tech-pkg: [PATCH] nbcompat fgetln loses on missing newline

Subject: [PATCH] nbcompat fgetln loses on missing newline
To: None <tech-pkg@NetBSD.org>
From: Eric Gillespie <epg@netbsd.org>
List: tech-pkg
Date: 05/15/2005 14:34:09

Run this program on a file with no trailing newline:
#include <nbcompat.h>
int
main(int argc, char *argv[])
{
 FILE *fp;
 size_t len;
 char *line;
 fp = fopen(argv[1], "r");
 while (line = fgetln(fp, &len)) {
 printf("%d ", len); fflush(stdout);
 write(1, line, len); write(1, "\n", 1);
 }
 return 0;
}
0 tmp% echo 'this file has no final newline' > test
0 tmp% echo -n 'oops' >> test
0 tmp% ./a.out test
31 this file has no final newline
8191 oopsfile has no final newline
The problem is the while loop looking for a newline doesn't
realize it may not be there. Because it uses fgets, which
null-terminates, we can get the length with strlen when at eof:
=== fgetln.c
==================================================================
--- fgetln.c (revision 343)
+++ fgetln.c (local)
@@ -60,9 +60,16 @@
 	*len = 0;
 
 	while ((ptr = strchr(&buf[*len], '\n')) == NULL) {
-		size_t nbufsiz = bufsiz + BUFSIZ;
-		char *nbuf = realloc(buf, nbufsiz);
+		size_t nbufsiz;
+		char *nbuf;
 
+		if (feof(fp)) {
+			*len = strlen(buf);
+			return buf;
+		}
+
+		nbufsiz = bufsiz + BUFSIZ;
+		nbuf = realloc(buf, nbufsiz);
 		if (nbuf == NULL) {
 			int oerrno = errno;
 			free(buf);
Any objections?