More Info on the

siginfo_t

Structure

The

siginfo_t

structure provides a lot of information to the signal handler,

sa_sigaction

:

typedef struct siginfo_t {
    int      si_signo;  // Signal number -------------------> Same as the first argument to sa_sigaction.
    int      si_errno;  // Error value ---------------------> If nonzero, contains the error code associated with this signal.
    int      si_code;   // Signal code ---------------------> An explanation of why/where the process received the signal.
    pid_t    si_pid;    // Sending process's PID -----------> For SIGCHLD, the pid of the process that terminated.
    uid_t    si_uid;    // Sending process's real UID ------> For SIGCHLD, the owner uid of the process that terminated.
    int      si_status; // Exit value or signal ------------> For SIGCHLD, the exit status of the process that terminated.
    clock_t  si_utime;  // User time consumed --------------> For SIGCHLD, the user time consumed of the process that terminated.
    clock_t  si_stime;  // System time consumed ------------> For SIGCHLD, the system time consumed of the process that terminated.
    sigval   si_value;  // Signal's payload value ----------> A union of si_int and si_ptr (see fields below.)
    int      si_int;    // POSIX.1b signal -----------------> Payload (data you wish to pass) in a form of an integer.
    void     *si_ptr;   // POSIX.1b signal -----------------> Payload (data you wish to pass) in a form of a void pointer.
    void     *si_addr;  // Memory location causeing fault --> For SIGBUS, SIGFPE, SIGILL, SIGSEGV, and SIGTRAP only.
    long     si_band;   // Band event ----------------------> For SIGPOLL (pollable events), out-of-band/priority info for si_fd.
    int      si_fd;     // File descriptor -----------------> For SIGPOLL, the fd for the file whose operation completed.
};