Jon LaBadie wrote:
On Wed, Jan 26, 2005 at 03:51:33PM +0100, Paul Bijnens wrote:
Jon LaBadie wrote:
It has been a couple of years since I looked at tar,
but IIRC two things that give a return code of 2 are
"file changed as we backed it up"
"file disappeared after we made the list of what to backup"
These conditions are common on active file systems.
Both cause the error message
"error exit delayed from previous errors"
which is a return code of 2.
Consulting sources of gnutar 1.13.25:
"file changed..." would set exit(2) but is neutralized
when given the --ignore-failed-read option to tar.
I believe you are correct on a "failed read", i.e. permissions
type changes, but I don't think "file changed ..."is affected
by the --ignore-failed-read option. I think it still prints
the message, and exits 2 with the "error exit delayed" message.
I *did* consult the source :-) :
Here are some checks when dumping a file:
tar-1.13.15/src/misc.c:
# an IO error while reading a file
1378 count = safe_read (f, start->buffer, bufsize);
1379 if (count < 0)
1380 {
1381 (ignore_failed_read_option
1382 ? read_warn_details
1383 : read_error_details)
1384 (p, current_stat.st_size - sizeleft, bufsize);
1385 goto padit;
1386 }
...
# file shrank while reading
1394 if (count != bufsize)
1395 {
1396 char buf[UINTMAX_STRSIZE_BOUND];
1397 memset (start->buffer + count, 0, bufsize - count);
1398 WARN ((0, 0,
1399 _("%s: File shrank by %s bytes; padding with
zeros"),
1400 quotearg_colon (p),
1401 STRINGIFY_BIGINT (sizeleft, buf)));
1402 if (! ignore_failed_read_option)
1403 exit_status = TAREXIT_FAILURE;
1404 goto padit; /* short read */
1405 }
...
# when at end of file, it can be disappeared already
1414 if (fstat (f, &final_stat) != 0)
1415 {
1416 if (ignore_failed_read_option)
1417 stat_warn (p);
1418 else
1419 stat_error (p);
1420 }
# ctime changed: someone wrote to it, or chmod it etc
1421 else if (final_stat.st_ctime != original_ctime)
1422 {
1423 char const *qp = quotearg_colon (p);
1424 WARN ((0, 0, _("%s: file changed as we read it"), qp));
1425 if (! ignore_failed_read_option)
1426 exit_status = TAREXIT_FAILURE;
1427 }
# even an IO error detected while closing
1428 if (close (f) != 0)
1429 {
1430 if (ignore_failed_read_option)
1431 close_warn (p);
1432 else
1433 close_error (p);
1434 }
In 1.15.1 the code is rearranged -- looks clearer -- but still does
the same.
As far as I can see in the sources, the --ignore-failed-read
option really avoids exit with a failure for all errors
involved on the reading side.
Sources of gnutar 1.15.1:
"file changed...." is never triggering an exit-code different
from zero (but warning is printed nevertheless).
"file shrank ..." however still needs --ignore-failed-read flag
to be neutralized.
Looks like the RE's ignored need to be revisited.
The "file disappeared..." is diagnosed as
"Warning: Cannot stat: No such file or directory", and that
one neither sets a exitcode different from zero (in 1.13.25
and 1.15.1).
With the --ignored-failed-read I'm sure you are correct.
Yes, indeed.
The "error exit delayed" situation can be set to be considered
"normal" in sendbackup-gnutar.c or it and a few others ignored
by defining "IGNORE_TAR_ERRORS" in amanda.h.
Amanda does pass the --ignore-failed-read option, and thus you
normally should not need to compile with IGNORE_TAR_ERRORS defined.
The last one classifies the printed warnings as "normal" instead
of "strange" and suppresses the STRANGE section in the amanda report.
And maybe it would ignore other more serious errors too?
These are the 3 messages added by the IGNORE_TAR_ERRORS macro.
"File .* shrunk by [0-9][0-9]* bytes, padding with zeros"
"Cannot add file .*: No such file or directory"
"Error exit delayed from previous errors"
Seem to be directly related to the current discussion.
Tar always prints a message for the problems, but --ignore-failed-read
option just inhibits setting the exit failure code 2 for some
of them.
When tar returns with 2, amanda trows away the archive.
Amanda classifies the messages in "NORMAL", "ERROR" and all
the rest as "STRANGE".
The IGNORE_TAR_ERRORS macro just classifies those three as NORMAL
instead of STRANGE.
But the macro also makes amanda change the gnutar exit code 2 into 0.
Because you can have other real errors, defining that macro is not
very wise, I believe. I strongly think about adding the first
two regexps to the normal list, just to suppress the noise
in the report, together with one like "File changed as we read it"
(why was that left out from the regexp list?), but keep the
decision from gnutar indicating if the archive is OK or not.
The message "Error exit delayed..." however means there was an
error that --ignore-failed-read did not neutralize, and I *am*
interested in knowing about those! That one should not be "normal".
And some which are neutralized by the --ignore-failed-read flag
should still be flagged as strange (e.g. IO error on reading a file
means I need to replace my disk soon), but the tar archive is
valid, and does contain useful data.
Maybe that macro got added to amanda when gnutar did not yet had the
--ignore-failed-read flag?
--
Paul Bijnens, Xplanation Tel +32 16 397.511
Technologielaan 21 bus 2, B-3001 Leuven, BELGIUM Fax +32 16 397.512
http://www.xplanation.com/ email: Paul.Bijnens AT xplanation DOT com
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