1 files changed, 89 insertions, 0 deletions
diff --git a/src/util/peekfd.c b/src/util/peekfd.c
new file mode 100644
index 0000000..e9480a2
--- /dev/null
+++ b/src/util/peekfd.c
@@ -0,0 +1,89 @@
+/*++
+/* NAME
+/*	peekfd 3
+/* SUMMARY
+/*	determine amount of data ready to read
+/* SYNOPSIS
+/*	#include <iostuff.h>
+/*
+/*	ssize_t	peekfd(fd)
+/*	int	fd;
+/* DESCRIPTION
+/*	peekfd() attempts to find out how many bytes are available to
+/*	be read from the named file descriptor. The result value is
+/*	the number of available bytes.
+/* DIAGNOSTICS
+/*	peekfd() returns -1 in case of trouble. The global \fIerrno\fR
+/*	variable reflects the nature of the problem.
+/* BUGS
+/*	On some systems, non-blocking read() may fail even after a
+/*	positive return from peekfd(). The smtp-sink program works
+/*	around this by using the readable() function instead.
+/* LICENSE
+/* .ad
+/* .fi
+/*	The Secure Mailer license must be distributed with this software.
+/* AUTHOR(S)
+/*	Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*
+/*	Wietse Venema
+/*	Google, Inc.
+/*	111 8th Avenue
+/*	New York, NY 10011, USA
+/*--*/
+
+/* System library. */
+
+#include <sys_defs.h>
+#include <sys/ioctl.h>
+#ifdef FIONREAD_IN_SYS_FILIO_H
+#include <sys/filio.h>
+#endif
+#ifdef FIONREAD_IN_TERMIOS_H
+#include <termios.h>
+#endif
+#include <unistd.h>
+
+#ifndef SHUT_RDWR
+#define SHUT_RDWR  2
+#endif
+
+/* Utility library. */
+
+#include "iostuff.h"
+
+/* peekfd - return amount of data ready to read */
+
+ssize_t peekfd(int fd)
+{
+
+    /*
+     * Anticipate a series of system-dependent code fragments.
+     */
+#ifdef FIONREAD
+    int     count;
+
+#ifdef SUNOS5
+
+    /*
+     * With Solaris10, write_wait() hangs in poll() until timeout, when
+     * invoked after peekfd() has received an ECONNRESET error indication.
+     * This happens when a client sends QUIT and closes the connection
+     * immediately.
+     */
+    if (ioctl(fd, FIONREAD, (char *) &count) < 0) {
+	(void) shutdown(fd, SHUT_RDWR);
+	return (-1);
+    } else {
+	return (count);
+    }
+#else						/* SUNOS5 */
+    return (ioctl(fd, FIONREAD, (char *) &count) < 0 ? -1 : count);
+#endif						/* SUNOS5 */
+#else
+#error "don't know how to look ahead"
+#endif
+}