1 /* Test of correct simulation for active stack. */ 2 3 #include <assert.h> 4 #include <signal.h> 5 #include <stdio.h> 6 #include <ucontext.h> 7 8 static char altstack_map[8096]; 9 static volatile stack_t *sp; 10 11 static void sighandler(int sig) 12 { 13 /* Check that the alternate stack is active. */ 14 assert(sp->ss_sp == altstack_map); 15 assert(sp->ss_size == sizeof(altstack_map)); 16 assert(sp->ss_flags == SS_ONSTACK); 17 } 18 19 int main(void) 20 { 21 stack_t mainstack; 22 stack_t altstack; 23 struct sigaction sa; 24 /* Obtain an address inside the stack using a dirty trick. */ 25 void *local = &sa; 26 27 /* Get an address for stack definition. */ 28 if (getustack((stack_t**)&sp)) { 29 perror("getustack"); 30 return 1; 31 } 32 33 /* Check the current stack. */ 34 assert(sp->ss_sp <= local); 35 assert(local < (void*)((char*)sp->ss_sp + sp->ss_size)); 36 assert(sp->ss_flags == 0); 37 38 /* Backup the current stack. */ 39 mainstack = *sp; 40 41 /* Setup a signal handler. */ 42 sa.sa_handler = sighandler; 43 sa.sa_flags = SA_ONSTACK; 44 if (sigfillset(&sa.sa_mask)) { 45 perror("sigfillset"); 46 return 1; 47 } 48 if (sigaction(SIGUSR1, &sa, NULL)) { 49 perror("sigaction"); 50 return 1; 51 } 52 53 /* Setup an alternate stack. */ 54 altstack.ss_sp = altstack_map; 55 altstack.ss_size = sizeof(altstack_map); 56 altstack.ss_flags = 0; 57 if (sigaltstack(&altstack, NULL)) { 58 perror("sigaltstack"); 59 return 1; 60 } 61 62 /* Raise a signal. */ 63 raise(SIGUSR1); 64 65 /* Check the current stack. */ 66 assert(mainstack.ss_sp == sp->ss_sp); 67 assert(mainstack.ss_size == sp->ss_size); 68 assert(mainstack.ss_flags == sp->ss_flags); 69 70 return 0; 71 } 72 73
