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authorGravatar Nicholas Clark <nicholas.clark@gmail.com>2018-01-25 19:00:19 +0100
committerGravatar Denys Vlasenko <vda.linux@googlemail.com>2018-01-25 19:00:19 +0100
commit77a6678c427db5ea15d6d0005a579f441277df06 (patch)
tree3dc09cfe78a10443d20ce3d35dac71b9101fc34d
parent043be556916ab0fbbece9d406cef199d397f8455 (diff)
downloadbusybox-77a6678c427db5ea15d6d0005a579f441277df06.tar.gz
busybox-77a6678c427db5ea15d6d0005a579f441277df06.tar.bz2
dd: add 'fullblock' iflag
Adds a fullblock iflag for improved compatibility with GNU dd. The new iflag can be used to ensure that dd calls retrieve the expected amount of data when reading from pipes or unusual filesystems. function old new delta packed_usage 32249 32334 +85 dd_main 1582 1632 +50 static.iflag_words 12 22 +10 ------------------------------------------------------------------------ (add/remove: 0/0 grow/shrink: 3/0 up/down: 145/0) Total: 145 bytes Signed-off-by: Nicholas Clark <nicholas.clark@gmail.com> Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r--coreutils/dd.c33
-rw-r--r--docs/posix_conformance.txt5
2 files changed, 26 insertions, 12 deletions
diff --git a/coreutils/dd.c b/coreutils/dd.c
index 38b2a6aa1..0f130bcad 100644
--- a/coreutils/dd.c
+++ b/coreutils/dd.c
@@ -37,7 +37,7 @@
//config: elapsed time and speed.
//config:
//config:config FEATURE_DD_IBS_OBS
-//config: bool "Enable ibs, obs and conv options"
+//config: bool "Enable ibs, obs, iflag and conv options"
//config: default y
//config: depends on DD
//config: help
@@ -57,7 +57,7 @@
//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] [iflag=skip_bytes]")
+//usage: " [seek=N]" IF_FEATURE_DD_IBS_OBS(" [conv=notrunc|noerror|sync|fsync] [iflag=skip_bytes|fullblock]")
//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"
@@ -79,6 +79,7 @@
//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: )
//usage: IF_FEATURE_DD_STATUS(
//usage: "\n status=noxfer Suppress rate output"
@@ -130,11 +131,12 @@ enum {
/* 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 */
- FLAG_TWOBUFS = (1 << 6) * ENABLE_FEATURE_DD_IBS_OBS,
- FLAG_COUNT = 1 << 7,
- FLAG_STATUS_NONE = 1 << 8,
- FLAG_STATUS_NOXFER = 1 << 9,
+ FLAG_TWOBUFS = (1 << 7) * ENABLE_FEATURE_DD_IBS_OBS,
+ FLAG_COUNT = 1 << 8,
+ FLAG_STATUS_NONE = 1 << 9,
+ FLAG_STATUS_NOXFER = 1 << 10,
};
static void dd_output_status(int UNUSED_PARAM cur_signal)
@@ -255,7 +257,7 @@ int dd_main(int argc UNUSED_PARAM, char **argv)
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";
+ "skip_bytes\0""fullblock\0";
#endif
#if ENABLE_FEATURE_DD_STATUS
static const char status_words[] ALIGN1 =
@@ -294,6 +296,7 @@ int dd_main(int argc UNUSED_PARAM, char **argv)
/* Partially implemented: */
//swab swap every pair of input bytes: will abort on non-even reads
OP_iflag_skip_bytes,
+ OP_iflag_fullblock,
#endif
};
smallint exitcode = EXIT_FAILURE;
@@ -454,7 +457,13 @@ int dd_main(int argc UNUSED_PARAM, char **argv)
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, blocksz);
+ 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)
@@ -469,8 +478,12 @@ int dd_main(int argc UNUSED_PARAM, char **argv)
while (!(G.flags & FLAG_COUNT) || (G.in_full + G.in_part != count)) {
ssize_t n;
-
- n = safe_read(ifd, ibuf, ibs);
+#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;
if (n < 0) {
diff --git a/docs/posix_conformance.txt b/docs/posix_conformance.txt
index 8b9112020..cdf89b744 100644
--- a/docs/posix_conformance.txt
+++ b/docs/posix_conformance.txt
@@ -178,9 +178,10 @@ dd POSIX options:
conv=noerror | yes | |
conv=notrunc | yes | |
conv=sync | yes | |
+dd compatibility options:
+ conv=fsync | yes | |
iflag=skip_bytes| yes | |
-dd Busybox specific options:
- conv=fsync
+ iflag=fullblock | yes | |
df POSIX options
option | exists | compliant | remarks