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/*
* Copyright 2010 The Native Client Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include <semaphore.h>
#include <errno.h>
#include <limits.h>
#include <pthread.h>
#include <signal.h>
#include <unistd.h>
#include <cstdlib>
#include <limits>
#include "native_client/tests/syscalls/test.h"
// Test error conditions of sem_init and return the number of failed checks.
//
// According to the man page on Linux:
// ===================================
// RETURN VALUE
// sem_init() returns 0 on success; on error, -1 is returned, and errno
// is set to indicate the error.
//
// ERRORS
// EINVAL value exceeds SEM_VALUE_MAX.
//
// ENOSYS pshared is non-zero, but the system does not support
// process-shared semaphores (see sem_overview(7)).
// ===================================
// However, pshared is not supported in NaCl currently, so a non-zero pshared
// value should yield an error (EINVAL).
int TestSemInitErrors() {
START_TEST("sem_init error conditions");
// First, make sure that it is possible to exceed SEM_VALUE_MAX
// for this test, otherwise we can't cause this failure mode.
EXPECT(SEM_VALUE_MAX < std::numeric_limits<unsigned int>::max());
sem_t my_semaphore;
// Create a value just beyond SEM_VALUE_MAX, try to initialize the semaphore.
const unsigned int sem_max_plus_1 = (unsigned) SEM_VALUE_MAX + 1;
// sem_init should return -1 and errno should equal EINVAL
EXPECT(-1 == sem_init(&my_semaphore, 0, sem_max_plus_1));
EXPECT(EINVAL == errno);
// Try with the largest possible unsigned int.
EXPECT(-1 == sem_init(&my_semaphore,
0,
std::numeric_limits<unsigned int>::max()));
EXPECT(EINVAL == errno);
#if !defined(__GLIBC__)
// nacl-newlib's semaphores do not currently support the pshared
// option, so this should fail with an ENOSYS error. If pshared
// gets added, we should begin testing it for proper successful
// behavior.
EXPECT(-1 == sem_init(&my_semaphore, 1, 0));
EXPECT(ENOSYS == errno);
#endif
END_TEST();
}
// Test error conditions of sem_post and return the number of failed checks.
//
// According to the man page on Linux:
// ===================================
// RETURN VALUE
// sem_post() returns 0 on success; on error, the value of the semaphore
// is left unchanged, -1 is returned, and errno is set to indicate the
// error.
//
// ERRORS
// EINVAL sem is not a valid semaphore.
//
// EOVERFLOW
// The maximum allowable value for a semaphore would be exceeded.
// ===================================
int TestSemPostErrors() {
START_TEST("sem_post error conditions");
// Initialize a semaphore with the max value, and try to post to it.
sem_t my_semaphore;
EXPECT(0 == sem_init(&my_semaphore, 0, SEM_VALUE_MAX));
EXPECT(-1 == sem_post(&my_semaphore));
EXPECT(EOVERFLOW == errno);
EXPECT(0 == sem_destroy(&my_semaphore));
END_TEST();
}
// The real type of the void* argument to PostThreadFunc. See PostThreadFunc
// for more information.
struct PostThreadArg {
// The semaphore to which PostThreadFunc will post.
sem_t* semaphore;
// An amount of time to sleep before each post (in microseconds).
unsigned int sleep_microseconds;
// The number of times to post before exiting the function.
unsigned int iterations;
};
// Post to the given semaphore some number of times, with a sleep before each
// post. poster_thread_arg must be of type PosterThreadArg. Returns NULL.
void* PostThreadFunc(void* poster_thread_arg) {
PostThreadArg* pta = static_cast<PostThreadArg*>(poster_thread_arg);
for (unsigned int i = 0; i < pta->iterations; ++i) {
usleep(pta->sleep_microseconds);
sem_post(pta->semaphore);
}
return NULL;
}
int TestSemNormalOperation() {
START_TEST("semaphore normal operation");
// Test 1 thread posting to 1 semaphore.
sem_t my_semaphore;
EXPECT(0 == sem_init(&my_semaphore, 0, 0));
PostThreadArg pta = { &my_semaphore, /* semaphore */
500000u, /* sleep_microseconds */
1 /* iterations */ };
pthread_t my_thread;
EXPECT(0 == pthread_create(&my_thread, 0, &PostThreadFunc, &pta));
EXPECT(0 == sem_wait(&my_semaphore));
EXPECT(0 == pthread_join(my_thread, 0));
EXPECT(0 == sem_destroy(&my_semaphore));
// Reinitialize a previously used semaphore, test 10 threads posting to 1
// semaphore, 5 times each.
EXPECT(0 == sem_init(&my_semaphore, 0, 0));
pta.iterations = 5;
pthread_t my_thread_array[10];
for (int i = 0; i < 10; ++i) {
EXPECT(0 == pthread_create(&my_thread_array[i], 0, &PostThreadFunc, &pta));
}
// Wait 5*10 times, once per post: 5 posts for each of 10 posting-threads.
for (int i = 0; i < 5*10; ++i) {
EXPECT(0 == sem_wait(&my_semaphore));
}
for (int i = 0; i < 10; ++i) {
EXPECT(0 == pthread_join(my_thread_array[i], 0));
}
EXPECT(0 == sem_destroy(&my_semaphore));
// Reinitialize the previously used semaphore again, this time with a positive
// starting value.
EXPECT(0 == sem_init(&my_semaphore, 0, 5));
pta.iterations = 1;
EXPECT(0 == pthread_create(&my_thread, 0, &PostThreadFunc, &pta));
// Wait 6 times, once for the post, 5 times for the initial starting value.
for (int i = 0; i < 6; ++i) {
EXPECT(0 == sem_wait(&my_semaphore));
}
EXPECT(0 == pthread_join(my_thread, 0));
EXPECT(0 == sem_destroy(&my_semaphore));
END_TEST();
}
int TestSemTryWait() {
START_TEST("test sem_trywait() and sem_getvalue()");
int start_value = 10;
sem_t sem;
EXPECT(0 == sem_init(&sem, 0, start_value));
int value = -1;
EXPECT(0 == sem_getvalue(&sem, &value));
EXPECT(10 == value);
// When the semaphore's value is positive, each call to
// sem_trywait() should decrement the semaphore's value.
for (int i = 1; i <= start_value; i++) {
EXPECT(0 == sem_trywait(&sem));
EXPECT(0 == sem_getvalue(&sem, &value));
EXPECT(start_value - i == value);
}
// When the semaphore's value is zero, sem_trywait() should fail.
EXPECT(-1 == sem_trywait(&sem));
EXPECT(EAGAIN == errno);
EXPECT(0 == sem_getvalue(&sem, &value));
EXPECT(0 == value);
EXPECT(0 == sem_destroy(&sem));
END_TEST();
}
int main() {
int fail_count = 0;
fail_count += TestSemInitErrors();
fail_count += TestSemPostErrors();
fail_count += TestSemNormalOperation();
fail_count += TestSemTryWait();
std::exit(fail_count);
}
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