From mboxrd@z Thu Jan 1 00:00:00 1970 From: Cyril Hrubis Date: Wed, 14 Oct 2020 14:13:43 +0200 Subject: [LTP] [PATCH V3 2/3] syscalls: select: Verify that data is available to read In-Reply-To: References: <6fbfc6919c0000e7a7745afbc3c94baab02603fa.1599558175.git.viresh.kumar@linaro.org> Message-ID: <20201014121343.GD31816@yuki.lan> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: ltp@lists.linux.it Hi! > select() returns a positive value on success if timeout hasn't happened, > else returns 0. Check that and send some data to the write file > descriptor for the same. > > Acked-by: Li Wang > Signed-off-by: Viresh Kumar > --- > testcases/kernel/syscalls/select/select01.c | 13 ++++++++++--- > 1 file changed, 10 insertions(+), 3 deletions(-) > > diff --git a/testcases/kernel/syscalls/select/select01.c b/testcases/kernel/syscalls/select/select01.c > index 1213aa931251..c6b30aa67dd7 100644 > --- a/testcases/kernel/syscalls/select/select01.c > +++ b/testcases/kernel/syscalls/select/select01.c > @@ -25,25 +25,32 @@ static struct select_info { > int *nfds; > fd_set *readfds; > fd_set *writefds; > + int *writefd; > char *desc; > } tests[] = { > - {&fd_reg, &readfds_reg, NULL, "with regular file"}, > - {&fds_pipe[1], &readfds_pipe, &writefds_pipe, "with system pipe"}, > - {&fd_npipe, &readfds_npipe, &writefds_npipe, "with named pipe (FIFO)"}, > + {&fd_reg, &readfds_reg, NULL, NULL, "with regular file"}, > + {&fds_pipe[1], &readfds_pipe, &writefds_pipe, &fds_pipe[1], "with system pipe"}, > + {&fd_npipe, &readfds_npipe, &writefds_npipe, &fd_npipe, "with named pipe (FIFO)"}, > }; > > static void run(unsigned int n) > { > struct select_info *tc = &tests[n]; > struct timeval timeout; > + char buf; > > timeout.tv_sec = 0; > timeout.tv_usec = 100000; > > + if (tc->writefd) > + SAFE_WRITE(0, *tc->writefd, &buf, sizeof(buf)); I'm not sure why we are writing data here. For both the pipe and fifo the select() will return that we can write there, hence the return would be non-zero regardless. Also I would like to be more specific. E.g. expecting specific return instead of just non-zero and also making sure the right bits are enabled in the fd sets. > TEST(do_select(*tc->nfds + 1, tc->readfds, tc->writefds, 0, &timeout)); > > if (TST_RET == -1) > tst_res(TFAIL | TTERRNO, "select() failed %s", tc->desc); > + else if (!TST_RET) > + tst_res(TFAIL, "select() timed out %s", tc->desc); > else > tst_res(TPASS, "select() passed %s", tc->desc); > } > -- > 2.25.0.rc1.19.g042ed3e048af > -- Cyril Hrubis chrubis@suse.cz