[Crash-utility] [PATCH] Allows to change the error output direction
Dave Anderson
anderson at redhat.com
Wed Jul 3 14:13:36 UTC 2019
----- Original Message -----
> I shouldn't use that message in the previous email. Yes, I am writing
> a command that does extra actions while doing 'dis' which gives you
> some extra information to make it easy to understand the code. As a
> part of it, it is trying to find symbols for any given values.
>
> Anyway, here I put another example that just does calling 'sym'
> command in exec_crash_command(). You can try it once load 'mpykdump'
> shared object.
Let me ask another question. Does mpykdump allow consumers of the
epython command to take advantage of all of the exported crash utility
functions that could be used in this case, e.g., value_symbol()?
Or does it restrict users to simply being able to run and parse the
output of that exec_crash_command() function?
Dave
>
> -----------------------------------------------------------------------------------
> $ pwd
> /root/Work
> $ cat test_cmd.py
> from pykdump.API import *
>
> def test_cmd():
> try:
> sym = exec_crash_command("sym 0x123")
> print("{%s}" % sym)
> except:
> pass
>
>
> if ( __name__ == '__main__'):
> test_cmd()
>
> $ ./crash
> ...
> crash> extend /root/.crash.d/mpykdump.so
> /root/.crash.d/mpykdump.so: shared object loaded
>
> crash> set stderr default
> stderr: default
> crash> epython /root/Work/test_cmd.py
> sym: invalid address: 0x123
> {sym: invalid address: 0x123
> }
>
> ** Execution took 0.00s (real) 0.00s (CPU)
> crash> set stderr fp
> stderr: fp
> crash> epython /root/Work/test_cmd.py
> {sym: invalid address: 0x123
> }
>
> ** Execution took 0.00s (real) 0.00s (CPU)
> crash> set stderr /tmp/output
> stderr: /tmp/output
> crash> epython /root/Work/test_cmd.py
> crash> !cat /tmp/output
> sym: invalid address: 0x123
> -----------------------------------------------------------------------------------
>
> Yes, in the above by using 'fp', we can redirect the error message
> into the same exec_crash_command() and prevent showing any messages on
> console. By doing that, we can have a full control for the messages.
> If we want to seperate error messages from the beginning, but not
> making duplicate, we could use file path instead.
>
> PS. I am attaching a new patch that has a small change as there was a
> memory leak when file open is failed.
>
> Regards,
> Daniel Kwon
>
> On Sun, Jun 30, 2019 at 1:42 AM Dave Anderson <anderson at redhat.com> wrote:
> >
> >
> >
> > ----- Original Message -----
> > > I am writing an extension based on 'mpykdump' and calling
> > > 'exec_crash_command()' to find symbol details as shown below.
> > >
> > > ---
> > > def find_symbol(str):
> > > try:
> > > sym = exec_crash_command("sym %s" % str)
> > > if sym.startswith("sym:") != True:
> > > return " <" + "".join(sym.split()[2:]) + ">"
> > > except:
> > > pass
> > >
> > > return ""
> > > ---
> > >
> > > In the below example, I am trying to interpret address
> > > '0xffff92a3fba0f100' by calling 'sym' crash command, but can't handle
> > > the situation where the symbol doesn't exist.
> > >
> > > ---
> > > ...
> > > 0xffffffff92858b75 <do_sys_poll+741>: callq 0xffffffff92986f80
> > > <__x86_indirect_thunk_rdx>
> > > sym: invalid address: 0xffff92a3fba0f100
> > > 0xffffffff92858b7a <do_sys_poll+746>: mov 0x50(%rsp),%rcx
> > > ;0xffff92a3fba0f100
> > > ...
> > > ---
> > >
> > > By using 'fp', I can redirect the error into the
> > > 'exec_crash_command()' result which I can use to identify the reason
> > > if there's error and can avoid showing unnecessary error on console.
> >
> > If you'll allow me to continue beating a dead horse...
> >
> > I've never used mpykdump before, and it's confusing because you are showing
> > disassembly
> > output, with a "sym" command error message appearing in the middle. Are
> > you calling
> > excec_crash_command() while you are parsing disassembly output from within
> > some other
> > mypkdump execution stream?
> >
> > Anyway, are you saying that -- with the current behavior -- when you
> > redirect the exec_crash_command()
> > function, that the sym error messages do *not* go to the redirected file or
> > pipe stream?
> >
> > It sounds like you're saying that your proposed "fp" setting would simply
> > not display the extra
> > "unnecessary" error message on the console.
> >
> > Dave
> >
> >
> > >
> > > Regards,
> > > Daniel
> > >
> > > Kind regards,
> > >
> > > Daniel Kwon, RHCA
> > >
> > > Principle Software Maintenance Engineer, CEE
> > >
> > > Red Hat APAC
> > >
> > >
> > >
> > > On Fri, Jun 28, 2019 at 11:41 PM Dave Anderson <anderson at redhat.com>
> > > wrote:
> > > >
> > > >
> > > >
> > > > ----- Original Message -----
> > > > > Hi Dave,
> > > > >
> > > > > Yes, that is violating the default behaviour. I recheck how it should
> > > > > be handled and made the below rules.
> > > > >
> > > > > - 'default' : Working just like the 'crash' before this 'stderr'
> > > > > implementation.
> > > > > - 'fp' : Only goes into one destination. It can be console in normal
> > > > > command, but will go into target file if redirection or pipe is used.
> > > >
> > > > I still don't understand why you want to bother with this "fp" option?
> > > > What's the problem you're trying to address?
> > > >
> > > > Dave
> > > >
> > > >
> > > > > - '<path>' : It will go into the specified file only and no console
> > > > > output.
> > > > >
> > > > > Below is the test I have done for the test. Hope this behaviour is
> > > > > reasonable.
> > > > >
> > > > > ---------------------------
> > > > > ## default: standard error handling behaviour.
> > > > >
> > > > > normal command: error prints on console
> > > > >
> > > > > crash> set stderr default
> > > > > stderr: default
> > > > >
> > > > > crash> sym 0x123
> > > > > sym: invalid address: 0x123
> > > > >
> > > > > redirect: goes into both console and redirected file.
> > > > >
> > > > > crash> sym 0x123 > /tmp/output
> > > > > sym: invalid address: 0x123
> > > > >
> > > > > crash> !cat /tmp/output
> > > > > sym: invalid address: 0x123
> > > > >
> > > > >
> > > > > pipe: goes into both console and piped direction.
> > > > >
> > > > > crash> sym 0x123 | cat
> > > > > sym: invalid address: 0x123
> > > > > sym: invalid address: 0x123
> > > > >
> > > > > crash> sym 0x123 | cat > /tmp/output
> > > > > sym: invalid address: 0x123
> > > > >
> > > > > crash> !cat /tmp/output
> > > > > sym: invalid address: 0x123
> > > > >
> > > > >
> > > > >
> > > > >
> > > > > ## fp: Only to the one target such as stdout, pipe, or redirected
> > > > > file
> > > > >
> > > > > normal command: error prints on console
> > > > >
> > > > > crash> set stderr fp
> > > > > stderr: fp
> > > > >
> > > > > crash> sym 0x123
> > > > > sym: invalid address: 0x123
> > > > >
> > > > > redirect: goes into redirected file only.
> > > > >
> > > > > crash> sym 0x123 > /tmp/output
> > > > > crash> !cat /tmp/output
> > > > > sym: invalid address: 0x123
> > > > >
> > > > >
> > > > > pipe: goes into piped direction only.
> > > > >
> > > > > crash> sym 0x123 | cat
> > > > > sym: invalid address: 0x123
> > > > >
> > > > > crash> sym 0x123 | cat > /tmp/output
> > > > >
> > > > > crash> !cat /tmp/output
> > > > > sym: invalid address: 0x123
> > > > >
> > > > >
> > > > >
> > > > > ## <file path>: Only to the specified file.
> > > > >
> > > > > normal command: error goes into the specified file only.
> > > > >
> > > > > crash> set stderr /tmp/stderr
> > > > > stderr: /tmp/stderr
> > > > > crash> sym 0x123
> > > > > crash> !cat /tmp/stderr
> > > > > sym: invalid address: 0x123
> > > > >
> > > > > redirect: error goes into the specified file only.
> > > > >
> > > > > crash> sym 0x124 > /tmp/output
> > > > > crash> !cat /tmp/output
> > > > > crash> !cat /tmp/stderr
> > > > > sym: invalid address: 0x123
> > > > > sym: invalid address: 0x124
> > > > >
> > > > > pipe: error goes into the specified file only.
> > > > >
> > > > > crash> sym 0x125 | cat
> > > > > crash> sym 0x126 | cat > /tmp/output
> > > > > crash> !cat /tmp/output
> > > > > crash> !cat /tmp/stderr
> > > > > sym: invalid address: 0x123
> > > > > sym: invalid address: 0x124
> > > > > sym: invalid address: 0x125
> > > > > sym: invalid address: 0x126
> > > > > ---------------------------
> > > > >
> > > > > Regards,
> > > > > Daniel Kwon
> > > > >
> > > > > Kind regards,
> > > > >
> > > > > Daniel Kwon, RHCA
> > > > >
> > > > > Principle Software Maintenance Engineer, CEE
> > > > >
> > > > > Red Hat APAC
> > > > >
> > > > >
> > > > >
> > > > > On Fri, Jun 28, 2019 at 5:27 AM Dave Anderson <anderson at redhat.com>
> > > > > wrote:
> > > > > >
> > > > > >
> > > > > >
> > > > > > ----- Original Message -----
> > > > > > > Hi Dave,
> > > > > > >
> > > > > > > It looks like __error() function has an extra output which can
> > > > > > > cause
> > > > > > > of
> > > > > > > confusion. I rewrote the code to cover that as well as the
> > > > > > > changes
> > > > > > > you
> > > > > > > had
> > > > > > > asked. Please let me know how it goes.
> > > > > >
> > > > > > Hi Daniel,
> > > > > >
> > > > > > Upon initial testing, I note that your patch changes the default
> > > > > > behavior,
> > > > > > which is unacceptable.
> > > > > >
> > > > > > By default, the idea is to get all error() messages out so that
> > > > > > they
> > > > > > are
> > > > > > seen by the user regardless of how the command's output may be
> > > > > > piped or
> > > > > > redirected. So if a command's output is redirected to a file or
> > > > > > pipe,
> > > > > > the error message goes both to the console as well as being
> > > > > > intermingled
> > > > > > in the pipe/file command output.
> > > > > >
> > > > > > Taking your simple example, by default, command output and error
> > > > > > messages
> > > > > > are piped (behind the scenes) to /usr/bin/less:
> > > > > >
> > > > > > crash> sym 0x523
> > > > > > sym: invalid address: 0x523
> > > > > > crash>
> > > > > >
> > > > > > If the default piping is turned off, command output and error
> > > > > > messages
> > > > > > go to stdout:
> > > > > >
> > > > > > crash> set scroll off
> > > > > > scroll: off (/usr/bin/less)
> > > > > > crash> sym 0x523
> > > > > > sym: invalid address: 0x523
> > > > > > crash>
> > > > > >
> > > > > > However, if the command is redirected to a file, any command output
> > > > > > and
> > > > > > error
> > > > > > messages go to the file, but error messages also go to the console:
> > > > > >
> > > > > > crash> sym 0x523 > /tmp/output
> > > > > > sym: invalid address: 0x523
> > > > > > crash> !cat /tmp/output
> > > > > > sym: invalid address: 0x523
> > > > > > crash>
> > > > > >
> > > > > > Similarly, if the command is piped to a command, command output and
> > > > > > error
> > > > > > messages
> > > > > > go to the pipe, and error messages also go to the console:
> > > > > >
> > > > > > crash> sym 0x523 | cat
> > > > > > sym: invalid address: 0x523
> > > > > > sym: invalid address: 0x523
> > > > > > crash>
> > > > > >
> > > > > > So with your patch applied, and the new stderr variable set to the
> > > > > > default
> > > > > > of "stdout":
> > > > > >
> > > > > > crash> set stderr
> > > > > > stderr: stdout
> > > > > > crash>
> > > > > >
> > > > > > Let's run the same set of commands as above:
> > > > > >
> > > > > > crash> sym 0x523
> > > > > > sym: invalid address: 0x523
> > > > > > crash> set scroll off
> > > > > > scroll: off (/usr/bin/less)
> > > > > > crash> sym 0x523
> > > > > > sym: invalid address: 0x523
> > > > > > crash>
> > > > > >
> > > > > > Same behavior as always. However, if a command is redirected to a
> > > > > > file,
> > > > > > the error message only goes to the console, but it is not sent to
> > > > > > the
> > > > > > output file:
> > > > > >
> > > > > > crash> sym 0x523 > /tmp/output
> > > > > > sym: invalid address: 0x523
> > > > > > crash> !cat /tmp/output
> > > > > > crash>
> > > > > >
> > > > > > Similarly, when piped to a command, the error message is only going
> > > > > > to
> > > > > > one of the destinations:
> > > > > >
> > > > > > crash> sym 0x523 | cat
> > > > > > sym: invalid address: 0x523
> > > > > > crash>
> > > > > >
> > > > > > So there's no way I'm going to change behavior from what it has
> > > > > > been forever.
> > > > > >
> > > > > > While I didn't test your alternative settings, it's not entirely
> > > > > > clear
> > > > > > what you're trying to accomplish. Seemingly it would make sense to
> > > > > > have
> > > > > > a binary setting for the new "stderr":
> > > > > >
> > > > > > (1) the current default behavior, or
> > > > > > (2) a setting allowing you to redirect all error() messages to a
> > > > > > designated file.
> > > > > >
> > > > > > Option (2) would *not* send them to the console *or* intermingle
> > > > > > them
> > > > > > with command output. But that's just me...
> > > > > >
> > > > > > Also, here's a minor compiler complaint:
> > > > > >
> > > > > > $ make warn
> > > > > > ...
> > > > > > cc -c -g -DX86_64 -DLZO -DSNAPPY -DGDB_7_6 main.c -Wall -O2
> > > > > > -Wstrict-prototypes -Wmissing-prototypes -fstack-protector
> > > > > > -Wformat-security
> > > > > > main.c: In function ‘setup_environment’:
> > > > > > main.c:1088:9: warning: implicit declaration of function
> > > > > > ‘set_stderr’
> > > > > > [-Wimplicit-function-declaration]
> > > > > > set_stderr("stdout");
> > > > > > ^
> > > > > > cc -c -g -DX86_64 -DLZO -DSNAPPY -DGDB_7_6 tools.c -Wall -O2
> > > > > > -Wstrict-prototypes -Wmissing-prototypes -fstack-protector
> > > > > > -Wformat-security
> > > > > > tools.c:42:1: warning: no previous prototype for ‘set_stderr’
> > > > > > [-Wmissing-prototypes]
> > > > > > set_stderr(char *target)
> > > > > > ^
> > > > > > ...
> > > > > >
> > > > > > Thanks,
> > > > > > Dave
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
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> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > >
> > > > > > >
> > > > > > > Kind regards,
> > > > > > > Daniel Kwon
> > > > > > >
> > > > > > > On Tue, Jun 25, 2019 at 2:06 AM Dave Anderson
> > > > > > > <anderson at redhat.com>
> > > > > > > wrote:
> > > > > > >
> > > > > > > >
> > > > > > > > ----- Original Message -----
> > > > > > > > > Hi Dave,
> > > > > > > > >
> > > > > > > > > Here I attach as a file for the patch. Thanks.
> > > > > > > > >
> > > > > > > > > Kind regards,
> > > > > > > > > Daniel
> > > > > > > >
> > > > > > > > Hi Daniel,
> > > > > > > >
> > > > > > > > As I mentioned before, the concept seems reasonable, which I
> > > > > > > > thought
> > > > > > > > was to allow a user to prevent error() messages from being
> > > > > > > > intermingled
> > > > > > > > with command output by redirecting them somewhere else. But
> > > > > > > > that's
> > > > > > > > apparently not the case, as a few simple examples show
> > > > > > > > otherwise.
> > > > > > > >
> > > > > > > > Here's the default setting, and a sample command generating an
> > > > > > > > error:
> > > > > > > >
> > > > > > > > crash> set -v
> > > > > > > > scroll: on (/usr/bin/less)
> > > > > > > > radix: 10 (decimal)
> > > > > > > > refresh: on
> > > > > > > > print_max: 256
> > > > > > > > print_array: off
> > > > > > > > console: (not assigned)
> > > > > > > > debug: 0
> > > > > > > > core: off
> > > > > > > > hash: on
> > > > > > > > silent: off
> > > > > > > > edit: vi
> > > > > > > > namelist:
> > > > > > > > /usr/lib/debug/lib/modules/3.10.0-957.21.2.el7.x86_64/vmlinux
> > > > > > > > dumpfile: (null)
> > > > > > > > unwind: off
> > > > > > > > zero_excluded: off
> > > > > > > > null-stop: off
> > > > > > > > gdb: off
> > > > > > > > scope: 0 (not set)
> > > > > > > > offline: show
> > > > > > > > redzone: on
> > > > > > > > stderr: stdout
> > > > > > > > crash> bt 33333
> > > > > > > > bt: invalid task or pid value: 33333
> > > > > > > > crash>
> > > > > > > >
> > > > > > > > Here I set stderr to /dev/null, which sets the new pc->stderr,
> > > > > > > > but the behavior is still the same:
> > > > > > > >
> > > > > > > > crash> set stderr /dev/null
> > > > > > > > stderr: /dev/null
> > > > > > > > crash> set -v
> > > > > > > > scroll: on (/usr/bin/less)
> > > > > > > > radix: 10 (decimal)
> > > > > > > > refresh: on
> > > > > > > > print_max: 256
> > > > > > > > print_array: off
> > > > > > > > console: (not assigned)
> > > > > > > > debug: 0
> > > > > > > > core: off
> > > > > > > > hash: on
> > > > > > > > silent: off
> > > > > > > > edit: vi
> > > > > > > > namelist:
> > > > > > > > /usr/lib/debug/lib/modules/3.10.0-957.21.2.el7.x86_64/vmlinux
> > > > > > > > dumpfile: (null)
> > > > > > > > unwind: off
> > > > > > > > zero_excluded: off
> > > > > > > > null-stop: off
> > > > > > > > gdb: off
> > > > > > > > scope: 0 (not set)
> > > > > > > > offline: show
> > > > > > > > redzone: on
> > > > > > > > stderr: /dev/null
> > > > > > > > crash> bt 33333
> > > > > > > > bt: invalid task or pid value: 33333
> > > > > > > > crash>
> > > > > > > >
> > > > > > > > Or if I set it to a file, the same thing happens:
> > > > > > > >
> > > > > > > > crash> set stderr /tmp/junk
> > > > > > > > stderr: /tmp/junk
> > > > > > > > crash> set -v
> > > > > > > > scroll: on (/usr/bin/less)
> > > > > > > > radix: 10 (decimal)
> > > > > > > > refresh: on
> > > > > > > > print_max: 256
> > > > > > > > print_array: off
> > > > > > > > console: (not assigned)
> > > > > > > > debug: 0
> > > > > > > > core: off
> > > > > > > > hash: on
> > > > > > > > silent: off
> > > > > > > > edit: vi
> > > > > > > > namelist:
> > > > > > > > /usr/lib/debug/lib/modules/3.10.0-957.21.2.el7.x86_64/vmlinux
> > > > > > > > dumpfile: (null)
> > > > > > > > unwind: off
> > > > > > > > zero_excluded: off
> > > > > > > > null-stop: off
> > > > > > > > gdb: off
> > > > > > > > scope: 0 (not set)
> > > > > > > > offline: show
> > > > > > > > redzone: on
> > > > > > > > stderr: /tmp/junk
> > > > > > > > crash> bt 33333
> > > > > > > > bt: invalid task or pid value: 33333
> > > > > > > > crash>
> > > > > > > >
> > > > > > > > With your patch applied, the help page indicates:
> > > > > > > >
> > > > > > > > stderr stdout | fp | <path> set the direction of error put.
> > > > > > > > 'stdout'
> > > > > > > > always
> > > > > > > > print on console. 'fp' follows
> > > > > > > > the
> > > > > > > > redirection
> > > > > > > > or pipe command. '<path>' can be
> > > > > > > > any
> > > > > > > > file
> > > > > > > > path
> > > > > > > > in the filesystem which can save
> > > > > > > > the
> > > > > > > > output
> > > > > > > >
> > > > > > > > Is states that "<path>" can be any file path in the filesystem
> > > > > > > > which
> > > > > > > > can
> > > > > > > > save
> > > > > > > > the output. But even I redirect a command, it still doesn't
> > > > > > > > seem
> > > > > > > > to do
> > > > > > > > what
> > > > > > > > it states:
> > > > > > > >
> > > > > > > > crash> set stderr /dev/null
> > > > > > > > stderr: /dev/null
> > > > > > > > crash> bt 33333 > /tmp/junk
> > > > > > > > crash> !cat /tmp/junk
> > > > > > > > bt: invalid task or pid value: 33333
> > > > > > > > crash>
> > > > > > > >
> > > > > > > > Or if I pipe it:
> > > > > > > >
> > > > > > > > crash> bt 33333 | cat
> > > > > > > > bt: invalid task or pid value: 33333
> > > > > > > > crash>
> > > > > > > >
> > > > > > > > What am I missing?
> > > > > > > >
> > > > > > > > And also, a couple more things...
> > > > > > > >
> > > > > > > > Please make pc->stderr_path a pointer:
> > > > > > > >
> > > > > > > > --- a/defs.h
> > > > > > > > +++ b/defs.h
> > > > > > > > @@ -553,6 +553,8 @@ struct program_context {
> > > > > > > > ulong scope; /* optional text
> > > > > > > > context
> > > > > > > > address
> > > > > > > > */
> > > > > > > > ulong nr_hash_queues; /* hash queue head
> > > > > > > > count
> > > > > > > > */
> > > > > > > > char *(*read_vmcoreinfo)(const char *);
> > > > > > > > + FILE *stderr; /* error() message
> > > > > > > > direction
> > > > > > > > */
> > > > > > > > + char stderr_path[PATH_MAX]; /* stderr path
> > > > > > > > information
> > > > > > > > */
> > > > > > > > };
> > > > > > > >
> > > > > > > > Since it's typically going to contain a handful of bytes, it's
> > > > > > > > kind
> > > > > > > > of
> > > > > > > > wasteful
> > > > > > > > to use PATH_MAX (4096). Just use malloc/free to get a buffer
> > > > > > > > of
> > > > > > > > the
> > > > > > > > correct
> > > > > > > > length.
> > > > > > > >
> > > > > > > > And please display pc->stderr and pc->stderr_path to
> > > > > > > > dump_program_context()
> > > > > > > > for use by "help -p".
> > > > > > > >
> > > > > > > > Thanks,
> > > > > > > > Dave
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > On Sat, Jun 22, 2019 at 5:24 AM Dave Anderson <
> > > > > > > > > anderson at redhat.com >
> > > > > > > > wrote:
> > > > > > > > >
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > Hi Daniel,
> > > > > > > > >
> > > > > > > > > The idea seems reasonable, but the patch below is malformed:
> > > > > > > > >
> > > > > > > > > $ patch -p1 < error.patch
> > > > > > > > > checking file defs.h
> > > > > > > > > Hunk #1 FAILED at 553.
> > > > > > > > > 1 out of 1 hunk FAILED
> > > > > > > > > checking file help.c
> > > > > > > > > patch: **** malformed patch at line 52: displayed by",
> > > > > > > > >
> > > > > > > > > $
> > > > > > > > >
> > > > > > > > > You can see that there are a quite a few unintended line
> > > > > > > > > wraps
> > > > > > > > > in the patch below.
> > > > > > > > >
> > > > > > > > > Can you make the patch a discrete attachment to your email?
> > > > > > > > >
> > > > > > > > > Thanks,
> > > > > > > > > Dave
> > > > > > > > >
> > > > > > > > >
> > > > > > > > > ----- Original Message -----
> > > > > > > > > > Currently, the error() is always printing the output to the
> > > > > > > > > > console
> > > > > > > > > > through 'stdout'. This does not follow redirection which is
> > > > > > > > > > good
> > > > > > > > > > when
> > > > > > > > > > you want to know error while redirecting commands output to
> > > > > > > > > > a
> > > > > > > > > > file.
> > > > > > > > > > However, there are situations that you want to hide error
> > > > > > > > > > messages
> > > > > > > > > > or
> > > > > > > > > > redirect it into somewhere else.
> > > > > > > > > >
> > > > > > > > > > Using 'set stderr' command, it can be changed to three
> > > > > > > > > > different
> > > > > > > > > > destination - fixed 'stdout', following redirection (fp),
> > > > > > > > > > or a
> > > > > > > > > > custom
> > > > > > > > > > file path.
> > > > > > > > > >
> > > > > > > > > > crash> set stderr
> > > > > > > > > > stderr: stdout
> > > > > > > > > > crash> sym 0x523 > /dev/null
> > > > > > > > > > sym: invalid address: 0x523
> > > > > > > > > > crash> set stderr fp
> > > > > > > > > > stderr: fp
> > > > > > > > > > crash> sym 0x523 > /dev/null
> > > > > > > > > > crash> set stderr /tmp/err.log
> > > > > > > > > > stderr: /tmp/err.log
> > > > > > > > > > crash> sym 0x523 > /dev/null
> > > > > > > > > > crash> set stderr stdout
> > > > > > > > > > stderr: stdout
> > > > > > > > > > crash> sym 0x523 > /dev/null
> > > > > > > > > > sym: invalid address: 0x523
> > > > > > > > > > ---
> > > > > > > > > > defs.h | 2 ++
> > > > > > > > > > help.c | 5 +++++
> > > > > > > > > > main.c | 2 ++
> > > > > > > > > > tools.c | 55
> > > > > > > > > > ++++++++++++++++++++++++++++++++++++++++++++++++++++---
> > > > > > > > > > 4 files changed, 61 insertions(+), 3 deletions(-)
> > > > > > > > > >
> > > > > > > > > > diff --git a/defs.h b/defs.h
> > > > > > > > > > index ccffe58..57850c6 100644
> > > > > > > > > > --- a/defs.h
> > > > > > > > > > +++ b/defs.h
> > > > > > > > > > @@ -553,6 +553,8 @@ struct program_context {
> > > > > > > > > > ulong scope; /* optional text context address */
> > > > > > > > > > ulong nr_hash_queues; /* hash queue head count */
> > > > > > > > > > char *(*read_vmcoreinfo)(const char *);
> > > > > > > > > > + FILE *stderr; /* error() message direction */
> > > > > > > > > > + char stderr_path[PATH_MAX]; /* stderr path information */
> > > > > > > > > > };
> > > > > > > > > >
> > > > > > > > > > #define READMEM pc->readmem
> > > > > > > > > > diff --git a/help.c b/help.c
> > > > > > > > > > index 581e616..ddc8e86 100644
> > > > > > > > > > --- a/help.c
> > > > > > > > > > +++ b/help.c
> > > > > > > > > > @@ -1093,6 +1093,10 @@ char *help_set[] = {
> > > > > > > > > > " redzone on | off if on, CONFIG_SLUB object addresses
> > > > > > > > > > displayed by",
> > > > > > > > > > " the kmem command will point to the
> > > > > > > > > > SLAB_RED_ZONE",
> > > > > > > > > > " padding inserted at the beginning of
> > > > > > > > > > the object.",
> > > > > > > > > > +" stderr stdout | fp | <path> set the direction of error
> > > > > > > > > > put.
> > > > > > > > > > 'stdout' always",
> > > > > > > > > > +" print on console. 'fp' follows the
> > > > > > > > > > redirection",
> > > > > > > > > > +" or pipe command. '<path>' can be any
> > > > > > > > > > file path",
> > > > > > > > > > +" in the filesystem which can save the
> > > > > > > > > > output",
> > > > > > > > > > " ",
> > > > > > > > > > " Internal variables may be set in four manners:\n",
> > > > > > > > > > " 1. entering the set command in $HOME/.%src.",
> > > > > > > > > > @@ -1144,6 +1148,7 @@ char *help_set[] = {
> > > > > > > > > > " scope: (not set)",
> > > > > > > > > > " offline: show",
> > > > > > > > > > " redzone: on",
> > > > > > > > > > +" stderr: stdout",
> > > > > > > > > > " ",
> > > > > > > > > > " Show the current context:\n",
> > > > > > > > > > " %s> set",
> > > > > > > > > > diff --git a/main.c b/main.c
> > > > > > > > > > index 83ccd31..68bdec4 100644
> > > > > > > > > > --- a/main.c
> > > > > > > > > > +++ b/main.c
> > > > > > > > > > @@ -1085,6 +1085,8 @@ setup_environment(int argc, char
> > > > > > > > > > **argv)
> > > > > > > > > > * to pipes or output files.
> > > > > > > > > > */
> > > > > > > > > > fp = stdout;
> > > > > > > > > > + pc->stderr = stdout;
> > > > > > > > > > + strcpy(pc->stderr_path, "stdout");
> > > > > > > > > >
> > > > > > > > > > /*
> > > > > > > > > > * Start populating the program_context structure. It's used
> > > > > > > > > > so
> > > > > > > > > > diff --git a/tools.c b/tools.c
> > > > > > > > > > index 2d95c3a..840d07c 100644
> > > > > > > > > > --- a/tools.c
> > > > > > > > > > +++ b/tools.c
> > > > > > > > > > @@ -58,6 +58,9 @@ __error(int type, char *fmt, ...)
> > > > > > > > > > void *retaddr[NUMBER_STACKFRAMES] = { 0 };
> > > > > > > > > > va_list ap;
> > > > > > > > > >
> > > > > > > > > > + if (!strcmp(pc->stderr_path, "fp"))
> > > > > > > > > > + pc->stderr = fp;
> > > > > > > > > > +
> > > > > > > > > > if (CRASHDEBUG(1) || (pc->flags & DROP_CORE)) {
> > > > > > > > > > SAVE_RETURN_ADDRESS(retaddr);
> > > > > > > > > > console("error() trace: %lx => %lx => %lx => %lx\n",
> > > > > > > > > > @@ -69,7 +72,7 @@ __error(int type, char *fmt, ...)
> > > > > > > > > > va_end(ap);
> > > > > > > > > >
> > > > > > > > > > if (!fmt && FATAL_ERROR(type)) {
> > > > > > > > > > - fprintf(stdout, "\n");
> > > > > > > > > > + fprintf(pc->stderr, "\n");
> > > > > > > > > > clean_exit(1);
> > > > > > > > > > }
> > > > > > > > > >
> > > > > > > > > > @@ -95,14 +98,14 @@ __error(int type, char *fmt, ...)
> > > > > > > > > > buf);
> > > > > > > > > > fflush(pc->stdpipe);
> > > > > > > > > > } else {
> > > > > > > > > > - fprintf(stdout, "%s%s%s %s%s",
> > > > > > > > > > + fprintf(pc->stderr, "%s%s%s %s%s",
> > > > > > > > > > new_line || end_of_line ? "\n" : "",
> > > > > > > > > > type == WARNING ? "WARNING" :
> > > > > > > > > > type == NOTE ? "NOTE" :
> > > > > > > > > > type == CONT ? spacebuf : pc->curcmd,
> > > > > > > > > > type == CONT ? " " : ":",
> > > > > > > > > > buf, end_of_line ? "\n" : "");
> > > > > > > > > > - fflush(stdout);
> > > > > > > > > > + fflush(pc->stderr);
> > > > > > > > > > }
> > > > > > > > > >
> > > > > > > > > > if ((fp != stdout) && (fp != pc->stdpipe) && (fp !=
> > > > > > > > > > pc->tmpfile)) {
> > > > > > > > > > @@ -2483,6 +2486,51 @@ cmd_set(void)
> > > > > > > > > > }
> > > > > > > > > > return;
> > > > > > > > > >
> > > > > > > > > > + } else if (STREQ(args[optind], "stderr")) {
> > > > > > > > > > + if (args[optind+1]) {
> > > > > > > > > > + FILE *tmp_fp = NULL;
> > > > > > > > > > + char tmp_path[PATH_MAX];
> > > > > > > > > > +
> > > > > > > > > > + optind++;
> > > > > > > > > > + if (STREQ(args[optind], "stdout")) {
> > > > > > > > > > + tmp_fp = stdout;
> > > > > > > > > > + strcpy(tmp_path, "stdout");
> > > > > > > > > > + } else if (STREQ(args[optind], "fp")) {
> > > > > > > > > > + tmp_fp = fp;
> > > > > > > > > > + strcpy(tmp_path, "fp");
> > > > > > > > > > + } else {
> > > > > > > > > > + if (strlen(args[optind]) >=
> > > > > > > > > > PATH_MAX) {
> > > > > > > > > > + error(INFO, "path
> > > > > > > > > > length %d is too long. (max=%d)\n",
> > > > > > > > > > +
> > > > > > > > > > strlen(args[optind]), PATH_MAX);
> > > > > > > > > > + return;
> > > > > > > > > > + }
> > > > > > > > > > + tmp_fp = fopen(args[optind], "a");
> > > > > > > > > > + if (tmp_fp != NULL) {
> > > > > > > > > > + strcpy(tmp_path,
> > > > > > > > > > args[optind]);
> > > > > > > > > > + } else {
> > > > > > > > > > + error(INFO, "invalid
> > > > > > > > > > path: %s\n",
> > > > > > > > > > + args[optind]);
> > > > > > > > > > + return;
> > > > > > > > > > + }
> > > > > > > > > > +
> > > > > > > > > > + }
> > > > > > > > > > +
> > > > > > > > > > + if (strcmp(pc->stderr_path, tmp_path)) {
> > > > > > > > > > + if (strcmp(pc->stderr_path,
> > > > > > > > > > "stdout")
> > > > > > > > > > + && strcmp(pc->stderr_path,
> > > > > > > > > > "fp")) {
> > > > > > > > > > + fclose(pc->stderr);
> > > > > > > > > > + }
> > > > > > > > > > + pc->stderr = tmp_fp;
> > > > > > > > > > + strcpy(pc->stderr_path, tmp_path);
> > > > > > > > > > + }
> > > > > > > > > > + }
> > > > > > > > > > +
> > > > > > > > > > + if (runtime) {
> > > > > > > > > > + fprintf(fp, "stderr: %s\n",
> > > > > > > > > > + pc->stderr_path);
> > > > > > > > > > + }
> > > > > > > > > > + return;
> > > > > > > > > > +
> > > > > > > > > > } else if (XEN_HYPER_MODE()) {
> > > > > > > > > > error(FATAL, "invalid argument for the Xen hypervisor\n");
> > > > > > > > > > } else if (pc->flags & MINIMAL_MODE) {
> > > > > > > > > > @@ -2590,6 +2638,7 @@ show_options(void)
> > > > > > > > > > fprintf(fp, "(not set)\n");
> > > > > > > > > > fprintf(fp, " offline: %s\n", pc->flags2 & OFFLINE_HIDE ?
> > > > > > > > > > "hide" : "show");
> > > > > > > > > > fprintf(fp, " redzone: %s\n", pc->flags2 & REDZONE ? "on" :
> > > > > > > > > > "off");
> > > > > > > > > > + fprintf(fp, " stderr: %s\n", pc->stderr_path);
> > > > > > > > > > }
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > --
> > > > > > > > > > 1.8.3.1
> > > > > > > > > >
> > > > > > > > > > --
> > > > > > > > > > Crash-utility mailing list
> > > > > > > > > > Crash-utility at redhat.com
> > > > > > > > > > https://www.redhat.com/mailman/listinfo/crash-utility
> > > > > > > > > >
> > > > > > > > >
> > > > > > > > > --
> > > > > > > > > Crash-utility mailing list
> > > > > > > > > Crash-utility at redhat.com
> > > > > > > > > https://www.redhat.com/mailman/listinfo/crash-utility
> > > > > > > > >
> > > > > > > > > --
> > > > > > > > > Crash-utility mailing list
> > > > > > > > > Crash-utility at redhat.com
> > > > > > > > > https://www.redhat.com/mailman/listinfo/crash-utility
> > > > > > > >
> > > > > > >
> > > > >
> > >
>
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