1966d4942c
Some boards have the WLAN EEPROM stored in flash in big-endian format, whereas the driver requires the EEPROM in little-endian format. The conv=swab option in dd is particularly useful in this case. This patch backports this feature from busybox-1.22 based on the following commits: commit b941316ae5313be523b64f0a9151ee4decb2b35b dd: support conv=swab commit 8395bd3f52f8ed46fa3ffc316b2d113afa748bae dd: fix example in a comment. No code changes. commit 5b9910f0a4a1b7976c46e6f849aaa263180e5521 dd: fail if swab is attempted on odd-sized block commit 0ff0b320a2dbb5e0b5fa245ffd9b2648d7026843 dd: code shrink v2: include the commit messages from upstream Signed-off-by: Matti Laakso <malaakso@elisanet.fi> SVN-Revision: 40327
97 lines
3.2 KiB
Diff
97 lines
3.2 KiB
Diff
--- a/coreutils/dd.c
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+++ b/coreutils/dd.c
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@@ -10,7 +10,7 @@
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//usage:#define dd_trivial_usage
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//usage: "[if=FILE] [of=FILE] " IF_FEATURE_DD_IBS_OBS("[ibs=N] [obs=N] ") "[bs=N] [count=N] [skip=N]\n"
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-//usage: " [seek=N]" IF_FEATURE_DD_IBS_OBS(" [conv=notrunc|noerror|sync|fsync]")
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+//usage: " [seek=N]" IF_FEATURE_DD_IBS_OBS(" [conv=notrunc|noerror|sync|fsync|swab]")
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//usage:#define dd_full_usage "\n\n"
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//usage: "Copy a file with converting and formatting\n"
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//usage: "\n if=FILE Read from FILE instead of stdin"
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@@ -30,6 +30,7 @@
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//usage: "\n conv=noerror Continue after read errors"
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//usage: "\n conv=sync Pad blocks with zeros"
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//usage: "\n conv=fsync Physically write data out before finishing"
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+//usage: "\n conv=swab Swap every pair of bytes"
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//usage: )
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//usage: "\n"
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//usage: "\nNumbers may be suffixed by c (x1), w (x2), b (x512), kD (x1000), k (x1024),"
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@@ -155,9 +156,10 @@ int dd_main(int argc UNUSED_PARAM, char
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FLAG_SYNC = 1 << 1,
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FLAG_NOERROR = 1 << 2,
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FLAG_FSYNC = 1 << 3,
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+ FLAG_SWAB = 1 << 4,
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/* end of conv flags */
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- FLAG_TWOBUFS = 1 << 4,
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- FLAG_COUNT = 1 << 5,
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+ FLAG_TWOBUFS = 1 << 5,
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+ FLAG_COUNT = 1 << 6,
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};
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static const char keywords[] ALIGN1 =
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"bs\0""count\0""seek\0""skip\0""if\0""of\0"
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@@ -167,7 +169,7 @@ int dd_main(int argc UNUSED_PARAM, char
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;
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#if ENABLE_FEATURE_DD_IBS_OBS
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static const char conv_words[] ALIGN1 =
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- "notrunc\0""sync\0""noerror\0""fsync\0";
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+ "notrunc\0""sync\0""noerror\0""fsync\0""swab\0";
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#endif
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enum {
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OP_bs = 0,
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@@ -185,11 +187,11 @@ int dd_main(int argc UNUSED_PARAM, char
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OP_conv_sync,
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OP_conv_noerror,
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OP_conv_fsync,
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+ OP_conv_swab,
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/* Unimplemented conv=XXX: */
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//nocreat do not create the output file
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//excl fail if the output file already exists
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//fdatasync physically write output file data before finishing
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- //swab swap every pair of input bytes
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//lcase change upper case to lower case
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//ucase change lower case to upper case
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//block pad newline-terminated records with spaces to cbs-size
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@@ -207,12 +209,14 @@ int dd_main(int argc UNUSED_PARAM, char
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struct {
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int flags;
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size_t oc;
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+ ssize_t prev_read_size; /* for detecting swab failure */
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off_t count;
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off_t seek, skip;
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const char *infile, *outfile;
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} Z;
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#define flags (Z.flags )
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#define oc (Z.oc )
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+#define prev_read_size (Z.prev_read_size)
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#define count (Z.count )
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#define seek (Z.seek )
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#define skip (Z.skip )
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@@ -375,6 +379,27 @@ int dd_main(int argc UNUSED_PARAM, char
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* conv=noerror just ignores input bad blocks */
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n = 0;
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}
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+ if (flags & FLAG_SWAB) {
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+ uint16_t *p16;
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+ ssize_t n2;
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+
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+ /* Our code allows only last read to be odd-sized */
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+ if (prev_read_size & 1)
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+ bb_error_msg_and_die("can't swab %lu byte buffer",
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+ (unsigned long)prev_read_size);
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+ prev_read_size = n;
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+
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+ /* If n is odd, last byte is not swapped:
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+ * echo -n "qwe" | dd conv=swab
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+ * prints "wqe".
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+ */
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+ p16 = (void*) ibuf;
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+ n2 = (n >> 1);
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+ while (--n2 >= 0) {
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+ *p16 = bswap_16(*p16);
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+ p16++;
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+ }
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+ }
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if ((size_t)n == ibs)
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G.in_full++;
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else {
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