From: Joey Hess <joey@kitenet.net>
Date: Mon, 13 Sep 2010 20:08:01 +0000 (-0400)
Subject: sponge: Ensure that output file permissions are always preserved if  it already exists.
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1ac3e2c08bae4bd8e5e771dab94564d79638d414;p=moreutils

sponge: Ensure that output file permissions are always preserved if  it already exists.
---

diff --git a/debian/changelog b/debian/changelog
index ae71b8c..9705e4b 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -3,6 +3,8 @@ moreutils (0.42) UNRELEASED; urgency=low
   * Typo. Closes: #596032
   * sponge: Guarantee that output file is always updated atomically,
     by renaming a temp file into place. Closes: #592144
+  * sponge: Ensure that output file permissions are always preserved
+    if it already exists.
 
  -- Joey Hess <joeyh@debian.org>  Wed, 08 Sep 2010 02:09:29 -0400
 
diff --git a/sponge.c b/sponge.c
index f9a521d..4d5a1f4 100644
--- a/sponge.c
+++ b/sponge.c
@@ -262,7 +262,6 @@ int main (int argc, char **argv) {
 	FILE *outfile, *tmpfile = 0;
 	ssize_t i = 0;
 	size_t mem_available = default_sponge_size();
-	struct stat statbuf;
 
 	if (argc > 2 || (argc == 2 && strcmp(argv[1], "-h") == 0)) {
 		usage();
@@ -309,41 +308,44 @@ int main (int argc, char **argv) {
 	}
 
 	if (outname) {
+		mode_t mode;
+		struct stat statbuf;
+		int exists = (lstat(outname, &statbuf) == 0);
+
+		/* Set temp file mode to match either
+		 * the old file mode, or the default file
+		 * mode for a newly created file. */
+		if (exists) {
+			mode = statbuf.st_mode;
+		}
+		else {
+			mode_t mask = umask(0);
+			umask(mask);
+			mode = 0666 & ~mask;
+		}
+		if (chmod(tmpname, mode) != 0) {
+			perror("chmod");
+			exit(1);
+		}
+
 		/* If it's a regular file, or does not yet exist,
 		 * attempt a fast rename of the temp file. */
-		if (((lstat(outname, &statbuf) == 0 &&
+		if (((exists &&
 		      S_ISREG(statbuf.st_mode) &&
 		      ! S_ISLNK(statbuf.st_mode)
-		     ) || errno == ENOENT) &&
+		     ) || ! exists) &&
 		    rename(tmpname, outname) == 0) {
-			tmpname=NULL;
-			/* Fix renamed file mode to match either
-			 * the old file mode, or the default file
-			 * mode for a newly created file. */
-			mode_t mode;
-			if (errno != ENOENT) {
-				mode = statbuf.st_mode;
-			}
-			else {
-				mode_t mask = umask(0);
-				umask(mask);
-				mode = 0666 & ~mask;
-			}
-			if (chmod(outname, mode) != 0) {
-				perror("chmod");
+			tmpname=NULL; /* don't try to cleanup tmpname */
+		}
+		else {	
+			/* Fall back to slow copy. */
+			outfile = fopen(outname, "w");
+			if (!outfile) {
+				perror("error opening output file");
 				exit(1);
 			}
-			return(0);
-		}
-			
-		/* Fall back to slow copy. */
-		outfile = fopen(outname, "w");
-		if (!outfile) {
-			perror("error opening output file");
-			exit(1);
+			copy_tmpfile(tmpfile, outfile, bufstart, bufsize);
 		}
-		copy_tmpfile(tmpfile, outfile, bufstart, bufsize);
-		fclose(outfile);
 	}
 	else {
 		copy_tmpfile(tmpfile, stdout, bufstart, bufsize);
diff --git a/sponge.docbook b/sponge.docbook
index ab2c42d..04447e3 100644
--- a/sponge.docbook
+++ b/sponge.docbook
@@ -58,8 +58,12 @@ USA
 			redirect, sponge soaks up all its input before
 			opening the output file. This allows constricting
 			pipelines that read from and write to
-			the same file. It also creates the output file
-	       		atomically by renaming a temp file into place.</para>
+			the same file.</para>
+		<para>
+			It also creates the output file
+			atomically by renaming a temp file into place.
+			If the output file is a special file or symlink,
+			the data will be written to it.</para>
 		<para>If no output file is specified, sponge outputs to
 			stdout.</para>