X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=miscutils%2Freadahead.c;h=972302a187d0d5ede77aac29a9900a59333b35c7;hb=115e0a719950f8f716f73d5e36e9483df9dbbf1e;hp=49cd7fd09da42a67b52856c39ad51c2682bc4f13;hpb=9213a9e0f2d8fd638ecd02e2628d96dd5c7d233e;p=oweals%2Fbusybox.git

diff --git a/miscutils/readahead.c b/miscutils/readahead.c
index 49cd7fd09..972302a18 100644
--- a/miscutils/readahead.c
+++ b/miscutils/readahead.c
@@ -7,25 +7,59 @@
  *
  * Copyright (C) 2006  Michael Opdenacker <michael@free-electrons.com>
  *
- * Licensed under GPLv2 or later, see file License in this tarball for details.
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  */
+//config:config READAHEAD
+//config:	bool "readahead (2 kb)"
+//config:	default y
+//config:	depends on LFS
+//config:	select PLATFORM_LINUX
+//config:	help
+//config:	Preload the files listed on the command line into RAM cache so that
+//config:	subsequent reads on these files will not block on disk I/O.
+//config:
+//config:	This applet just calls the readahead(2) system call on each file.
+//config:	It is mainly useful in system startup scripts to preload files
+//config:	or executables before they are used. When used at the right time
+//config:	(in particular when a CPU bound process is running) it can
+//config:	significantly speed up system startup.
+//config:
+//config:	As readahead(2) blocks until each file has been read, it is best to
+//config:	run this applet as a background job.
 
-#include "busybox.h"
+//applet:IF_READAHEAD(APPLET(readahead, BB_DIR_USR_SBIN, BB_SUID_DROP))
 
-int readahead_main(int argc, char **argv)
+//kbuild:lib-$(CONFIG_READAHEAD) += readahead.o
+
+//usage:#define readahead_trivial_usage
+//usage:       "[FILE]..."
+//usage:#define readahead_full_usage "\n\n"
+//usage:       "Preload FILEs to RAM"
+
+#include "libbb.h"
+
+int readahead_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int readahead_main(int argc UNUSED_PARAM, char **argv)
 {
-	FILE *f;
 	int retval = EXIT_SUCCESS;
 
-	if (argc == 1) bb_show_usage();
+	if (!argv[1]) {
+		bb_show_usage();
+	}
 
 	while (*++argv) {
-		if ((f = bb_wfopen(*argv, "r")) != NULL) {
-			int r, fd=fileno(f);
+		int fd = open_or_warn(*argv, O_RDONLY);
+		if (fd >= 0) {
+			off_t len;
+			int r;
 
-			r = readahead(fd, 0, fdlength(fd));
-			fclose(f);
-			if (r >= 0) continue;
+			/* fdlength was reported to be unreliable - use seek */
+			len = xlseek(fd, 0, SEEK_END);
+			xlseek(fd, 0, SEEK_SET);
+			r = readahead(fd, 0, len);
+			close(fd);
+			if (r >= 0)
+				continue;
 		}
 		retval = EXIT_FAILURE;
 	}