Does the default action of SIGCONT resume the execution of a stopped process before or after first handling...
http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html#tag_15_04 says:
The default action for SIGCONT is to resume execution at the point where the process was stopped, after first handling any pending unblocked signals.
What does "after" mean here? Shouldn't it be "before" instead?
Is there some example to show what it means?
Similarly from APUE:
Since the process group is orphaned when the parentterminates, POSIX.1 requires that every process in the newly orphaned process
group that is stopped (as our child is) be sent the hang-up signal
(SIGHUP) followed by the continue signal (SIGCONT)
This causes the child to be continued, after processing the hang-up signal. The default action for the hang-up signal is to
terminate the process, so we have to provide a signal handler to catch
the signal. We therefore expect the printf in the sig_hup function to
appear before the printf in the pr_ids function.
Shouldn't "after" be "before" instead?
https://stackoverflow.com/a/17769300/156458 seems to suggest "before" instead of "after" in the above two quotes, or I misunderstand it:
The SIGHUP cannot be delivered until the child's execution is resumed.
When a process is stopped, all signal delivery is suspended except for
SIGCONT and SIGKILL.
So, the SIGHUP does arrive first, but it cannot be processed until the
SIGCONT awakens the process execution.
Thanks.
https://stackoverflow.com/questions/50635458/when-several-signals-arrive-at-a-process-what-is-the-order-between-the-process#comment94663185_50671773
linux signals
asked Dec 24 '18 at 17:55
Tim
26.1k74246455
add a comment |
http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html#tag_15_04 says:
The default action for SIGCONT is to resume execution at the point where the process was stopped, after first handling any pending unblocked signals.
What does "after" mean here? Shouldn't it be "before" instead?
Is there some example to show what it means?
Similarly from APUE:
Since the process group is orphaned when the parentterminates, POSIX.1 requires that every process in the newly orphaned process
group that is stopped (as our child is) be sent the hang-up signal
(SIGHUP) followed by the continue signal (SIGCONT)
This causes the child to be continued, after processing the hang-up signal. The default action for the hang-up signal is to
terminate the process, so we have to provide a signal handler to catch
the signal. We therefore expect the printf in the sig_hup function to
appear before the printf in the pr_ids function.
Shouldn't "after" be "before" instead?
https://stackoverflow.com/a/17769300/156458 seems to suggest "before" instead of "after" in the above two quotes, or I misunderstand it:
The SIGHUP cannot be delivered until the child's execution is resumed.
When a process is stopped, all signal delivery is suspended except for
SIGCONT and SIGKILL.
So, the SIGHUP does arrive first, but it cannot be processed until the
SIGCONT awakens the process execution.
Thanks.
https://stackoverflow.com/questions/50635458/when-several-signals-arrive-at-a-process-what-is-the-order-between-the-process#comment94663185_50671773
linux signals
asked Dec 24 '18 at 17:55
Tim
26.1k74246455
add a comment |
http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html#tag_15_04 says:
The default action for SIGCONT is to resume execution at the point where the process was stopped, after first handling any pending unblocked signals.
What does "after" mean here? Shouldn't it be "before" instead?
Is there some example to show what it means?
Similarly from APUE:
Since the process group is orphaned when the parentterminates, POSIX.1 requires that every process in the newly orphaned process
group that is stopped (as our child is) be sent the hang-up signal
(SIGHUP) followed by the continue signal (SIGCONT)
This causes the child to be continued, after processing the hang-up signal. The default action for the hang-up signal is to
terminate the process, so we have to provide a signal handler to catch
the signal. We therefore expect the printf in the sig_hup function to
appear before the printf in the pr_ids function.
Shouldn't "after" be "before" instead?
https://stackoverflow.com/a/17769300/156458 seems to suggest "before" instead of "after" in the above two quotes, or I misunderstand it:
The SIGHUP cannot be delivered until the child's execution is resumed.
When a process is stopped, all signal delivery is suspended except for
SIGCONT and SIGKILL.
So, the SIGHUP does arrive first, but it cannot be processed until the
SIGCONT awakens the process execution.
Thanks.
https://stackoverflow.com/questions/50635458/when-several-signals-arrive-at-a-process-what-is-the-order-between-the-process#comment94663185_50671773
linux signals
asked Dec 24 '18 at 17:55
Tim
26.1k74246455
http://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html#tag_15_04 says:
The default action for SIGCONT is to resume execution at the point where the process was stopped, after first handling any pending unblocked signals.
What does "after" mean here? Shouldn't it be "before" instead?
Is there some example to show what it means?
Similarly from APUE:
Since the process group is orphaned when the parentterminates, POSIX.1 requires that every process in the newly orphaned process
group that is stopped (as our child is) be sent the hang-up signal
(SIGHUP) followed by the continue signal (SIGCONT)
This causes the child to be continued, after processing the hang-up signal. The default action for the hang-up signal is to
terminate the process, so we have to provide a signal handler to catch
the signal. We therefore expect the printf in the sig_hup function to
appear before the printf in the pr_ids function.
Shouldn't "after" be "before" instead?
https://stackoverflow.com/a/17769300/156458 seems to suggest "before" instead of "after" in the above two quotes, or I misunderstand it:
The SIGHUP cannot be delivered until the child's execution is resumed.
When a process is stopped, all signal delivery is suspended except for
SIGCONT and SIGKILL.
So, the SIGHUP does arrive first, but it cannot be processed until the
SIGCONT awakens the process execution.
Thanks.
https://stackoverflow.com/questions/50635458/when-several-signals-arrive-at-a-process-what-is-the-order-between-the-process#comment94663185_50671773
linux signals
linux signals
asked Dec 24 '18 at 17:55
Tim
26.1k74246455
asked Dec 24 '18 at 17:55
Tim
26.1k74246455
edited Dec 24 '18 at 18:03
asked Dec 24 '18 at 17:55
Tim
26.1k74246455
asked Dec 24 '18 at 17:55
Tim
26.1k74246455
asked Dec 24 '18 at 17:55
Tim
26.1k74246455
26.1k74246455
add a comment |
add a comment |
2 Answers
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No, it means after. The key is "resume execution at the point where the process was stopped".
Signal processing is performed first, and then execution continues.
answered Dec 24 '18 at 18:29
Stephen Harris
25.2k24477
add a comment |
https://github.com/torvalds/linux/blob/master/kernel/signal.c
POSIX 1b compliant signal kernel code
Do a search on SIGCONT. You will see that when SIGCONT is encountered the code then looks for pending signals.
edited 1 hour ago
Rui F Ribeiro
39.1k1479130
answered Dec 24 '18 at 18:30
jim mcnamara
513
Thanks. Could you point out which line in the source file is for "when SIGCONT is encountered the code then looks for pending signals"?
– Tim
Dec 24 '18 at 21:10
Try the comments found on lines 661, 862, 2028. Reading the code is time consuming , so consider starting with comments. If you search on "SIGCONT" you will find all of the comments and some of the relevant lines of code.
– jim mcnamara
Dec 25 '18 at 5:07
add a comment |
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2 Answers
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2 Answers
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active
oldest
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No, it means after. The key is "resume execution at the point where the process was stopped".
Signal processing is performed first, and then execution continues.
answered Dec 24 '18 at 18:29
Stephen Harris
25.2k24477
add a comment |
No, it means after. The key is "resume execution at the point where the process was stopped".
Signal processing is performed first, and then execution continues.
answered Dec 24 '18 at 18:29
Stephen Harris
25.2k24477
add a comment |
No, it means after. The key is "resume execution at the point where the process was stopped".
Signal processing is performed first, and then execution continues.
answered Dec 24 '18 at 18:29
Stephen Harris
25.2k24477
No, it means after. The key is "resume execution at the point where the process was stopped".
Signal processing is performed first, and then execution continues.
answered Dec 24 '18 at 18:29
Stephen Harris
25.2k24477
answered Dec 24 '18 at 18:29
Stephen Harris
25.2k24477
answered Dec 24 '18 at 18:29
Stephen Harris
25.2k24477
answered Dec 24 '18 at 18:29
Stephen Harris
25.2k24477
25.2k24477
add a comment |
add a comment |
https://github.com/torvalds/linux/blob/master/kernel/signal.c
POSIX 1b compliant signal kernel code
Do a search on SIGCONT. You will see that when SIGCONT is encountered the code then looks for pending signals.
edited 1 hour ago
Rui F Ribeiro
39.1k1479130
answered Dec 24 '18 at 18:30
jim mcnamara
513
Thanks. Could you point out which line in the source file is for "when SIGCONT is encountered the code then looks for pending signals"?
– Tim
Dec 24 '18 at 21:10
Try the comments found on lines 661, 862, 2028. Reading the code is time consuming , so consider starting with comments. If you search on "SIGCONT" you will find all of the comments and some of the relevant lines of code.
– jim mcnamara
Dec 25 '18 at 5:07
add a comment |
https://github.com/torvalds/linux/blob/master/kernel/signal.c
POSIX 1b compliant signal kernel code
Do a search on SIGCONT. You will see that when SIGCONT is encountered the code then looks for pending signals.
edited 1 hour ago
Rui F Ribeiro
39.1k1479130
answered Dec 24 '18 at 18:30
jim mcnamara
513
Thanks. Could you point out which line in the source file is for "when SIGCONT is encountered the code then looks for pending signals"?
– Tim
Dec 24 '18 at 21:10
Try the comments found on lines 661, 862, 2028. Reading the code is time consuming , so consider starting with comments. If you search on "SIGCONT" you will find all of the comments and some of the relevant lines of code.
– jim mcnamara
Dec 25 '18 at 5:07
add a comment |
https://github.com/torvalds/linux/blob/master/kernel/signal.c
POSIX 1b compliant signal kernel code
Do a search on SIGCONT. You will see that when SIGCONT is encountered the code then looks for pending signals.
edited 1 hour ago
Rui F Ribeiro
39.1k1479130
answered Dec 24 '18 at 18:30
jim mcnamara
513
https://github.com/torvalds/linux/blob/master/kernel/signal.c
POSIX 1b compliant signal kernel code
Do a search on SIGCONT. You will see that when SIGCONT is encountered the code then looks for pending signals.
edited 1 hour ago
Rui F Ribeiro
39.1k1479130
answered Dec 24 '18 at 18:30
jim mcnamara
513
edited 1 hour ago
Rui F Ribeiro
39.1k1479130
edited 1 hour ago
Rui F Ribeiro
39.1k1479130
edited 1 hour ago
Rui F Ribeiro
39.1k1479130
39.1k1479130
answered Dec 24 '18 at 18:30
jim mcnamara
513
answered Dec 24 '18 at 18:30
jim mcnamara
513
answered Dec 24 '18 at 18:30
jim mcnamara
513
513
Thanks. Could you point out which line in the source file is for "when SIGCONT is encountered the code then looks for pending signals"?
– Tim
Dec 24 '18 at 21:10
Try the comments found on lines 661, 862, 2028. Reading the code is time consuming , so consider starting with comments. If you search on "SIGCONT" you will find all of the comments and some of the relevant lines of code.
– jim mcnamara
Dec 25 '18 at 5:07
add a comment |
Thanks. Could you point out which line in the source file is for "when SIGCONT is encountered the code then looks for pending signals"?
– Tim
Dec 24 '18 at 21:10
Try the comments found on lines 661, 862, 2028. Reading the code is time consuming , so consider starting with comments. If you search on "SIGCONT" you will find all of the comments and some of the relevant lines of code.
– jim mcnamara
Dec 25 '18 at 5:07
Thanks. Could you point out which line in the source file is for "when SIGCONT is encountered the code then looks for pending signals"?
– Tim
Dec 24 '18 at 21:10
Thanks. Could you point out which line in the source file is for "when SIGCONT is encountered the code then looks for pending signals"?
– Tim
Dec 24 '18 at 21:10
Try the comments found on lines 661, 862, 2028. Reading the code is time consuming , so consider starting with comments. If you search on "SIGCONT" you will find all of the comments and some of the relevant lines of code.
– jim mcnamara
Dec 25 '18 at 5:07
Try the comments found on lines 661, 862, 2028. Reading the code is time consuming , so consider starting with comments. If you search on "SIGCONT" you will find all of the comments and some of the relevant lines of code.
– jim mcnamara
Dec 25 '18 at 5:07
add a comment |
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