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 command 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>
---
.gitignore | 1 +
Documentation/git-supported-features.txt | 37 +++++++++++++++++
Makefile | 1 +
builtin-supported-features.c | 66 ++++++++++++++++++++++++++++++
builtin.h | 1 +
git.c | 1 +
t/t0000-basic.sh | 10 +++++
7 files changed, 117 insertions(+), 0 deletions(-)
create mode 100644 Documentation/git-supported-features.txt
create mode 100644 builtin-supported-features.c
diff --git a/.gitignore b/.gitignore
index 4dc0c39..6ff18d4 100644
--- a/.gitignore
+++ b/.gitignore
@@ -126,6 +126,7 @@ git-ssh-push
git-ssh-upload
git-status
git-stripspace
+git-supported-features
git-svn
git-svnimport
git-symbolic-ref
diff --git a/Documentation/git-supported-features.txt b/Documentation/git-supported-features.txt
new file mode 100644
index 0000000..28e2c21
--- /dev/null
+++ b/Documentation/git-supported-features.txt
@@ -0,0 +1,37 @@
+git-supported-features(1)
+===================
+
+NAME
+----
+git-supported-features - Report capabilities of the plumbing
+
+SYNOPSIS
+--------
+'git-supported-features' [<name>]
+
+DESCRIPTION
+-----------
+Given no arguments this plumbing utility displays a list of feature
+strings, one per line, that this particular version of the Git
+plumbing supports. These strings can be matched by higher level
+porcelain to determine what capabilities are available to its use.
+
+Given one argument (the name of the feature to test) the program
+exits with 0 if the feature is supported, and 1 if it is not.
+Other exit codes are undefined at this time.
+
+NOTES
+-----
+The exact list of feature strings is undefined by this manual page.
+
+Feature strings use a restricted character set, relying only on
+`a`-`z` (lowercase), `0`-`9` and `-` (hypen). This restriction is
+intentional, as it makes parsing output in shell quite simple.
+
+Author
+------
+Written by Shawn O. Pearce <spearce@xxxxxxxxxxx>.
+
+GIT
+---
+Part of the gitlink:git[7] suite
diff --git a/Makefile b/Makefile
index 7527734..03ab471 100644
--- a/Makefile
+++ b/Makefile
@@ -372,6 +372,7 @@ BUILTIN_OBJS = \
builtin-shortlog.o \
builtin-show-branch.o \
builtin-stripspace.o \
+ builtin-supported-features.o \
builtin-symbolic-ref.o \
builtin-tar-tree.o \
builtin-unpack-objects.o \
diff --git a/builtin-supported-features.c b/builtin-supported-features.c
new file mode 100644
index 0000000..79007f4
--- /dev/null
+++ b/builtin-supported-features.c
@@ -0,0 +1,66 @@
+#include "builtin.h"
+
+static const char *features[] = {
+ "git-k",
+ "redirect-stderr",
+ "supported-features",
+};
+
+static int is_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 sort_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(features);
+ unsigned i;
+
+ qsort(features, cnt, sizeof(features[0]), sort_feature);
+ for (i = 0; i < cnt; i++) {
+ if (!is_sane(features[i]))
+ die("feature name \"%s\" is bogus", features[i]);
+ printf("%s\n", features[i]);
+ }
+}
+
+static int test_feature(const char *the_feature)
+{
+ unsigned cnt = ARRAY_SIZE(features);
+ unsigned i;
+
+ for (i = 0; i < cnt; i++) {
+ if (!strcmp(features[i], the_feature))
+ return 0;
+ }
+ return 1;
+}
+
+static const char supported_features_usage[] =
+"git-supported-features [<feature>]";
+
+int cmd_supported_features(int argc, const char **argv, const char *prefix)
+{
+ if (argc == 1)
+ list_features();
+ else if (argc == 2)
+ return test_feature(argv[1]);
+ else
+ usage(supported_features_usage);
+ return 0;
+}
diff --git a/builtin.h b/builtin.h
index 39290d1..f33432c 100644
--- a/builtin.h
+++ b/builtin.h
@@ -71,6 +71,7 @@ extern int cmd_shortlog(int argc, const char **argv, const char *prefix);
extern int cmd_show(int argc, const char **argv, const char *prefix);
extern int cmd_show_branch(int argc, const char **argv, const char *prefix);
extern int cmd_stripspace(int argc, const char **argv, const char *prefix);
+extern int cmd_supported_features(int argc, const char **argv, const char *prefix);
extern int cmd_symbolic_ref(int argc, const char **argv, const char *prefix);
extern int cmd_tar_tree(int argc, const char **argv, const char *prefix);
extern int cmd_unpack_objects(int argc, const char **argv, const char *prefix);
diff --git a/git.c b/git.c
index 29b55a1..377fae9 100644
--- a/git.c
+++ b/git.c
@@ -284,6 +284,7 @@ static void handle_internal_command(int argc, const char **argv, char **envp)
{ "show-branch", cmd_show_branch, RUN_SETUP },
{ "show", cmd_show, RUN_SETUP | USE_PAGER },
{ "stripspace", cmd_stripspace },
+ { "supported-features", cmd_supported_features },
{ "symbolic-ref", cmd_symbolic_ref, RUN_SETUP },
{ "tar-tree", cmd_tar_tree },
{ "unpack-objects", cmd_unpack_objects, RUN_SETUP },
diff --git a/t/t0000-basic.sh b/t/t0000-basic.sh
index 186de70..7d0d9c9 100755
--- a/t/t0000-basic.sh
+++ b/t/t0000-basic.sh
@@ -31,6 +31,16 @@ fi
. ./test-lib.sh
################################################################
+# git-supported-features should always work.
+
+test_expect_success \
+ 'supported-features is functional' \
+ 'git-supported-features'
+test_expect_success \
+ 'supported-features recognizes itself' \
+ 'git-supported-features supported-features'
+
+################################################################
# git-init has been done in an empty repository.
# make sure it is empty.
--
1.5.2.869.g6b3ba
-
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