system_data_types(7) Miscellaneous Information Manual system_data_types(7)
NAME
system_data_types - overview of system data types
DESCRIPTION
sigevent
Include: <signal.h>. Alternatively, <aio.h>, <mqueue.h>, or
<time.h>.
struct sigevent {
int sigev_notify; /* Notification type */
int sigev_signo; /* Signal number */
union sigval sigev_value; /* Signal value */
void (*sigev_notify_function)(union sigval);
/* Notification function */
pthread_attr_t *sigev_notify_attributes;
/* Notification attributes */
};
For further details about this type, see sigevent(7).
Versions: <aio.h> and <time.h> define sigevent since
POSIX.1-2008.
Conforming to: POSIX.1-2001 and later.
See also: timer_create(2), getaddrinfo_a(3), lio_listio(3),
mq_notify(3)
See also the aiocb structure in this page.
siginfo_t
Include: <signal.h>. Alternatively, <sys/wait.h>.
typedef struct {
int si_signo; /* Signal number */
int si_code; /* Signal code */
pid_t si_pid; /* Sending process ID */
uid_t si_uid; /* Real user ID of sending process */
void *si_addr; /* Address of faulting instruction */
int si_status; /* Exit value or signal */
union sigval si_value; /* Signal value */
} siginfo_t;
Information associated with a signal. For further details on
this structure (including additional, Linux-specific fields),
see sigaction(2).
Conforming to: POSIX.1-2001 and later.
See also: pidfd_send_signal(2), rt_sigqueueinfo(2), sigac-
tion(2), sigwaitinfo(2), psiginfo(3)
sigset_t
Include: <signal.h>. Alternatively, <spawn.h>, or <sys/se-
lect.h>.
This is a type that represents a set of signals. According to
POSIX, this shall be an integer or structure type.
Conforming to: POSIX.1-2001 and later.
See also: epoll_pwait(2), ppoll(2), pselect(2), sigaction(2),
signalfd(2), sigpending(2), sigprocmask(2), sigsuspend(2), sig-
waitinfo(2), signal(7)
sigval
Include: <signal.h>.
union sigval {
int sigval_int; /* Integer value */
void *sigval_ptr; /* Pointer value */
};
Data passed with a signal.
Conforming to: POSIX.1-2001 and later.
See also: pthread_sigqueue(3), sigqueue(3), sigevent(7)
See also the sigevent structure and the siginfo_t type in this
page.
NOTES
The structures described in this manual page shall contain, at least,
the members shown in their definition, in no particular order.
Most of the integer types described in this page don't have a corre-
sponding length modifier for the printf(3) and the scanf(3) families of
functions. To print a value of an integer type that doesn't have a
length modifier, it should be converted to intmax_t or uintmax_t by an
explicit cast. To scan into a variable of an integer type that doesn't
have a length modifier, an intermediate temporary variable of type int-
max_t or uintmax_t should be used. When copying from the temporary
variable to the destination variable, the value could overflow. If the
type has upper and lower limits, the user should check that the value
is within those limits, before actually copying the value. The example
below shows how these conversions should be done.
Conventions used in this page
In "Conforming to" we only concern ourselves with C99 and later and
POSIX.1-2001 and later. Some types may be specified in earlier ver-
sions of one of these standards, but in the interests of simplicity we
omit details from earlier standards.
In "Include", we first note the "primary" header(s) that define the
type according to either the C or POSIX.1 standards. Under "Alterna-
tively", we note additional headers that the standards specify shall
define the type.
EXAMPLES
The program shown below scans from a string and prints a value stored
in a variable of an integer type that doesn't have a length modifier.
The appropriate conversions from and to intmax_t, and the appropriate
range checks, are used as explained in the notes section above.
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
int
main (void)
{
static const char *const str = "500000 us in half a second";
suseconds_t us;
intmax_t tmp;
/* Scan the number from the string into the temporary variable. */
sscanf(str, "%jd", &tmp);
/* Check that the value is within the valid range of suseconds_t. */
if (tmp < -1 || tmp > 1000000) {
fprintf(stderr, "Scanned value outside valid range!\n");
exit(EXIT_FAILURE);
}
/* Copy the value to the suseconds_t variable 'us'. */
us = tmp;
/* Even though suseconds_t can hold the value -1, this isn't
a sensible number of microseconds. */
if (us < 0) {
fprintf(stderr, "Scanned value shouldn't be negative!\n");
exit(EXIT_FAILURE);
}
/* Print the value. */
printf("There are %jd microseconds in half a second.\n",
(intmax_t) us);
exit(EXIT_SUCCESS);
}
SEE ALSO
feature_test_macros(7), standards(7)
Linux man-pages 6.03 2023-02-05 system_data_types(7)
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