threads / patch / 38058

v4git-new-workdir: Don't fail if the target directory is empty

Subject: [PATCH v4] git-new-workdir: Don't fail if the target directory is empty

## tl;dr

6 messages between Nov 26, 2014 and Dec 10, 2014. Diffs are folded; open one to read it.

replies: 5people: 2as markdown or json

Paul Smith· Nov 26, 2014, 20:38 UTC · lore

Allow new workdirs to be created in an empty directory (similar to "git clone"). Provide more error checking and clean up on failure.

Signed-off-by: Paul Smith <paul@mad-scientist.net>
---

Hopefully this doesn't contain unwanted stylistic changes. There's a kind of gross thing about the behavior here: because we cd much earlier than in my previous version we could actually trap and "rm -rf" while our current working directory is inside the removed location (inside $cleandir). On a traditional UNIX filesystem this is fine, of course, but it's possible that some filesystems don't like this in some way. In Windows for example this will definitely fail (but new-workdir doesn't support Windows anyway). The only options are (a) don't worry about it (that's what this patch does), (b) put the "cd" after the trap reset again, (c) move the trap reset earlier and don't clean up if we get failures after we "cd", or (d) "cd" again inside the cleanup function. Of these, (d) is the most complex and hence my least favorite.

 contrib/workdir/git-new-workdir | 53 +++++++++++++++++++++++++++++------------
 1 file changed, 38 insertions(+), 15 deletions(-)
Show changes to contrib/workdir/git-new-workdir +38 −15
diff --git a/contrib/workdir/git-new-workdir b/contrib/workdir/git-new-workdir
index 75e8b25..d1d7f32 100755
--- a/contrib/workdir/git-new-workdir
+++ b/contrib/workdir/git-new-workdir
@@ -10,6 +10,10 @@ die () {
 	exit 128
 }
 
+failed () {
+	die "unable to create new workdir \"$new_workdir\"!"
+}
+
 if test $# -lt 2 || test $# -gt 3
 then
 	usage "$0 <repository> <new_workdir> [<branch>]"
@@ -35,7 +39,7 @@ esac
 
 # don't link to a configured bare repository
 isbare=$(git --git-dir="$git_dir" config --bool --get core.bare)
-if test ztrue = z$isbare
+if test ztrue = "z$isbare"
 then
 	die "\"$git_dir\" has core.bare set to true," \
 		" remove from \"$git_dir/config\" to use $0"
@@ -48,35 +52,54 @@ then
 		"a complete repository."
 fi
 
-# don't recreate a workdir over an existing repository
-if test -e "$new_workdir"
+# make sure the links in the workdir have full paths to the original repo
+git_dir=$(cd "$git_dir" && pwd) || exit 1
+
+# don't recreate a workdir over an existing directory, unless it's empty
+if test -d "$new_workdir"
 then
-	die "destination directory '$new_workdir' already exists."
+	if test $(ls -a1 "$new_workdir/." | wc -l) -ne 2
+	then
+		die "destination directory '$new_workdir' is not empty."
+	fi
+	cleandir="$new_workdir/.git"
+else
+	cleandir="$new_workdir"
 fi
 
-# make sure the links use full paths
-git_dir=$(cd "$git_dir"; pwd)
+mkdir -p "$new_workdir/.git" || failed
+cleandir=$(cd "$cleandir" && pwd) || failed
 
-# create the workdir
-mkdir -p "$new_workdir/.git" || die "unable to create \"$new_workdir\"!"
+cleanup () {
+	rm -rf "$cleandir"
+}
+siglist="0 1 2 15"
+trap cleanup $siglist
 
 # create the links to the original repo.  explicitly exclude index, HEAD and
 # logs/HEAD from the list since they are purely related to the current working
 # directory, and should not be shared.
 for x in config refs logs/refs objects info hooks packed-refs remotes rr-cache svn
 do
+	# create a containing directory if needed
 	case $x in
 	*/*)
-		mkdir -p "$(dirname "$new_workdir/.git/$x")"
+		mkdir -p "$new_workdir/.git/${x%/*}"
 		;;
 	esac
-	ln -s "$git_dir/$x" "$new_workdir/.git/$x"
+
+	ln -s "$git_dir/$x" "$new_workdir/.git/$x" || failed
 done
 
-# now setup the workdir
-cd "$new_workdir"
+# commands below this are run in the context of the new workdir
+cd "$new_workdir" || failed
+
 # copy the HEAD from the original repository as a default branch
-cp "$git_dir/HEAD" .git/HEAD
-# checkout the branch (either the same as HEAD from the original repository, or
-# the one that was asked for)
+cp "$git_dir/HEAD" .git/HEAD || failed
+
+# the workdir is set up.  if the checkout fails, the user can fix it.
+trap - $siglist
+
+# checkout the branch (either the same as HEAD from the original repository,
+# or the one that was asked for)
 git checkout -f $branch

-- 
1.8.5.3
Junio C Hamano· Nov 26, 2014, 21:55 UTC · re: Paul Smith · lore

Re: [PATCH v4] git-new-workdir: Don't fail if the target directory is empty

Paul Smith <paul@mad-scientist.net> writes:
Show 7 quoted lines
> Allow new workdirs to be created in an empty directory (similar to "git
> clone").  Provide more error checking and clean up on failure.
>
> Signed-off-by: Paul Smith <paul@mad-scientist.net>
> ---
>
> Hopefully this doesn't contain unwanted stylistic changes.
;-)
Unwanted, no, but unrelated yes.
>  
> +failed () {
> +	die "unable to create new workdir \"$new_workdir\"!"
> +}
Use '$new_workdir' instead to match the existing message below?
Show 17 quoted lines
> -# don't recreate a workdir over an existing repository
> -if test -e "$new_workdir"
> +# make sure the links in the workdir have full paths to the original repo
> +git_dir=$(cd "$git_dir" && pwd) || exit 1
> +
> +# don't recreate a workdir over an existing directory, unless it's empty
> +if test -d "$new_workdir"
>  then
> -	die "destination directory '$new_workdir' already exists."
> +	if test $(ls -a1 "$new_workdir/." | wc -l) -ne 2
> +	then
> +		die "destination directory '$new_workdir' is not empty."
> +	fi
> +	cleandir="$new_workdir/.git"
> +else
> +	cleandir="$new_workdir"
>  fi

The comment in the original is somewhat misleading, but "test -e" was "test -e" and not "test -d" to stop when an existing file was given by mistake as $new_workdir, I think. I do not know what happens in the new code in that case.

Paul Smith· Nov 26, 2014, 22:31 UTC · re: Junio C Hamano · lore

Re: [PATCH v4] git-new-workdir: Don't fail if the target directory is empty

On Wed, 2014-11-26 at 13:55 -0800, Junio C Hamano wrote:
> The comment in the original is somewhat misleading, but "test -e"
> was "test -e" and not "test -d" to stop when an existing file was
> given by mistake as $new_workdir, I think.  I do not know what
> happens in the new code in that case.

I did test that. I have a little set of tests with a no directory, empty directory, non-empty directory, plus various permissions issues (existing directory without write privs, no write privs to the parent directory), and also if the new directory name is a file, a symlink pointing to something, a symlink pointing to nothing, etc.

This is what happens for a file:
$ rm -f foo
$ touch foo

$ ./src/git/contrib/workdir/git-new-workdir src/git foo master mkdir: cannot create directory ‘foo’: Not a directory unable to create new workdir "foo"!

Junio C Hamano· Nov 26, 2014, 23:16 UTC · re: Paul Smith · lore

Re: [PATCH v4] git-new-workdir: Don't fail if the target directory is empty

Paul Smith <paul@mad-scientist.net> writes:
Show 9 quoted lines
> This is what happens for a file:
>
> $ rm -f foo
>
> $ touch foo
>
> $ ./src/git/contrib/workdir/git-new-workdir src/git foo master
> mkdir: cannot create directory ‘foo’: Not a directory
> unable to create new workdir "foo"!
;-)  That comes from mkdir || fail which is indeed sufficient.
Paul Smith· Nov 28, 2014, 18:34 UTC · re: Junio C Hamano · lore

Re: [PATCH v4] git-new-workdir: Don't fail if the target directory is empty

On Wed, 2014-11-26 at 15:16 -0800, Junio C Hamano wrote:
Show 5 quoted lines
> > $ ./src/git/contrib/workdir/git-new-workdir src/git foo master
> > mkdir: cannot create directory ‘foo’: Not a directory
> > unable to create new workdir "foo"!
> 
> ;-)  That comes from mkdir || fail which is indeed sufficient.

Right. Often I find it simpler/clearer to let the underlying commands give the errors: they use perror() and can often provide more specific error messages than my script can, unless I spend a lot of effort trying to determine exactly what the problem is (permissions, disk space, bad symlink, existing file, whatever).

Should I respin this with the \"$new_workdir\" -> '$new_workdir' change (I actually prefer the latter myself but the former was used somewhere so I kept it)?

Paul Smith· Dec 10, 2014, 17:16 UTC · re: Junio C Hamano · lore

Re: [PATCH v4] git-new-workdir: Don't fail if the target directory is empty

On Wed, 2014-11-26 at 15:16 -0800, Junio C Hamano wrote:
Show 13 quoted lines
> Paul Smith <paul@mad-scientist.net> writes:
> 
> > This is what happens for a file:
> >
> > $ rm -f foo
> >
> > $ touch foo
> >
> > $ ./src/git/contrib/workdir/git-new-workdir src/git foo master
> > mkdir: cannot create directory ‘foo’: Not a directory
> > unable to create new workdir "foo"!
> 
> ;-)  That comes from mkdir || fail which is indeed sufficient.
Hi Junio;
Is this all set to be applied or is there more to do?
Cheers!

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