# HG changeset patch
# User Paul Eggert <eggert@cs.ucla.edu>
# Date 1063742438 0
# Node ID c3e2b42bdca3618b16903586e0cc8d73223f7f81
# Parent  39841d2009edc9d1518638a07a5c6498f485b4b2
linebuffer.c (readlinebuffer): Return NULL immediately upon input error.

diff --git a/lib/ChangeLog b/lib/ChangeLog
--- a/lib/ChangeLog
+++ b/lib/ChangeLog
@@ -1,6 +1,12 @@
+2003-09-16  Paul Eggert  <eggert@twinsun.com>
+
+	* linebuffer.c (readlinebuffer): Return NULL immediately upon
+	input error, instead of returning NULL the next time we are called
+	(and therefore losing track of errno).
+
 2003-09-15  Paul Eggert  <eggert@twinsun.com>
 
-	* lib/getndelim2.c (getndelim2): Don't trash errno when a read
+	* getndelim2.c (getndelim2): Don't trash errno when a read
 	fails, so that the caller gets the proper errno.
 
 	* readutmp.c (read_utmp): Likewise.
diff --git a/lib/linebuffer.c b/lib/linebuffer.c
--- a/lib/linebuffer.c
+++ b/lib/linebuffer.c
@@ -45,7 +45,9 @@
    that ends in a non-newline character.  Do not null terminate.
    Therefore the stream can contain NUL bytes, and the length
    (including the newline) is returned in linebuffer->length.
-   Return NULL upon error, or when STREAM is empty.
+   Return NULL when stream is empty.  Return NULL and set errno upon
+   error; callers can distinguish this case from the empty case by
+   invoking ferror (stream).
    Otherwise, return LINEBUFFER.  */
 struct linebuffer *
 readlinebuffer (struct linebuffer *linebuffer, FILE *stream)
@@ -55,7 +57,7 @@
   char *p = linebuffer->buffer;
   char *end = buffer + linebuffer->size; /* Sentinel. */
 
-  if (feof (stream) || ferror (stream))
+  if (feof (stream))
     return NULL;
 
   do
@@ -63,7 +65,7 @@
       c = getc (stream);
       if (c == EOF)
 	{
-	  if (p == buffer)
+	  if (p == buffer || ferror (stream))
 	    return NULL;
 	  if (p[-1] == '\n')
 	    break;