CVS commit: [netbsd-10] src/lib/libc/stdio

[Martin Husemann]

Module Name:    src
Committed By:   martin
Date:           Sat Jul 20 15:28:14 UTC 2024

Modified Files:
        src/lib/libc/stdio [netbsd-10]: fvwrite.c

Log Message:
Pull up following revision(s) (requested by rin in ticket #754):

        lib/libc/stdio/fvwrite.c: revision 1.31

>From enh at google dot com in tech-userlevel. Don't limit writes to
BUFSIZ, change the limit to INT_MAX; improves performance dramatically. From:
https://github.com/apple-oss-distributions/Libc/commit/c5a3293354e22262702a3add5b2dfc9bb0b93b85#diff-3b844a19cfb0aab1a23f7fbc457d3bce7453513730c489a72f66ff89d6557ff3


To generate a diff of this commit:
cvs rdiff -u -r1.30 -r1.30.2.1 src/lib/libc/stdio/fvwrite.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.


Modified files:

Index: src/lib/libc/stdio/fvwrite.c
diff -u src/lib/libc/stdio/fvwrite.c:1.30 src/lib/libc/stdio/fvwrite.c:1.30.2.1
--- src/lib/libc/stdio/fvwrite.c:1.30	Thu Jul 22 17:08:15 2021
+++ src/lib/libc/stdio/fvwrite.c	Sat Jul 20 15:28:14 2024
@@ -1,4 +1,4 @@
-/*	$NetBSD: fvwrite.c,v 1.30 2021/07/22 17:08:15 christos Exp $	*/
+/*	$NetBSD: fvwrite.c,v 1.30.2.1 2024/07/20 15:28:14 martin Exp $	*/
 
 /*-
  * Copyright (c) 1990, 1993
@@ -37,7 +37,7 @@
 #if 0
 static char sccsid[] = "@(#)fvwrite.c	8.1 (Berkeley) 6/4/93";
 #else
-__RCSID("$NetBSD: fvwrite.c,v 1.30 2021/07/22 17:08:15 christos Exp $");
+__RCSID("$NetBSD: fvwrite.c,v 1.30.2.1 2024/07/20 15:28:14 martin Exp $");
 #endif
 #endif /* LIBC_SCCS and not lint */
 
@@ -99,11 +99,12 @@ __sfvwrite(FILE *fp, struct __suio *uio)
 	}
 	if (fp->_flags & __SNBF) {
 		/*
-		 * Unbuffered: write up to BUFSIZ bytes at a time.
+		 * Unbuffered: write up to INT_MAX bytes at a time, to not
+		 * truncate the value of len if it is greater than 2^31 bytes.
 		 */
 		do {
 			GETIOV(;);
-			w = (*fp->_write)(fp->_cookie, p, MIN(len, BUFSIZ));
+			w = (*fp->_write)(fp->_cookie, p, MIN(len, INT_MAX));
 			if (w <= 0)
 				goto err;
 			p += w;
@@ -113,7 +114,8 @@ __sfvwrite(FILE *fp, struct __suio *uio)
 		/*
 		 * Fully buffered: fill partially full buffer, if any,
 		 * and then flush.  If there is no partial buffer, write
-		 * one _bf._size byte chunk directly (without copying).
+		 * entire payload directly (without copying) up to a multiple
+		 * of the buffer size.
 		 *
 		 * String output is a special case: write as many bytes
 		 * as fit, but pretend we wrote everything.  This makes
@@ -159,7 +161,15 @@ __sfvwrite(FILE *fp, struct __suio *uio)
 				if (fflush(fp))
 					goto err;
 			} else if (len >= (size_t)(w = fp->_bf._size)) {
-				/* write directly */
+				/*
+				 * write directly up to INT_MAX or greatest
+				 * multiple of buffer size (whatever is
+				 * smaller), keeping in the memory buffer the
+				 * remaining part of payload that is smaller
+				 * than buffer size.
+				 */
+				if (w != 0)
+					w = MIN(w * (len / w), INT_MAX);
 				w = (*fp->_write)(fp->_cookie, p, (size_t)w);
 				if (w <= 0)
 					goto err;