c - Linux - ioctl with FIONREAD always 0 - Stack Overflow
WEBAug 14, 2013 · I'm trying to get to know how many bytes there are readable at my TCP socket. I am calling ioctl with the Flag "FIONREAD" which should actually give me this value. When I call the function I get as return val 0 ( so no Error ) but also my integer argument gets the value 0.
ioctl_tty(2) - Linux manual page - man7.org
WEBBuffer count and flushing FIONREAD Argument: int *argp Get the number of bytes in the input buffer. TIOCINQ Argument: int *argp Same as FIONREAD. TIOCOUTQ Argument: int *argp Get the number of bytes in the output buffer. TCFLSH Argument: int …
What does FIONREAD of UDP (datagram) sockets return?
WEBJun 8, 2013 · FIONREAD (SIOCINQ) Gets a pointer to an integer as argument. Returns the size of the next pending datagram in the integer in bytes, or 0 when no datagram is pending. Warning: Using FIONREAD, it is impossible to distinguish the case where no datagram is pending from the case where the next pending datagram contains zero …
unix - C++ Serial port reading issue: does ioctl(FIONREAD) set …
WEBAug 30, 2016 · You cannot use FIONREAD to wait for more bytes to be written because the writer may also be waiting for you. Instead, read the bytes as they become available, thus ensuring you unblock the writer.
tty_ioctl(4): ioctls for terminals/serial lines - Linux man page
WEBName. tty_ioctl - ioctls for terminals and serial lines. Synopsis. #include < termios.h > int ioctl (int fd, int cmd, ...); Description. The ioctl (2) call for terminals and serial ports accepts many possible command arguments. Most require a third argument, of varying type, here called argp or arg . Use of ioctl makes for nonportable programs.
inotify(7) - Linux manual page - man7.org
WEBThe FIONREAD ioctl(2) returns the number of bytes available to read from an inotify file descriptor. Limitations and caveats The inotify API provides no information about the user or process that triggered the inotify event.
ioctl(2) - FreeBSD
WEBThese include: FIONREAD int Get the number of bytes that are immediately available for reading. FIONWRITE int Get the number of bytes in the descriptor's send queue. These bytes are data which has been written to the descriptor but which are being held by the kernel for further processing.
FIONREAD - STREAMS Programming Guide - Oracle
WEBFIONREAD. The FIONREAD ioctl returns the number of data bytes (in all data messages queued) in the location pointed to by the arg parameter. The ioctl returns a 32-bit quantity for both 32-bit and 64-bit application., Therefore, code that passes the address of a long variable needs to be changed to pass an int variable for 64–bit applications ...
ioctl(2) - Linux manual page - man7.org
WEBDESCRIPTION top. The ioctl () system call manipulates the underlying device parameters of special files. In particular, many operating characteristics of character special files (e.g., terminals) may be controlled with ioctl () requests. The argument fd must be an open file descriptor. The second argument is a device-dependent request code.
ioctl(2) - OpenBSD manual pages
WEBSep 11, 2022 · FIONREADint * Get the number of bytes that are immediately available for reading. FIONBIOint * Set non-blocking I/O mode if the argument is non-zero. In non-blocking mode, read (2) or write (2) calls return -1 and set errno to EAGAIN immediately when no data is available. FIOASYNCint * Set asynchronous I/O mode if the argument …
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