[sanitizer] Check if directory exists before trying to create

Add a DirExists mechanism, modeled after FileExists. Use it to guard
creation of the report path directory.

This should avoid failures running the sanitizer in a sandbox where the
file creation attempt causes hard failures, even for an existing
directory. Problem reported on D109794 for ChromeOS in sandbox
(https://issuetracker.google.com/209296420).

Differential Revision: https://reviews.llvm.org/D119495

compiler-rt/lib/sanitizer_common/sanitizer_file.cpp

@@ -84,8 +84,12 @@ static void RecursiveCreateParentDirs(char *path) {
     if (!IsPathSeparator(path[i]))
       continue;
     path[i] = '\0';
-    /* Some of these will fail, because the directory exists, ignore it. */
-    CreateDir(path);
+    if (!DirExists(path) && !CreateDir(path)) {
+      const char *ErrorMsgPrefix = "ERROR: Can't create directory: ";
+      WriteToFile(kStderrFd, ErrorMsgPrefix, internal_strlen(ErrorMsgPrefix));
+      WriteToFile(kStderrFd, path, internal_strlen(path));
+      Die();
+    }
     path[i] = save;
   }
 }

compiler-rt/lib/sanitizer_common/sanitizer_file.h

@@ -77,6 +77,7 @@ bool SupportsColoredOutput(fd_t fd);
 // OS
 const char *GetPwd();
 bool FileExists(const char *filename);
+bool DirExists(const char *path);
 char *FindPathToBinary(const char *name);
 bool IsPathSeparator(const char c);
 bool IsAbsolutePath(const char *path);

compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp

@@ -499,7 +499,18 @@ bool FileExists(const char *filename) {
   return S_ISREG(st.st_mode);
 }
 
-#if !SANITIZER_NETBSD
+bool DirExists(const char *path) {
+  struct stat st;
+#  if SANITIZER_USES_CANONICAL_LINUX_SYSCALLS
+  if (internal_syscall(SYSCALL(newfstatat), AT_FDCWD, path, &st, 0))
+#  else
+  if (internal_stat(path, &st))
+#  endif
+    return false;
+  return S_ISDIR(st.st_mode);
+}
+
+#  if !SANITIZER_NETBSD
 tid_t GetTid() {
 #if SANITIZER_FREEBSD
   long Tid;

compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp

@@ -393,6 +393,13 @@ bool FileExists(const char *filename) {
   return S_ISREG(st.st_mode);
 }
 
+bool DirExists(const char *path) {
+  struct stat st;
+  if (stat(path, &st))
+    return false;
+  return S_ISDIR(st.st_mode);
+}
+
 tid_t GetTid() {
   tid_t tid;
   pthread_threadid_np(nullptr, &tid);

compiler-rt/lib/sanitizer_common/sanitizer_win.cpp

@@ -93,6 +93,11 @@ bool FileExists(const char *filename) {
   return ::GetFileAttributesA(filename) != INVALID_FILE_ATTRIBUTES;
 }
 
+bool DirExists(const char *path) {
+  auto attr = ::GetFileAttributesA(path);
+  return (attr != INVALID_FILE_ATTRIBUTES) && (attr & FILE_ATTRIBUTE_DIRECTORY);
+}
+
 uptr internal_getpid() {
   return GetProcessId(GetCurrentProcess());
 }

compiler-rt/lib/sanitizer_common/tests/sanitizer_libc_test.cpp

@@ -63,6 +63,20 @@ struct stat_and_more {
   unsigned char z;
 };
 
+static void get_temp_dir(char *buf, size_t bufsize) {
+#if SANITIZER_WINDOWS
+  buf[0] = '\0';
+  if (!::GetTempPathA(bufsize, buf))
+    return;
+#else
+  const char *tmpdir = "/tmp";
+#  if SANITIZER_ANDROID
+  tmpdir = GetEnv("TMPDIR");
+#  endif
+  internal_snprintf(buf, bufsize, "%s", tmpdir);
+#endif
+}
+
 static void temp_file_name(char *buf, size_t bufsize, const char *prefix) {
 #if SANITIZER_WINDOWS
   buf[0] = '\0';
@@ -340,3 +354,19 @@ TEST(SanitizerCommon, ReportFile) {
   report_file.SetReportPath("stderr");
   Unlink(tmpfile);
 }
+
+TEST(SanitizerCommon, FileExists) {
+  char tmpfile[128];
+  temp_file_name(tmpfile, sizeof(tmpfile), "sanitizer_common.fileexists.tmp.");
+  fd_t fd = OpenFile(tmpfile, WrOnly);
+  ASSERT_NE(fd, kInvalidFd);
+  EXPECT_TRUE(FileExists(tmpfile));
+  CloseFile(fd);
+  Unlink(tmpfile);
+}
+
+TEST(SanitizerCommon, DirExists) {
+  char tmpdir[128];
+  get_temp_dir(tmpdir, sizeof(tmpdir));
+  EXPECT_TRUE(DirExists(tmpdir));
+}

compiler-rt/test/asan/TestCases/log-path_test.cpp

@@ -16,10 +16,14 @@
 // RUN: %env_asan_opts=log_path=%t.log not %run %t 2> %t.out
 // RUN: FileCheck %s --check-prefix=CHECK-ERROR < %t.log.*
 
-// Invalid log_path.
-// RUN: %env_asan_opts=log_path=/dev/null/INVALID not %run %t 2> %t.out
+// Invalid log_path in existing directory.
+// RUN: %env_asan_opts=log_path=/INVALID not %run %t 2> %t.out
 // RUN: FileCheck %s --check-prefix=CHECK-INVALID < %t.out
 
+// Directory of log_path can't be created.
+// RUN: %env_asan_opts=log_path=/dev/null/INVALID not %run %t 2> %t.out
+// RUN: FileCheck %s --check-prefix=CHECK-BAD-DIR < %t.out
+
 // Too long log_path.
 // RUN: %env_asan_opts=log_path=`for((i=0;i<10000;i++)); do echo -n $i; done` \
 // RUN:   not %run %t 2> %t.out
@@ -44,5 +48,6 @@ int main(int argc, char **argv) {
   return res;
 }
 // CHECK-ERROR: ERROR: AddressSanitizer
-// CHECK-INVALID: ERROR: Can't open file: /dev/null/INVALID
+// CHECK-INVALID: ERROR: Can't open file: /INVALID
+// CHECK-BAD-DIR: ERROR: Can't create directory: /dev/null
 // CHECK-LONG: ERROR: Path is too long: 01234

compiler-rt/test/memprof/TestCases/log_path_test.cpp

@@ -3,18 +3,21 @@
 //
 // RUN: %clangxx_memprof  %s -o %t
 
-// stderr print_text=true:log_path
+// stderr log_path
 // RUN: %env_memprof_opts=print_text=true:log_path=stderr %run %t 2>&1 | FileCheck %s --check-prefix=CHECK-GOOD --dump-input=always
 
-// Good print_text=true:log_path.
+// Good log_path.
 // RUN: rm -f %t.log.*
 // RUN: %env_memprof_opts=print_text=true:log_path=%t.log %run %t
 // RUN: FileCheck %s --check-prefix=CHECK-GOOD --dump-input=always < %t.log.*
 
-// Invalid print_text=true:log_path.
-// RUN: %env_memprof_opts=print_text=true:log_path=/dev/null/INVALID not %run %t 2>&1 | FileCheck %s --check-prefix=CHECK-INVALID --dump-input=always
+// Invalid log_path.
+// RUN: %env_memprof_opts=print_text=true:log_path=/INVALID not %run %t 2>&1 | FileCheck %s --check-prefix=CHECK-INVALID --dump-input=always
 
-// Too long print_text=true:log_path.
+// Directory of log_path can't be created.
+// RUN: %env_memprof_opts=print_text=true:log_path=/dev/null/INVALID not %run %t 2>&1 | FileCheck %s --check-prefix=CHECK-BAD-DIR --dump-input=always
+
+// Too long log_path.
 // RUN: %env_memprof_opts=print_text=true:log_path=`for((i=0;i<10000;i++)); do echo -n $i; done` \
 // RUN:   not %run %t 2>&1 | FileCheck %s --check-prefix=CHECK-LONG --dump-input=always
 
@@ -24,7 +27,7 @@
 // Using an automatically generated name via %t can cause weird issues with
 // unexpected macro expansion if the path includes tokens that match a build
 // system macro (e.g. "linux").
-// RUN: %clangxx_memprof  %s -o %t -DPROFILE_NAME_VAR="/dev/null/INVALID"
+// RUN: %clangxx_memprof  %s -o %t -DPROFILE_NAME_VAR="/INVALID"
 // RUN: not %run %t 2>&1 | FileCheck %s --check-prefix=CHECK-INVALID --dump-input=always
 
 #include <sanitizer/memprof_interface.h>
@@ -45,5 +48,6 @@ int main(int argc, char **argv) {
   return 0;
 }
 // CHECK-GOOD: Memory allocation stack id
-// CHECK-INVALID: ERROR: Can't open file: /dev/null/INVALID
+// CHECK-INVALID: ERROR: Can't open file: /INVALID
+// CHECK-BAD-DIR: ERROR: Can't create directory: /dev/null
 // CHECK-LONG: ERROR: Path is too long: 01234

compiler-rt/test/sanitizer_common/TestCases/Posix/sanitizer_set_report_path_test.cpp

@@ -1,6 +1,11 @@
 // Test __sanitizer_set_report_path and __sanitizer_get_report_path:
+// RUN: rm -rf %t.report_path
 // RUN: %clangxx -O2 %s -o %t
 // RUN: %run %t | FileCheck %s
+// Try again with a directory without write access.
+// RUN: rm -rf %t.report_path && mkdir -p %t.report_path
+// RUN: chmod u-w %t.report_path || true
+// RUN: not %run %t 2>&1 | FileCheck %s --check-prefix=FAIL
 
 #include <assert.h>
 #include <sanitizer/common_interface_defs.h>
@@ -18,3 +23,4 @@ int main(int argc, char **argv) {
 }
 
 // CHECK: Path {{.*}}Posix/Output/sanitizer_set_report_path_test.cpp.tmp.report_path/report.
+// FAIL: ERROR: Can't open file: {{.*}}Posix/Output/sanitizer_set_report_path_test.cpp.tmp.report_path/report.