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However, this issue was discussed at the April 2008 meeting of ISO/IEC WG14 and it was agreed that there are no known implementations in which it would be an error to read a value to from a volatile static variable and the original intent of the committee was that both reading and writing variables of volatile sig_atomic_t would be strictly conforming.
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Portably, signal handlers can only unconditionally get or set a flag of type volatile sig_atomic_t and return.
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#include <signal.h> #include <stdlib.h> #include <string.h> volatile sig_atomic_t e_flag = 0; volatile sig_atomic_t e_value = 1; void handler(int signum) { e_flag = 1e_value; } int main(void) { char *err_msg; enum { MAX_MSG_SIZE = 24 }; signal(SIGINT, handler); err_msg = (char *)malloc(MAX_MSG_SIZE); if (err_msg == NULL) { /* handle error condition */ } strcpy(err_msg, "No errors yet."); /* main code loop */ if (e_flag) { strcpy(err_msg, "SIGINT received."); } return 0; } |
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