From f4c0d5309a3e5f16ca3c3854b1e719dace843e03 Mon Sep 17 00:00:00 2001
From: Ian Rogers <irogers@google.com>
Date: Wed, 7 Jun 2023 23:18:11 -0700
Subject: [PATCH] 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: Ian 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: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/lib/api/io.h | 28 +++++++++++++++++++++++++++-
1 file changed, 27 insertions(+), 1 deletion(-)
diff --git a/tools/lib/api/io.h b/tools/lib/api/io.h
index d5e8cf0dada0d..9fc429d2852d7 100644
--- a/tools/lib/api/io.h
+++ b/tools/lib/api/io.h
@@ -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;