lib/libc/gen/minix/sysconf.c

   1 /* sysconf.c                                            POSIX 4.8.1
   2  *      long int sysconf(int name);
   3  *
   4  *      POSIX allows some of the values in <limits.h> to be increased at
   5  *      run time.  The sysconf() function allows such values to be checked
   6  *      at run time.  MINIX does not use this facility - the run time
   7  *      limits are those given in <limits.h>.
   8  */
   9 #include <sys/cdefs.h>
  10 #include "namespace.h"
  11
  12 #include <lib.h>
  13 #include <unistd.h>
  14 #include <time.h>
  15 #include <stdio.h>
  16 #include <paths.h>
  17
  18 #ifdef __weak_alias
  19 __weak_alias(sysconf, __sysconf)
  20 #endif
  21
  22 static u32_t get_hz(void)
  23 {
  24   FILE *fp;
  25   u32_t hz;
  26   int r;
  27
  28   if ((fp = fopen(_PATH_PROC "hz", "r")) != NULL)
  29   {
  30         r = fscanf(fp, "%u", &hz);
  31
  32         fclose(fp);
  33
  34         if (r == 1)
  35                 return hz;
  36   }
  37
  38   return DEFAULT_HZ;
  39 }
  40
  41 long int sysconf(name)
  42 int name;                       /* property being inspected */
  43 {
  44   switch(name) {
  45         case _SC_ARG_MAX:
  46                 return (long) ARG_MAX;
  47
  48         case _SC_CHILD_MAX:
  49                 return (long) CHILD_MAX;
  50
  51         case _SC_CLK_TCK:
  52                 return (long) get_hz();
  53
  54         case _SC_NGROUPS_MAX:
  55                 return (long) NGROUPS_MAX;
  56
  57         case _SC_OPEN_MAX:
  58                 return (long) OPEN_MAX;
  59
  60         case _SC_JOB_CONTROL:
  61                 return -1L;                     /* no job control */
  62
  63         case _SC_SAVED_IDS:
  64                 return -1L;                     /* no saved uid/gid */
  65
  66         case _SC_VERSION:
  67                 return (long) _POSIX_VERSION;
  68
  69         case _SC_STREAM_MAX:
  70                 return (long) STREAM_MAX;
  71
  72         case _SC_TZNAME_MAX:
  73                 return (long) TZNAME_MAX;
  74
  75         case _SC_PAGESIZE:
  76                 return getpagesize();
  77
  78         default:
  79                 errno = EINVAL;
  80                 return -1L;
  81   }
  82 }