From 2fdb27e7f21c99174d35556575e3d25bf2bdc23e Mon Sep 17 00:00:00 2001
From: Eelco Dolstra <e.dolstra@tudelft.nl>
Date: Wed, 29 Dec 2004 19:04:21 +0000
Subject: [PATCH] * Atomic file replacement is good.

---
 scripts/generate-patches.pl | 12 ++++++++++--
 scripts/readmanifest.pm.in  |  5 ++++-
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/scripts/generate-patches.pl b/scripts/generate-patches.pl
index e084b994d..7d957839b 100755
--- a/scripts/generate-patches.pl
+++ b/scripts/generate-patches.pl
@@ -198,9 +198,17 @@ foreach my $p (keys %dstOutPaths) {
     
         my $finalName =
             "$narBz2Hash-$name-$closestVersion-to-$version.nar-diff";
-    
-        system("cp '$tmpdir/DIFF' '$patchesDir/$finalName'") == 0
+
+        if (-e "$patchesDir/$finalName") {
+            print "    not copying, already exists\n";
+            next;
+        }
+        
+        system("cp '$tmpdir/DIFF' '$patchesDir/$finalName.tmp'") == 0
             or die "cannot copy diff";
+
+        rename("$patchesDir/$finalName.tmp", "$patchesDir/$finalName")
+            or die "cannot rename $patchesDir/$finalName.tmp";
         
         # Add the patch to the manifest.
         addPatch \%dstPatches, $p,
diff --git a/scripts/readmanifest.pm.in b/scripts/readmanifest.pm.in
index 766aa4219..31ea5f43c 100644
--- a/scripts/readmanifest.pm.in
+++ b/scripts/readmanifest.pm.in
@@ -146,7 +146,7 @@ sub writeManifest
     my $patches = shift;
     my $successors = shift;
 
-    open MANIFEST, ">$manifest";
+    open MANIFEST, ">$manifest.tmp"; # !!! check exclusive
 
     foreach my $storePath (keys %{$narFiles}) {
         my $narFileList = $$narFiles{$storePath};
@@ -184,6 +184,9 @@ sub writeManifest
     
     
     close MANIFEST;
+
+    rename("$manifest.tmp", $manifest)
+        or die "cannot rename $manifest.tmp: $!";
 }