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pipe - create an interprocess channel


include "sys.m";
sys := load Sys Sys->PATH;

pipe: fn(fds: array of ref FD): int;


Pipe creates a buffered channel for interprocess I/O via file descriptors. It allocates a pipe from the pipe device and returns in the array fds file descriptors for the two pipe ends. Both returned file descriptors are opened for both reading and writing (Sys->ORDWR). Data written on one file descriptor can be read from the other. The details of flow control and buffering are given in pipe(3). When no references remain to the file descriptor representing one end of a pipe, and all remaining data has been read at the other end, subsequent reads at that end will return 0 bytes. Writes to a pipe with no reader produce an exception.

The array fds passed to the system call must have a length of at least 2; only entries 0 and 1 are updated.

Limbo applications typically use typed Limbo channels, not pipes, for efficient communication by cooperating processes. Pipes are still useful, however, to connect applications that do not (or cannot) share such channels, or when a system interface requires a file descriptor. For instance, a process that serves the Styx protocol can pass the file descriptor for one end of a pipe to Sys->mount (see sys-bind(2)), and read and write Styx messages on the other end of the pipe.


Returns 0 on success; -1 on failure.



SYS-PIPE(2 ) Rev:  Thu Feb 15 14:43:26 GMT 2007