359 lines
6.2 KiB
C
359 lines
6.2 KiB
C
/*
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* Copyright (C) 1984-2020 Mark Nudelman
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*
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* You may distribute under the terms of either the GNU General Public
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* License or the Less License, as specified in the README file.
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*
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* For more information, see the README file.
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*/
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/*
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* Operating system dependent routines.
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*
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* Most of the stuff in here is based on Unix, but an attempt
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* has been made to make things work on other operating systems.
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* This will sometimes result in a loss of functionality, unless
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* someone rewrites code specifically for the new operating system.
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*
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* The makefile provides defines to decide whether various
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* Unix features are present.
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*/
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#include "less.h"
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#include <signal.h>
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#include <setjmp.h>
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#if HAVE_TIME_H
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#include <time.h>
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#endif
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#if HAVE_ERRNO_H
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#include <errno.h>
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#endif
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#if HAVE_VALUES_H
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#include <values.h>
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#endif
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/*
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* BSD setjmp() saves (and longjmp() restores) the signal mask.
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* This costs a system call or two per setjmp(), so if possible we clear the
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* signal mask with sigsetmask(), and use _setjmp()/_longjmp() instead.
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* On other systems, setjmp() doesn't affect the signal mask and so
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* _setjmp() does not exist; we just use setjmp().
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*/
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#if HAVE__SETJMP && HAVE_SIGSETMASK
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#define SET_JUMP _setjmp
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#define LONG_JUMP _longjmp
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#else
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#define SET_JUMP setjmp
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#define LONG_JUMP longjmp
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#endif
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public int reading;
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static jmp_buf read_label;
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extern int sigs;
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/*
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* Like read() system call, but is deliberately interruptible.
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* A call to intread() from a signal handler will interrupt
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* any pending iread().
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*/
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public int
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iread(fd, buf, len)
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int fd;
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unsigned char *buf;
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unsigned int len;
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{
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int n;
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start:
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#if MSDOS_COMPILER==WIN32C
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if (ABORT_SIGS())
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return (READ_INTR);
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#else
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#if MSDOS_COMPILER && MSDOS_COMPILER != DJGPPC
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if (kbhit())
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{
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int c;
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c = getch();
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if (c == '\003')
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return (READ_INTR);
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ungetch(c);
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}
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#endif
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#endif
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if (SET_JUMP(read_label))
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{
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/*
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* We jumped here from intread.
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*/
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reading = 0;
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#if HAVE_SIGPROCMASK
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{
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sigset_t mask;
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sigemptyset(&mask);
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sigprocmask(SIG_SETMASK, &mask, NULL);
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}
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#else
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#if HAVE_SIGSETMASK
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sigsetmask(0);
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#else
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#ifdef _OSK
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sigmask(~0);
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#endif
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#endif
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#endif
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return (READ_INTR);
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}
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flush();
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reading = 1;
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#if MSDOS_COMPILER==DJGPPC
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if (isatty(fd))
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{
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/*
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* Don't try reading from a TTY until a character is
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* available, because that makes some background programs
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* believe DOS is busy in a way that prevents those
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* programs from working while "less" waits.
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*/
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fd_set readfds;
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FD_ZERO(&readfds);
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FD_SET(fd, &readfds);
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if (select(fd+1, &readfds, 0, 0, 0) == -1)
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return (-1);
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}
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#endif
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n = read(fd, buf, len);
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#if 1
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/*
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* This is a kludge to workaround a problem on some systems
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* where terminating a remote tty connection causes read() to
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* start returning 0 forever, instead of -1.
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*/
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{
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extern int ignore_eoi;
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if (!ignore_eoi)
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{
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static int consecutive_nulls = 0;
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if (n == 0)
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consecutive_nulls++;
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else
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consecutive_nulls = 0;
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if (consecutive_nulls > 20)
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quit(QUIT_ERROR);
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}
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}
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#endif
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reading = 0;
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if (n < 0)
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{
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#if HAVE_ERRNO
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/*
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* Certain values of errno indicate we should just retry the read.
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*/
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#if MUST_DEFINE_ERRNO
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extern int errno;
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#endif
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#ifdef EINTR
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if (errno == EINTR)
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goto start;
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#endif
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#ifdef EAGAIN
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if (errno == EAGAIN)
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goto start;
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#endif
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#endif
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return (-1);
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}
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return (n);
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}
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/*
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* Interrupt a pending iread().
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*/
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public void
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intread(VOID_PARAM)
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{
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LONG_JUMP(read_label, 1);
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}
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/*
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* Return the current time.
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*/
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#if HAVE_TIME
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public time_type
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get_time(VOID_PARAM)
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{
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time_type t;
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time(&t);
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return (t);
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}
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#endif
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#if !HAVE_STRERROR
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/*
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* Local version of strerror, if not available from the system.
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*/
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static char *
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strerror(err)
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int err;
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{
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#if HAVE_SYS_ERRLIST
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static char buf[16];
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extern char *sys_errlist[];
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extern int sys_nerr;
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if (err < sys_nerr)
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return sys_errlist[err];
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sprintf(buf, "Error %d", err);
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return buf;
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#else
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return ("cannot open");
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#endif
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}
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#endif
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/*
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* errno_message: Return an error message based on the value of "errno".
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*/
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public char *
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errno_message(filename)
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char *filename;
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{
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char *p;
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char *m;
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int len;
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#if HAVE_ERRNO
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#if MUST_DEFINE_ERRNO
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extern int errno;
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#endif
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p = strerror(errno);
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#else
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p = "cannot open";
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#endif
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len = (int) (strlen(filename) + strlen(p) + 3);
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m = (char *) ecalloc(len, sizeof(char));
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SNPRINTF2(m, len, "%s: %s", filename, p);
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return (m);
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}
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/* #define HAVE_FLOAT 0 */
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static POSITION
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muldiv(val, num, den)
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POSITION val, num, den;
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{
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#if HAVE_FLOAT
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double v = (((double) val) * num) / den;
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return ((POSITION) (v + 0.5));
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#else
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POSITION v = ((POSITION) val) * num;
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if (v / num == val)
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/* No overflow */
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return (POSITION) (v / den);
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else
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/* Above calculation overflows;
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* use a method that is less precise but won't overflow. */
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return (POSITION) (val / (den / num));
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#endif
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}
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/*
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* Return the ratio of two POSITIONS, as a percentage.
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* {{ Assumes a POSITION is a long int. }}
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*/
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public int
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percentage(num, den)
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POSITION num;
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POSITION den;
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{
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return (int) muldiv(num, (POSITION) 100, den);
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}
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/*
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* Return the specified percentage of a POSITION.
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*/
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public POSITION
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percent_pos(pos, percent, fraction)
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POSITION pos;
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int percent;
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long fraction;
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{
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/* Change percent (parts per 100) to perden (parts per NUM_FRAC_DENOM). */
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POSITION perden = (percent * (NUM_FRAC_DENOM / 100)) + (fraction / 100);
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if (perden == 0)
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return (0);
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return (POSITION) muldiv(pos, perden, (POSITION) NUM_FRAC_DENOM);
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}
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#if !HAVE_STRCHR
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/*
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* strchr is used by regexp.c.
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*/
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char *
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strchr(s, c)
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char *s;
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int c;
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{
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for ( ; *s != '\0'; s++)
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if (*s == c)
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return (s);
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if (c == '\0')
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return (s);
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return (NULL);
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}
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#endif
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#if !HAVE_MEMCPY
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VOID_POINTER
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memcpy(dst, src, len)
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VOID_POINTER dst;
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VOID_POINTER src;
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int len;
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{
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char *dstp = (char *) dst;
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char *srcp = (char *) src;
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int i;
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for (i = 0; i < len; i++)
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dstp[i] = srcp[i];
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return (dst);
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}
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#endif
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#ifdef _OSK_MWC32
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/*
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* This implements an ANSI-style intercept setup for Microware C 3.2
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*/
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public int
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os9_signal(type, handler)
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int type;
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RETSIGTYPE (*handler)();
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{
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intercept(handler);
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}
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#include <sgstat.h>
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int
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isatty(f)
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int f;
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{
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struct sgbuf sgbuf;
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if (_gs_opt(f, &sgbuf) < 0)
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return -1;
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return (sgbuf.sg_class == 0);
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}
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#endif
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