61 lines
1.2 KiB
C
61 lines
1.2 KiB
C
/*++
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/* NAME
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/* peekfd 3
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/* SUMMARY
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/* determine amount of data ready to read
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/* SYNOPSIS
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/* #include <iostuff.h>
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/*
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/* int peekfd(fd)
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/* int fd;
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/* DESCRIPTION
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/* peekfd() attempts to find out how many bytes are available to
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/* be read from the named file descriptor. The result value is
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/* the number of available bytes.
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/* DIAGNOSTICS
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/* peekfd() returns -1 in case of trouble. The global \fIerrno\fR
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/* variable reflects the nature of the problem.
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/* LICENSE
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/* .ad
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/* .fi
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/* The Secure Mailer license must be distributed with this software.
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/* AUTHOR(S)
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/* Wietse Venema
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/* IBM T.J. Watson Research
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/* P.O. Box 704
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/* Yorktown Heights, NY 10598, USA
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/*--*/
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/* System library. */
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#include <sys_defs.h>
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#include <sys/ioctl.h>
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#ifdef FIONREAD_IN_SYS_FILIO_H
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#include <sys/filio.h>
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#endif
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#ifdef FIONREAD_IN_TERMIOS_H
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#include <termios.h>
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#endif
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#include <unistd.h>
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/* Utility library. */
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#include "iostuff.h"
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/* peekfd - return amount of data ready to read */
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int peekfd(int fd)
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{
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int count;
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/*
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* Anticipate a series of system-dependent code fragments.
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*/
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#ifdef FIONREAD
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return (ioctl(fd, FIONREAD, (char *) &count) < 0 ? -1 : count);
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#else
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#error "don't know how to look ahead"
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#endif
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}
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