Implement rcutils_strnlen.

This is a portable version that uses memchr as its
underlying implementation.

Signed-off-by: Chris Lalancette <[email protected]>

Author: clalancette

CMakeLists.txt

@@ -72,6 +72,7 @@ set(rcutils_sources
   src/strerror.c
   src/string_array.c
   src/string_map.c
+  src/strnlen.c
   src/testing/fault_injection.c
   src/time.c
   ${time_impl_c}
@@ -276,7 +277,7 @@ if(BUILD_TESTING)
   )
   if(TARGET test_error_handling_helpers)
     target_include_directories(test_error_handling_helpers PUBLIC include)
-    target_link_libraries(test_error_handling_helpers osrf_testing_tools_cpp::memory_tools)
+    target_link_libraries(test_error_handling_helpers ${PROJECT_NAME} osrf_testing_tools_cpp::memory_tools)
   endif()
 
   ament_add_gtest(test_split

include/rcutils/error_handling.h

@@ -22,9 +22,6 @@ extern "C"
 {
 #endif
 
-#ifndef __STDC_WANT_LIB_EXT1__
-#define __STDC_WANT_LIB_EXT1__ 1  // indicate we would like strnlen_s if available
-#endif
 #include <assert.h>
 #include <stdbool.h>
 #include <stddef.h>
@@ -36,23 +33,18 @@ extern "C"
 #include "rcutils/allocator.h"
 #include "rcutils/macros.h"
 #include "rcutils/snprintf.h"
+#include "rcutils/strnlen.h"
 #include "rcutils/testing/fault_injection.h"
 #include "rcutils/types/rcutils_ret.h"
 #include "rcutils/visibility_control.h"
 
-#ifdef __STDC_LIB_EXT1__
 /// Write the given msg out to stderr, limiting the buffer size in the `fwrite`.
 /**
  * This ensures that there is an upper bound to a buffer overrun if `msg` is
  * non-null terminated.
  */
 #define RCUTILS_SAFE_FWRITE_TO_STDERR(msg) \
-  do {fwrite(msg, sizeof(char), strnlen_s(msg, 4096), stderr);} while (0)
-#else
-/// Write the given msg out to stderr.
-#define RCUTILS_SAFE_FWRITE_TO_STDERR(msg) \
-  do {fwrite(msg, sizeof(char), strlen(msg), stderr);} while (0)
-#endif
+  do {fwrite(msg, sizeof(char), rcutils_strnlen(msg, 4096), stderr);} while (0)
 
 /// Set the error message to stderr using a format string and format arguments.
 /**

include/rcutils/strnlen.h

@@ -0,0 +1,44 @@
+// Copyright 2023 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+/// \file
+
+#ifndef RCUTILS__STRNLEN_H_
+#define RCUTILS__STRNLEN_H_
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+#include "rcutils/macros.h"
+#include "rcutils/visibility_control.h"
+
+/// Determine the length of a fixed-size string
+/**
+ * \param[in] s Null terminated string to find the length of.
+ * \param[in] maxlen Maximum length to look to find the trailing \0.
+ * \return The length of the string if it is less than maxlen, or
+ * \return maxlen if there is no \0 among the first maxlen characters.
+ */
+RCUTILS_PUBLIC
+RCUTILS_WARN_UNUSED
+size_t
+rcutils_strnlen(const char * s, size_t maxlen);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  // RCUTILS__STRNLEN_H_

src/error_handling.c

@@ -25,12 +25,12 @@ extern "C"
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
-#define __STDC_WANT_LIB_EXT1__ 1
 #include <string.h>
 
 #include <rcutils/allocator.h>
 #include <rcutils/macros.h>
 #include <rcutils/strdup.h>
+#include <rcutils/strnlen.h>
 
 // RCUTILS_REPORT_ERROR_HANDLING_ERRORS and RCUTILS_WARN_ON_TRUNCATION are set in the header below
 #include "./error_handling_helpers.h"
@@ -199,11 +199,7 @@ rcutils_set_error_state(
   error_state.line_number = line_number;
 #if RCUTILS_REPORT_ERROR_HANDLING_ERRORS
   // Only warn of overwritting if the new error is different from the old ones.
-#ifdef __STDC_LIB_EXT1__
-  size_t characters_to_compare = strnlen_s(error_string, RCUTILS_ERROR_MESSAGE_MAX_LENGTH);
-#else
-  size_t characters_to_compare = strnlen(error_string, RCUTILS_ERROR_MESSAGE_MAX_LENGTH);
-#endif
+  size_t characters_to_compare = rcutils_strnlen(error_string, RCUTILS_ERROR_MESSAGE_MAX_LENGTH);
   // assumption is that message length is <= max error string length
   static_assert(
     sizeof(gtls_rcutils_error_state.message) <= sizeof(gtls_rcutils_error_string.str),

src/error_handling_helpers.h

@@ -36,10 +36,10 @@
 #endif
 #include <assert.h>
 #include <stdlib.h>
-#define __STDC_WANT_LIB_EXT1__ 1
 #include <string.h>
 
 #include <rcutils/error_handling.h>
+#include <rcutils/strnlen.h>
 
 #ifdef __cplusplus
 extern "C"
@@ -131,11 +131,7 @@ __rcutils_convert_uint64_t_into_c_str(uint64_t number, char * buffer, size_t buf
   buffer[i] = '\0';
 
   // reverse the string in place
-#ifdef __STDC_LIB_EXT1__
-  __rcutils_reverse_str(buffer, strnlen_s(buffer, 21));
-#else
-  __rcutils_reverse_str(buffer, strnlen(buffer, 21));
-#endif
+  __rcutils_reverse_str(buffer, rcutils_strnlen(buffer, 21));
 }
 
 // do not use externally, internal function which is only to be used by error_handling.c

src/strnlen.c

@@ -0,0 +1,24 @@
+// Copyright 2023 Open Source Robotics Foundation, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <string.h>
+
+#include "rcutils/strnlen.h"
+
+size_t
+rcutils_strnlen(const char * s, size_t maxlen)
+{
+  const char * found = memchr(s, '\0', maxlen);
+  return found ? (size_t)(found - s) : maxlen;
+}

test/test_error_handling_helpers.cpp

@@ -18,6 +18,8 @@
 
 #include "osrf_testing_tools_cpp/memory_tools/gtest_quickstart.hpp"
 
+#include "rcutils/strnlen.h"
+
 #include "../src/error_handling_helpers.h"
 
 TEST(test_error_handling, copy_string) {
@@ -32,7 +34,7 @@ TEST(test_error_handling, copy_string) {
     written = __rcutils_copy_string(buffer, 3, "0123456789");
   });
   EXPECT_EQ(written, 2u);
-  EXPECT_EQ(strnlen(buffer, sizeof(buffer)), 2u);
+  EXPECT_EQ(rcutils_strnlen(buffer, sizeof(buffer)), 2u);
   EXPECT_STREQ(buffer, "01");
 
   // normal truncation, 1 short of buffer length
@@ -41,7 +43,7 @@ TEST(test_error_handling, copy_string) {
     written = __rcutils_copy_string(buffer, 9, "0123456789");
   });
   EXPECT_EQ(written, 8u);
-  EXPECT_EQ(strnlen(buffer, sizeof(buffer)), 8u);
+  EXPECT_EQ(rcutils_strnlen(buffer, sizeof(buffer)), 8u);
   EXPECT_STREQ(buffer, "01234567");
 
   // input smaller than buffer, 1 short of buffer length
@@ -50,7 +52,7 @@ TEST(test_error_handling, copy_string) {
     written = __rcutils_copy_string(buffer, 9, "");
   });
   EXPECT_EQ(written, 0u);
-  EXPECT_EQ(strnlen(buffer, sizeof(buffer)), 0u);
+  EXPECT_EQ(rcutils_strnlen(buffer, sizeof(buffer)), 0u);
   EXPECT_STREQ(buffer, "");
 
   // copy where src and dst overlap (testing use of memmove vs memcpy)
@@ -65,7 +67,7 @@ TEST(test_error_handling, copy_string) {
     written = __rcutils_copy_string(buffer, sizeof(buffer), buffer + 3);
   });
   EXPECT_EQ(written, 6u);
-  EXPECT_EQ(strnlen(buffer, sizeof(buffer)), (sizeof(buffer) - 1) - 3);
+  EXPECT_EQ(rcutils_strnlen(buffer, sizeof(buffer)), (sizeof(buffer) - 1) - 3);
   EXPECT_STREQ(buffer, "456789");
 }
 
@@ -75,23 +77,23 @@ TEST(test_error_handling, reverse_str) {
     char buffer[] = "even";
     EXPECT_NO_MEMORY_OPERATIONS(
     {
-      __rcutils_reverse_str(buffer, strnlen(buffer, sizeof(buffer)));
+      __rcutils_reverse_str(buffer, rcutils_strnlen(buffer, sizeof(buffer)));
     });
     EXPECT_STREQ(buffer, "neve");
   }
   {
     char buffer[] = "reverseme";
     EXPECT_NO_MEMORY_OPERATIONS(
     {
-      __rcutils_reverse_str(buffer, strnlen(buffer, sizeof(buffer)));
+      __rcutils_reverse_str(buffer, rcutils_strnlen(buffer, sizeof(buffer)));
     });
     EXPECT_STREQ(buffer, "emesrever");
   }
   {
     char buffer[] = "a";
     EXPECT_NO_MEMORY_OPERATIONS(
     {
-      __rcutils_reverse_str(buffer, strnlen(buffer, sizeof(buffer)));
+      __rcutils_reverse_str(buffer, rcutils_strnlen(buffer, sizeof(buffer)));
     });
     EXPECT_STREQ(buffer, "a");
   }