Merge "Have pthread_attr_getstack for the main thread report RLIMIT_STACK..."
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 @@
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 @@
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 @@
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 @@
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
-
- // 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);
-
- //
- // What if the rlimit is smaller than the stack's current extent?
- //
+ // The stack size should correspond to RLIMIT_STACK.
rlimit rl;
+ ASSERT_EQ(0, getrlimit(RLIMIT_STACK, &rl));
+ EXPECT_EQ(rl.rlim_cur, stack_size);
+
+ // 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 RLIMIT_STACK is smaller than the stack's current extent?
+ //
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 @@
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;