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- /*
- * Copyright (c) 1995 Colin Plumb. All rights reserved.
- * For licensing and other legal details, see the file legal.c.
- *
- * This file includes <unistd.h>, if it's available, and
- * declares a bunch of functions with "traditional" values if not.
- * The GNU Libc Manual (node "Version Supported") says this is impossible;
- * I wonder what they think of this.
- */
- #include <limits.h>
- /*
- * See if this is a POSIX <limits.h>. A POSIX system *may* define
- * a macro for ARG_MAX, but it may instead defined _SC_ARG_MAX
- * in <unistd.h> and require you yo use sysconf() to get the value.
- * However, a POSIX system is supposed to defined _POSIX_ARG_MAX
- * in <limits.h> with the value of 4096, the POSIX-mandated lower
- * bound on ARG_MAX or sysconf(_SC_ARG_MAX).
- * A POSIX system is supposed to define most of these, so checking for
- * them *all* is overkill, but it's easy enough...
- */
- #ifndef HAVE_UNISTD_H
- #ifdef __POSIX__ /* Defined by GCC on POSIX systems */
- #define HAVE_UNISTD_H 1
- #elif defined(_POSIX_ARG_MAX) || defined(_POSIX_CHILD_MAX)
- #define HAVE_UNISTD_H 1
- #elif defined(_POSIX_LINK_MAX) || defined(_POSIX_MAX_CANON)
- #define HAVE_UNISTD_H 1
- #elif defined(_POSIX_MAX_INPUT) || defined(_POSIX_NAME_MAX)
- #define HAVE_UNISTD_H 1
- #elif defined(_POSIX_NGROUPS_MAX) || defined(_POSIX_OPEN_MAX)
- #define HAVE_UNISTD_H 1
- #elif defined(_POSIX_PATH_MAX) || defined(_POSIX_PIPE_BUF)
- #define HAVE_UNISTD_H 1
- #elif defined(_POSIX_RE_DUP_MAX) || defined(_POSIX_SSIZE_MAX)
- #define HAVE_UNISTD_H 1
- #elif defined(_POSIX_STREAM_MAX) || defined (_POSIX_TZNAME_MAX)
- #define HAVE_UNISTD_H 1
- #endif
- #endif
- #if HAVE_UNISTD_H
- #include <unistd.h>
- #elif defined(MSDOS)
- #include <io.h> /* Where MSDOS keeps such things */
- #else
- /* Not POSIX - declare the portions of <unistd.h> we need manually. */
- int ioctl(int fd, int request, void *arg);
- int isatty(int fd);
- int read(int fd, void *buf, int nbytes);
- unsigned sleep(unsigned seconds);
- #endif
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