sponge: add append option '-a' (Closes: #623197)

With this patch, option '-a' is introduced to append to the output file
instead of doing backup and recreation.

Original-by: Michael Stummvoll <michael@stummi.org>
Signed-off-by: Nicolas Schier <nicolas@hjem.rpa.no>

2 files changed, 27 insertions, 3 deletions

diff --git a/sponge.c b/sponge.c
index 969703f..61e6a42 100644
--- a/sponge.c
+++ b/sponge.c
@@ -42,7 +42,8 @@
 char *tmpname = NULL;
 
 void usage() {
-	printf("sponge <file>: soak up all input from stdin and write it to <file>\n");
+	printf("sponge [-a] <file>: soak up all input from stdin and write it "
+	       "to <file>\n");
 	exit(0);
 }
 
@@ -278,6 +279,12 @@ int main (int argc, char **argv) {
 	ssize_t i = 0;
 	size_t mem_available = default_sponge_size();
 	int tmpfile_used=0;
+	int append=0;
+
+	if ((argc == 3) && (!strcmp(argv[1], "-a"))) {
+		append = 1;
+		argc--,	argv++;
+	}
 
 	if (argc > 2 || (argc == 2 && strcmp(argv[1], "-h") == 0)) {
 		usage();
@@ -342,6 +349,7 @@ int main (int argc, char **argv) {
 		/* If it's a regular file, or does not yet exist,
 		 * attempt a fast rename of the temp file. */
 		if (((exists &&
+		      !append &&
 		      S_ISREG(statbuf.st_mode) &&
 		      ! S_ISLNK(statbuf.st_mode)
 		     ) || ! exists) &&
@@ -350,7 +358,7 @@ int main (int argc, char **argv) {
 		}
 		else {	
 			/* Fall back to slow copy. */
-			outfile = fopen(outname, "w");
+			outfile = fopen(outname, append ? "a" : "w");
 			if (!outfile) {
 				perror("error opening output file");
 				exit(1);
diff --git a/sponge.docbook b/sponge.docbook
index 07a2645..a892837 100644
--- a/sponge.docbook
+++ b/sponge.docbook
@@ -48,7 +48,7 @@ USA
 
 	<refsynopsisdiv>
 		<cmdsynopsis>
-			<command>sed '...' file | grep '...' | sponge file</command>
+			<command>sed '...' file | grep '...' | sponge [-a] file</command>
 		</cmdsynopsis>
 	</refsynopsisdiv>
 
@@ -72,6 +72,22 @@ USA
 			stdout.</para>
 
 	</refsect1>
+
+	<refsect1>
+		<title>OPTIONS</title>
+
+		<variablelist>
+
+		<varlistentry>
+			<term><option>-a</option></term>
+			<listitem>
+				<para>Append the output to the specified file
+				instead possible backup and re-creation.</para>
+			</listitem>
+		</varlistentry>
+
+		</variablelist>
+	</refsect1>
 	
 	<refsect1>
 		<title>AUTHOR</title>