[PATCH v2] truncate: new applet
Ari Sundholm
ari at tuxera.com
Wed Mar 4 16:04:40 UTC 2015
Hi!
Thanks for the comments. Please see my responses below.
On Wed, 2015-03-04 at 16:17 +0100, Bartosz Gołaszewski wrote:
> 2015-03-04 15:11 GMT+01:00 Ari Sundholm <ari at tuxera.com>:
> > From: Ari Sundholm <ari at tuxera.com>
> >
> > bloat-o-meter:
> >
> > function old new delta
> > .rodata 154411 154491 +80
> > ------------------------------------------------------------------------------
> > (add/remove: 0/0 grow/shrink: 1/0 up/down: 80/0) Total: 80 bytes
> >
> > v2: Make dd and truncate share a common suffix struct.
> >
> > Signed-off-by: Ari Sundholm <ari at tuxera.com>
> > ---
> > coreutils/dd.c | 31 +++++-----------------
> > coreutils/truncate.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> > include/libbb.h | 1 +
> > libbb/xatonum.c | 19 ++++++++++++++
> > 4 files changed, 99 insertions(+), 25 deletions(-)
> > create mode 100644 coreutils/truncate.c
> >
> > diff --git a/coreutils/dd.c b/coreutils/dd.c
> > index 3024970..53a843c 100644
> > --- a/coreutils/dd.c
> > +++ b/coreutils/dd.c
> > @@ -99,25 +99,6 @@ enum {
> > ofd = STDOUT_FILENO,
> > };
> >
> > -static const struct suffix_mult dd_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 }
> > -};
> > -
> > struct globals {
> > off_t out_full, out_part, in_full, in_part;
> > #if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
> > @@ -326,11 +307,11 @@ int dd_main(int argc UNUSED_PARAM, char **argv)
> > #if ENABLE_FEATURE_DD_IBS_OBS
> > if (what == OP_ibs) {
> > /* Must fit into positive ssize_t */
> > - ibs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, dd_suffixes);
> > + ibs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, cwbkMG_suffixes);
> > /*continue;*/
> > }
> > if (what == OP_obs) {
> > - obs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, dd_suffixes);
> > + obs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, cwbkMG_suffixes);
> > /*continue;*/
> > }
> > if (what == OP_conv) {
> > @@ -356,22 +337,22 @@ int dd_main(int argc UNUSED_PARAM, char **argv)
> > }
> > #endif
> > if (what == OP_bs) {
> > - ibs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, dd_suffixes);
> > + ibs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, cwbkMG_suffixes);
> > obs = ibs;
> > /*continue;*/
> > }
> > /* These can be large: */
> > if (what == OP_count) {
> > G.flags |= FLAG_COUNT;
> > - count = XATOU_SFX(val, dd_suffixes);
> > + count = XATOU_SFX(val, cwbkMG_suffixes);
> > /*continue;*/
> > }
> > if (what == OP_seek) {
> > - seek = XATOU_SFX(val, dd_suffixes);
> > + seek = XATOU_SFX(val, cwbkMG_suffixes);
> > /*continue;*/
> > }
> > if (what == OP_skip) {
> > - skip = XATOU_SFX(val, dd_suffixes);
> > + skip = XATOU_SFX(val, cwbkMG_suffixes);
> > /*continue;*/
> > }
> > if (what == OP_if) {
> > diff --git a/coreutils/truncate.c b/coreutils/truncate.c
> > new file mode 100644
> > index 0000000..36b2f2c
> > --- /dev/null
> > +++ b/coreutils/truncate.c
> > @@ -0,0 +1,73 @@
> > +/*
> > + * 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-$(CONFIG_TRUNCATE) += truncate.o
> > +//applet:IF_TRUNCATE(APPLET(truncate, BB_DIR_USR_BIN, BB_SUID_DROP))
>
> This looks like a good candidate for a NOFORK applet.
>
Indeed. Will be done in v3.
> > +
> > +//usage:#define truncate_trivial_usage
> > +//usage: "[-c] -s SIZE FILE..."
> > +//usage:#define truncate_full_usage "\n\n"
> > +//usage: "Truncate FILEs to the given size.\n"
> > +//usage: "\n -c Do not create any files."
> > +//usage: "\n -s SIZE Truncate to SIZE."
> > +//usage:
> > +//usage:#define truncate_example_usage
> > +//usage: "$ truncate -s 1G foo"
> > +
> > +#include "libbb.h"
> > +#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;
>
> bb_perror_msg_and_die()?
>
Would we not get an unrelated error string appended?
By changing the above to bb_perror_msg_and_die("no files specified"):
$ ./busybox truncate -c -s 1M
truncate: no files specified: No such file or directory
... which is a bit weird.
Maybe bb_error_msg() followed by xfunc_die()?
> > + }
> > +
> > + if (opts & OPT_NOCREATE)
> > + flags = O_RDWR;
> > +
> > + size = XATOU_SFX(size_str, cwbkMG_suffixes);
> > +
> > + while (*argv) {
> > + fd = xopen(*argv, flags);
> > + if (ftruncate(fd, size) == -1)
> > + bb_perror_msg_and_die("ftruncate failed");
> > + xclose(fd);
> > + ++argv;
> > + }
> > +
> > + return 0;
> > +}
> > diff --git a/include/libbb.h b/include/libbb.h
> > index be792d6..e4fcf7c 100644
> > --- a/include/libbb.h
> > +++ b/include/libbb.h
> > @@ -861,6 +861,7 @@ struct suffix_mult {
> > };
> > extern const struct suffix_mult bkm_suffixes[];
> > #define km_suffixes (bkm_suffixes + 1)
> > +extern const struct suffix_mult cwbkMG_suffixes[];
> >
> > #include "xatonum.h"
> > /* Specialized: */
> > diff --git a/libbb/xatonum.c b/libbb/xatonum.c
> > index 6f4e023..19b54fb 100644
> > --- a/libbb/xatonum.c
> > +++ b/libbb/xatonum.c
> > @@ -75,3 +75,22 @@ const struct suffix_mult bkm_suffixes[] = {
> > { "m", 1024*1024 },
> > { "", 0 }
> > };
> > +
> > +const struct suffix_mult cwbkMG_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 }
> > +};
> > --
>
> Maybe replace bkm_suffixes by cwbkMG_suffixes globally?
>
We may need to be careful. libbb.h contains the following:
#define km_suffixes (bkm_suffixes + 1)
svlogd uses km_suffixes and a few applets use bkm_suffixes. These may be
intentionally using a more restricted set of suffixes. I am not quite
sure what to do here.
Maybe Denys could give his opinion on this?
> I would also suggest splitting this patch in two parts: one moving the
> suffixes array out of dd, and the second one implementing truncate.
Will do.
Best regards,
Ari Sundholm
ari at tuxera.com
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