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sockatmark(3) [netbsd man page]

SOCKATMARK(3)						   BSD Library Functions Manual 					     SOCKATMARK(3)

NAME
sockatmark -- determine whether a socket is at the out-of-band mark LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <sys/socket.h> int sockatmark(int s); DESCRIPTION
The sockatmark function determines whether the socket referenced by the file descriptor s is at the out-of-band mark. RETURN VALUES
If successful, the sockatmark function returns 1 to indicate that the socket is at an out-of-band mark; 0 is returned if there is no out-of- band mark or the mark is preceded by in-band data. Otherwise, -1 is returned and errno is set to indicate the error. ERRORS
The sockatmark function will fail if: [EBADF] The argument s is not a valid file descriptor. [ENOTTY] The file descriptor s does not refer to a socket. SEE ALSO
ioctl(2), recv(2), socket(2) Stuart Sechrest, An Introductory 4.4BSD Interprocess Communication Tutorial. (see /usr/share/doc/psd/20.ipctut) Samuel J. Leffler, Robert S. Fabry, William N. Joy, Phil Lapsley, Steve Miller, and Chris Torek, Advanced 4.4BSD IPC Tutorial. (see /usr/share/doc/psd/21.ipc) STANDARDS
The sockatmark function conforms to IEEE Std 1003.1-2001 (``POSIX.1''). HISTORY
The sockatmark function appeared in IEEE Std 1003.1g-2000 (``POSIX.1'') as a replacement for the SIOCATMARK ioctl(2) interface. BSD
May 15, 2003 BSD

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SOCKATMARK(3)						   BSD Library Functions Manual 					     SOCKATMARK(3)

NAME
sockatmark -- determine whether the read pointer is at the OOB mark LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <sys/socket.h> int sockatmark(int s); DESCRIPTION
To find out if the read pointer is currently pointing at the mark in the data stream, the sockatmark() function is provided. If sockatmark() returns 1, the next read will return data after the mark. Otherwise (assuming out of band data has arrived), the next read will provide data sent by the client prior to transmission of the out of band signal. The routine used in the remote login process to flush output on receipt of an interrupt or quit signal is shown below. It reads the normal data up to the mark (to discard it), then reads the out-of-band byte. #include <sys/socket.h> ... oob() { int out = FWRITE, mark; char waste[BUFSIZ]; /* flush local terminal output */ ioctl(1, TIOCFLUSH, (char *)&out); for (;;) { if ((mark = sockatmark(rem)) < 0) { perror("sockatmark"); break; } if (mark) break; (void) read(rem, waste, sizeof (waste)); } if (recv(rem, &mark, 1, MSG_OOB) < 0) { perror("recv"); ... } ... } RETURN VALUES
Upon successful completion, the sockatmark() function returns the value 1 if the read pointer is pointing at the OOB mark, 0 if it is not. Otherwise, the value -1 is returned and the global variable errno is set to indicate the error. ERRORS
The sockatmark() call fails if: [EBADF] The s argument is not a valid descriptor. [ENOTTY] The s argument is a descriptor for a file, not a socket. SEE ALSO
recv(2), send(2) HISTORY
The sockatmark() function was introduced by IEEE Std 1003.1-2001 (``POSIX.1''), to standardize the historical SIOCATMARK ioctl(2). The ENOTTY error instead of the usual ENOTSOCK is to match the historical behavior of SIOCATMARK. BSD
October 13, 2002 BSD
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