/*++ /* NAME /* non_blocking 3 /* SUMMARY /* set/clear non-blocking flag /* SYNOPSIS /* #include <iostuff.h> /* /* int non_blocking(int fd, int on) /* DESCRIPTION /* the \fInon_blocking\fR() function manipulates the non-blocking /* flag for the specified open file, and returns the old setting. /* /* Arguments: /* .IP fd /* A file descriptor. /* .IP on /* For non-blocking I/O, specify a non-zero value (or use the /* NON_BLOCKING constant); for blocking I/O, specify zero /* (or use the BLOCKING constant). /* /* The result is non-zero when the non-blocking flag was enabled. /* DIAGNOSTICS /* All errors are fatal. /* 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 /*--*/ /* System interfaces. */ #include "sys_defs.h" #include <fcntl.h> /* Utility library. */ #include "msg.h" #include "iostuff.h" /* Backwards compatibility */ #ifndef O_NONBLOCK #define PATTERN FNDELAY #else #define PATTERN O_NONBLOCK #endif /* non_blocking - set/clear non-blocking flag */ int non_blocking(fd, on) int fd; int on; { int flags; if ((flags = fcntl(fd, F_GETFL, 0)) < 0) msg_fatal("fcntl: get flags: %m"); if (fcntl(fd, F_SETFL, on ? flags | PATTERN : flags & ~PATTERN) < 0) msg_fatal("fcntl: set non-blocking flag %s: %m", on ? "on" : "off"); return ((flags & PATTERN) != 0); }