From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Thu, 7 Nov 2019 00:42:02 +0000 (+0000)
Subject: make-secnet-sites: Write output to ...~tmp~ and rename
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ian/git?a=commitdiff_plain;h=672d4525ebe7dcbcdadcd8c9c964da1ce6aa483d;p=secnet.git

make-secnet-sites: Write output to ...~tmp~ and rename

This avoids leaving a truncated output file if we crash.  It also
avoids concurrent readers ever seeing a truncated output file.

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
---

diff --git a/make-secnet-sites b/make-secnet-sites
index 66b4cb1..574eb20 100755
--- a/make-secnet-sites
+++ b/make-secnet-sites
@@ -211,6 +211,7 @@ def parse_args():
 	global header
 	global groupfiledir
 	global sitesfile
+	global outputfile
 	global group
 	global user
 	global of
@@ -258,8 +259,6 @@ def parse_args():
 			print("Too many arguments")
 			sys.exit(1)
 		(inputfile, outputfile) = (av.arg + [None]*2)[0:2]
-		if outputfile is None: of=sys.stdout
-		else: of=open(outputfile,'w')
 
 parse_args()
 
@@ -776,4 +775,11 @@ if service:
 	f.close()
 	os.rename(sitesfile+"-tmp",sitesfile)
 else:
+	if outputfile is None:
+		of=sys.stdout
+	else:
+		tmp_outputfile=outputfile+'~tmp~'
+		of=open(tmp_outputfile,'w')
 	outputsites(of)
+	if outputfile is not None:
+		os.rename(tmp_outputfile,outputfile)