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cdbbcfb8f5
commit 201995f382 introduced a hack
utilizing the signedness of character constants at the preprocessor
level to avoid depending on the gcc-specific __CHAR_UNSIGNED__ predef.
while this trick works on gcc and presumably other compilers being
used, it's not clear that the behavior it depends on is actually
conforming. C11 6.4.4.4 ¶10 defines character constants as having type
int, and 6.10.1 ¶4 defines preprocessor #if arithmetic to take place
in intmax_t or uintmax_t, depending on the signedness of the integer
operand types, and it is specified that "this includes interpreting
character constants".
if character literals had type char and just promoted to int, it would
be clear that when char is unsigned they should behave as uintmax_t at
the preprocessor level. however, as written the text of the standard
seems to require that character constants always behave as intmax_t,
corresponding to int, at the preprocessor level.
since there is a good deal of ambiguity about the correct behavior and
a risk that compilers will disagree or that an interpretation may
mandate a change in the behavior, do not rely on it for defining
CHAR_MIN and CHAR_MAX correctly. instead, use the signedness of the
value (as opposed to the type) of '\xff', which will be positive if
and only if plain char is unsigned. this behavior is clearly
specified, and the specific case '\xff' is even used in an example,
under 6.4.4.4 of the standard.
159 lines
3.9 KiB
C
159 lines
3.9 KiB
C
#ifndef _LIMITS_H
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#define _LIMITS_H
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#include <features.h>
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/* Most limits are system-specific */
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#include <bits/limits.h>
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/* Support signed or unsigned plain-char */
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#if '\xff' > 0
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#define CHAR_MIN 0
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#define CHAR_MAX 255
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#else
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#define CHAR_MIN (-128)
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#define CHAR_MAX 127
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#endif
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/* Some universal constants... */
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#define CHAR_BIT 8
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#define SCHAR_MIN (-128)
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#define SCHAR_MAX 127
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#define UCHAR_MAX 255
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#define SHRT_MIN (-1-0x7fff)
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#define SHRT_MAX 0x7fff
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#define USHRT_MAX 0xffff
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#define INT_MIN (-1-0x7fffffff)
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#define INT_MAX 0x7fffffff
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#define UINT_MAX 0xffffffffU
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#define LONG_MIN (-LONG_MAX-1)
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#define ULONG_MAX (2UL*LONG_MAX+1)
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#define LLONG_MIN (-LLONG_MAX-1)
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#define ULLONG_MAX (2ULL*LLONG_MAX+1)
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#define MB_LEN_MAX 4
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#if defined(_POSIX_SOURCE) || defined(_POSIX_C_SOURCE) \
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|| defined(_XOPEN_SOURCE) || defined(_GNU_SOURCE) || defined(_BSD_SOURCE)
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#define PIPE_BUF 4096
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#define FILESIZEBITS 64
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#define NAME_MAX 255
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#define PATH_MAX 4096
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#define NGROUPS_MAX 32
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#define ARG_MAX 131072
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#define IOV_MAX 1024
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#define SYMLOOP_MAX 40
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#define WORD_BIT 32
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#define SSIZE_MAX LONG_MAX
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#define TZNAME_MAX 6
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#define TTY_NAME_MAX 32
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#define HOST_NAME_MAX 255
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/* Implementation choices... */
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#define PTHREAD_KEYS_MAX 128
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#define PTHREAD_STACK_MIN 2048
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#define PTHREAD_DESTRUCTOR_ITERATIONS 4
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#define SEM_VALUE_MAX 0x7fffffff
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#define SEM_NSEMS_MAX 256
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#define DELAYTIMER_MAX 0x7fffffff
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#define MQ_PRIO_MAX 32768
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#define LOGIN_NAME_MAX 256
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/* Arbitrary numbers... */
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#define BC_BASE_MAX 99
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#define BC_DIM_MAX 2048
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#define BC_SCALE_MAX 99
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#define BC_STRING_MAX 1000
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#define CHARCLASS_NAME_MAX 14
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#define COLL_WEIGHTS_MAX 2
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#define EXPR_NEST_MAX 32
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#define LINE_MAX 4096
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#define RE_DUP_MAX 255
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#define NL_ARGMAX 9
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#define NL_MSGMAX 32767
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#define NL_SETMAX 255
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#define NL_TEXTMAX 2048
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#endif
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#if defined(_GNU_SOURCE) || defined(_BSD_SOURCE) || defined(_XOPEN_SOURCE)
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#ifdef PAGESIZE
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#define PAGE_SIZE PAGESIZE
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#endif
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#define NZERO 20
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#define NL_LANGMAX 32
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#endif
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#if defined(_GNU_SOURCE) || defined(_BSD_SOURCE) \
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|| (defined(_XOPEN_SOURCE) && _XOPEN_SOURCE+0 < 700)
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#define NL_NMAX 16
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#endif
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/* POSIX/SUS requirements follow. These numbers come directly
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* from SUS and have nothing to do with the host system. */
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#define _POSIX_AIO_LISTIO_MAX 2
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#define _POSIX_AIO_MAX 1
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#define _POSIX_ARG_MAX 4096
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#define _POSIX_CHILD_MAX 25
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#define _POSIX_CLOCKRES_MIN 20000000
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#define _POSIX_DELAYTIMER_MAX 32
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#define _POSIX_HOST_NAME_MAX 255
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#define _POSIX_LINK_MAX 8
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#define _POSIX_LOGIN_NAME_MAX 9
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#define _POSIX_MAX_CANON 255
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#define _POSIX_MAX_INPUT 255
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#define _POSIX_MQ_OPEN_MAX 8
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#define _POSIX_MQ_PRIO_MAX 32
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#define _POSIX_NAME_MAX 14
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#define _POSIX_NGROUPS_MAX 8
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#define _POSIX_OPEN_MAX 20
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#define _POSIX_PATH_MAX 256
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#define _POSIX_PIPE_BUF 512
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#define _POSIX_RE_DUP_MAX 255
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#define _POSIX_RTSIG_MAX 8
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#define _POSIX_SEM_NSEMS_MAX 256
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#define _POSIX_SEM_VALUE_MAX 32767
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#define _POSIX_SIGQUEUE_MAX 32
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#define _POSIX_SSIZE_MAX 32767
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#define _POSIX_STREAM_MAX 8
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#define _POSIX_SS_REPL_MAX 4
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#define _POSIX_SYMLINK_MAX 255
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#define _POSIX_SYMLOOP_MAX 8
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#define _POSIX_THREAD_DESTRUCTOR_ITERATIONS 4
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#define _POSIX_THREAD_KEYS_MAX 128
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#define _POSIX_THREAD_THREADS_MAX 64
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#define _POSIX_TIMER_MAX 32
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#define _POSIX_TRACE_EVENT_NAME_MAX 30
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#define _POSIX_TRACE_NAME_MAX 8
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#define _POSIX_TRACE_SYS_MAX 8
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#define _POSIX_TRACE_USER_EVENT_MAX 32
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#define _POSIX_TTY_NAME_MAX 9
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#define _POSIX_TZNAME_MAX 6
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#define _POSIX2_BC_BASE_MAX 99
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#define _POSIX2_BC_DIM_MAX 2048
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#define _POSIX2_BC_SCALE_MAX 99
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#define _POSIX2_BC_STRING_MAX 1000
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#define _POSIX2_CHARCLASS_NAME_MAX 14
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#define _POSIX2_COLL_WEIGHTS_MAX 2
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#define _POSIX2_EXPR_NEST_MAX 32
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#define _POSIX2_LINE_MAX 2048
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#define _POSIX2_RE_DUP_MAX 255
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#define _XOPEN_IOV_MAX 16
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#define _XOPEN_NAME_MAX 255
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#define _XOPEN_PATH_MAX 1024
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#endif
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