[PATCH] truncate: new applet

Ari Sundholm ari at tuxera.com
Tue Mar 3 16:11:55 UTC 2015


I wrote this for my own purposes and cleaned it up in hopes it is useful.

Signed-off-by: Ari Sundholm <ari at tuxera.com>
---
 coreutils/truncate.c | 92 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 92 insertions(+)
 create mode 100644 coreutils/truncate.c

diff --git a/coreutils/truncate.c b/coreutils/truncate.c
new file mode 100644
index 0000000..f997cd2
--- /dev/null
+++ b/coreutils/truncate.c
@@ -0,0 +1,92 @@
+/*
+ * Mini truncate implementation for busybox
+ *
+ * Copyright (C) 2015 by Ari Sundholm <ari at tuxera.com>
+ *
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
+ */
+
+//config:config TRUNCATE
+//config:	bool "truncate"
+//config:	default y
+//config:	help
+//config:	  truncate truncates files to a given size. If a file does
+//config:	  not exist, it is created unless told otherwise.
+
+//kbuild:lib-$(CONFIG_TRUNCATE) += truncate.o
+//applet:IF_TRUNCATE(APPLET(truncate, BB_DIR_USR_BIN, BB_SUID_DROP))
+
+//usage:#define truncate_trivial_usage
+//usage:       "[-c] -s SIZE FILE..."
+//usage:#define truncate_full_usage "\n\n"
+//usage:	"Truncate FILEs to the given size.\n"
+//usage:	"\n	-c	Do not create any files."
+//usage:	"\n	-s SIZE	Truncate to SIZE."
+//usage:
+//usage:#define truncate_example_usage
+//usage:	"$ truncate -s 1G foo"
+
+#include "libbb.h"
+
+static const struct suffix_mult truncate_suffixes[] = {
+	{ "c", 1 },
+	{ "w", 2 },
+	{ "b", 512 },
+	{ "kB", 1000 },
+	{ "kD", 1000 },
+	{ "k", 1024 },
+	{ "K", 1024 },  /* compat with coreutils dd (it also accepts KB and KD, TODO?) */
+	{ "MB", 1000000 },
+	{ "MD", 1000000 },
+	{ "M", 1024*1024 },
+	{ "GB", 1000000000 },
+	{ "GD", 1000000000 },
+	{ "G", 1024*1024*1024 },
+	/* "D" suffix for decimal is not in coreutils manpage, looks like it's deprecated */
+	/* coreutils also understands TPEZY suffixes for tera- and so on, with B suffix for decimal */
+	{ "", 0 }
+};
+
+#if ENABLE_LFS
+# define XATOU_SFX xatoull_sfx
+#else
+# define XATOU_SFX xatoul_sfx
+#endif
+
+int truncate_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int truncate_main(int argc UNUSED_PARAM, char **argv) {
+	unsigned opts;
+	int flags = O_CREAT|O_RDWR;
+	int fd;
+	char *size_str;
+	off_t size;
+
+	enum {
+		OPT_NOCREATE  = (1 << 0),
+		OPT_SIZE = (1 << 1),
+	};
+
+	opt_complementary = "s";
+	opts = getopt32(argv, "cs:", &size_str);
+
+	argv += optind;
+	if (!*argv) {
+		bb_error_msg("truncate: no files specified!\n");
+		return 1;
+	}
+
+	if (opts & OPT_NOCREATE)
+		flags = O_RDWR;
+
+	size = XATOU_SFX(size_str, truncate_suffixes);
+
+	while (*argv) {
+		fd = xopen(*argv, flags);
+		if (ftruncate(fd, size) == -1)
+			bb_perror_msg_and_die("ftruncate failed");
+		xclose(fd);
+		++argv;
+	}
+
+	return 0;
+}
-- 
1.9.1





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