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author | Ben Gamari <bgamari.foss@gmail.com> | 2017-04-21 12:11:28 -0400 |
---|---|---|
committer | Ben Gamari <ben@smart-cactus.org> | 2017-04-21 12:11:36 -0400 |
commit | e5732d2a28dfb8a754ee73e124e3558222a543bb (patch) | |
tree | d2481cc029034b90de02db594aeacc2170c84d51 | |
parent | 3672cf6d0962dd6bf0a05e6e3433c81bbdf04a11 (diff) | |
download | haskell-e5732d2a28dfb8a754ee73e124e3558222a543bb.tar.gz |
base: Fix hWaitForInput with timeout on POSIX
This was previously broken (#13252) by
f46369b8a1bf90a3bdc30f2b566c3a7e03672518, which ported the fdReady
function from `select` to `poll` and in so doing dropping support for
timeouts. Unfortunately, while `select` tells us the amount of time not
slept (on Linux anyways; it turns out this is implementation dependent),
`poll` does not give us this luxury. Consequently, we manually need to
track time slept in this case.
Unfortunately, portably measuring time is hard. Ideally we would use
`clock_gettime` with the monotonic clock here, but sadly this isn't
supported on most versions of Darwin. Consequently, we instead use
`gettimeofday`, running the risk of system time changes messing us up.
Test Plan: Validate
Reviewers: simonmar, austin, hvr
Reviewed By: simonmar
Subscribers: rwbarton, thomie
GHC Trac Issues: #13252
Differential Revision: https://phabricator.haskell.org/D3473
-rw-r--r-- | libraries/base/cbits/inputReady.c | 40 | ||||
-rw-r--r-- | libraries/base/tests/T13525.hs | 5 | ||||
-rw-r--r-- | libraries/base/tests/all.T | 2 |
3 files changed, 35 insertions, 12 deletions
diff --git a/libraries/base/cbits/inputReady.c b/libraries/base/cbits/inputReady.c index 230e592260..1530d5be90 100644 --- a/libraries/base/cbits/inputReady.c +++ b/libraries/base/cbits/inputReady.c @@ -9,11 +9,13 @@ #include "HsBase.h" #if !defined(_WIN32) #include <poll.h> +#include <sys/time.h> #endif /* * inputReady(fd) checks to see whether input is available on the file - * descriptor 'fd'. Input meaning 'can I safely read at least a + * descriptor 'fd' within 'msecs' milliseconds (or indefinitely if 'msecs' is + * negative). "Input is available" is defined as 'can I safely read at least a * *character* from this file object without blocking?' */ int @@ -21,23 +23,41 @@ fdReady(int fd, int write, int msecs, int isSock) { #if !defined(_WIN32) + struct pollfd fds[1]; - // We only handle msecs == 0 on non-Windows, because this is the - // only case we need. Non-zero waiting is handled by the IO manager. - if (msecs != 0) { - fprintf(stderr, "fdReady: msecs != 0, this shouldn't happen"); - abort(); + // if we need to track the then record the current time in case we are + // interrupted. + struct timeval tv0; + if (msecs > 0) { + if (gettimeofday(&tv0, NULL) != 0) { + fprintf(stderr, "fdReady: gettimeofday failed: %s\n", + strerror(errno)); + abort(); + } } - struct pollfd fds[1]; - fds[0].fd = fd; fds[0].events = write ? POLLOUT : POLLIN; fds[0].revents = 0; int res; - while ((res = poll(fds, 1, 0)) < 0) { - if (errno != EINTR) { + while ((res = poll(fds, 1, msecs)) < 0) { + if (errno == EINTR) { + if (msecs > 0) { + struct timeval tv; + if (gettimeofday(&tv, NULL) != 0) { + fprintf(stderr, "fdReady: gettimeofday failed: %s\n", + strerror(errno)); + abort(); + } + + int elapsed = 1000 * (tv.tv_sec - tv0.tv_sec) + + (tv.tv_usec - tv0.tv_usec) / 1000; + msecs -= elapsed; + if (msecs <= 0) return 0; + tv0 = tv; + } + } else { return (-1); } } diff --git a/libraries/base/tests/T13525.hs b/libraries/base/tests/T13525.hs index 1bb01b6a18..b4b589e0b4 100644 --- a/libraries/base/tests/T13525.hs +++ b/libraries/base/tests/T13525.hs @@ -1,7 +1,10 @@ +import System.Posix.Files import System.IO import System.Timeout main :: IO () main = do - hWaitForInput stdin (5 * 1000) + createNamedPipe "test" accessModes + h <- openFile "test" ReadMode + hWaitForInput h (5 * 1000) return () diff --git a/libraries/base/tests/all.T b/libraries/base/tests/all.T index 69705bc91e..f3cdeaa512 100644 --- a/libraries/base/tests/all.T +++ b/libraries/base/tests/all.T @@ -212,4 +212,4 @@ test('T13191', , only_ways(['normal'])], compile_and_run, ['-O']) -test('T13525', expect_broken(13525), compile_and_run, ['']) +test('T13525', normal, compile_and_run, ['']) |