sed: improve handling of NULs
diff --git a/libbb/get_line_from_file.c b/libbb/get_line_from_file.c
index b424d59..3f2c609 100644
--- a/libbb/get_line_from_file.c
+++ b/libbb/get_line_from_file.c
@@ -11,8 +11,8 @@
 
 #include "libbb.h"
 
-/* This function reads an entire line from a text file,
- * up to a newline or NUL byte.  It returns a malloc'ed char * which must be
+/* This function reads an entire line from a text file, up to a newline 
+ * or NUL byte, inclusive.  It returns a malloc'ed char * which must be
  * stored and free'ed  by the caller.  If end is null '\n' isn't considered
  * end of line.  If end isn't null, length of the chunk read is stored in it. */
 
@@ -25,7 +25,7 @@
 
 	while ((ch = getc(file)) != EOF) {
 		/* grow the line buffer as necessary */
-		if (idx > linebufsz - 2) {
+		if (idx >= linebufsz) {
 			linebuf = xrealloc(linebuf, linebufsz += 80);
 		}
 		linebuf[idx++] = (char) ch;
@@ -35,14 +35,14 @@
 	if (end)
 		*end = idx;
 	if (linebuf) {
-		// huh, is fgets discards prior data on error like this?
+		// huh, does fgets discard prior data on error like this?
 		// I don't think so....
 		//if (ferror(file)) {
 		//	free(linebuf);
 		//	return NULL;
 		//}
 		linebuf = xrealloc(linebuf, idx+1);
-		linebuf[idx] = 0;
+		linebuf[idx] = '\0';
 	}
 	return linebuf;
 }