include/limits.h

   1 /* The <limits.h> header defines some basic sizes, both of the language types
   2  * (e.g., the number of bits in an integer), and of the operating system (e.g.
   3  * the number of characters in a file name.
   4  */
   5
   6 #ifndef _LIMITS_H
   7 #define _LIMITS_H
   8
   9 /* Definitions about chars (8 bits in MINIX, and signed). */
  10 #define CHAR_BIT           8    /* # bits in a char */
  11 #define CHAR_MIN        -128    /* minimum value of a char */
  12 #define CHAR_MAX         127    /* maximum value of a char */
  13 #define SCHAR_MIN       -128    /* minimum value of a signed char */
  14 #define SCHAR_MAX        127    /* maximum value of a signed char */
  15 #define UCHAR_MAX        255    /* maximum value of an unsigned char */
  16 #define MB_LEN_MAX         1    /* maximum length of a multibyte char */
  17
  18 /* Definitions about shorts (16 bits in MINIX). */
  19 #define SHRT_MIN  (-32767-1)    /* minimum value of a short */
  20 #define SHRT_MAX       32767    /* maximum value of a short */
  21 #define USHRT_MAX     0xFFFF    /* maximum value of unsigned short */
  22
  23 /* _EM_WSIZE is a compiler-generated symbol giving the word size in bytes. */
  24 #if _EM_WSIZE == 2
  25 #define INT_MIN   (-32767-1)    /* minimum value of a 16-bit int */
  26 #define INT_MAX        32767    /* maximum value of a 16-bit int */
  27 #define UINT_MAX      0xFFFF    /* maximum value of an unsigned 16-bit int */
  28 #endif
  29
  30 #if _EM_WSIZE == 4
  31 #define INT_MIN (-2147483647-1) /* minimum value of a 32-bit int */
  32 #define INT_MAX   2147483647    /* maximum value of a 32-bit int */
  33 #define UINT_MAX  0xFFFFFFFF    /* maximum value of an unsigned 32-bit int */
  34 #endif
  35
  36 /*Definitions about longs (32 bits in MINIX). */
  37 #define LONG_MIN (-2147483647L-1)/* minimum value of a long */
  38 #define LONG_MAX  2147483647L   /* maximum value of a long */
  39 #define ULONG_MAX 0xFFFFFFFFL   /* maximum value of an unsigned long */
  40
  41 #include <sys/dir.h>
  42
  43 /* Minimum sizes required by the POSIX P1003.1 standard (Table 2-3). */
  44 #ifdef _POSIX_SOURCE            /* these are only visible for POSIX */
  45 #define _POSIX_ARG_MAX    4096  /* exec() may have 4K worth of args */
  46 #define _POSIX_CHILD_MAX     6  /* a process may have 6 children */
  47 #define _POSIX_LINK_MAX      8  /* a file may have 8 links */
  48 #define _POSIX_MAX_CANON   255  /* size of the canonical input queue */
  49 #define _POSIX_MAX_INPUT   255  /* you can type 255 chars ahead */
  50 #define _POSIX_NAME_MAX DIRSIZ  /* max. file name length */
  51 #define _POSIX_NGROUPS_MAX   0  /* supplementary group IDs are optional */
  52 #define _POSIX_OPEN_MAX     16  /* a process may have 16 files open */
  53 #define _POSIX_PATH_MAX    255  /* a pathname may contain 255 chars */
  54 #define _POSIX_PIPE_BUF    512  /* pipes writes of 512 bytes must be atomic */
  55 #define _POSIX_STREAM_MAX    8  /* at least 8 FILEs can be open at once */
  56 #define _POSIX_TZNAME_MAX    3  /* time zone names can be at least 3 chars */
  57 #define _POSIX_SSIZE_MAX 32767  /* read() must support 32767 byte reads */
  58
  59 /* Values actually implemented by MINIX (Tables 2-4, 2-5, 2-6, and 2-7). */
  60 /* Some of these old names had better be defined when not POSIX. */
  61 #define _NO_LIMIT          100  /* arbitrary number; limit not enforced */
  62
  63 #define NGROUPS_MAX          0  /* supplemental group IDs not available */
  64 #if _EM_WSIZE > 2
  65 #define ARG_MAX          16384  /* # bytes of args + environ for exec() */
  66 #else
  67 #define ARG_MAX           4096  /* args + environ on small machines */
  68 #endif
  69 #define CHILD_MAX    _NO_LIMIT  /* MINIX does not limit children */
  70 #define OPEN_MAX            30  /* # open files a process may have */
  71 #if 0                   /* V1 file system */
  72 #define LINK_MAX      CHAR_MAX  /* # links a file may have */
  73 #else                   /* V2 or better file system */
  74 #define LINK_MAX      SHRT_MAX  /* # links a file may have */
  75 #endif
  76 #define MAX_CANON          255  /* size of the canonical input queue */
  77 #define MAX_INPUT          255  /* size of the type-ahead buffer */
  78 #define NAME_MAX        DIRSIZ  /* # chars in a file name */
  79 #define PATH_MAX           255  /* # chars in a path name */
  80 #define PIPE_BUF          7168  /* # bytes in atomic write to a pipe */
  81 #define STREAM_MAX          20  /* must be the same as FOPEN_MAX in stdio.h */
  82 #define TZNAME_MAX           3  /* maximum bytes in a time zone name is 3 */
  83 #define SSIZE_MAX        32767  /* max defined byte count for read() */
  84
  85 #endif /* _POSIX_SOURCE */
  86
  87 #endif /* _LIMITS_H */