rev-parse: add --show-superproject-working-tree

In some situations it is useful to know if the given repository
is a submodule of another repository.

Add the flag --show-superproject-working-tree to git-rev-parse
to make it easy to find out if there is a superproject. When no
superproject exists, the output will be empty.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/git-rev-parse.txt b/Documentation/git-rev-parse.txt
index 91c02b8c856abf2c24af9ea23f0ee01710b8cd12..c40c4704486dd9d1a5650562540db7379818ab03 100644 (file)
--- a/Documentation/git-rev-parse.txt
+++ b/Documentation/git-rev-parse.txt
@@ -261,6 +261,12 @@ print a message to stderr and exit with nonzero status.
 --show-toplevel::
        Show the absolute path of the top-level directory.
 
+--show-superproject-working-tree
+       Show the absolute path of the root of the superproject's
+       working tree (if exists) that uses the current repository as
+       its submodule.  Outputs nothing if the current repository is
+       not used as a submodule by any project.
+
 --shared-index-path::
        Show the path to the shared index file in split index mode, or
        empty if not in split-index mode.

diff --git a/builtin/rev-parse.c b/builtin/rev-parse.c
index e08677e559f443f8a290f200f691ef770ecde3ef..2549643267440c5742690e3b808943de6fad19af 100644 (file)
--- a/builtin/rev-parse.c
+++ b/builtin/rev-parse.c
@@ -12,6 +12,7 @@
 #include "diff.h"
 #include "revision.h"
 #include "split-index.h"
+#include "submodule.h"
 
 #define DO_REVS                1
 #define DO_NOREV       2
@@ -779,6 +780,12 @@ int cmd_rev_parse(int argc, const char **argv, const char *prefix)
                                        puts(work_tree);
                                continue;
                        }
+                       if (!strcmp(arg, "--show-superproject-working-tree")) {
+                               const char *superproject = get_superproject_working_tree();
+                               if (superproject)
+                                       puts(superproject);
+                               continue;
+                       }
                        if (!strcmp(arg, "--show-prefix")) {
                                if (prefix)
                                        puts(prefix);

diff --git a/submodule.c b/submodule.c
index 3b98766a6bcfe983e5f94e84edd6fcec7ce74f8d..bb405653fd29686e25faf978a760b8e33d80dff3 100644 (file)
--- a/submodule.c
+++ b/submodule.c
@@ -1514,3 +1514,85 @@ void absorb_git_dir_into_superproject(const char *prefix,
                strbuf_release(&sb);
        }
 }
+
+const char *get_superproject_working_tree(void)
+{
+       struct child_process cp = CHILD_PROCESS_INIT;
+       struct strbuf sb = STRBUF_INIT;
+       const char *one_up = real_path_if_valid("../");
+       const char *cwd = xgetcwd();
+       const char *ret = NULL;
+       const char *subpath;
+       int code;
+       ssize_t len;
+
+       if (!is_inside_work_tree())
+               /*
+                * FIXME:
+                * We might have a superproject, but it is harder
+                * to determine.
+                */
+               return NULL;
+
+       if (!one_up)
+               return NULL;
+
+       subpath = relative_path(cwd, one_up, &sb);
+
+       prepare_submodule_repo_env(&cp.env_array);
+       argv_array_pop(&cp.env_array);
+
+       argv_array_pushl(&cp.args, "--literal-pathspecs", "-C", "..",
+                       "ls-files", "-z", "--stage", "--full-name", "--",
+                       subpath, NULL);
+       strbuf_reset(&sb);
+
+       cp.no_stdin = 1;
+       cp.no_stderr = 1;
+       cp.out = -1;
+       cp.git_cmd = 1;
+
+       if (start_command(&cp))
+               die(_("could not start ls-files in .."));
+
+       len = strbuf_read(&sb, cp.out, PATH_MAX);
+       close(cp.out);
+
+       if (starts_with(sb.buf, "160000")) {
+               int super_sub_len;
+               int cwd_len = strlen(cwd);
+               char *super_sub, *super_wt;
+
+               /*
+                * There is a superproject having this repo as a submodule.
+                * The format is <mode> SP <hash> SP <stage> TAB <full name> \0,
+                * We're only interested in the name after the tab.
+                */
+               super_sub = strchr(sb.buf, '\t') + 1;
+               super_sub_len = sb.buf + sb.len - super_sub - 1;
+
+               if (super_sub_len > cwd_len ||
+                   strcmp(&cwd[cwd_len - super_sub_len], super_sub))
+                       die (_("BUG: returned path string doesn't match cwd?"));
+
+               super_wt = xstrdup(cwd);
+               super_wt[cwd_len - super_sub_len] = '\0';
+
+               ret = real_path(super_wt);
+               free(super_wt);
+       }
+       strbuf_release(&sb);
+
+       code = finish_command(&cp);
+
+       if (code == 128)
+               /* '../' is not a git repository */
+               return NULL;
+       if (code == 0 && len == 0)
+               /* There is an unrelated git repository at '../' */
+               return NULL;
+       if (code)
+               die(_("ls-tree returned unexpected return code %d"), code);
+
+       return ret;
+}

diff --git a/submodule.h b/submodule.h
index 05ab674f069282b3d5b20ca69d9a1fe8f295879b..c8a0c9cb2971219b807f7fe931c4dc5355b978ea 100644 (file)
--- a/submodule.h
+++ b/submodule.h
@@ -93,4 +93,12 @@ extern void prepare_submodule_repo_env(struct argv_array *out);
 extern void absorb_git_dir_into_superproject(const char *prefix,
                                             const char *path,
                                             unsigned flags);
+
+/*
+ * Return the absolute path of the working tree of the superproject, which this
+ * project is a submodule of. If this repository is not a submodule of
+ * another repository, return NULL.
+ */
+extern const char *get_superproject_working_tree(void);
+
 #endif

diff --git a/t/t1500-rev-parse.sh b/t/t1500-rev-parse.sh
index 9ed8b8ccba5db702eaf7b872bd4a1e1af1fd2192..03d3c7f6d65b46bf977adf76a6d68582206768c2 100755 (executable)
--- a/t/t1500-rev-parse.sh
+++ b/t/t1500-rev-parse.sh
@@ -116,4 +116,18 @@ test_expect_success 'git-path inside sub-dir' '
        test_cmp expect actual
 '
 
+test_expect_success 'showing the superproject correctly' '
+       git rev-parse --show-superproject-working-tree >out &&
+       test_must_be_empty out &&
+
+       test_create_repo super &&
+       test_commit -C super test_commit &&
+       test_create_repo sub &&
+       test_commit -C sub test_commit &&
+       git -C super submodule add ../sub dir/sub &&
+       echo $(pwd)/super >expect  &&
+       git -C super/dir/sub rev-parse --show-superproject-working-tree >out &&
+       test_cmp expect out
+'
+
 test_done