When will Linux kernel reset the signal handler for SIGSEGV to SIG_DFL?
If I have set a signal handler for SIGSEGV, whereas a segmentation fault is generated like:
int *a = NULL;
*a = 1;
The handler will be invoked, but this signal handler will be invoked only once. So, I guess Linux kernel will reset the signal handler to SIG_DFL, but when? I want to know the details, so I checked the Linux kernel source code, but couldn't find the clue yet. Please show me the code if you know the details.
c linux-kernel segmentation-fault signal-handling
edited Nov 13 '18 at 21:59
red0ct
1,30531023
asked Nov 13 '18 at 11:22
congcong
381212
add a comment |
If I have set a signal handler for SIGSEGV, whereas a segmentation fault is generated like:
int *a = NULL;
*a = 1;
The handler will be invoked, but this signal handler will be invoked only once. So, I guess Linux kernel will reset the signal handler to SIG_DFL, but when? I want to know the details, so I checked the Linux kernel source code, but couldn't find the clue yet. Please show me the code if you know the details.
c linux-kernel segmentation-fault signal-handling
edited Nov 13 '18 at 21:59
red0ct
1,30531023
asked Nov 13 '18 at 11:22
congcong
381212
add a comment |
If I have set a signal handler for SIGSEGV, whereas a segmentation fault is generated like:
int *a = NULL;
*a = 1;
The handler will be invoked, but this signal handler will be invoked only once. So, I guess Linux kernel will reset the signal handler to SIG_DFL, but when? I want to know the details, so I checked the Linux kernel source code, but couldn't find the clue yet. Please show me the code if you know the details.
c linux-kernel segmentation-fault signal-handling
edited Nov 13 '18 at 21:59
red0ct
1,30531023
asked Nov 13 '18 at 11:22
congcong
381212
If I have set a signal handler for SIGSEGV, whereas a segmentation fault is generated like:
int *a = NULL;
*a = 1;
The handler will be invoked, but this signal handler will be invoked only once. So, I guess Linux kernel will reset the signal handler to SIG_DFL, but when? I want to know the details, so I checked the Linux kernel source code, but couldn't find the clue yet. Please show me the code if you know the details.
c linux-kernel segmentation-fault signal-handling
c linux-kernel segmentation-fault signal-handling
edited Nov 13 '18 at 21:59
red0ct
1,30531023
asked Nov 13 '18 at 11:22
congcong
381212
edited Nov 13 '18 at 21:59
red0ct
1,30531023
asked Nov 13 '18 at 11:22
congcong
381212
edited Nov 13 '18 at 21:59
red0ct
1,30531023
edited Nov 13 '18 at 21:59
red0ct
1,30531023
edited Nov 13 '18 at 21:59
red0ct
1,30531023
1,30531023
asked Nov 13 '18 at 11:22
congcong
381212
asked Nov 13 '18 at 11:22
congcong
381212
asked Nov 13 '18 at 11:22
congcong
381212
381212
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
It depends on how you register the signal handler.
With sigaction and without the SA_RESETHAND flag, there will be no resetting to SIG_DFL (although returning from a signal handler run in response to a SIGSEGV delivered due to a segmentation fault is technically UB).
With SA_RESETHAND it will get reset, and if you register the handler with signal, then whether the handler will be reset or not is unspecified (so don't use signal()).
Example:
#include <signal.h>
#include <unistd.h>
int volatile*a;
void h(int Sig) write(1,"hn", 2);
int main()
//sigaction(SIGSEGV,&(struct sigaction).sa_handler=h, 0); //won't reset the handler, will likely loop
sigaction(SIGSEGV,&(struct sigaction).sa_handler=h,.sa_flags=SA_RESETHAND, 0); //will reset the handler
//signal(SIGSEGV,h); //may or may not reset the handler
*a=1;
return 0;
answered Nov 13 '18 at 15:07
PSkocikPSkocik
33.3k65273
add a comment |
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1 Answer
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It depends on how you register the signal handler.
With sigaction and without the SA_RESETHAND flag, there will be no resetting to SIG_DFL (although returning from a signal handler run in response to a SIGSEGV delivered due to a segmentation fault is technically UB).
With SA_RESETHAND it will get reset, and if you register the handler with signal, then whether the handler will be reset or not is unspecified (so don't use signal()).
Example:
#include <signal.h>
#include <unistd.h>
int volatile*a;
void h(int Sig) write(1,"hn", 2);
int main()
//sigaction(SIGSEGV,&(struct sigaction).sa_handler=h, 0); //won't reset the handler, will likely loop
sigaction(SIGSEGV,&(struct sigaction).sa_handler=h,.sa_flags=SA_RESETHAND, 0); //will reset the handler
//signal(SIGSEGV,h); //may or may not reset the handler
*a=1;
return 0;
answered Nov 13 '18 at 15:07
PSkocikPSkocik
33.3k65273
add a comment |
It depends on how you register the signal handler.
With sigaction and without the SA_RESETHAND flag, there will be no resetting to SIG_DFL (although returning from a signal handler run in response to a SIGSEGV delivered due to a segmentation fault is technically UB).
With SA_RESETHAND it will get reset, and if you register the handler with signal, then whether the handler will be reset or not is unspecified (so don't use signal()).
Example:
#include <signal.h>
#include <unistd.h>
int volatile*a;
void h(int Sig) write(1,"hn", 2);
int main()
//sigaction(SIGSEGV,&(struct sigaction).sa_handler=h, 0); //won't reset the handler, will likely loop
sigaction(SIGSEGV,&(struct sigaction).sa_handler=h,.sa_flags=SA_RESETHAND, 0); //will reset the handler
//signal(SIGSEGV,h); //may or may not reset the handler
*a=1;
return 0;
answered Nov 13 '18 at 15:07
PSkocikPSkocik
33.3k65273
add a comment |
It depends on how you register the signal handler.
With sigaction and without the SA_RESETHAND flag, there will be no resetting to SIG_DFL (although returning from a signal handler run in response to a SIGSEGV delivered due to a segmentation fault is technically UB).
With SA_RESETHAND it will get reset, and if you register the handler with signal, then whether the handler will be reset or not is unspecified (so don't use signal()).
Example:
#include <signal.h>
#include <unistd.h>
int volatile*a;
void h(int Sig) write(1,"hn", 2);
int main()
//sigaction(SIGSEGV,&(struct sigaction).sa_handler=h, 0); //won't reset the handler, will likely loop
sigaction(SIGSEGV,&(struct sigaction).sa_handler=h,.sa_flags=SA_RESETHAND, 0); //will reset the handler
//signal(SIGSEGV,h); //may or may not reset the handler
*a=1;
return 0;
answered Nov 13 '18 at 15:07
PSkocikPSkocik
33.3k65273
It depends on how you register the signal handler.
With sigaction and without the SA_RESETHAND flag, there will be no resetting to SIG_DFL (although returning from a signal handler run in response to a SIGSEGV delivered due to a segmentation fault is technically UB).
With SA_RESETHAND it will get reset, and if you register the handler with signal, then whether the handler will be reset or not is unspecified (so don't use signal()).
Example:
#include <signal.h>
#include <unistd.h>
int volatile*a;
void h(int Sig) write(1,"hn", 2);
int main()
//sigaction(SIGSEGV,&(struct sigaction).sa_handler=h, 0); //won't reset the handler, will likely loop
sigaction(SIGSEGV,&(struct sigaction).sa_handler=h,.sa_flags=SA_RESETHAND, 0); //will reset the handler
//signal(SIGSEGV,h); //may or may not reset the handler
*a=1;
return 0;
answered Nov 13 '18 at 15:07
PSkocikPSkocik
33.3k65273
edited Nov 14 '18 at 2:25
answered Nov 13 '18 at 15:07
PSkocikPSkocik
33.3k65273
answered Nov 13 '18 at 15:07
PSkocikPSkocik
33.3k65273
answered Nov 13 '18 at 15:07
PSkocikPSkocik
33.3k65273
33.3k65273
add a comment |
add a comment |
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