stack_violation(3c)

1stack_violation(3C)      Standard C Library Functions      stack_violation(3C)
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NAME

6       stack_violation - determine stack boundary violation event
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SYNOPSIS

9       #include <ucontext.h>
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11       int stack_violation(int sig, const siginfo_t *sip,
12            const ucontext_t *ucp);
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DESCRIPTION

16       The  stack_violation()  function  returns  a  boolean  value indicating
17       whether the signal, sig, and accompanying signal information, sip,  and
18       saved  context,  ucp,  represent  a stack boundary violation event or a
19       stack overflow.
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RETURN VALUES

22       The stack_violation() function returns 0 if the signal does not  repre‐
23       sent  a  stack boundary violation event and 1 if the signal does repre‐
24       sent a stack boundary violation event.
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ERRORS

27       No errors are defined.
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EXAMPLES

30       Example 1 Set up a signal handler to run on an alternate stack.
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33       The following example sets up a signal handler for SIGSEGV to run on an
34       alternate signal stack. For each signal it handles, the handler emits a
35       message to indicate if the signal was produced due to a stack  boundary
36       violation.
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38
39         #include <stdlib.h>
40         #include <unistd.h>
41         #include <ucontext.h>
42         #include <signal.h>
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45         static void
46         handler(int sig, siginfo_t *sip, void *p)
47         {
48                 ucontext_t *ucp = p;
49                 const char *str;
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51                 if (stack_violation(sig, sip, ucp))
52                         str = "stack violation.\n";
53                 else
54                         str = "no stack violation.\n";
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56                 (void) write(STDERR_FILENO, str, strlen(str));
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58                 exit(1);
59         }
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61         int
62         main(int argc, char **argv)
63         {
64                 struct sigaction sa;
65                 stack_t altstack;
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67                 altstack.ss_size = SIGSTKSZ;
68                 altstack.ss_sp = malloc(SIGSTKSZ);
69                 altstack.ss_flags = 0;
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71                 (void) sigaltstack(&altstack, NULL);
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73                 sa.sa_sigaction = handler;
74                 (void) sigfillset(&sa.sa_mask);
75                 sa.sa_flags = SA_ONSTACK | SA_SIGINFO;
76                 (void) sigaction(SIGSEGV, &sa, NULL);
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78                 /*
79                  * The application is now set up to use stack_violation(3C).
80                  */
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82                 return (0);
83         }
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USAGE

87       An  application  typically  uses  stack_violation() in a signal handler
88       that has been installed for SIGSEGV using sigaction(2) with the SA_SIG‐
89       INFO flag set and is configured to run on an alternate signal stack.
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ATTRIBUTES

92       See attributes(5) for descriptions of the following attributes:
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97       ┌─────────────────────────────┬─────────────────────────────┐
98       │      ATTRIBUTE TYPE         │      ATTRIBUTE VALUE        │
99       ├─────────────────────────────┼─────────────────────────────┤
100       │Interface Stability          │Evolving                     │
101       ├─────────────────────────────┼─────────────────────────────┤
102       │MT-Level                     │Async-Signal-Safe            │
103       └─────────────────────────────┴─────────────────────────────┘
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