utils

commit: 5915894ac5e44873a510c511e58056391cefea66
parent 29bcecfe0cf7ee999aa592c2d0da02358a357987
Author: Haelwenn (lanodan) Monnier <contact@hacktivis.me>
Date:   Fri, 28 Jul 2023 07:24:59 +0200

cmd/cat: Add sendfile(2)-based optimisation

Diffstat:
M
cmd/cat.c
36
++++++++++++++++++++++++++++++++++--

1 file changed, 34 insertions(+), 2 deletions(-)
diff --git a/cmd/cat.c b/cmd/cat.c
@@ -1,5 +1,5 @@
 // Collection of Unix tools, comparable to coreutils
-// SPDX-FileCopyrightText: 2017-2022 Haelwenn (lanodan) Monnier <contact+utils@hacktivis.me>
+// SPDX-FileCopyrightText: 2017-2023 Haelwenn (lanodan) Monnier <contact+utils@hacktivis.me>
 // SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only
 
 #define _POSIX_C_SOURCE 200809L
@@ -33,6 +33,38 @@ concat(int fd, const char *fdname)
 	return 0;
 }
 
+// FreeBSD also has sendfile(2) but it's only for sockets
+#ifdef __linux__
+#include <sys/sendfile.h>
+// Grabbed from /usr/src/hare/stdlib/io/+linux/platform_file.ha
+#ifndef SENDFILE_MAX
+#define SENDFILE_MAX 2147479552
+#endif // SENDFILE_MAX
+int
+fd_copy(int fd, const char *fdname)
+{
+	ssize_t c = 0;
+	off_t off = 0;
+
+	while((c = sendfile(1, fd, &off, SENDFILE_MAX)) > 0)
+		;
+
+	if(c < 0)
+	{
+		if(errno == EINVAL && off == 0)
+		{
+			return concat(fd, fdname);
+		}
+		fprintf(stderr, "cat: Error copying ‘%s’: %s\n", fdname, strerror(errno));
+		return 1;
+	}
+
+	return 0;
+}
+#else // __linux__
+#define fd_copy concat
+#endif // __linux__
+
 int
 main(int argc, char *argv[])
 {
@@ -63,7 +95,7 @@ main(int argc, char *argv[])
 				return 1;
 			}
 
-			if(concat(fd, argv[argi]) != 0)
+			if(fd_copy(fd, argv[argi]) != 0)
 			{
 				return 1;
 			}