I found a bit of time to work on this and installed the attached patch,
which should address the issue. Thanks for reporting it.From 3368b8745046aeaa89f418f560e714b374f1a560 Mon Sep 17 00:00:00 2001
From: Paul Eggert
Date: Fri, 28 Jan 2022 00:01:07 -0800
Subject: [PATCH] dd: synchronize output after write errors
Problem reported by Sworddragon (Bug#51345).
* src/dd.c (cleanup): Synchronize output unless dd has been interrupted.
(synchronize_output): New function, split out from dd_copy.
Update conversions_mask so synchronization is done at most once.
(main): Do not die with the output file open, since we want to be
able to synchronize it before exiting. Synchronize output before
exiting.
---
NEWS | 3 ++
doc/coreutils.texi | 10 +++---
src/dd.c | 76 +-
3 files changed, 64 insertions(+), 25 deletions(-)
diff --git a/NEWS b/NEWS
index 15c9428bd..757abee15 100644
--- a/NEWS
+++ b/NEWS
@@ -41,6 +41,9 @@ GNU coreutils NEWS-*- outline -*-
padding them with zeros to 9 digits. It uses clock_getres and
clock_gettime to infer the clock resolution.
+ dd conv=fsync now synchronizes output even after a write error,
+ and similarly for dd conv=fdatasync.
+
timeout --foreground --kill-after=... will now exit with status 137
if the kill signal was sent, which is consistent with the behavior
when the --foreground option is not specified. This allows users to
diff --git a/doc/coreutils.texi b/doc/coreutils.texi
index c17406550..088d1764c 100644
--- a/doc/coreutils.texi
+++ b/doc/coreutils.texi
@@ -9397,14 +9397,16 @@ Continue after read errors.
@item fdatasync
@opindex fdatasync
@cindex synchronized data writes, before finishing
-Synchronize output data just before finishing. This forces a physical
-write of output data.
+Synchronize output data just before finishing,
+even if there were write errors.
+This forces a physical write of output data.
@item fsync
@opindex fsync
@cindex synchronized data and metadata writes, before finishing
-Synchronize output data and metadata just before finishing. This
-forces a physical write of output data and metadata.
+Synchronize output data and metadata just before finishing,
+even if there were write errors.
+This forces a physical write of output data and metadata.
@end table
diff --git a/src/dd.c b/src/dd.c
index 957ad129e..4ddc6db12 100644
--- a/src/dd.c
+++ b/src/dd.c
@@ -939,6 +939,8 @@ iclose (int fd)
return 0;
}
+static int synchronize_output (void);
+
static void
cleanup (void)
{
@@ -948,6 +950,13 @@ cleanup (void)
alignfree (obuf);
#endif
+ if (!interrupt_signal)
+{
+ int sync_status = synchronize_output ();
+ if (sync_status)
+exit (sync_status);
+}
+
if (iclose (STDIN_FILENO) != 0)
die (EXIT_FAILURE, errno, _("closing input file %s"), quoteaf (input_file));
@@ -2377,17 +2386,33 @@ dd_copy (void)
&& 0 <= reported_w_bytes && reported_w_bytes < w_bytes)
print_xfer_stats (0);
- if ((conversions_mask & C_FDATASYNC) && ifdatasync (STDOUT_FILENO) != 0)
+ return exit_status;
+}
+
+/* Synchronize output according to conversions_mask.
+ Do this even if w_bytes is zero, as fsync and fdatasync
+ flush out write requests from other processes too.
+ Clear bits in conversions_mask so that synchronization is done only once.
+ Return zero if successful, an exit status otherwise. */
+
+static int
+synchronize_output (void)
+{
+ int exit_status = 0;
+ int mask = conversions_mask;
+ conversions_mask &= ~ (C_FDATASYNC | C_FSYNC);
+
+ if ((mask & C_FDATASYNC) && ifdatasync (STDOUT_FILENO) != 0)
{
if (errno != ENOSYS && errno != EINVAL)
{
error (0, errno, _("fdatasync failed for %s"), quoteaf (output_file));
exit_status = EXIT_FAILURE;
}
- conversions_mask |= C_FSYNC;
+ mask |= C_FSYNC;
}
- if ((conversions_mask & C_FSYNC) && ifsync (STDOUT_FILENO) != 0)
+ if ((mask & C_FSYNC) && ifsync (STDOUT_FILENO) != 0)
{
error (0, errno, _("fsync failed for %s"), quoteaf (output_file));
return EXIT_FAILURE;
@@ -2460,6 +2485,16 @@ main (int argc, char **argv)
| (conversions_mask & C_EXCL ? O_EXCL : 0)
| (seek_records || (conversions_mask & C_NOTRUNC) ? 0 : O_TRUNC));
+ off_t size;
+ if ((INT_MULTIPLY_WRAPV (seek_records, output_blocksize, )
+ || INT_ADD_WRAPV (seek_bytes, size, ))
+ && !(conversions_mask & C_NOTRUNC))
+die (EXIT_FAILURE, 0,
+ _("offset too large: "
+ "cannot truncate to a length of seek=%"PRIdMAX""
+ " (%td-byte) blocks"),
+ seek_records, output_blocksize);
+
/* Open the output file with *read* access only if we might
need to read to satisfy a 'seek=' request. If we can't read
the file, go ahead with write-only access; it might work. */
