diff options
| -rw-r--r-- | libc/bionic/pthread_attr.cpp | 23 | ||||
| -rw-r--r-- | tests/pthread_test.cpp | 31 |
2 files changed, 24 insertions, 30 deletions
diff --git a/libc/bionic/pthread_attr.cpp b/libc/bionic/pthread_attr.cpp index 8df3bff..c93970a 100644 --- a/libc/bionic/pthread_attr.cpp +++ b/libc/bionic/pthread_attr.cpp @@ -116,6 +116,16 @@ int pthread_attr_setstack(pthread_attr_t* attr, void* stack_base, size_t stack_s static int __pthread_attr_getstack_main_thread(void** stack_base, size_t* stack_size) { ErrnoRestorer errno_restorer; + rlimit stack_limit; + if (getrlimit(RLIMIT_STACK, &stack_limit) == -1) { + return errno; + } + + // If the current RLIMIT_STACK is RLIM_INFINITY, only admit to an 8MiB stack for sanity's sake. + if (stack_limit.rlim_cur == RLIM_INFINITY) { + stack_limit.rlim_cur = 8 * 1024 * 1024; + } + // It doesn't matter which thread we are; we're just looking for "[stack]". FILE* fp = fopen("/proc/self/maps", "re"); if (fp == NULL) { @@ -126,17 +136,8 @@ static int __pthread_attr_getstack_main_thread(void** stack_base, size_t* stack_ if (ends_with(line, " [stack]\n")) { uintptr_t lo, hi; if (sscanf(line, "%" SCNxPTR "-%" SCNxPTR, &lo, &hi) == 2) { - *stack_base = reinterpret_cast<void*>(lo); - *stack_size = hi - lo; - - // Does our current RLIMIT_STACK mean we won't actually get everything /proc/maps promises? - rlimit stack_limit; - if (getrlimit(RLIMIT_STACK, &stack_limit) != -1) { - if (*stack_size > stack_limit.rlim_cur) { - *stack_size = stack_limit.rlim_cur; - } - } - + *stack_size = stack_limit.rlim_cur; + *stack_base = reinterpret_cast<void*>(hi - *stack_size); fclose(fp); return 0; } diff --git a/tests/pthread_test.cpp b/tests/pthread_test.cpp index 5f74e38..6557738 100644 --- a/tests/pthread_test.cpp +++ b/tests/pthread_test.cpp @@ -842,8 +842,7 @@ TEST(pthread, pthread_attr_getstack__main_thread) { EXPECT_EQ(stack_size, stack_size2); // What does /proc/self/maps' [stack] line say? - void* maps_stack_base = NULL; - size_t maps_stack_size = 0; + void* maps_stack_hi = NULL; FILE* fp = fopen("/proc/self/maps", "r"); ASSERT_TRUE(fp != NULL); char line[BUFSIZ]; @@ -852,31 +851,25 @@ TEST(pthread, pthread_attr_getstack__main_thread) { char name[10]; sscanf(line, "%" PRIxPTR "-%" PRIxPTR " %*4s %*x %*x:%*x %*d %10s", &lo, &hi, name); if (strcmp(name, "[stack]") == 0) { - maps_stack_base = reinterpret_cast<void*>(lo); - maps_stack_size = hi - lo; + maps_stack_hi = reinterpret_cast<void*>(hi); break; } } fclose(fp); -#if defined(__BIONIC__) - // bionic thinks that the stack base and size should correspond to the mapped region. - EXPECT_EQ(maps_stack_base, stack_base); - EXPECT_EQ(maps_stack_size, stack_size); -#else - // glibc doesn't give the true extent for some reason. -#endif + // The stack size should correspond to RLIMIT_STACK. + rlimit rl; + ASSERT_EQ(0, getrlimit(RLIMIT_STACK, &rl)); + EXPECT_EQ(rl.rlim_cur, stack_size); - // Both bionic and glibc agree that the high address you can compute from the returned - // values should match what /proc/self/maps says. - void* stack_end = reinterpret_cast<uint8_t*>(stack_base) + stack_size; - void* maps_stack_end = reinterpret_cast<uint8_t*>(maps_stack_base) + maps_stack_size; - EXPECT_EQ(maps_stack_end, stack_end); + // The high address of the /proc/self/maps [stack] region should equal stack_base + stack_size. + // Remember that the stack grows down (and is mapped in on demand), so the low address of the + // region isn't very interesting. + EXPECT_EQ(maps_stack_hi, reinterpret_cast<uint8_t*>(stack_base) + stack_size); // - // What if the rlimit is smaller than the stack's current extent? + // What if RLIMIT_STACK is smaller than the stack's current extent? // - rlimit rl; rl.rlim_cur = rl.rlim_max = 1024; // 1KiB. We know the stack must be at least a page already. rl.rlim_max = RLIM_INFINITY; ASSERT_EQ(0, setrlimit(RLIMIT_STACK, &rl)); @@ -889,7 +882,7 @@ TEST(pthread, pthread_attr_getstack__main_thread) { ASSERT_EQ(1024U, stack_size); // - // What if the rlimit isn't a whole number of pages? + // What if RLIMIT_STACK isn't a whole number of pages? // rl.rlim_cur = rl.rlim_max = 6666; // Not a whole number of pages. rl.rlim_max = RLIM_INFINITY; |