path: root/coreutils/dd.c (plain)
blob: 3d1ba2ee61d4493792752eecbc518ea1d06a6dad

1	/* vi: set sw=4 ts=4: */
2	/*
3	* Mini dd implementation for busybox
4	*
5	* Copyright (C) 2000,2001 Matt Kraai
6	*
7	* Licensed under GPLv2 or later, see file LICENSE in this source tree.
8	*/
9	//config:config DD
10	//config: bool "dd"
11	//config: default y
12	//config: help
13	//config: dd copies a file (from standard input to standard output,
14	//config: by default) using specific input and output blocksizes,
15	//config: while optionally performing conversions on it.
16	//config:
17	//config:config FEATURE_DD_SIGNAL_HANDLING
18	//config: bool "Enable signal handling for status reporting"
19	//config: default y
20	//config: depends on DD
21	//config: help
22	//config: Sending a SIGUSR1 signal to a running `dd' process makes it
23	//config: print to standard error the number of records read and written
24	//config: so far, then to resume copying.
25	//config:
26	//config: $ dd if=/dev/zero of=/dev/null &
27	//config: $ pid=$!; kill -USR1 $pid; sleep 1; kill $pid
28	//config: 10899206+0 records in
29	//config: 10899206+0 records out
30	//config:
31	//config:config FEATURE_DD_THIRD_STATUS_LINE
32	//config: bool "Enable the third status line upon signal"
33	//config: default y
34	//config: depends on DD && FEATURE_DD_SIGNAL_HANDLING
35	//config: help
36	//config: Displays a coreutils-like third status line with transferred bytes,
37	//config: elapsed time and speed.
38	//config:
39	//config:config FEATURE_DD_IBS_OBS
40	//config: bool "Enable ibs, obs and conv options"
41	//config: default y
42	//config: depends on DD
43	//config: help
44	//config: Enables support for writing a certain number of bytes in and out,
45	//config: at a time, and performing conversions on the data stream.
46	//config:
47	//config:config FEATURE_DD_STATUS
48	//config: bool "Enable status display options"
49	//config: default y
50	//config: depends on DD
51	//config: help
52	//config: Enables support for status=noxfer/none option.
53
54	//applet:IF_DD(APPLET_NOEXEC(dd, dd, BB_DIR_BIN, BB_SUID_DROP, dd))
55
56	//kbuild:lib-$(CONFIG_DD) += dd.o
57
58	//usage:#define dd_trivial_usage
59	//usage: "[if=FILE] [of=FILE] " IF_FEATURE_DD_IBS_OBS("[ibs=N] [obs=N] ") "[bs=N] [count=N] [skip=N]\n"
60	//usage: " [seek=N]" IF_FEATURE_DD_IBS_OBS(" [conv=notrunc|noerror|sync|fsync] [iflag=skip_bytes]")
61	//usage:#define dd_full_usage "\n\n"
62	//usage: "Copy a file with converting and formatting\n"
63	//usage: "\n if=FILE Read from FILE instead of stdin"
64	//usage: "\n of=FILE Write to FILE instead of stdout"
65	//usage: "\n bs=N Read and write N bytes at a time"
66	//usage: IF_FEATURE_DD_IBS_OBS(
67	//usage: "\n ibs=N Read N bytes at a time"
68	//usage: )
69	//usage: IF_FEATURE_DD_IBS_OBS(
70	//usage: "\n obs=N Write N bytes at a time"
71	//usage: )
72	//usage: "\n count=N Copy only N input blocks"
73	//usage: "\n skip=N Skip N input blocks"
74	//usage: "\n seek=N Skip N output blocks"
75	//usage: IF_FEATURE_DD_IBS_OBS(
76	//usage: "\n conv=notrunc Don't truncate output file"
77	//usage: "\n conv=noerror Continue after read errors"
78	//usage: "\n conv=sync Pad blocks with zeros"
79	//usage: "\n conv=fsync Physically write data out before finishing"
80	//usage: "\n conv=swab Swap every pair of bytes"
81	//usage: "\n iflag=skip_bytes skip=N is in bytes"
82	//usage: )
83	//usage: IF_FEATURE_DD_STATUS(
84	//usage: "\n status=noxfer Suppress rate output"
85	//usage: "\n status=none Suppress all output"
86	//usage: )
87	//usage: "\n"
88	//usage: "\nN may be suffixed by c (1), w (2), b (512), kB (1000), k (1024), MB, M, GB, G"
89	//usage:
90	//usage:#define dd_example_usage
91	//usage: "$ dd if=/dev/zero of=/dev/ram1 bs=1M count=4\n"
92	//usage: "4+0 records in\n"
93	//usage: "4+0 records out\n"
94
95	#include "libbb.h"
96	#include "common_bufsiz.h"
97
98	/* This is a NOEXEC applet. Be very careful! */
99
100
101	enum {
102	ifd = STDIN_FILENO,
103	ofd = STDOUT_FILENO,
104	};
105
106	struct globals {
107	off_t out_full, out_part, in_full, in_part;
108	#if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
109	unsigned long long total_bytes;
110	unsigned long long begin_time_us;
111	#endif
112	int flags;
113	} FIX_ALIASING;
114	#define G (*(struct globals*)bb_common_bufsiz1)
115	#define INIT_G() do { \
116	setup_common_bufsiz(); \
117	/* we have to zero it out because of NOEXEC */ \
118	memset(&G, 0, sizeof(G)); \
119	} while (0)
120
121	enum {
122	/* Must be in the same order as OP_conv_XXX! */
123	/* (see "flags |= (1 << what)" below) */
124	FLAG_NOTRUNC = (1 << 0) * ENABLE_FEATURE_DD_IBS_OBS,
125	FLAG_SYNC = (1 << 1) * ENABLE_FEATURE_DD_IBS_OBS,
126	FLAG_NOERROR = (1 << 2) * ENABLE_FEATURE_DD_IBS_OBS,
127	FLAG_FSYNC = (1 << 3) * ENABLE_FEATURE_DD_IBS_OBS,
128	FLAG_SWAB = (1 << 4) * ENABLE_FEATURE_DD_IBS_OBS,
129	/* end of conv flags */
130	/* start of input flags */
131	FLAG_IFLAG_SHIFT = 5,
132	FLAG_SKIP_BYTES = (1 << 5) * ENABLE_FEATURE_DD_IBS_OBS,
133	/* end of input flags */
134	FLAG_TWOBUFS = (1 << 6) * ENABLE_FEATURE_DD_IBS_OBS,
135	FLAG_COUNT = 1 << 7,
136	FLAG_STATUS = 1 << 8,
137	FLAG_STATUS_NONE = 1 << 9,
138	FLAG_STATUS_NOXFER = 1 << 10,
139	};
140
141	static void dd_output_status(int UNUSED_PARAM cur_signal)
142	{
143	#if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
144	double seconds;
145	unsigned long long bytes_sec;
146	unsigned long long now_us = monotonic_us(); /* before fprintf */
147	#endif
148
149	/* Deliberately using %u, not %d */
150	fprintf(stderr, "%"OFF_FMT"u+%"OFF_FMT"u records in\n"
151	"%"OFF_FMT"u+%"OFF_FMT"u records out\n",
152	G.in_full, G.in_part,
153	G.out_full, G.out_part);
154
155	#if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
156	# if ENABLE_FEATURE_DD_STATUS
157	if (G.flags & FLAG_STATUS_NOXFER) /* status=noxfer active? */
158	return;
159	//TODO: should status=none make dd stop reacting to USR1 entirely?
160	//So far we react to it (we print the stats),
161	//status=none only suppresses final, non-USR1 generated status message.
162	# endif
163	fprintf(stderr, "%llu bytes (%sB) copied, ",
164	G.total_bytes,
165	/* show fractional digit, use suffixes */
166	make_human_readable_str(G.total_bytes, 1, 0)
167	);
168	/* Corner cases:
169	* ./busybox dd </dev/null >/dev/null
170	* ./busybox dd bs=1M count=2000 </dev/zero >/dev/null
171	* (echo DONE) | ./busybox dd >/dev/null
172	* (sleep 1; echo DONE) | ./busybox dd >/dev/null
173	*/
174	seconds = (now_us - G.begin_time_us) / 1000000.0;
175	bytes_sec = G.total_bytes / seconds;
176	fprintf(stderr, "%f seconds, %sB/s\n",
177	seconds,
178	/* show fractional digit, use suffixes */
179	make_human_readable_str(bytes_sec, 1, 0)
180	);
181	#endif
182	}
183
184	static ssize_t full_write_or_warn(const void *buf, size_t len,
185	const char *const filename)
186	{
187	ssize_t n = full_write(ofd, buf, len);
188	if (n < 0)
189	bb_perror_msg("writing '%s'", filename);
190	return n;
191	}
192
193	static bool write_and_stats(const void *buf, size_t len, size_t obs,
194	const char *filename)
195	{
196	ssize_t n = full_write_or_warn(buf, len, filename);
197	if (n < 0)
198	return 1;
199	if ((size_t)n == obs)
200	G.out_full++;
201	else if (n) /* > 0 */
202	G.out_part++;
203	#if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
204	G.total_bytes += n;
205	#endif
206	return 0;
207	}
208
209	#if ENABLE_LFS
210	# define XATOU_SFX xatoull_sfx
211	#else
212	# define XATOU_SFX xatoul_sfx
213	#endif
214
215	#if ENABLE_FEATURE_DD_IBS_OBS
216	static int parse_comma_flags(char *val, const char *words, const char *error_in)
217	{
218	int flags = 0;
219	while (1) {
220	int n;
221	char *arg;
222	/* find ',', replace them with NUL so we can use val for
223	* index_in_strings() without copying.
224	* We rely on val being non-null, else strchr would fault.
225	*/
226	arg = strchr(val, ',');
227	if (arg)
228	*arg = '\0';
229	n = index_in_strings(words, val);
230	if (n < 0)
231	bb_error_msg_and_die(bb_msg_invalid_arg_to, val, error_in);
232	flags |= (1 << n);
233	if (!arg) /* no ',' left, so this was the last specifier */
234	break;
235	*arg = ','; /* to preserve ps listing */
236	val = arg + 1; /* skip this keyword and ',' */
237	}
238	return flags;
239	}
240	#endif
241
242	int dd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
243	int dd_main(int argc UNUSED_PARAM, char **argv)
244	{
245	static const char keywords[] ALIGN1 =
246	"bs\0""count\0""seek\0""skip\0""if\0""of\0"IF_FEATURE_DD_STATUS("status\0")
247	#if ENABLE_FEATURE_DD_IBS_OBS
248	"ibs\0""obs\0""conv\0""iflag\0"
249	#endif
250	;
251	#if ENABLE_FEATURE_DD_IBS_OBS
252	static const char conv_words[] ALIGN1 =
253	"notrunc\0""sync\0""noerror\0""fsync\0""swab\0";
254	static const char iflag_words[] ALIGN1 =
255	"skip_bytes\0";
256	#endif
257	#if ENABLE_FEATURE_DD_STATUS
258	static const char status_words[] ALIGN1 =
259	"none\0""noxfer\0";
260	#endif
261	enum {
262	OP_bs = 0,
263	OP_count,
264	OP_seek,
265	OP_skip,
266	OP_if,
267	OP_of,
268	IF_FEATURE_DD_STATUS(OP_status,)
269	#if ENABLE_FEATURE_DD_IBS_OBS
270	OP_ibs,
271	OP_obs,
272	OP_conv,
273	OP_iflag,
274	/* Must be in the same order as FLAG_XXX! */
275	OP_conv_notrunc = 0,
276	OP_conv_sync,
277	OP_conv_noerror,
278	OP_conv_fsync,
279	OP_conv_swab,
280	/* Unimplemented conv=XXX: */
281	//nocreat do not create the output file
282	//excl fail if the output file already exists
283	//fdatasync physically write output file data before finishing
284	//lcase change upper case to lower case
285	//ucase change lower case to upper case
286	//block pad newline-terminated records with spaces to cbs-size
287	//unblock replace trailing spaces in cbs-size records with newline
288	//ascii from EBCDIC to ASCII
289	//ebcdic from ASCII to EBCDIC
290	//ibm from ASCII to alternate EBCDIC
291	/* Partially implemented: */
292	//swab swap every pair of input bytes: will abort on non-even reads
293	OP_iflag_skip_bytes,
294	#endif
295	};
296	smallint exitcode = EXIT_FAILURE;
297	int i;
298	size_t ibs = 512;
299	char *ibuf;
300	#if ENABLE_FEATURE_DD_IBS_OBS
301	size_t obs = 512;
302	char *obuf;
303	#else
304	# define obs ibs
305	# define obuf ibuf
306	#endif
307	/* These are all zeroed at once! */
308	struct {
309	size_t oc;
310	ssize_t prev_read_size; /* for detecting swab failure */
311	off_t count;
312	off_t seek, skip;
313	const char *infile, *outfile;
314	} Z;
315	#define oc (Z.oc )
316	#define prev_read_size (Z.prev_read_size)
317	#define count (Z.count )
318	#define seek (Z.seek )
319	#define skip (Z.skip )
320	#define infile (Z.infile )
321	#define outfile (Z.outfile)
322
323	memset(&Z, 0, sizeof(Z));
324	INIT_G();
325	//fflush_all(); - is this needed because of NOEXEC?
326
327	for (i = 1; argv[i]; i++) {
328	int what;
329	char *val;
330	char *arg = argv[i];
331
332	#if ENABLE_DESKTOP
333	/* "dd --". NB: coreutils 6.9 will complain if they see
334	* more than one of them. We wouldn't. */
335	if (arg[0] == '-' && arg[1] == '-' && arg[2] == '\0')
336	continue;
337	#endif
338	val = strchr(arg, '=');
339	if (val == NULL)
340	bb_show_usage();
341	*val = '\0';
342	what = index_in_strings(keywords, arg);
343	if (what < 0)
344	bb_show_usage();
345	/* *val = '='; - to preserve ps listing? */
346	val++;
347	#if ENABLE_FEATURE_DD_IBS_OBS
348	if (what == OP_ibs) {
349	/* Must fit into positive ssize_t */
350	ibs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, cwbkMG_suffixes);
351	/*continue;*/
352	}
353	if (what == OP_obs) {
354	obs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, cwbkMG_suffixes);
355	/*continue;*/
356	}
357	if (what == OP_conv) {
358	G.flags |= parse_comma_flags(val, conv_words, "conv");
359	/*continue;*/
360	}
361	if (what == OP_iflag) {
362	G.flags |= parse_comma_flags(val, iflag_words, "iflag") << FLAG_IFLAG_SHIFT;
363	/*continue;*/
364	}
365	#endif
366	if (what == OP_bs) {
367	ibs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, cwbkMG_suffixes);
368	obs = ibs;
369	/*continue;*/
370	}
371	/* These can be large: */
372	if (what == OP_count) {
373	G.flags |= FLAG_COUNT;
374	count = XATOU_SFX(val, cwbkMG_suffixes);
375	/*continue;*/
376	}
377	if (what == OP_seek) {
378	seek = XATOU_SFX(val, cwbkMG_suffixes);
379	/*continue;*/
380	}
381	if (what == OP_skip) {
382	skip = XATOU_SFX(val, cwbkMG_suffixes);
383	/*continue;*/
384	}
385	if (what == OP_if) {
386	infile = val;
387	/*continue;*/
388	}
389	if (what == OP_of) {
390	outfile = val;
391	/*continue;*/
392	}
393	#if ENABLE_FEATURE_DD_STATUS
394	if (what == OP_status) {
395	int n;
396	n = index_in_strings(status_words, val);
397	if (n < 0)
398	bb_error_msg_and_die(bb_msg_invalid_arg_to, val, "status");
399	G.flags |= FLAG_STATUS << n;
400	/*continue;*/
401	}
402	#endif
403	} /* end of "for (argv[i])" */
404
405	//XXX:FIXME for huge ibs or obs, malloc'ing them isn't the brightest idea ever
406	ibuf = xmalloc(ibs);
407	obuf = ibuf;
408	#if ENABLE_FEATURE_DD_IBS_OBS
409	if (ibs != obs) {
410	G.flags |= FLAG_TWOBUFS;
411	obuf = xmalloc(obs);
412	}
413	#endif
414
415	#if ENABLE_FEATURE_DD_SIGNAL_HANDLING
416	signal_SA_RESTART_empty_mask(SIGUSR1, dd_output_status);
417	#endif
418	#if ENABLE_FEATURE_DD_THIRD_STATUS_LINE
419	G.begin_time_us = monotonic_us();
420	#endif
421
422	if (infile) {
423	xmove_fd(xopen(infile, O_RDONLY), ifd);
424	} else {
425	infile = bb_msg_standard_input;
426	}
427	if (outfile) {
428	int oflag = O_WRONLY | O_CREAT;
429
430	if (!seek && !(G.flags & FLAG_NOTRUNC))
431	oflag |= O_TRUNC;
432
433	xmove_fd(xopen(outfile, oflag), ofd);
434
435	if (seek && !(G.flags & FLAG_NOTRUNC)) {
436	if (ftruncate(ofd, seek * obs) < 0) {
437	struct stat st;
438
439	if (fstat(ofd, &st) < 0
440	|| S_ISREG(st.st_mode)
441	|| S_ISDIR(st.st_mode)
442	) {
443	goto die_outfile;
444	}
445	}
446	}
447	} else {
448	outfile = bb_msg_standard_output;
449	}
450	if (skip) {
451	size_t blocksz = (G.flags & FLAG_SKIP_BYTES) ? 1 : ibs;
452	if (lseek(ifd, skip * blocksz, SEEK_CUR) < 0) {
453	do {
454	ssize_t n = safe_read(ifd, ibuf, blocksz);
455	if (n < 0)
456	goto die_infile;
457	if (n == 0)
458	break;
459	} while (--skip != 0);
460	}
461	}
462	if (seek) {
463	if (lseek(ofd, seek * obs, SEEK_CUR) < 0)
464	goto die_outfile;
465	}
466
467	while (!(G.flags & FLAG_COUNT) || (G.in_full + G.in_part != count)) {
468	ssize_t n;
469
470	n = safe_read(ifd, ibuf, ibs);
471	if (n == 0)
472	break;
473	if (n < 0) {
474	/* "Bad block" */
475	if (!(G.flags & FLAG_NOERROR))
476	goto die_infile;
477	bb_simple_perror_msg(infile);
478	/* GNU dd with conv=noerror skips over bad blocks */
479	xlseek(ifd, ibs, SEEK_CUR);
480	/* conv=noerror,sync writes NULs,
481	* conv=noerror just ignores input bad blocks */
482	n = 0;
483	}
484	if (G.flags & FLAG_SWAB) {
485	uint16_t *p16;
486	ssize_t n2;
487
488	/* Our code allows only last read to be odd-sized */
489	if (prev_read_size & 1)
490	bb_error_msg_and_die("can't swab %lu byte buffer",
491	(unsigned long)prev_read_size);
492	prev_read_size = n;
493
494	/* If n is odd, last byte is not swapped:
495	* echo -n "qwe" | dd conv=swab
496	* prints "wqe".
497	*/
498	p16 = (void*) ibuf;
499	n2 = (n >> 1);
500	while (--n2 >= 0) {
501	*p16 = bswap_16(*p16);
502	p16++;
503	}
504	}
505	if ((size_t)n == ibs)
506	G.in_full++;
507	else {
508	G.in_part++;
509	if (G.flags & FLAG_SYNC) {
510	memset(ibuf + n, 0, ibs - n);
511	n = ibs;
512	}
513	}
514	if (G.flags & FLAG_TWOBUFS) {
515	char *tmp = ibuf;
516	while (n) {
517	size_t d = obs - oc;
518
519	if (d > (size_t)n)
520	d = n;
521	memcpy(obuf + oc, tmp, d);
522	n -= d;
523	tmp += d;
524	oc += d;
525	if (oc == obs) {
526	if (write_and_stats(obuf, obs, obs, outfile))
527	goto out_status;
528	oc = 0;
529	}
530	}
531	} else {
532	if (write_and_stats(ibuf, n, obs, outfile))
533	goto out_status;
534	}
535
536	if (G.flags & FLAG_FSYNC) {
537	if (fsync(ofd) < 0)
538	goto die_outfile;
539	}
540	}
541
542	if (ENABLE_FEATURE_DD_IBS_OBS && oc) {
543	if (write_and_stats(obuf, oc, obs, outfile))
544	goto out_status;
545	}
546	if (close(ifd) < 0) {
547	die_infile:
548	bb_simple_perror_msg_and_die(infile);
549	}
550
551	if (close(ofd) < 0) {
552	die_outfile:
553	bb_simple_perror_msg_and_die(outfile);
554	}
555
556	exitcode = EXIT_SUCCESS;
557	out_status:
558	if (!ENABLE_FEATURE_DD_STATUS || !(G.flags & FLAG_STATUS_NONE))
559	dd_output_status(0);
560
561	if (ENABLE_FEATURE_CLEAN_UP) {
562	free(obuf);
563	if (G.flags & FLAG_TWOBUFS)
564	free(ibuf);
565	}
566
567	return exitcode;
568	}
569