff_options *options,
else if (!strcmp(arg, "--no-follow")) {
DIFF_OPT_CLR(options, FOLLOW_RENAMES);
DIFF_OPT_CLR(options, DEFAULT_FOLLOW_RENAMES);
- } else if (!strcmp(arg, "--color"))
+ } else if (!strcmp(arg, "--dereference"))
+ DIFF_OPT_SET(options, DEREFERENCE);
+ else if (!strcmp(arg, "--no-dereference"))
+ DIFF_OPT_CLR(options, DEREFERENCE);
+ else if (!strcmp(arg, "--color"))
options->use_color = 1;
else if (skip_prefix(arg, "--color=", &arg)) {
int value = git_config_colorbool(NULL, arg);
diff --git a/diff.h b/diff.h
index 25ae60d5ff..db33dc67f6 100644
--- a/diff.h
+++ b/diff.h
@@ -69,7 +69,7 @@ typedef struct strbuf *(*diff_prefix_fn_t)(struct diff_options *opt, void *data)
#define DIFF_OPT_FIND_COPIES_HARDER (1 << 6)
#define DIFF_OPT_FOLLOW_RENAMES (1 << 7)
#define DIFF_OPT_RENAME_EMPTY (1 << 8)
-/* (1 << 9) unused */
+#define DIFF_OPT_DEREFERENCE (1 << 9)
#define DIFF_OPT_HAS_CHANGES (1 << 10)
#define DIFF_OPT_QUICK (1 << 11)
#define DIFF_OPT_NO_INDEX (1 << 12)
diff --git a/t/t4011-diff-symlink.sh b/t/t4011-diff-symlink.sh
index 13e7f621ab..68ee39f26f 100755
--- a/t/t4011-diff-symlink.sh
+++ b/t/t4011-diff-symlink.sh
@@ -154,4 +154,10 @@ test_expect_success SYMLINKS 'symlinks do not respect userdiff config by path' '
test_cmp expect actual
'
+test_expect_success SYMLINKS 'diff does not accept --dereference without --no-index' '
+ ln -s dest link1 &&
+ ln -s dest link2 &&
+ test_must_fail git diff --dereference link1 link2
+'
+
test_done
diff --git a/t/t4053-diff-no-index.sh b/t/t4053-diff-no-index.sh
index 453e6c35eb..8c87bffb34 100755
--- a/t/t4053-diff-no-index.sh
+++ b/t/t4053-diff-no-index.sh
@@ -127,4 +127,48 @@ test_expect_success 'diff --no-index from repo subdir respects config (implicit)
test_cmp expect actual.head
'
+test_expect_success SYMLINKS 'diff --no-index does not follows symlinks' '
+ echo a >1 &&
+ echo b >2 &&
+ ln -s 1 3 &&
+ ln -s 2 4 &&
+ cat >expect <<-EOF &&
+ --- a/3
+ +++ b/4
+ @@ -1 +1 @@
+ -1
+ \ No newline at end of file
+ +2
+ \ No newline at end of file
+ EOF
+ test_expect_code 1 git diff --no-index 3 4 | tail -n +3 >actual &&
+ test_cmp expect actual
+'
+
+test_expect_success SYMLINKS 'diff --no-index --dereference does follows symlinks' '
+ cat >expect <<-EOF &&
+ --- a/3
+ +++ b/4
+ @@ -1 +1 @@
+ -a
+ +b
+ EOF
+ test_expect_code 1 git diff --no-index --dereference 3 4 | tail -n +3 >actual &&
+ test_cmp expect actual
+'
+
+test_expect_success SYMLINKS 'diff --no-index --no-dereference does not follow symlinks' '
+ cat >expect <<-EOF &&
+ --- a/3
+ +++ b/4
+ @@ -1 +1 @@
+ -1
+ \ No newline at end of file
+ +2
+ \ No newline at end of file
+ EOF
+ test_expect_code 1 git diff --no-index --no-dereference 3 4 | tail -n +3 > actual &&
+ test_cmp expect actual
+'
+
test_done
--
2.12.0-488-gd3584ba