minix3/lib/libc/gen/sysconf.c

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2020-02-21 00:59:27 +05:30
/* sysconf.c POSIX 4.8.1
* long int sysconf(int name);
*
* POSIX allows some of the values in <limits.h> to be increased at
* run time. The sysconf() function allows such values to be checked
* at run time. MINIX does not use this facility - the run time
* limits are those given in <limits.h>.
*/
#include <sys/cdefs.h>
#include "namespace.h"
#include <lib.h>
#include <unistd.h>
#include <time.h>
#include <stdio.h>
#include <minix/paths.h>
#ifdef __weak_alias
__weak_alias(sysconf, __sysconf)
#endif
static u32_t get_hz(void)
{
FILE *fp;
u32_t hz;
int r;
if ((fp = fopen(_PATH_PROC "hz", "r")) != NULL)
{
r = fscanf(fp, "%u", &hz);
fclose(fp);
if (r == 1)
return hz;
}
return DEFAULT_HZ;
}
long int sysconf(name)
int name; /* property being inspected */
{
switch(name) {
case _SC_ARG_MAX:
return (long) ARG_MAX;
case _SC_CHILD_MAX:
return (long) CHILD_MAX;
case _SC_CLK_TCK:
return (long) get_hz();
case _SC_NGROUPS_MAX:
return (long) NGROUPS_MAX;
case _SC_OPEN_MAX:
return (long) OPEN_MAX;
case _SC_JOB_CONTROL:
return -1L; /* no job control */
case _SC_SAVED_IDS:
return -1L; /* no saved uid/gid */
case _SC_VERSION:
return (long) _POSIX_VERSION;
case _SC_STREAM_MAX:
return (long) _POSIX_STREAM_MAX;
case _SC_TZNAME_MAX:
return (long) _POSIX_TZNAME_MAX;
case _SC_PAGESIZE:
return getpagesize();
case _SC_LINE_MAX:
return (long) LINE_MAX;
default:
errno = EINVAL;
return -1L;
}
}