git-branch, git-checkout: autosetup for remote branch tracking

In order to track and build on top of a branch 'topic' you track from
your upstream repository, you often would end up doing this sequence:

  git checkout -b mytopic origin/topic
  git config --add branch.mytopic.remote origin
  git config --add branch.mytopic.merge refs/heads/topic

This would first fork your own 'mytopic' branch from the 'topic'
branch you track from the 'origin' repository; then it would set up two
configuration variables so that 'git pull' without parameters does the
right thing while you are on your own 'mytopic' branch.

This commit adds a --track option to git-branch, so that "git
branch --track mytopic origin/topic" performs the latter two actions
when creating your 'mytopic' branch.

If the configuration variable branch.autosetupmerge is set to true, you
do not have to pass the --track option explicitly; further patches in
this series allow setting the variable with a "git remote add" option.
The configuration variable is off by default, and there is a --no-track
option to countermand it even if the variable is set.

Signed-off-by: Paolo Bonzini  <bonzini@gnu.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/Documentation/git-branch.txt b/Documentation/git-branch.txt
index 3ea3b8063520fe2a6f97b767d5f2e2ac05d147d9..603f87f3b59358697da821ffe240be9caff43fa7 100644 (file)
--- a/Documentation/git-branch.txt
+++ b/Documentation/git-branch.txt
@@ -10,7 +10,7 @@ SYNOPSIS
 [verse]
 'git-branch' [--color | --no-color] [-r | -a]
           [-v [--abbrev=<length> | --no-abbrev]]
-'git-branch' [-l] [-f] <branchname> [<start-point>]
+'git-branch' [--track | --no-track] [-l] [-f] <branchname> [<start-point>]
 'git-branch' (-m | -M) [<oldbranch>] <newbranch>
 'git-branch' (-d | -D) [-r] <branchname>...
 
@@ -26,6 +26,13 @@ It will start out with a head equal to the one given as <start-point>.
 If no <start-point> is given, the branch will be created with a head
 equal to that of the currently checked out branch.
 
+When a local branch is started off a remote branch, git can setup the
+branch so that gitlink:git-pull[1] will appropriately merge from that
+remote branch.  If this behavior is desired, it is possible to make it
+the default using the global `branch.autosetupmerge` configuration
+flag.  Otherwise, it can be chosen per-branch using the `--track`
+and `--no-track` options.
+
 With a '-m' or '-M' option, <oldbranch> will be renamed to <newbranch>.
 If <oldbranch> had a corresponding reflog, it is renamed to match
 <newbranch>, and a reflog entry is created to remember the branch

diff --git a/Documentation/git-checkout.txt b/Documentation/git-checkout.txt
index 1ae77be45055418b9c784d15db520841dd7bdd7a..f5b2d5017b5710a08c89a7cb150d8ef45527bf99 100644 (file)
--- a/Documentation/git-checkout.txt
+++ b/Documentation/git-checkout.txt
@@ -8,7 +8,7 @@ git-checkout - Checkout and switch to a branch
 SYNOPSIS
 --------
 [verse]
-'git-checkout' [-q] [-f] [-b <new_branch> [-l]] [-m] [<branch>]
+'git-checkout' [-q] [-f] [-b [--track | --no-track] <new_branch> [-l]] [-m] [<branch>]
 'git-checkout' [<tree-ish>] <paths>...
 
 DESCRIPTION
@@ -18,7 +18,8 @@ When <paths> are not given, this command switches branches by
 updating the index and working tree to reflect the specified
 branch, <branch>, and updating HEAD to be <branch> or, if
 specified, <new_branch>.  Using -b will cause <new_branch> to
-be created.
+be created; in this case you can use the --track or --no-track
+options, which will be passed to `git branch`.
 
 When <paths> are given, this command does *not* switch
 branches.  It updates the named paths in the working tree from
@@ -45,6 +46,16 @@ OPTIONS
        by gitlink:git-check-ref-format[1].  Some of these checks
        may restrict the characters allowed in a branch name.
 
+--track::
+       When -b is given and a branch is created off a remote branch,
+       setup so that git-pull will automatically retrieve data from
+       the remote branch.
+
+--no-track::
+       When -b is given and a branch is created off a remote branch,
+       force that git-pull will automatically retrieve data from
+       the remote branch independent of the configuration settings.
+
 -l::
        Create the new branch's ref log.  This activates recording of
        all changes to made the branch ref, enabling use of date

diff --git a/builtin-branch.c b/builtin-branch.c
index 06d8a8ce0432134f994aa30ac4133baf4ba7fef5..e161e00978d5b26d7c5f520600359e6650f2fb34 100644 (file)
--- a/builtin-branch.c
+++ b/builtin-branch.c
@@ -12,7 +12,7 @@
 #include "builtin.h"
 
 static const char builtin_branch_usage[] =
-  "git-branch [-r] (-d | -D) <branchname> | [-l] [-f] <branchname> [<start-point>] | (-m | -M) [<oldbranch>] <newbranch> | [--color | --no-color] [-r | -a] [-v [--abbrev=<length> | --no-abbrev]]";
+  "git-branch [-r] (-d | -D) <branchname> | [--track | --no-track] [-l] [-f] <branchname> [<start-point>] | (-m | -M) [<oldbranch>] <newbranch> | [--color | --no-color] [-r | -a] [-v [--abbrev=<length> | --no-abbrev]]";
 
 #define REF_UNKNOWN_TYPE    0x00
 #define REF_LOCAL_BRANCH    0x01
@@ -22,6 +22,8 @@ static const char builtin_branch_usage[] =
 static const char *head;
 static unsigned char head_sha1[20];
 
+static int branch_track_remotes;
+
 static int branch_use_color;
 static char branch_colors[][COLOR_MAXLEN] = {
        "\033[m",       /* reset */
@@ -64,6 +66,9 @@ int git_branch_config(const char *var, const char *value)
                color_parse(value, var, branch_colors[slot]);
                return 0;
        }
+       if (!strcmp(var, "branch.autosetupmerge"))
+               branch_track_remotes = git_config_bool(var, value);
+
        return git_default_config(var, value);
 }
 
@@ -309,14 +314,109 @@ static void print_ref_list(int kinds, int detached, int verbose, int abbrev)
        free_ref_list(&ref_list);
 }
 
+static char *config_repo;
+static char *config_remote;
+static const char *start_ref;
+static int start_len;
+static int base_len;
+
+static int get_remote_branch_name(const char *value)
+{
+       const char *colon;
+       const char *end;
+
+       if (*value == '+')
+               value++;
+
+       colon = strchr(value, ':');
+       if (!colon)
+               return 0;
+
+       end = value + strlen(value);
+
+       /* Try an exact match first.  */
+       if (!strcmp(colon + 1, start_ref)) {
+               /* Truncate the value before the colon.  */
+               nfasprintf(&config_repo, "%.*s", colon - value, value);
+               return 1;
+       }
+
+       /* Try with a wildcard match now.  */
+       if (end - value > 2 && end[-2] == '/' && end[-1] == '*' &&
+           colon - value > 2 && colon[-2] == '/' && colon[-1] == '*' &&
+           (end - 2) - (colon + 1) == base_len &&
+           !strncmp(colon + 1, start_ref, base_len)) {
+               /* Replace the star with the remote branch name.  */
+               nfasprintf(&config_repo, "%.*s%s",
+                          (colon - 2) - value, value,
+                          start_ref + base_len);
+               return 1;
+       }
+
+       return 0;
+}
+
+static int get_remote_config(const char *key, const char *value)
+{
+       const char *var;
+       if (prefixcmp(key, "remote."))
+               return 0;
+
+       var = strrchr(key, '.');
+       if (var == key + 6)
+               return 0;
+
+       if (!strcmp(var, ".fetch") && get_remote_branch_name(value))
+               nfasprintf(&config_remote, "%.*s", var - (key + 7), key + 7);
+
+       return 0;
+}
+
+static void set_branch_defaults(const char *name, const char *real_ref)
+{
+       char key[1024];
+       const char *slash = strrchr(real_ref, '/');
+
+       if (!slash)
+               return;
+
+       start_ref = real_ref;
+       start_len = strlen(real_ref);
+       base_len = slash - real_ref;
+       git_config(get_remote_config);
+
+       if (config_repo && config_remote) {
+               if (sizeof(key) <=
+                   snprintf(key, sizeof(key), "branch.%s.remote", name))
+                       die("what a long branch name you have!");
+               git_config_set(key, config_remote);
+
+               /*
+                * We do not have to check if we have enough space for
+                * the 'merge' key, since it's shorter than the
+                * previous 'remote' key, which we already checked.
+                */
+               snprintf(key, sizeof(key), "branch.%s.merge", name);
+               git_config_set(key, config_repo);
+
+               printf("Branch %s set up to track remote branch %s.\n",
+                      name, real_ref);
+       }
+
+       if (config_repo)
+               free(config_repo);
+       if (config_remote)
+               free(config_remote);
+}
+
 static void create_branch(const char *name, const char *start_name,
                          unsigned char *start_sha1,
-                         int force, int reflog)
+                         int force, int reflog, int track)
 {
        struct ref_lock *lock;
        struct commit *commit;
        unsigned char sha1[20];
-       char ref[PATH_MAX], msg[PATH_MAX + 20];
+       char *real_ref, ref[PATH_MAX], msg[PATH_MAX + 20];
        int forcing = 0;
 
        snprintf(ref, sizeof ref, "refs/heads/%s", name);
@@ -331,10 +431,14 @@ static void create_branch(const char *name, const char *start_name,
                forcing = 1;
        }
 
-       if (start_sha1)
+       if (start_sha1) {
                /* detached HEAD */
                hashcpy(sha1, start_sha1);
-       else if (get_sha1(start_name, sha1))
+               real_ref = NULL;
+       }
+       else if (dwim_ref(start_name, strlen(start_name), sha1, &real_ref) > 1)
+               die("Ambiguous object name: '%s'.", start_name);
+       else if (real_ref == NULL)
                die("Not a valid object name: '%s'.", start_name);
 
        if ((commit = lookup_commit_reference(sha1)) == NULL)
@@ -355,8 +459,17 @@ static void create_branch(const char *name, const char *start_name,
                snprintf(msg, sizeof msg, "branch: Created from %s",
                         start_name);
 
+       /* When branching off a remote branch, set up so that git-pull
+          automatically merges from there.  So far, this is only done for
+          remotes registered via .git/config.  */
+       if (real_ref && track)
+               set_branch_defaults(name, real_ref);
+
        if (write_ref_sha1(lock, sha1, msg) < 0)
                die("Failed to write ref: %s.", strerror(errno));
+
+       if (real_ref)
+               free(real_ref);
 }
 
 static void rename_branch(const char *oldname, const char *newname, int force)
@@ -398,11 +511,12 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
        int delete = 0, force_delete = 0, force_create = 0;
        int rename = 0, force_rename = 0;
        int verbose = 0, abbrev = DEFAULT_ABBREV, detached = 0;
-       int reflog = 0;
+       int reflog = 0, track;
        int kinds = REF_LOCAL_BRANCH;
        int i;
 
        git_config(git_branch_config);
+       track = branch_track_remotes;
 
        for (i = 1; i < argc; i++) {
                const char *arg = argv[i];
@@ -413,6 +527,14 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
                        i++;
                        break;
                }
+               if (!strcmp(arg, "--track")) {
+                       track = 1;
+                       continue;
+               }
+               if (!strcmp(arg, "--no-track")) {
+                       track = 0;
+                       continue;
+               }
                if (!strcmp(arg, "-d")) {
                        delete = 1;
                        continue;
@@ -499,9 +621,11 @@ int cmd_branch(int argc, const char **argv, const char *prefix)
        else if (rename && (i == argc - 2))
                rename_branch(argv[i], argv[i + 1], force_rename);
        else if (i == argc - 1)
-               create_branch(argv[i], head, head_sha1, force_create, reflog);
+               create_branch(argv[i], head, head_sha1, force_create, reflog,
+                             track);
        else if (i == argc - 2)
-               create_branch(argv[i], argv[i+1], NULL, force_create, reflog);
+               create_branch(argv[i], argv[i+1], NULL, force_create, reflog,
+                             track);
        else
                usage(builtin_branch_usage);
 

diff --git a/cache.h b/cache.h
index f172d02a653475fcf715eb5605012abf50c5621b..faed2a8994ee6b8262c7929bfabf80e0a3e6a974 100644 (file)
--- a/cache.h
+++ b/cache.h
@@ -480,6 +480,7 @@ extern struct tag *alloc_tag_node(void);
 extern void alloc_report(void);
 
 /* trace.c */
+extern int nfasprintf(char **str, const char *fmt, ...);
 extern int nfvasprintf(char **str, const char *fmt, va_list va);
 extern void trace_printf(const char *format, ...);
 extern void trace_argv_printf(const char **argv, int count, const char *format, ...);

diff --git a/git-checkout.sh b/git-checkout.sh
index 14835a4aa982af88d758ea014afacf7b2fb1bb1e..6caa9fdcc660b6fee063bfccbc51e46331e911c7 100755 (executable)
--- a/git-checkout.sh
+++ b/git-checkout.sh
@@ -12,6 +12,7 @@ new=
 new_name=
 force=
 branch=
+track=
 newbranch=
 newbranch_log=
 merge=
@@ -33,7 +34,10 @@ while [ "$#" != "0" ]; do
                        die "git checkout: we do not like '$newbranch' as a branch name."
                ;;
        "-l")
-               newbranch_log=1
+               newbranch_log=-l
+               ;;
+       "--track"|"--no-track")
+               track="$arg"
                ;;
        "-f")
                force=1
@@ -85,6 +89,11 @@ while [ "$#" != "0" ]; do
     esac
 done
 
+case "$new_branch,$track" in
+,--*)
+       die "git checkout: --track and --no-track require -b"
+esac
+
 case "$force$merge" in
 11)
        die "git checkout: -f and -m are incompatible"
@@ -235,11 +244,7 @@ fi
 #
 if [ "$?" -eq 0 ]; then
        if [ "$newbranch" ]; then
-               if [ "$newbranch_log" ]; then
-                       mkdir -p $(dirname "$GIT_DIR/logs/refs/heads/$newbranch")
-                       touch "$GIT_DIR/logs/refs/heads/$newbranch"
-               fi
-               git-update-ref -m "checkout: Created from $new_name" "refs/heads/$newbranch" $new || exit
+               git-branch $track $newbranch_log "$newbranch" "$new_name" || exit
                branch="$newbranch"
        fi
        if test -n "$branch"

diff --git a/t/t3200-branch.sh b/t/t3200-branch.sh
index 5565c27033ab89959f2a39dfa9abaea99e40432b..75c000a968c4b3a371393062e14801aa90ee53f1 100755 (executable)
--- a/t/t3200-branch.sh
+++ b/t/t3200-branch.sh
@@ -47,17 +47,6 @@ test_expect_success \
         test ! -f .git/refs/heads/d/e/f &&
         test ! -f .git/logs/refs/heads/d/e/f'
 
-cat >expect <<EOF
-0000000000000000000000000000000000000000 $HEAD $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> 1117150200 +0000     checkout: Created from master
-EOF
-test_expect_success \
-    'git checkout -b g/h/i -l should create a branch and a log' \
-       'GIT_COMMITTER_DATE="2005-05-26 23:30" \
-     git-checkout -b g/h/i -l master &&
-        test -f .git/refs/heads/g/h/i &&
-        test -f .git/logs/refs/heads/g/h/i &&
-        diff expect .git/logs/refs/heads/g/h/i'
-
 test_expect_success \
     'git branch j/k should work after branch j has been deleted' \
        'git-branch j &&
@@ -117,4 +106,58 @@ test_expect_failure \
      ln -s real-u .git/logs/refs/heads/u &&
      git-branch -m u v'
 
+test_expect_success 'test tracking setup via --track' \
+    'git-config remote.local.url . &&
+     git-config remote.local.fetch refs/heads/*:refs/remotes/local/* &&
+     (git-show-ref -q refs/remotes/local/master || git-fetch local) &&
+     git-branch --track my1 local/master &&
+     test $(git-config branch.my1.remote) = local &&
+     test $(git-config branch.my1.merge) = refs/heads/master'
+
+test_expect_success 'test tracking setup (non-wildcard, matching)' \
+    'git-config remote.local.url . &&
+     git-config remote.local.fetch refs/heads/master:refs/remotes/local/master &&
+     (git-show-ref -q refs/remotes/local/master || git-fetch local) &&
+     git-branch --track my4 local/master &&
+     test $(git-config branch.my4.remote) = local &&
+     test $(git-config branch.my4.merge) = refs/heads/master'
+
+test_expect_success 'test tracking setup (non-wildcard, not matching)' \
+    'git-config remote.local.url . &&
+     git-config remote.local.fetch refs/heads/s:refs/remotes/local/s &&
+     (git-show-ref -q refs/remotes/local/master || git-fetch local) &&
+     git-branch --track my5 local/master &&
+     ! test $(git-config branch.my5.remote) = local &&
+     ! test $(git-config branch.my5.merge) = refs/heads/master'
+
+test_expect_success 'test tracking setup via config' \
+    'git-config branch.autosetupmerge true &&
+     git-config remote.local.url . &&
+     git-config remote.local.fetch refs/heads/*:refs/remotes/local/* &&
+     (git-show-ref -q refs/remotes/local/master || git-fetch local) &&
+     git-branch my3 local/master &&
+     test $(git-config branch.my3.remote) = local &&
+     test $(git-config branch.my3.merge) = refs/heads/master'
+
+test_expect_success 'test overriding tracking setup via --no-track' \
+    'git-config branch.autosetupmerge true &&
+     git-config remote.local.url . &&
+     git-config remote.local.fetch refs/heads/*:refs/remotes/local/* &&
+     (git-show-ref -q refs/remotes/local/master || git-fetch local) &&
+     git-branch --no-track my2 local/master &&
+     ! test $(git-config branch.my2.remote) = local &&
+     ! test $(git-config branch.my2.merge) = refs/heads/master'
+
+# Keep this test last, as it changes the current branch
+cat >expect <<EOF
+0000000000000000000000000000000000000000 $HEAD $GIT_COMMITTER_NAME <$GIT_COMMITTER_EMAIL> 1117150200 +0000     branch: Created from master
+EOF
+test_expect_success \
+    'git checkout -b g/h/i -l should create a branch and a log' \
+       'GIT_COMMITTER_DATE="2005-05-26 23:30" \
+     git-checkout -b g/h/i -l master &&
+        test -f .git/refs/heads/g/h/i &&
+        test -f .git/logs/refs/heads/g/h/i &&
+        diff expect .git/logs/refs/heads/g/h/i'
+
 test_done

diff --git a/trace.c b/trace.c
index 27fef868c4e2276638873cbda7d353cf4b8f67ed..7961a27a2ed4f32c766dabdf12c4115c3d3b36ba 100644 (file)
--- a/trace.c
+++ b/trace.c
@@ -26,14 +26,14 @@
 #include "quote.h"
 
 /* Stolen from "imap-send.c". */
-static int git_vasprintf(char **strp, const char *fmt, va_list ap)
+int nfvasprintf(char **strp, const char *fmt, va_list ap)
 {
        int len;
        char tmp[1024];
 
        if ((len = vsnprintf(tmp, sizeof(tmp), fmt, ap)) < 0 ||
            !(*strp = xmalloc(len + 1)))
-               return -1;
+               die("Fatal: Out of memory\n");
        if (len >= (int)sizeof(tmp))
                vsprintf(*strp, fmt, ap);
        else
@@ -41,13 +41,15 @@ static int git_vasprintf(char **strp, const char *fmt, va_list ap)
        return len;
 }
 
-/* Stolen from "imap-send.c". */
-int nfvasprintf(char **str, const char *fmt, va_list va)
+int nfasprintf(char **str, const char *fmt, ...)
 {
-       int ret = git_vasprintf(str, fmt, va);
-       if (ret < 0)
-               die("Fatal: Out of memory\n");
-       return ret;
+       int rc;
+       va_list args;
+
+       va_start(args, fmt);
+       rc = nfvasprintf(str, fmt, args);
+       va_end(args);
+       return rc;
 }
 
 /* Get a trace file descriptor from GIT_TRACE env variable. */