stricter error checking in file streams (input, output)

This also makes the programs exit with a non-zero status when a read or write
error occurs.

This makes checking the exit status more reliable in scripts.

A simple example to simulate a disk with no space left:

	curl -s 'https://codemadness.org/atom.xml' | sfeed > f
	/mnt/test: write failed, file system is full
	echo $?
	0

Which now produces:

	curl -s 'https://codemadness.org/atom.xml' | sfeed > f
	/mnt/test: write failed, file system is full
	write error: <stdout>
	echo $?
	1

Tested with a small mfs on OpenBSD, fstab entry:

	swap /mnt/test mfs rw,nodev,nosuid,-s=1M 0 0

1 files changed, 6 insertions, 5 deletions

diff --git a/sfeed_html.c b/sfeed_html.c
index 240ea66..f3cff2b 100644
--- a/sfeed_html.c
+++ b/sfeed_html.c
@@ -34,7 +34,8 @@ printfeed(FILE *fp, struct feed *f)
 	}
 	fputs("<pre>\n", stdout);
 
-	while ((linelen = getline(&line, &linesize, fp)) > 0) {
+	while ((linelen = getline(&line, &linesize, fp)) > 0 &&
+	       !ferror(stdout)) {
 		if (line[linelen - 1] == '\n')
 			line[--linelen] = '\0';
 		parseline(line, fields);
@@ -109,8 +110,7 @@ main(int argc, char *argv[])
 	if (argc == 1) {
 		feeds[0].name = "";
 		printfeed(stdin, &feeds[0]);
-		if (ferror(stdin))
-			err(1, "ferror: <stdin>:");
+		checkfileerror(stdin, "<stdin>", 'r');
 	} else {
 		for (i = 1; i < argc; i++) {
 			name = ((name = strrchr(argv[i], '/'))) ? name + 1 : argv[i];
@@ -118,8 +118,7 @@ main(int argc, char *argv[])
 			if (!(fp = fopen(argv[i], "r")))
 				err(1, "fopen: %s", argv[i]);
 			printfeed(fp, &feeds[i - 1]);
-			if (ferror(fp))
-				err(1, "ferror: %s", argv[i]);
+			checkfileerror(fp, argv[i], 'r');
 			fclose(fp);
 		}
 	}
@@ -150,5 +149,7 @@ main(int argc, char *argv[])
 	fprintf(stdout, "\t</body>\n\t<title>(%lu/%lu) - Newsfeed</title>\n</html>\n",
 	        totalnew, total);
 
+	checkfileerror(stdout, "<stdout>", 'w');
+
 	return 0;
 }