From: Joey Hess <joey@kodama.kitenet.net>
Date: Fri, 11 Apr 2008 20:10:18 +0000 (-0400)
Subject: fix edge cases
X-Git-Tag: 0.29~11
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ee4e74dd6a20706f29ef30a2613a1977f6f325fa;p=moreutils

fix edge cases

If a file an exact multiple of the max buffer size were sponged, it
would fail at the end due to trying to write 0 remaining bytes from the
buffer to the temp file. A similar bug occurred if sponge's input was
empty. Amazing how such a seemingly simple thing can get so tricky..

Also added check for read error from the temp file, just in case.
---

diff --git a/sponge.c b/sponge.c
index 4a56222..948edf0 100644
--- a/sponge.c
+++ b/sponge.c
@@ -206,11 +206,14 @@ static void copy_tmpfile(FILE *tmpfile, FILE *outfd) {
 		fclose(tmpfile);
 		exit(1);
 	}
-	// XXX I'd catch signals or writes errors here, but I
-	// I don't think it matters as the file is overwritten
-	while(fread(buf, BUFF_SIZE, 1, tmpfile) == 1) {
+	while (fread(buf, BUFF_SIZE, 1, tmpfile) > 0) {
 		write_buff_out(buf, BUFF_SIZE, outfd);
 	}
+	if (ferror(tmpfile)) {
+		perror("read temporary file");
+		fclose(tmpfile);
+		exit(1);
+	}
 	fclose(tmpfile);
 	fclose(outfd);
 }
@@ -274,7 +277,8 @@ int main (int argc, char **argv) {
 	}
 	if (tmpfile) {
 		/* write whatever we have in memory to tmpfile */
-		write_buff_tmp(bufstart, bufused, tmpfile);
+		if (bufused) 
+			write_buff_tmp(bufstart, bufused, tmpfile);
 		struct stat statbuf;
 		if (outname && !stat(outname, &statbuf)) {
 			/* regular file */
@@ -306,7 +310,8 @@ int main (int argc, char **argv) {
 				exit(1);
 			}
 		}
-		write_buff_out(bufstart, bufused, outfd);
+		if (bufused)
+			write_buff_out(bufstart, bufused, outfd);
 		fclose(outfd);
 	}