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>

1 files changed, 10 insertions, 8 deletions

diff --git a/trace.c b/trace.c
index 27fef86..7961a27 100644
--- 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. */