From f4c0d5309a3e5f16ca3c3854b1e719dace843e03 Mon Sep 17 00:00:00 2001 From: Ian Rogers Date: Wed, 7 Jun 2023 23:18:11 -0700 Subject: 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 Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Jiri Olsa Cc: Mark Rutland Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Yang Jihong Link: http://lore.kernel.org/lkml/20230608061812.3715566-1-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/lib/api/io.h | 28 +++++++++++++++++++++++++++- 1 file changed, 27 insertions(+), 1 deletion(-) (limited to 'tools/lib/api/io.h') diff --git a/tools/lib/api/io.h b/tools/lib/api/io.h index d5e8cf0dada0..9fc429d2852d 100644 --- a/tools/lib/api/io.h +++ b/tools/lib/api/io.h @@ -8,6 +8,7 @@ #define __API_IO__ #include +#include #include #include #include @@ -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; -- cgit