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dd: support iflag=skip_bytes

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It allows specifying amount of bytes directly (not only amount of
blocks) is also supported by GNU's Coreutils.

function                                             old     new   delta
parse_comma_flags                                      -      93     +93
static.iflag_words                                     -      12     +12
dd_main                                             1569    1580     +11
packed_usage                                       30591   30600      +9
------------------------------------------------------------------------------
(add/remove: 2/0 grow/shrink: 2/0 up/down: 125/0)             Total: 125 bytes

Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Rafał Miłecki
2016-02-01 02:17:28 +01:00
committed by Denys Vlasenko
parent 40eea690c7
commit c30a5b1373
2 changed files with 52 additions and 27 deletions
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78
coreutils/dd.c
View File

@@ -55,7 +55,7 @@
//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]\n"
//usage: " [seek=N]" IF_FEATURE_DD_IBS_OBS(" [conv=notrunc|noerror|sync|fsync]")
//usage: " [seek=N]" IF_FEATURE_DD_IBS_OBS(" [conv=notrunc|noerror|sync|fsync] [iflag=skip_bytes]")
//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"
@@ -76,6 +76,7 @@
//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: )
//usage: IF_FEATURE_DD_STATUS(
//usage: "\n status=noxfer Suppress rate output"
@@ -122,11 +123,15 @@ enum {
FLAG_FSYNC = (1 << 3) * ENABLE_FEATURE_DD_IBS_OBS,
FLAG_SWAB = (1 << 4) * ENABLE_FEATURE_DD_IBS_OBS,
/* end of conv flags */
FLAG_TWOBUFS = (1 << 5) * ENABLE_FEATURE_DD_IBS_OBS,
FLAG_COUNT = 1 << 6,
FLAG_STATUS = 1 << 7,
FLAG_STATUS_NONE = 1 << 7,
FLAG_STATUS_NOXFER = 1 << 8,
/* start of input flags */
FLAG_IFLAG_SHIFT = 5,
FLAG_SKIP_BYTES = (1 << 5) * ENABLE_FEATURE_DD_IBS_OBS,
/* end of input flags */
FLAG_TWOBUFS = (1 << 6) * ENABLE_FEATURE_DD_IBS_OBS,
FLAG_COUNT = 1 << 7,
FLAG_STATUS = 1 << 8,
FLAG_STATUS_NONE = 1 << 9,
FLAG_STATUS_NOXFER = 1 << 10,
};
static void dd_output_status(int UNUSED_PARAM cur_signal)
@@ -203,18 +208,47 @@ static bool write_and_stats(const void *buf, size_t len, size_t obs,
# 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;
int dd_main(int argc UNUSED_PARAM, char **argv)
{
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"
"ibs\0""obs\0""conv\0""iflag\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";
#endif
#if ENABLE_FEATURE_DD_STATUS
static const char status_words[] ALIGN1 =
@@ -232,6 +266,7 @@ int dd_main(int argc UNUSED_PARAM, char **argv)
OP_ibs,
OP_obs,
OP_conv,
OP_iflag,
/* Must be in the same order as FLAG_XXX! */
OP_conv_notrunc = 0,
OP_conv_sync,
@@ -251,6 +286,7 @@ int dd_main(int argc UNUSED_PARAM, char **argv)
//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,
#endif
};
smallint exitcode = EXIT_FAILURE;
@@ -315,24 +351,11 @@ int dd_main(int argc UNUSED_PARAM, char **argv)
/*continue;*/
}
if (what == OP_conv) {
while (1) {
int n;
/* 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(conv_words, val);
if (n < 0)
bb_error_msg_and_die(bb_msg_invalid_arg_to, val, "conv");
G.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 ',' */
}
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;*/
}
#endif
@@ -421,9 +444,10 @@ int dd_main(int argc UNUSED_PARAM, char **argv)
outfile = bb_msg_standard_output;
}
if (skip) {
if (lseek(ifd, skip * ibs, SEEK_CUR) < 0) {
size_t blocksz = (G.flags & FLAG_SKIP_BYTES) ? 1 : ibs;
if (lseek(ifd, skip * blocksz, SEEK_CUR) < 0) {
do {
ssize_t n = safe_read(ifd, ibuf, ibs);
ssize_t n = safe_read(ifd, ibuf, blocksz);
if (n < 0)
goto die_infile;
if (n == 0)