[compiler-rt] Reapply freadlink interception for macOs.

Fixed test, needed explicit O_SYMLINK on symbolic link opening.

Author: devnexen

compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc

@@ -10350,6 +10350,23 @@ INTERCEPTOR(SSIZE_T, pwritev2, int fd, __sanitizer_iovec *iov, int iovcnt,
 #define INIT_PWRITEV2
 #endif
 
+#if SANITIZER_INTERCEPT_FREADLINK
+INTERCEPTOR(SSIZE_T, freadlink, int fd, char *buf, SIZE_T bufsiz) {
+  void *ctx;
+  COMMON_INTERCEPTOR_ENTER(ctx, freadlink, fd, buf, bufsiz);
+  COMMON_INTERCEPTOR_FD_ACCESS(ctx, fd);
+  SSIZE_T res = REAL(freadlink)(fd, buf, bufsiz);
+  if (res > 0)
+    COMMON_INTERCEPTOR_WRITE_RANGE(ctx, buf, res);
+  if (res >= 0 && fd > 0)
+    COMMON_INTERCEPTOR_FD_ACQUIRE(ctx, fd);
+  return res;
+}
+#  define INIT_FREADLINK COMMON_INTERCEPT_FUNCTION(freadlink)
+#else
+#  define INIT_FREADLINK
+#endif
+
 #include "sanitizer_common_interceptors_netbsd_compat.inc"
 
 namespace __sanitizer {
@@ -10671,6 +10688,7 @@ static void InitializeCommonInterceptors() {
   INIT_CPUSET_GETAFFINITY;
   INIT_PREADV2;
   INIT_PWRITEV2;
+  INIT_FREADLINK;
 
   INIT___PRINTF_CHK;
 }

compiler-rt/lib/sanitizer_common/sanitizer_platform_interceptors.h

@@ -607,7 +607,13 @@
 // FIXME: also available from musl 1.2.5
 #define SANITIZER_INTERCEPT_PREADV2 (SI_LINUX && __GLIBC_PREREQ(2, 26))
 #define SANITIZER_INTERCEPT_PWRITEV2 (SI_LINUX && __GLIBC_PREREQ(2, 26))
-
+#if defined(__MAC_OS_X_VERSION_MIN_REQUIRED) && \
+    __MAC_OS_X_VERSION_MIN_REQUIRED >= 130000
+#  define SI_MAC_OS_DEPLOYMENT_MIN_13_00 1
+#else
+#  define SI_MAC_OS_DEPLOYMENT_MIN_13_00 0
+#endif
+#define SANITIZER_INTERCEPT_FREADLINK (SI_MAC && SI_MAC_OS_DEPLOYMENT_MIN_13_00)
 // This macro gives a way for downstream users to override the above
 // interceptor macros irrespective of the platform they are on. They have
 // to do two things:

compiler-rt/test/sanitizer_common/TestCases/Darwin/freadlink.c

@@ -0,0 +1,32 @@
+
+// RUN: %clang -O0 %s -o %t && %run %t
+
+#include <assert.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+int main(int argc, char **argv) {
+  char symlink_path[PATH_MAX];
+  snprintf(symlink_path, sizeof(symlink_path), "%s_%d.symlink", argv[0],
+           getpid());
+  remove(symlink_path);
+  int res = symlink(argv[0], symlink_path);
+  assert(!res);
+
+  int fd;
+  char readlink_path[PATH_MAX];
+  fd = open(symlink_path, O_RDONLY | O_SYMLINK);
+  assert(fd > 0);
+  ssize_t res2 = freadlink(fd, readlink_path, sizeof(readlink_path));
+  assert(res2 >= 0);
+  readlink_path[res2] = '\0';
+  assert(!strcmp(readlink_path, argv[0]));
+  close(fd);
+
+  return 0;
+}
+