[PATCH] cvsimport - streamline temp index file creation and avoid creating empty tmpfiles

[Martin Langhoff <martin@catalyst.net.nz>]

On 6/24/06, Johannes Schindelin <Johannes.Schindelin@gmx.de> wrote:
> It seems that git-cvsimport makes a temporary file of size 0, which cannot
> get mmap()ed, because it has size 0.

This switch to tmpnam() avoids creating the tmpfile in the first place and
streamlines the code. This handling of tmpfiles is slightly safer, but there
is an inherent race condition.

---
NOTE: (a) I cannot reproduce the problem and (b) this is only lightly tested,
if trivial.

However, this switch to tmpnam() avoids creating the tmpfile in the first place
and streamlines the code. This usage of tempfiles is open to a race condition
if someone could guess the name returned by tmpnam, but even this is safer than
what we did before, which was creating a file, closing the fh and then
clobbering it from git-read-tree.

And if someone can guess the name that tmpnam() returns their magic is strong
enough that they'll go for more interesting targets.
Signed-off-by: Martin Langhoff <martin@catalyst.net.nz>
---
 git-cvsimport.perl |   20 +++++---------------
 1 files changed, 5 insertions(+), 15 deletions(-)

diff --git a/git-cvsimport.perl b/git-cvsimport.perl
index f3daa6c..d961b7b 100644
--- a/git-cvsimport.perl
+++ b/git-cvsimport.perl
@@ -17,7 +17,7 @@ use strict;
 use warnings;
 use Getopt::Std;
 use File::Spec;
-use File::Temp qw(tempfile);
+use File::Temp qw(tempfile tmpnam);
 use File::Path qw(mkpath);
 use File::Basename qw(basename dirname);
 use Time::Local;
@@ -467,12 +467,8 @@ my $orig_git_index;
 $orig_git_index = $ENV{GIT_INDEX_FILE} if exists $ENV{GIT_INDEX_FILE};
 
 my %index; # holds filenames of one index per branch
-{   # init with an index for origin
-    my ($fh, $fn) = tempfile('gitXXXXXX', SUFFIX => '.idx',
-			     DIR => File::Spec->tmpdir());
-    close ($fh);
-    $index{$opt_o} = $fn;
-}
+$index{$opt_o} = tmpnam();
+
 $ENV{GIT_INDEX_FILE} = $index{$opt_o};
 unless(-d $git_dir) {
 	system("git-init-db");
@@ -502,10 +498,7 @@ unless(-d $git_dir) {
 
 	# populate index
 	unless ($index{$last_branch}) {
-	    my ($fh, $fn) = tempfile('gitXXXXXX', SUFFIX => '.idx',
-				     DIR => File::Spec->tmpdir());
-	    close ($fh);
-	    $index{$last_branch} = $fn;
+	    $index{$last_branch} = tmpnam();
 	}
 	$ENV{GIT_INDEX_FILE} = $index{$last_branch};
 	system('git-read-tree', $last_branch);
@@ -818,10 +811,7 @@ while(<CVS>) {
 		if(($ancestor || $branch) ne $last_branch) {
 			print "Switching from $last_branch to $branch\n" if $opt_v;
 			unless ($index{$branch}) {
-			    my ($fh, $fn) = tempfile('gitXXXXXX', SUFFIX => '.idx',
-						     DIR => File::Spec->tmpdir());
-			    close ($fh);
-			    $index{$branch} = $fn;
+			    $index{$branch} = tmpnam();
 			    $ENV{GIT_INDEX_FILE} = $index{$branch};
 			    system("git-read-tree", $branch);
 			    die "read-tree failed: $?\n" if $?;
-- 
1.4.0.gcda2