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system_data_types(7) Miscellaneous Information Manualsystem_data_types(7)
system_data_types - overview of system data types
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; /* Memory location which caused fault */
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),
sigaction(2), sigwaitinfo(2), psiginfo(3)
sigset_t
Include: <signal.h>. Alternatively, <spawn.h>, or
<sys/select.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), sigwaitinfo(2), signal(7)
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
corresponding 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 intmax_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 versions 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
"Alternatively", we note additional headers that the standards
specify shall define the type.
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);
}
feature_test_macros(7), standards(7)
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2025-02-02. If you discover any rendering problems in this HTML
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man-pages@man7.org
Linux man-pages 6.10 2024-06-15 system_data_types(7)
Pages that refer to this page: intro(2), intro(3), sigevent(3type), credentials(7), feature_test_macros(7), standards(7)
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