As a porcelain author I'm finding it difficult to keep track of
what features I can use in git-gui. Newer versions of Git have
newer capabilities but they don't always immediately get newer
version numbers that I can easily test for.
This is a simple plumbing option that lets a porcelain ask the
plumbing for its capabilities, at which point the porcelain can
work around anything missing, or recommend to the user that they
upgrade their plumbing layer.
Signed-off-by: Shawn O. Pearce <spearce@xxxxxxxxxxx>
---
Because 'maint' does not support `git-blame -w` I can't apply your
recent (and insanely good idea) 'git-gui: use "blame -w -C -C" for
"where did it come from, originally?"' without something like the
following, so I know that `git blame -w -C -C` will be accepted
by the underlying plumbing. ;-)
help.c | 77 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
t/t0000-basic.sh | 16 +++++++++++
2 files changed, 91 insertions(+), 2 deletions(-)
diff --git a/help.c b/help.c
index 1cd33ec..9f24a0f 100644
--- a/help.c
+++ b/help.c
@@ -9,6 +9,11 @@
#include "common-cmds.h"
#include <sys/ioctl.h>
+static const char *supported_features[] = {
+ "blame-ignore-whitespace",
+ "list-features",
+};
+
/* most GUI terminals set COLUMNS (although some don't export it) */
static int term_columns(void)
{
@@ -190,10 +195,78 @@ void help_unknown_cmd(const char *cmd)
exit(1);
}
+static int is_feature_name_sane(const char *a)
+{
+ if (!*a || *a == '-')
+ return 0;
+ for (; *a; a++) {
+ if (! ((*a >= 'a' && *a <= 'z')
+ || (*a >= '0' && *a <= '9')
+ || *a == '-'))
+ return 0;
+ }
+ return 1;
+}
+
+static int cmp_feature(const void *a_, const void *b_)
+{
+ const char *a = *((const char **)a_);
+ const char *b = *((const char **)b_);
+ return strcmp(a, b);
+}
+
+static void list_features()
+{
+ unsigned cnt = ARRAY_SIZE(supported_features);
+ unsigned i;
+
+ qsort(supported_features, cnt,
+ sizeof(supported_features[0]), cmp_feature);
+ for (i = 0; i < cnt; i++) {
+ const char *f = supported_features[i];
+ if (!is_feature_name_sane(f))
+ die("feature name \"%s\" is bogus", f);
+ printf("%s\n", f);
+ }
+}
+
+static int supports_feature(const char *the_feature)
+{
+ unsigned cnt = ARRAY_SIZE(supported_features);
+ unsigned i;
+
+ for (i = 0; i < cnt; i++) {
+ if (!strcmp(supported_features[i], the_feature))
+ return 0;
+ }
+ return 1;
+}
+
+static const char version_usage[] =
+"git-version [(--list-features | --supports-feature=<name>*)]";
+
int cmd_version(int argc, const char **argv, const char *prefix)
{
- printf("git version %s\n", git_version_string);
- return 0;
+ int i, ret = 0, list = 0, test = 0;
+
+ for (i = 1; i < argc; i++) {
+ const char *arg = argv[i];
+ if (!strcmp(arg, "--list-features"))
+ list = 1;
+ else if (!prefixcmp(arg, "--supports-feature=")) {
+ test = 1;
+ ret |= supports_feature(arg + 19);
+ } else
+ usage(version_usage);
+ }
+
+ if (list && test)
+ die("cannot use both --list-features and --supports-feature");
+ if (list)
+ list_features();
+ if (!list && !test)
+ printf("git version %s\n", git_version_string);
+ return ret;
}
int cmd_help(int argc, const char **argv, const char *prefix)
diff --git a/t/t0000-basic.sh b/t/t0000-basic.sh
index 8bfe832..9fc5824 100755
--- a/t/t0000-basic.sh
+++ b/t/t0000-basic.sh
@@ -31,6 +31,22 @@ fi
. ./test-lib.sh
################################################################
+# git version
+
+test_expect_success \
+ 'git version is functional' \
+ 'git version'
+test_expect_success \
+ 'git version --list-features' \
+ 'git version --list-features'
+test_expect_success \
+ 'feature "list-features" is supported' \
+ 'git version --supports-feature=list-features'
+test_expect_failure \
+ 'feature "THISNEVERWILLBEAGITFEATURE" is not supported' \
+ 'git version --supports-feature=THISNEVERWILLBEAGITFEATURE'
+
+################################################################
# git-init has been done in an empty repository.
# make sure it is empty.
--
1.5.2.2.1050.g51a8b
-
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