It allows specifying amount of bytes directly (not only amount of blocks) is also supported by GNU's Coreutils.
Signed-off-by: Rafał Miłecki <[email protected]> --- coreutils/dd.c | 65 ++++++++++++++++++++++++++++++++++++++-------- docs/posix_conformance.txt | 1 + 2 files changed, 55 insertions(+), 11 deletions(-) diff --git a/coreutils/dd.c b/coreutils/dd.c index 6a5288d..de58cb3 100644 --- a/coreutils/dd.c +++ b/coreutils/dd.c @@ -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 Treat skip=N value as amount of 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_FIRST = 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) @@ -209,12 +214,14 @@ 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 +239,7 @@ 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 +259,7 @@ 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; @@ -335,6 +344,27 @@ int dd_main(int argc UNUSED_PARAM, char **argv) } /*continue;*/ } + if (what == OP_iflag) { + 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(iflag_words, val); + if (n < 0) + bb_error_msg_and_die(bb_msg_invalid_arg_to, val, "iflag"); + G.flags |= (1 << (FLAG_IFLAG_FIRST + n)); + if (!arg) /* no ',' left, so this was the last specifier */ + break; + /* *arg = ','; - to preserve ps listing? */ + val = arg + 1; /* skip this keyword and ',' */ + } + /*continue;*/ + } #endif if (what == OP_bs) { ibs = xatoul_range_sfx(val, 1, ((size_t)-1L)/2, cwbkMG_suffixes); @@ -421,14 +451,27 @@ int dd_main(int argc UNUSED_PARAM, char **argv) outfile = bb_msg_standard_output; } if (skip) { - if (lseek(ifd, skip * ibs, SEEK_CUR) < 0) { - do { - ssize_t n = safe_read(ifd, ibuf, ibs); + bool skip_bytes = G.flags & FLAG_SKIP_BYTES; + size_t bytes = skip * (skip_bytes ? 1 : ibs); + ssize_t sought; + + sought = lseek(ifd, bytes, SEEK_CUR); + if (sought > 0) + bytes -= sought; + if (sought < 0 || skip_bytes) { + while (bytes) { + size_t min = (skip_bytes && bytes < ibs) ? bytes : ibs; + ssize_t n = safe_read(ifd, ibuf, min); if (n < 0) goto die_infile; if (n == 0) break; - } while (--skip != 0); + if (skip_bytes) { + bytes -= n; + } else { + bytes -= ibs; + } + } } } if (seek) { diff --git a/docs/posix_conformance.txt b/docs/posix_conformance.txt index 5b616d7..c0582dc 100644 --- a/docs/posix_conformance.txt +++ b/docs/posix_conformance.txt @@ -178,6 +178,7 @@ dd POSIX options: conv=noerror | yes | | conv=notrunc | yes | | conv=sync | yes | | + iflag=skip_bytes| yes | | dd Busybox specific options: conv=fsync -- 1.8.4.5 _______________________________________________ busybox mailing list [email protected] http://lists.busybox.net/mailman/listinfo/busybox
