Commit f4c0d530 authored by Ian Rogers's avatar Ian Rogers Committed by Arnaldo Carvalho de Melo
Browse files

tools api: Add simple timeout to io read 



In situations like reading from a pipe it can be useful to have a
timeout so that the caller doesn't block indefinitely. Implement a
simple one based on poll.

Signed-off-by: default avatarIan Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Yang Jihong <yangjihong1@huawei.com>
Link: http://lore.kernel.org/lkml/20230608061812.3715566-1-irogers@google.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 99d48500

tools/lib/api/io.h

+27 −1
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ 
#define __API_IO__



#include <errno.h>

#include <poll.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>
@@ -23,6 +24,8 @@ struct io { 
	char *end;

	/* Currently accessed data pointer. */

	char *data;

	/* Read timeout, 0 implies no timeout. */

	int timeout_ms;

	/* Set true on when the end of file on read error. */

	bool eof;

};
@@ -35,6 +38,7 @@ static inline void io__init(struct io *io, int fd, 
	io->buf = buf;

	io->end = buf;

	io->data = buf;

	io->timeout_ms = 0;

	io->eof = false;

}
@@ -47,7 +51,29 @@ static inline int io__get_char(struct io *io) 
		return -1;



	if (ptr == io->end) {

		ssize_t n = read(io->fd, io->buf, io->buf_len);

		ssize_t n;



		if (io->timeout_ms != 0) {

			struct pollfd pfds[] = {

				{

					.fd = io->fd,

					.events = POLLIN,

				},

			};



			n = poll(pfds, 1, io->timeout_ms);

			if (n == 0)

				errno = ETIMEDOUT;

			if (n > 0 && !(pfds[0].revents & POLLIN)) {

				errno = EIO;

				n = -1;

			}

			if (n <= 0) {

				io->eof = true;

				return -1;

			}

		}

		n = read(io->fd, io->buf, io->buf_len);



		if (n <= 0) {

			io->eof = true;