[libc] Update errno usage in integration tests. (#158147)

Instead of using libc_errno directly, include <errno.h> and use regular
"errno" in the code. (to verify that errno-as-an-interface works
properly).

This is the recipe prescribed in the libc/src/__support/libc_errno.h
header - let's actually follow it in the integration tests.

Author: vonosmas

libc/test/IntegrationTest/test.h

@@ -68,9 +68,9 @@
 ////////////////////////////////////////////////////////////////////////////////
 // Errno checks.
 
-#define ASSERT_ERRNO_EQ(VAL) ASSERT_EQ(VAL, static_cast<int>(libc_errno))
-#define ASSERT_ERRNO_SUCCESS() ASSERT_EQ(0, static_cast<int>(libc_errno))
-#define ASSERT_ERRNO_FAILURE() ASSERT_NE(0, static_cast<int>(libc_errno))
+#define ASSERT_ERRNO_EQ(VAL) ASSERT_EQ(VAL, static_cast<int>(errno))
+#define ASSERT_ERRNO_SUCCESS() ASSERT_EQ(0, static_cast<int>(errno))
+#define ASSERT_ERRNO_FAILURE() ASSERT_NE(0, static_cast<int>(errno))
 
 // Integration tests are compiled with -ffreestanding which stops treating
 // the main function as a non-overloadable special function. Hence, we use a

libc/test/integration/src/pthread/pthread_create_test.cpp

@@ -29,10 +29,9 @@
 #include "src/__support/CPP/new.h"
 #include "src/__support/threads/thread.h"
 
-#include "src/__support/libc_errno.h"
-
 #include "test/IntegrationTest/test.h"
 
+#include <errno.h>
 #include <linux/param.h> // For EXEC_PAGESIZE.
 #include <pthread.h>
 
@@ -332,7 +331,7 @@ static void run_failure_tests() {
 }
 
 TEST_MAIN() {
-  libc_errno = 0;
+  errno = 0;
   run_success_tests();
   run_failure_tests();
   return 0;

libc/test/integration/src/pthread/pthread_join_test.cpp

@@ -9,9 +9,9 @@
 #include "src/pthread/pthread_create.h"
 #include "src/pthread/pthread_join.h"
 
-#include "src/__support/libc_errno.h"
-
 #include "test/IntegrationTest/test.h"
+
+#include <errno.h>
 #include <pthread.h>
 
 static void *simpleFunc(void *) { return nullptr; }
@@ -25,7 +25,7 @@ static void nullJoinTest() {
 }
 
 TEST_MAIN() {
-  libc_errno = 0;
+  errno = 0;
   nullJoinTest();
   return 0;
 }

libc/test/integration/src/pthread/pthread_name_test.cpp

@@ -8,7 +8,6 @@
 
 #include "hdr/stdint_proxy.h" // uintptr_t
 #include "src/__support/CPP/string_view.h"
-#include "src/__support/libc_errno.h"
 #include "src/pthread/pthread_create.h"
 #include "src/pthread/pthread_getname_np.h"
 #include "src/pthread/pthread_join.h"
@@ -20,6 +19,7 @@
 #include "src/pthread/pthread_setname_np.h"
 #include "test/IntegrationTest/test.h"
 
+#include <errno.h>
 #include <pthread.h>
 
 using string_view = LIBC_NAMESPACE::cpp::string_view;

libc/test/integration/src/unistd/getcwd_test.cpp

@@ -7,12 +7,12 @@
 //===----------------------------------------------------------------------===//
 
 #include "src/__support/CPP/string_view.h"
-#include "src/__support/libc_errno.h"
 #include "src/stdlib/getenv.h"
 #include "src/unistd/getcwd.h"
 
 #include "test/IntegrationTest/test.h"
 
+#include <errno.h>
 #include <stdlib.h> // For malloc and free
 
 using LIBC_NAMESPACE::cpp::string_view;
@@ -31,13 +31,12 @@ TEST_MAIN(int argc, char **argv, char **envp) {
   cwd = LIBC_NAMESPACE::getcwd(buffer, 0);
   ASSERT_TRUE(cwd == nullptr);
   ASSERT_ERRNO_EQ(EINVAL);
-  libc_errno = 0;
 
   // Insufficient size
+  errno = 0;
   cwd = LIBC_NAMESPACE::getcwd(buffer, 2);
   ASSERT_TRUE(cwd == nullptr);
-  int err = libc_errno;
-  ASSERT_EQ(err, ERANGE);
+  ASSERT_ERRNO_EQ(ERANGE);
 
   return 0;
 }

libc/test/integration/startup/linux/tls_test.cpp

@@ -6,10 +6,10 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "src/__support/libc_errno.h"
 #include "src/sys/mman/mmap.h"
 #include "test/IntegrationTest/test.h"
 
+#include <errno.h>
 #include <sys/mman.h>
 
 constexpr int threadLocalDataSize = 101;