Support custom attributes in pthread_create

Only functional for stack growsdown (same as before), but custom
`stack`, `stacksize`, `guardsize`, and `detachstate` all should be
working.

Differential Revision: https://reviews.llvm.org/D148290

1 files changed, 58 insertions, 4 deletions

diff --git a/libc/src/pthread/pthread_create.cpp b/libc/src/pthread/pthread_create.cpp
index 7064125..9eebb80 100644
--- a/libc/src/pthread/pthread_create.cpp
+++ b/libc/src/pthread/pthread_create.cpp
@@ -8,7 +8,15 @@
 
 #include "pthread_create.h"
 
+#include "pthread_attr_destroy.h"
+#include "pthread_attr_init.h"
+
+#include "pthread_attr_getdetachstate.h"
+#include "pthread_attr_getguardsize.h"
+#include "pthread_attr_getstack.h"
+
 #include "src/__support/common.h"
+#include "src/__support/macros/optimization.h"
 #include "src/__support/threads/thread.h"
 
 #include <errno.h>
@@ -20,12 +28,58 @@ static_assert(sizeof(pthread_t) == sizeof(__llvm_libc::Thread),
               "Mismatch between pthread_t and internal Thread.");
 
 LLVM_LIBC_FUNCTION(int, pthread_create,
-                   (pthread_t *__restrict th, const pthread_attr_t *__restrict,
+                   (pthread_t *__restrict th,
+                    const pthread_attr_t *__restrict attr,
                     __pthread_start_t func, void *arg)) {
+  pthread_attr_t default_attr;
+  if (attr == nullptr) {
+    // We failed to initialize attributes (should be impossible)
+    if (LIBC_UNLIKELY(__llvm_libc::pthread_attr_init(&default_attr) != 0))
+      return EINVAL;
+
+    attr = &default_attr;
+  }
+
+  void *stack;
+  size_t stacksize, guardsize;
+  int detachstate;
+
+  // As of writing this all the `pthread_attr_get*` functions always succeed.
+  if (LIBC_UNLIKELY(
+          __llvm_libc::pthread_attr_getstack(attr, &stack, &stacksize) != 0))
+    return EINVAL;
+
+  if (LIBC_UNLIKELY(__llvm_libc::pthread_attr_getguardsize(attr, &guardsize) !=
+                    0))
+    return EINVAL;
+
+  if (LIBC_UNLIKELY(
+          __llvm_libc::pthread_attr_getdetachstate(attr, &detachstate) != 0))
+    return EINVAL;
+
+  if (attr == &default_attr)
+    // Should we fail here? Its non-issue as the moment as pthread_attr_destroy
+    // can only succeed.
+    if (LIBC_UNLIKELY(__llvm_libc::pthread_attr_destroy(&default_attr) != 0))
+      return EINVAL;
+
+  if (stacksize && stacksize < PTHREAD_STACK_MIN)
+    return EINVAL;
+
+  if (guardsize % EXEC_PAGESIZE != 0)
+    return EINVAL;
+
+  if (detachstate != PTHREAD_CREATE_DETACHED &&
+      detachstate != PTHREAD_CREATE_JOINABLE)
+    return EINVAL;
+
+  // Thread::run will check validity of the `stack` argument (stack alignment is
+  // universal, not sure a pthread requirement).
+
   auto *thread = reinterpret_cast<__llvm_libc::Thread *>(th);
-  // TODO: Use the attributes parameter to set up thread properties.
-  int result = thread->run(func, arg, nullptr, 0);
-  if (result != 0 && result != EPERM)
+  int result = thread->run(func, arg, stack, stacksize, guardsize,
+                           detachstate == PTHREAD_CREATE_DETACHED);
+  if (result != 0 && result != EPERM && result != EINVAL)
     return EAGAIN;
   return result;
 }