busybox/coreutils/dd.c

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/* vi: set sw=4 ts=4: */
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/*
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* Mini dd implementation for busybox
*
* Copyright (C) 2000,2001 Matt Kraai
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*
* Licensed under GPLv2 or later, see file LICENSE in this source tree.
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*/
//config:config DD
//config: bool "dd (7.5 kb)"
//config: default y
//config: help
//config: dd copies a file (from standard input to standard output,
//config: by default) using specific input and output blocksizes,
//config: while optionally performing conversions on it.
//config:
//config:config FEATURE_DD_SIGNAL_HANDLING
//config: bool "Enable signal handling for status reporting"
//config: default y
//config: depends on DD
//config: help
//config: Sending a SIGUSR1 signal to a running 'dd' process makes it
//config: print to standard error the number of records read and written
//config: so far, then to resume copying.
//config:
//config: $ dd if=/dev/zero of=/dev/null &
//config: $ pid=$!; kill -USR1 $pid; sleep 1; kill $pid
//config: 10899206+0 records in
//config: 10899206+0 records out
//config:
//config:config FEATURE_DD_THIRD_STATUS_LINE
//config: bool "Enable the third status line upon signal"
//config: default y
//config: depends on DD && FEATURE_DD_SIGNAL_HANDLING
//config: help
//config: Displays a coreutils-like third status line with transferred bytes,
//config: elapsed time and speed.
//config:
//config:config FEATURE_DD_IBS_OBS
//config: bool "Enable ibs, obs, iflag, oflag and conv options"
//config: default y
//config: depends on DD
//config: help
//config: Enable support for writing a certain number of bytes in and out,
//config: at a time, and performing conversions on the data stream.
//config:
//config:config FEATURE_DD_STATUS
//config: bool "Enable status display options"
//config: default y
//config: depends on DD
//config: help
//config: Enable support for status=noxfer/none option.
//applet:IF_DD(APPLET_NOEXEC(dd, dd, BB_DIR_BIN, BB_SUID_DROP, dd))
//kbuild:lib-$(CONFIG_DD) += dd.o
//usage:#define dd_trivial_usage
//usage: "[if=FILE] [of=FILE] [" IF_FEATURE_DD_IBS_OBS("ibs=N obs=N/") "bs=N] [count=N] [skip=N] [seek=N]\n"
//usage: IF_FEATURE_DD_IBS_OBS(
//usage: " [conv=notrunc|noerror|sync|fsync]\n"
//usage: " [iflag=skip_bytes|fullblock] [oflag=seek_bytes|append]"
//usage: )
//usage:#define dd_full_usage "\n\n"
//usage: "Copy a file with converting and formatting\n"
//usage: "\n if=FILE Read from FILE instead of stdin"
//usage: "\n of=FILE Write to FILE instead of stdout"
//usage: "\n bs=N Read and write N bytes at a time"
//usage: IF_FEATURE_DD_IBS_OBS(
//usage: "\n ibs=N Read N bytes at a time"
//usage: )
//usage: IF_FEATURE_DD_IBS_OBS(
//usage: "\n obs=N Write N bytes at a time"
//usage: )
//usage: "\n count=N Copy only N input blocks"
//usage: "\n skip=N Skip N input blocks"
//usage: "\n seek=N Skip N output blocks"
//usage: IF_FEATURE_DD_IBS_OBS(
//usage: "\n conv=notrunc Don't truncate output file"
//usage: "\n conv=noerror Continue after read errors"
//usage: "\n conv=sync Pad blocks with zeros"
//usage: "\n conv=fsync Physically write data out before finishing"
//usage: "\n conv=swab Swap every pair of bytes"
//usage: "\n iflag=skip_bytes skip=N is in bytes"
//usage: "\n iflag=fullblock Read full blocks"
//usage: "\n oflag=seek_bytes seek=N is in bytes"
//usage: "\n oflag=append Open output file in append mode"
//usage: )
//usage: IF_FEATURE_DD_STATUS(
//usage: "\n status=noxfer Suppress rate output"
//usage: "\n status=none Suppress all output"
//usage: )
//usage: "\n"
//usage: "\nN may be suffixed by c (1), w (2), b (512), kB (1000), k (1024), MB, M, GB, G"
//usage:
//usage:#define dd_example_usage
//usage: "$ dd if=/dev/zero of=/dev/ram1 bs=1M count=4\n"
//usage: "4+0 records in\n"
//usage: "4+0 records out\n"
#include "libbb.h"
#include "common_bufsiz.h"
/* This is a NOEXEC applet. Be very careful! */
enum {
ifd = STDIN_FILENO,
ofd = STDOUT_FILENO,
};
struct globals {
off_t out_full, out_part, in_full, in_part;
#if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
unsigned long long total_bytes;
unsigned long long begin_time_us;
#endif
int flags;
} FIX_ALIASING;
#define G (*(struct globals*)bb_common_bufsiz1)
#define INIT_G() do { \
setup_common_bufsiz(); \
/* we have to zero it out because of NOEXEC */ \
memset(&G, 0, sizeof(G)); \
} while (0)
enum {
/* Must be in the same order as OP_conv_XXX! */
/* (see "flags |= (1 << what)" below) */
FLAG_NOTRUNC = (1 << 0) * ENABLE_FEATURE_DD_IBS_OBS,
FLAG_SYNC = (1 << 1) * ENABLE_FEATURE_DD_IBS_OBS,
FLAG_NOERROR = (1 << 2) * ENABLE_FEATURE_DD_IBS_OBS,
FLAG_FSYNC = (1 << 3) * ENABLE_FEATURE_DD_IBS_OBS,
FLAG_SWAB = (1 << 4) * ENABLE_FEATURE_DD_IBS_OBS,
/* end of conv flags */
/* start of input flags */
FLAG_IFLAG_SHIFT = 5,
FLAG_SKIP_BYTES = (1 << 5) * ENABLE_FEATURE_DD_IBS_OBS,
FLAG_FULLBLOCK = (1 << 6) * ENABLE_FEATURE_DD_IBS_OBS,
/* end of input flags */
/* start of output flags */
FLAG_OFLAG_SHIFT = 7,
FLAG_SEEK_BYTES = (1 << 7) * ENABLE_FEATURE_DD_IBS_OBS,
FLAG_APPEND = (1 << 8) * ENABLE_FEATURE_DD_IBS_OBS,
/* end of output flags */
FLAG_TWOBUFS = (1 << 9) * ENABLE_FEATURE_DD_IBS_OBS,
FLAG_COUNT = 1 << 10,
FLAG_STATUS_NONE = 1 << 11,
FLAG_STATUS_NOXFER = 1 << 12,
};
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static void dd_output_status(int UNUSED_PARAM cur_signal)
{
#if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
double seconds;
unsigned long long bytes_sec;
unsigned long long now_us = monotonic_us(); /* before fprintf */
#endif
/* Deliberately using %u, not %d */
fprintf(stderr, "%"OFF_FMT"u+%"OFF_FMT"u records in\n"
"%"OFF_FMT"u+%"OFF_FMT"u records out\n",
G.in_full, G.in_part,
G.out_full, G.out_part);
#if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
# if ENABLE_FEATURE_DD_STATUS
if (G.flags & FLAG_STATUS_NOXFER) /* status=noxfer active? */
return;
//TODO: should status=none make dd stop reacting to USR1 entirely?
//So far we react to it (we print the stats),
//status=none only suppresses final, non-USR1 generated status message.
# endif
fprintf(stderr, "%llu bytes (%sB) copied, ",
G.total_bytes,
/* show fractional digit, use suffixes */
make_human_readable_str(G.total_bytes, 1, 0)
);
/* Corner cases:
* ./busybox dd </dev/null >/dev/null
* ./busybox dd bs=1M count=2000 </dev/zero >/dev/null
* (echo DONE) | ./busybox dd >/dev/null
* (sleep 1; echo DONE) | ./busybox dd >/dev/null
*/
seconds = (now_us - G.begin_time_us) / 1000000.0;
bytes_sec = G.total_bytes / seconds;
fprintf(stderr, "%f seconds, %sB/s\n",
seconds,
/* show fractional digit, use suffixes */
make_human_readable_str(bytes_sec, 1, 0)
);
#endif
}
static bool write_and_stats(const void *buf, size_t len, size_t obs,
const char *filename)
{
ssize_t n;
n = full_write(ofd, buf, len);
#if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
if (n > 0)
G.total_bytes += n;
#endif
if ((size_t)n == obs) {
G.out_full++;
return 0;
}
if ((size_t)n == len) {
G.out_part++;
return 0;
}
/* n is < len (and possibly is -1).
* Even if n >= 0, errno is usually set correctly.
* For example, if writing to block device and getting ENOSPC,
* full_write() first sees a short write, then tries to write
* the remainder and gets errno set to ENOSPC.
* It returns n > 0 (the amount which it did write).
*/
bb_perror_msg("error writing '%s'", filename);
return 1;
}
#if ENABLE_LFS
# define XATOU_SFX xatoull_sfx
#else
# define XATOU_SFX xatoul_sfx
#endif
#if ENABLE_FEATURE_DD_IBS_OBS
static int parse_comma_flags(char *val, const char *words, const char *error_in)
{
int flags = 0;
while (1) {
int n;
char *arg;
/* find ',', replace them with NUL so we can use val for
* index_in_strings() without copying.
* We rely on val being non-null, else strchr would fault.
*/
arg = strchr(val, ',');
if (arg)
*arg = '\0';
n = index_in_strings(words, val);
if (n < 0)
bb_error_msg_and_die(bb_msg_invalid_arg_to, val, error_in);
flags |= (1 << n);
if (!arg) /* no ',' left, so this was the last specifier */
break;
*arg = ','; /* to preserve ps listing */
val = arg + 1; /* skip this keyword and ',' */
}
return flags;
}
#endif
int dd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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int dd_main(int argc UNUSED_PARAM, char **argv)
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{
static const char keywords[] ALIGN1 =
"bs\0""count\0""seek\0""skip\0""if\0""of\0"IF_FEATURE_DD_STATUS("status\0")
#if ENABLE_FEATURE_DD_IBS_OBS
"ibs\0""obs\0""conv\0""iflag\0""oflag\0"
#endif
;
#if ENABLE_FEATURE_DD_IBS_OBS
static const char conv_words[] ALIGN1 =
"notrunc\0""sync\0""noerror\0""fsync\0""swab\0";
static const char iflag_words[] ALIGN1 =
"skip_bytes\0""fullblock\0";
static const char oflag_words[] ALIGN1 =
"seek_bytes\0append\0";
#endif
#if ENABLE_FEATURE_DD_STATUS
static const char status_words[] ALIGN1 =
"none\0""noxfer\0";
#endif
enum {
OP_bs = 0,
OP_count,
OP_seek,
OP_skip,
OP_if,
OP_of,
IF_FEATURE_DD_STATUS(OP_status,)
#if ENABLE_FEATURE_DD_IBS_OBS
OP_ibs,
OP_obs,
OP_conv,
OP_iflag,
OP_oflag,
/* Must be in the same order as FLAG_XXX! */
OP_conv_notrunc = 0,
OP_conv_sync,
OP_conv_noerror,
OP_conv_fsync,
OP_conv_swab,
/* Unimplemented conv=XXX: */
//nocreat do not create the output file
//excl fail if the output file already exists
//fdatasync physically write output file data before finishing
//lcase change upper case to lower case
//ucase change lower case to upper case
//block pad newline-terminated records with spaces to cbs-size
//unblock replace trailing spaces in cbs-size records with newline
//ascii from EBCDIC to ASCII
//ebcdic from ASCII to EBCDIC
//ibm from ASCII to alternate EBCDIC
/* Partially implemented: */
//swab swap every pair of input bytes: will abort on non-even reads
OP_iflag_skip_bytes,
OP_iflag_fullblock,
OP_oflag_seek_bytes,
#endif
};
smallint exitcode = EXIT_FAILURE;
int i;
size_t ibs = 512;
char *ibuf;
#if ENABLE_FEATURE_DD_IBS_OBS
size_t obs = 512;
char *obuf;
#else
# define obs ibs
# define obuf ibuf
#endif
/* These are all zeroed at once! */
struct {
IF_FEATURE_DD_IBS_OBS(size_t ocount;)
ssize_t prev_read_size; /* for detecting swab failure */
off_t count;
off_t seek, skip;
const char *infile, *outfile;
} Z;
#define ocount (Z.ocount )
#define prev_read_size (Z.prev_read_size)
#define count (Z.count )
#define seek (Z.seek )
#define skip (Z.skip )
#define infile (Z.infile )
#define outfile (Z.outfile)
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memset(&Z, 0, sizeof(Z));
INIT_G();
//fflush_all(); - is this needed because of NOEXEC?
for (i = 1; argv[i]; i++) {
int what;
char *val;
char *arg = argv[i];
#if ENABLE_DESKTOP
/* "dd --". NB: coreutils 6.9 will complain if they see
* more than one of them. We wouldn't. */
if (arg[0] == '-' && arg[1] == '-' && arg[2] == '\0')
continue;
#endif
val = strchr(arg, '=');
if (val == NULL)
bb_show_usage();
*val = '\0';
what = index_in_strings(keywords, arg);
if (what < 0)
bb_show_usage();
/* *val = '='; - to preserve ps listing? */
val++;
#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, cwbkMG_suffixes);
/*continue;*/
}
if (what == OP_obs) {
obs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, cwbkMG_suffixes);
/*continue;*/
}
if (what == OP_conv) {
G.flags |= parse_comma_flags(val, conv_words, "conv");
/*continue;*/
}
if (what == OP_iflag) {
G.flags |= parse_comma_flags(val, iflag_words, "iflag") << FLAG_IFLAG_SHIFT;
/*continue;*/
}
if (what == OP_oflag) {
G.flags |= parse_comma_flags(val, oflag_words, "oflag") << FLAG_OFLAG_SHIFT;
/*continue;*/
}
#endif
if (what == OP_bs) {
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, cwbkMG_suffixes);
/*continue;*/
}
if (what == OP_seek) {
seek = XATOU_SFX(val, cwbkMG_suffixes);
/*continue;*/
}
if (what == OP_skip) {
skip = XATOU_SFX(val, cwbkMG_suffixes);
/*continue;*/
}
if (what == OP_if) {
infile = val;
/*continue;*/
}
if (what == OP_of) {
outfile = val;
/*continue;*/
}
#if ENABLE_FEATURE_DD_STATUS
if (what == OP_status) {
int n;
n = index_in_strings(status_words, val);
if (n < 0)
bb_error_msg_and_die(bb_msg_invalid_arg_to, val, "status");
G.flags |= FLAG_STATUS_NONE << n;
/*continue;*/
}
#endif
} /* end of "for (argv[i])" */
//XXX:FIXME for huge ibs or obs, malloc'ing them isn't the brightest idea ever
ibuf = xmalloc(ibs);
obuf = ibuf;
#if ENABLE_FEATURE_DD_IBS_OBS
if (ibs != obs) {
G.flags |= FLAG_TWOBUFS;
obuf = xmalloc(obs);
}
#endif
#if ENABLE_FEATURE_DD_SIGNAL_HANDLING
signal_SA_RESTART_empty_mask(SIGUSR1, dd_output_status);
#endif
#if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
G.begin_time_us = monotonic_us();
#endif
if (infile) {
xmove_fd(xopen(infile, O_RDONLY), ifd);
} else {
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infile = bb_msg_standard_input;
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}
if (outfile) {
int oflag = O_WRONLY | O_CREAT;
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if (!seek && !(G.flags & FLAG_NOTRUNC))
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oflag |= O_TRUNC;
if (G.flags & FLAG_APPEND)
oflag |= O_APPEND;
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xmove_fd(xopen(outfile, oflag), ofd);
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if (seek && !(G.flags & FLAG_NOTRUNC)) {
size_t blocksz = (G.flags & FLAG_SEEK_BYTES) ? 1 : obs;
if (ftruncate(ofd, seek * blocksz) < 0) {
struct stat st;
if (fstat(ofd, &st) < 0
|| S_ISREG(st.st_mode)
|| S_ISDIR(st.st_mode)
) {
goto die_outfile;
}
}
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}
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} else {
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outfile = bb_msg_standard_output;
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}
if (skip) {
size_t blocksz = (G.flags & FLAG_SKIP_BYTES) ? 1 : ibs;
if (lseek(ifd, skip * blocksz, SEEK_CUR) < 0) {
do {
ssize_t n;
#if ENABLE_FEATURE_DD_IBS_OBS
if (G.flags & FLAG_FULLBLOCK)
n = full_read(ifd, ibuf, blocksz);
else
#endif
n = safe_read(ifd, ibuf, blocksz);
if (n < 0)
goto die_infile;
if (n == 0)
break;
} while (--skip != 0);
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}
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}
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if (seek) {
size_t blocksz = (G.flags & FLAG_SEEK_BYTES) ? 1 : obs;
if (lseek(ofd, seek * blocksz, SEEK_CUR) < 0)
goto die_outfile;
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}
while (!(G.flags & FLAG_COUNT) || (G.in_full + G.in_part != count)) {
ssize_t n;
#if ENABLE_FEATURE_DD_IBS_OBS
if (G.flags & FLAG_FULLBLOCK)
n = full_read(ifd, ibuf, ibs);
else
#endif
n = safe_read(ifd, ibuf, ibs);
if (n == 0)
break;
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if (n < 0) {
/* "Bad block" */
if (!(G.flags & FLAG_NOERROR))
goto die_infile;
bb_simple_perror_msg(infile);
/* GNU dd with conv=noerror skips over bad blocks */
xlseek(ifd, ibs, SEEK_CUR);
/* conv=noerror,sync writes NULs,
* conv=noerror just ignores input bad blocks */
n = 0;
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}
if (G.flags & FLAG_SWAB) {
uint16_t *p16;
ssize_t n2;
/* Our code allows only last read to be odd-sized */
if (prev_read_size & 1)
bb_error_msg_and_die("can't swab %lu byte buffer",
(unsigned long)prev_read_size);
prev_read_size = n;
/* If n is odd, last byte is not swapped:
* echo -n "qwe" | dd conv=swab
* prints "wqe".
*/
p16 = (void*) ibuf;
n2 = (n >> 1);
while (--n2 >= 0) {
*p16 = bswap_16(*p16);
p16++;
}
}
if ((size_t)n == ibs)
G.in_full++;
else {
G.in_part++;
if (G.flags & FLAG_SYNC) {
memset(ibuf + n, 0, ibs - n);
n = ibs;
}
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}
#if ENABLE_FEATURE_DD_IBS_OBS
if (G.flags & FLAG_TWOBUFS) {
char *tmp = ibuf;
while (n) {
size_t d = obs - ocount;
if (d > (size_t)n)
d = n;
memcpy(obuf + ocount, tmp, d);
n -= d;
tmp += d;
ocount += d;
if (ocount == obs) {
if (write_and_stats(obuf, obs, obs, outfile))
goto out_status;
ocount = 0;
}
}
} else
#endif
{
if (write_and_stats(ibuf, n, obs, outfile))
goto out_status;
}
}
if (G.flags & FLAG_FSYNC) {
if (fsync(ofd) < 0)
goto die_outfile;
}
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#if ENABLE_FEATURE_DD_IBS_OBS
if (ocount != 0) {
if (write_and_stats(obuf, ocount, obs, outfile))
goto out_status;
}
#endif
if (close(ifd) < 0) {
die_infile:
bb_simple_perror_msg_and_die(infile);
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}
if (close(ofd) < 0) {
die_outfile:
bb_simple_perror_msg_and_die(outfile);
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}
exitcode = EXIT_SUCCESS;
out_status:
if (!ENABLE_FEATURE_DD_STATUS || !(G.flags & FLAG_STATUS_NONE))
dd_output_status(0);
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if (ENABLE_FEATURE_CLEAN_UP) {
free(obuf);
if (G.flags & FLAG_TWOBUFS)
free(ibuf);
}
return exitcode;
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}