On Monday 21 July 2008 12:53:08 you wrote:
> Much better thanks. The following description might be improved though?
>
> "Read full blocks from input if possible. If 'read' call is terminated
> during read of input block, it will be called again for the remainder
> input. This flag can be used only for iflag option."
>
> How about:
>
> "Read full blocks from input if possible. read() may return early
> if a full block is not available, so retry until data is available
> or end of file is reached. This flag can be used only for the iflag
> option."
Ok, description improved. Also applied some Jim's recommendations
from another RFE - new patch in attachment...
> BTW, are we sure we're restricting this to iflag?
I hope so, similar behavior is default while writing - see iwrite() function
implementation.
> thanks,
> Pádraig.
You're wellcome.
Kamil
From 9f8be4b0b83d1e0cbf1326f8cb7e077d026d9b0b Mon Sep 17 00:00:00 2001
From: Kamil Dudka <[EMAIL PROTECTED]>
Date: Wed, 23 Jul 2008 11:29:21 +0200
Subject: [PATCH] dd: iflag=fullblock now read full blocks if possible
* src/dd.c (iread_fullblock): New function for reading full blocks.
* (scanargs): Check for new parameter iflag=fullblock.
* (skip): Use iread_fnc pointer instead of iread function.
* (dd_copy): Use iread_fnc pointer instead of iread function.
* tests/dd/misc: Add test for dd - read full blocks.
* doc/coretuils.texi: Mention new parameter iflag=fullblock.
* NEWS: Mentioned the change.
---
NEWS | 4 ++++
doc/coreutils.texi | 6 ++++++
src/dd.c | 39 +++++++++++++++++++++++++++++++++++++--
tests/dd/misc | 9 +++++++++
4 files changed, 56 insertions(+), 2 deletions(-)
diff --git a/NEWS b/NEWS
index d6ed89e..68a27fa 100644
--- a/NEWS
+++ b/NEWS
@@ -27,6 +27,10 @@ GNU coreutils NEWS -*- outline -*-
represents the maximum number of inputs that will be merged at once.
When processing more than NMERGE inputs, sort uses temporary files.
+ dd accepts a new parameter iflag=fullblock which turn on reading of full
+ blocks where possible. If this parameter is used and 'read' call is
+ terminated during read, it will be called again for remainder input.
+
** Bug fixes
chcon --verbose now prints a newline after each message
diff --git a/doc/coreutils.texi b/doc/coreutils.texi
index 81e3b91..b95f8dc 100644
--- a/doc/coreutils.texi
+++ b/doc/coreutils.texi
@@ -7719,6 +7719,12 @@ platforms that distinguish binary from text I/O.
Use text I/O. Like @samp{binary}, this option has no effect on
standard platforms.
[EMAIL PROTECTED] fullblock
[EMAIL PROTECTED] fullblock
+Read full blocks from input if possible. read() may return early
+if a full block is not available, so retry until data is available
+or end of file is reached. This flag can be used only for the iflag option.
+
@end table
These flags are not supported on all systems, and @samp{dd} rejects
diff --git a/src/dd.c b/src/dd.c
index ead9574..1b620df 100644
--- a/src/dd.c
+++ b/src/dd.c
@@ -225,6 +225,9 @@ static sig_atomic_t volatile interrupt_signal;
/* A count of the number of pending info signals that have been received. */
static sig_atomic_t volatile info_signal_count;
+/* Function used for read (to handle iflag=fullblock parameter) */
+static ssize_t (*iread_fnc) (int fd, char *buf, size_t size);
+
/* A longest symbol in the struct symbol_values tables below. */
#define LONGEST_SYMBOL "fdatasync"
@@ -257,6 +260,7 @@ static struct symbol_value const conversions[] =
};
/* Flags, for iflag="..." and oflag="...". */
+#define O_FULLBLOCK 010000000 /* Read only full blocks from input */
static struct symbol_value const flags[] =
{
{"append", O_APPEND},
@@ -271,6 +275,7 @@ static struct symbol_value const flags[] =
{"nonblock", O_NONBLOCK},
{"sync", O_SYNC},
{"text", O_TEXT},
+ {"fullblock", O_FULLBLOCK}, /* Read only full blocks from input */
{"", 0}
};
@@ -762,6 +767,27 @@ iread (int fd, char *buf, size_t size)
}
}
+/* Wrapper around iread function which reads full blocks if possible */
+static ssize_t
+iread_fullblock (int fd, char *buf, size_t size)
+{
+ ssize_t nread = 0;
+
+ while (0 < size)
+ {
+ ssize_t ncurr = iread(fd, buf, size);
+ if (ncurr < 0)
+ return ncurr;
+ if (ncurr == 0)
+ break;
+ nread += ncurr;
+ buf += ncurr;
+ size -= ncurr;
+ }
+
+ return nread;
+}
+
/* Write to FD the buffer BUF of size SIZE, processing any signals
that arrive. Return the number of bytes written, setting errno if
this is less than SIZE. Keep trying if there are partial
@@ -1000,6 +1026,15 @@ scanargs (int argc, char *const *argv)
if (input_flags & (O_DSYNC | O_SYNC))
input_flags |= O_RSYNC;
+ if (output_flags & O_FULLBLOCK)
+ {
+ error (0, 0, "%s: %s", _("invalid output flag"), "'fullblock'");
+ usage (EXIT_FAILURE);
+ }
+ iread_fnc = (input_flags & O_FULLBLOCK)?
+ iread_fullblock:
+ iread;
+
if (multiple_bits_set (conversions_mask & (C_ASCII | C_EBCDIC | C_IBM)))
error (EXIT_FAILURE, 0, _("cannot combine any two of {ascii,ebcdic,ibm}"));
if (multiple_bits_set (conversions_mask & (C_BLOCK | C_UNBLOCK)))
@@ -1197,7 +1232,7 @@ skip (int fdesc, char const *file, uintmax_t records, size_t blocksize,
do
{
- ssize_t nread = iread (fdesc, buf, blocksize);
+ ssize_t nread = iread_fnc (fdesc, buf, blocksize);
if (nread < 0)
{
if (fdesc == STDIN_FILENO)
@@ -1508,7 +1543,7 @@ dd_copy (void)
(conversions_mask & (C_BLOCK | C_UNBLOCK)) ? ' ' : '\0',
input_blocksize);
- nread = iread (STDIN_FILENO, ibuf, input_blocksize);
+ nread = iread_fnc (STDIN_FILENO, ibuf, input_blocksize);
if (nread == 0)
break; /* EOF. */
diff --git a/tests/dd/misc b/tests/dd/misc
index d54fbfa..24e5eba 100755
--- a/tests/dd/misc
+++ b/tests/dd/misc
@@ -88,6 +88,15 @@ fi
outbytes=`echo x | dd bs=3 ibs=10 obs=10 conv=sync 2>/dev/null | wc -c`
test "$outbytes" -eq 3 || fail=1
+(echo a; sleep .1; echo b) \
+ | LC_ALL=C dd bs=4 status=noxfer iflag=fullblock >out 2>err || fail=1
+echo "a
+b" > out_ok
+echo "1+0 records in
+1+0 records out" > err_ok
+compare out out_ok || fail=1
+compare err err_ok || fail=1
+
test $fail -eq 0 && fail=$warn
(exit $fail); exit $fail
--
1.5.4.1
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