Charusso updated this revision to Diff 140330.
Charusso marked 2 inline comments as done.
Charusso added a comment.

Fixed everything according to the comments.


https://reviews.llvm.org/D45050

Files:
  clang-tidy/bugprone/BugproneTidyModule.cpp
  clang-tidy/bugprone/CMakeLists.txt
  clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp
  clang-tidy/bugprone/NotNullTerminatedResultCheck.h
  docs/ReleaseNotes.rst
  docs/clang-tidy/checks/bugprone-not-null-terminated-result.rst
  docs/clang-tidy/checks/list.rst
  test/clang-tidy/bugprone-not-null-terminated-result-strlen-before-cxx11.cpp
  test/clang-tidy/bugprone-not-null-terminated-result-strlen-cxx11.cpp
  test/clang-tidy/bugprone-not-null-terminated-result-wcslen-before-cxx11.cpp
  test/clang-tidy/bugprone-not-null-terminated-result-wcslen-cxx11.cpp

Index: test/clang-tidy/bugprone-not-null-terminated-result-wcslen-cxx11.cpp
===================================================================
--- /dev/null
+++ test/clang-tidy/bugprone-not-null-terminated-result-wcslen-cxx11.cpp
@@ -0,0 +1,153 @@
+// RUN: %check_clang_tidy %s bugprone-not-null-terminated-result %t -- -- -std=c++11
+
+typedef unsigned int size_t;
+typedef int errno_t;
+size_t wcslen(const wchar_t *);
+wchar_t *wcschr(const wchar_t *, int);
+errno_t *wcsncpy_s(wchar_t *, const wchar_t *, size_t);
+
+void *alloca(size_t);
+void *calloc(size_t, size_t);
+void *malloc(size_t);
+void *realloc(void *, size_t);
+
+void *wmemcpy(void *, const void *, size_t);
+errno_t wmemcpy_s(void *, size_t, const void *, size_t);
+void *wmemchr(const void *, int, size_t);
+void *wmemmove(void *, const void *, size_t);
+errno_t wmemmove_s(void *, size_t, const void *, size_t);
+void *wmemset(void *, int, size_t);
+
+int wcsncmp(const wchar_t *, const wchar_t *, size_t);
+size_t wcsxfrm(wchar_t *, const wchar_t *, size_t);
+
+namespace std {
+using ::wcsncpy_s;
+using ::wmemcpy;
+using ::wcslen;
+}
+
+void bad_alloca(wchar_t *dest, const wchar_t *src) {
+  dest = (wchar_t *)alloca(wcslen(src));
+  // CHECK-MESSAGES: :[[@LINE-1]]:21: warning: 'alloca' function's allocated memory cannot hold the null-terminator [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: alloca(wcslen(src) + 1);
+}
+
+void good_alloca(wchar_t *dest, const wchar_t *src) {
+  dest = (wchar_t *)alloca(wcslen(src) + 1);
+}
+
+void bad_calloc(wchar_t *dest, const wchar_t *src) {
+  dest = (wchar_t *)calloc(wcslen(src), sizeof(wchar_t));
+  // CHECK-MESSAGES: :[[@LINE-1]]:21: warning: 'calloc' function's allocated memory cannot hold the null-terminator [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: calloc((wcslen(src) + 1), sizeof(wchar_t));
+}
+
+void good_calloc(wchar_t *dest, const wchar_t *src) {
+  dest = (wchar_t *)calloc((wcslen(src) + 1), sizeof(wchar_t));
+}
+
+void bad_malloc(wchar_t *dest, const wchar_t *src) {
+  dest = (wchar_t *)malloc(wcslen(src) * 2);
+  // CHECK-MESSAGES: :[[@LINE-1]]:21: warning: 'malloc' function's allocated memory cannot hold the null-terminator [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: malloc((wcslen(src) * 2) + 1);
+}
+
+void good_malloc(wchar_t *dest, const wchar_t *src) {
+  dest = (wchar_t *)malloc((wcslen(src) * 2) + 1);
+}
+
+void bad_realloc(wchar_t *dest, const wchar_t *src) {
+  dest = (wchar_t *)realloc(dest, (wcslen(dest) + wcslen(src)));
+  // CHECK-MESSAGES: :[[@LINE-1]]:21: warning: 'realloc' function's allocated memory cannot hold the null-terminator [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: realloc(dest, (wcslen(dest) + (wcslen(src) + 1)));
+}
+
+void good_realloc(wchar_t *dest, const wchar_t *src) {
+  dest = (wchar_t *)realloc(dest, (wcslen(dest) + (wcslen(src) + 1)));
+}
+
+void bad_wmemcpy(wchar_t *dest, const wchar_t *src) {
+  std::wmemcpy(dest, src, std::wcslen(src));
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: 'wmemcpy' function's result is not null-terminated [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: std::wcsncpy_s(dest, src, std::wcslen(src));
+}
+
+void good_wmemcpy_cxx11(wchar_t *dest, const wchar_t *src) {
+  std::wcsncpy_s(dest, src, std::wcslen(src));
+}
+
+void bad_wmemcpy_s(wchar_t *dest, const wchar_t *src) {
+  wmemcpy_s(dest, wcslen(dest), src, wcslen(src));
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: 'wmemcpy_s' function's result is not null-terminated [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: wcsncpy_s(dest, src, wcslen(src));
+}
+
+void good_wmemcpy_s(wchar_t *dest, const wchar_t *src) {
+  wcsncpy_s(dest, src, wcslen(src));
+}
+
+void bad_wmemchr(wchar_t *dest, const wchar_t *src) {
+  dest = (wchar_t *)wmemchr(src, '\0', wcslen(src));
+  // CHECK-MESSAGES: :[[@LINE-1]]:21: warning: 'wmemchr' function's result is not null-terminated [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: wcschr(src, '\0');
+}
+
+void good_wmemchr(wchar_t *dest, const wchar_t *src) {
+  dest = wcschr(src, '\0');
+}
+
+void bad_wmemmove(wchar_t *dest, const wchar_t *src) {
+  wmemmove(dest, src, wcslen(src));
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: 'wmemmove' function's result is not null-terminated [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: wmemmove_s(dest, wcslen(dest), src, (wcslen(src) + 1));
+}
+
+void good_wmemmove_cxx11(wchar_t *dest, const wchar_t *src) {
+  wmemmove_s(dest, wcslen(dest), src, (wcslen(src) + 1));
+}
+
+void bad_wmemmove_s(wchar_t *dest, const wchar_t *src) {
+  wmemmove_s(dest, wcslen(dest), src, wcslen(src));
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: 'wmemmove_s' function's result is not null-terminated [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: wmemmove_s(dest, wcslen(dest), src, (wcslen(src) + 1));
+}
+
+void good_wmemmove_s_1(wchar_t *dest, const wchar_t *src) {
+  wmemmove_s(dest, wcslen(dest), src, (wcslen(src) + 1));
+}
+
+void good_wmemmove_s_2(wchar_t *dest, const wchar_t *src) {
+  wmemmove_s(dest, wcslen(dest), (src + 1), wcslen(src));
+}
+
+void bad_wmemset(wchar_t *dest, const wchar_t *src) {
+  wmemset(dest, '-', (wcslen(src) + 1));
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: 'wmemset' function's result is not null-terminated [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: wmemset(dest, '-', wcslen(src));
+}
+
+void good_wmemset(wchar_t *dest, const wchar_t *src) {
+  wmemset(dest, '-', wcslen(src));
+}
+
+int bad_wcsncmp(const wchar_t *str1, const wchar_t *str2) {
+  return wcsncmp(str1, str2, (wcslen(str1) + 1));
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: 'wcsncmp' function's comparison's length is too long [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: wcsncmp(str1, str2, wcslen(str1));
+}
+
+int good_wcsncmp(const wchar_t *str1, const wchar_t *str2) {
+  return wcsncmp(str1, str2, wcslen(str1));
+}
+
+void bad_wcsxfrm(wchar_t *dest, const wchar_t *src) {
+  wcsxfrm(dest, src, wcslen(src));
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: 'wcsxfrm' function's result is not null-terminated [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: wcsxfrm(dest, src, (wcslen(src) + 1));
+}
+
+void good_wcsxfrm(wchar_t *dest, const wchar_t *src) {
+  wcsxfrm(dest, src, (wcslen(src) + 1));
+}
+
Index: test/clang-tidy/bugprone-not-null-terminated-result-wcslen-before-cxx11.cpp
===================================================================
--- /dev/null
+++ test/clang-tidy/bugprone-not-null-terminated-result-wcslen-before-cxx11.cpp
@@ -0,0 +1,33 @@
+// RUN: %check_clang_tidy %s bugprone-not-null-terminated-result %t -- -- -std=c++98
+
+typedef unsigned int size_t;
+size_t wcslen(const char *);
+char *wcsncpy(char *, const char *, size_t);
+
+void *wmemcpy(void *, const void *, size_t);
+void *wmemmove(void *, const void *, size_t);
+
+void bad_wmemcpy(char *dest, const char *src) {
+  wmemcpy(dest, src, wcslen(src));
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: 'wmemcpy' function's result is not null-terminated [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: wcsncpy(dest, src, (wcslen(src) + 1));
+}
+
+void good_wmemcpy_not_cxx11(char *dest, const char *src) {
+  wcsncpy(dest, src, (wcslen(src) + 1));
+}
+
+void bad_wmemmove(char *dest, const char *src) {
+  wmemmove(dest, src, wcslen(src));
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: 'wmemmove' function's result is not null-terminated [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: wmemmove(dest, src, (wcslen(src) + 1));
+}
+
+void good_wmemmove_not_cxx11_1(char *dest, const char *src) {
+  wmemmove(dest, src, (wcslen(src) + 1));
+}
+
+void good_wmemmove_not_cxx11_2(char *dest, const char *src) {
+  wmemmove(dest, (src + 1), wcslen(src));
+}
+
Index: test/clang-tidy/bugprone-not-null-terminated-result-strlen-cxx11.cpp
===================================================================
--- /dev/null
+++ test/clang-tidy/bugprone-not-null-terminated-result-strlen-cxx11.cpp
@@ -0,0 +1,167 @@
+// RUN: %check_clang_tidy %s bugprone-not-null-terminated-result %t -- -- -std=c++11
+
+typedef unsigned int size_t;
+typedef int errno_t;
+size_t strlen(const char *);
+char *strerror(int);
+char *strchr(const char *, int);
+errno_t *strncpy_s(char *, const char *, size_t);
+
+void *alloca(size_t);
+void *calloc(size_t, size_t);
+void *malloc(size_t);
+void *realloc(void *, size_t);
+
+void *memcpy(void *, const void *, size_t);
+errno_t memcpy_s(void *, size_t, const void *, size_t);
+void *memchr(const void *, int, size_t);
+void *memmove(void *, const void *, size_t);
+errno_t memmove_s(void *, size_t, const void *, size_t);
+void *memset(void *, int, size_t);
+
+errno_t strerror_s(char *, size_t, int);
+int strncmp(const char *, const char *, size_t);
+size_t strxfrm(char *, const char *, size_t);
+
+namespace std {
+using ::memcpy;
+using ::strlen;
+using ::strncpy_s;
+} // namespace std
+
+void bad_alloca(char *dest, const char *src) {
+  dest = (char *)alloca(strlen(src));
+  // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: 'alloca' function's allocated memory cannot hold the null-terminator [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: alloca(strlen(src) + 1);
+}
+
+void good_alloca(char *dest, const char *src) {
+  dest = (char *)alloca(strlen(src) + 1);
+}
+
+void bad_calloc(char *dest, const char *src) {
+  dest = (char *)calloc(strlen(src), sizeof(char));
+  // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: 'calloc' function's allocated memory cannot hold the null-terminator [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: calloc((strlen(src) + 1), sizeof(char));
+}
+
+void good_calloc(char *dest, const char *src) {
+  dest = (char *)calloc((strlen(src) + 1), sizeof(char));
+}
+
+void bad_malloc(char *dest, const char *src) {
+  dest = (char *)malloc(strlen(src) * 2);
+  // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: 'malloc' function's allocated memory cannot hold the null-terminator [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: malloc((strlen(src) * 2) + 1);
+}
+
+void good_malloc(char *dest, const char *src) {
+  dest = (char *)malloc((strlen(src) * 2) + 1);
+}
+
+void bad_realloc(char *dest, const char *src) {
+  dest = (char *)realloc(dest, (strlen(dest) + strlen(src)));
+  // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: 'realloc' function's allocated memory cannot hold the null-terminator [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: realloc(dest, (strlen(dest) + (strlen(src) + 1)));
+}
+
+void good_realloc(char *dest, const char *src) {
+  dest = (char *)realloc(dest, (strlen(dest) + (strlen(src) + 1)));
+}
+
+void bad_memcpy(char *dest, const char *src) {
+  std::memcpy(dest, src, std::strlen(src));
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: 'memcpy' function's result is not null-terminated [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: std::strncpy_s(dest, src, std::strlen(src));
+}
+
+void good_memcpy_cxx11(char *dest, const char *src) {
+  std::strncpy_s(dest, src, std::strlen(src));
+}
+
+void bad_memcpy_s(char *dest, const char *src) {
+  memcpy_s(dest, strlen(dest), src, strlen(src));
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: 'memcpy_s' function's result is not null-terminated [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: strncpy_s(dest, src, strlen(src));
+}
+
+void good_memcpy_s(char *dest, const char *src) {
+  strncpy_s(dest, src, strlen(src));
+}
+
+void bad_memchr(char *dest, const char *src) {
+  dest = (char *)memchr(src, '\0', strlen(src));
+  // CHECK-MESSAGES: :[[@LINE-1]]:18: warning: 'memchr' function's result is not null-terminated [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: strchr(src, '\0');
+}
+
+void good_memchr(char *dest, const char *src) {
+  dest = strchr(src, '\0');
+}
+
+void bad_memmove(char *dest, const char *src) {
+  memmove(dest, src, strlen(src));
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: 'memmove' function's result is not null-terminated [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: memmove_s(dest, strlen(dest), src, (strlen(src) + 1));
+}
+
+void good_memmove_cxx11(char *dest, const char *src) {
+  memmove_s(dest, strlen(dest), src, (strlen(src) + 1));
+}
+
+void bad_memmove_s(char *dest, const char *src) {
+  memmove_s(dest, strlen(dest), src, strlen(src));
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: 'memmove_s' function's result is not null-terminated [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: memmove_s(dest, strlen(dest), src, (strlen(src) + 1));
+}
+
+void good_memmove_s_1(char *dest, const char *src) {
+  memmove_s(dest, strlen(dest), src, (strlen(src) + 1));
+}
+
+void good_memmove_s_2(char *dest, const char *src) {
+  memmove_s(dest, strlen(dest), (src + 1), strlen(src));
+}
+
+void bad_memset(char *dest, const char *src) {
+  memset(dest, '-', (strlen(src) + 1));
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: 'memset' function's result is not null-terminated [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: memset(dest, '-', strlen(src));
+}
+
+void good_memset(char *dest, const char *src) {
+  memset(dest, '-', strlen(src));
+}
+
+void bad_strerror_s(char *dest, int errno) {
+  strerror_s(dest, strlen(strerror(errno)), errno);
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: 'strerror_s' function's result is not null-terminated and missing the last character of the error message [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: strerror_s(dest, (strlen(strerror(errno)) + 1), errno);
+}
+
+void good_strerror_s(char *dest, int errno) {
+  strerror_s(dest, (strlen(strerror(errno)) + 1), errno);
+}
+
+int bad_strncmp(char *str1, const char *str2) {
+  return strncmp(str1, str2, (strlen(str1) + 1));
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: 'strncmp' function's comparison's length is too long [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: strncmp(str1, str2, strlen(str1));
+}
+
+int good_strncmp(const char *str1, const char *str2) {
+  return strncmp(str1, str2, strlen(str1));
+}
+
+void bad_strxfrm(char *long_destination_name, const char *long_source_name) {
+  strxfrm(long_destination_name, long_source_name,
+          strlen(long_source_name));
+  // CHECK-MESSAGES: :[[@LINE-2]]:3: warning: 'strxfrm' function's result is not null-terminated [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: strxfrm(long_destination_name, long_source_name,
+  // CHECK-FIXES-NEXT: strlen(long_source_name) + 1);
+}
+
+void good_strxfrm(char *long_destination_name, const char *long_source_name) {
+  strxfrm(long_destination_name, long_source_name,
+          (strlen(long_source_name) + 1));
+}
Index: test/clang-tidy/bugprone-not-null-terminated-result-strlen-before-cxx11.cpp
===================================================================
--- /dev/null
+++ test/clang-tidy/bugprone-not-null-terminated-result-strlen-before-cxx11.cpp
@@ -0,0 +1,33 @@
+// RUN: %check_clang_tidy %s bugprone-not-null-terminated-result %t -- -- -std=c++98
+
+typedef unsigned int size_t;
+size_t strlen(const char *);
+char *strncpy(char *, const char *, size_t);
+
+void *memcpy(void *, const void *, size_t);
+void *memmove(void *, const void *, size_t);
+
+void bad_memcpy(char *dest, const char *src) {
+  memcpy(dest, src, strlen(src));
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: 'memcpy' function's result is not null-terminated [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: strncpy(dest, src, (strlen(src) + 1));
+}
+
+void good_memcpy_not_cxx11(char *dest, const char *src) {
+  strncpy(dest, src, (strlen(src) + 1));
+}
+
+void bad_memmove(char *dest, const char *src) {
+  memmove(dest, src, strlen(src));
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: 'memmove' function's result is not null-terminated [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: memmove(dest, src, (strlen(src) + 1));
+}
+
+void good_memmove_not_cxx11_1(char *dest, const char *src) {
+  memmove(dest, src, (strlen(src) + 1));
+}
+
+void good_memmove_not_cxx11_2(char *dest, const char *src) {
+  memmove(dest, (src + 1), strlen(src));
+}
+
Index: docs/clang-tidy/checks/list.rst
===================================================================
--- docs/clang-tidy/checks/list.rst
+++ docs/clang-tidy/checks/list.rst
@@ -36,6 +36,7 @@
    bugprone-misplaced-widening-cast
    bugprone-move-forwarding-reference
    bugprone-multiple-statement-macro
+   bugprone-not-null-terminated-result
    bugprone-sizeof-container
    bugprone-sizeof-expression
    bugprone-string-constructor
Index: docs/clang-tidy/checks/bugprone-not-null-terminated-result.rst
===================================================================
--- /dev/null
+++ docs/clang-tidy/checks/bugprone-not-null-terminated-result.rst
@@ -0,0 +1,94 @@
+.. title:: clang-tidy - bugprone-not-null-terminated-result
+
+bugprone-not-null-terminated-result
+===================================
+
+Finds function calls where ``strlen`` or ``wcslen`` function is passed as an
+argument and caused a not null-terminated result. Depending on the case of
+use, it may insert or remove the increase operation to ensure the result is
+null-terminated.
+
+The following function calls are checked:
+
+``alloca``, ``calloc``, ``malloc``, ``realloc``, ``memcpy``, ``wmemcpy``,
+``memcpy_s``, ``wmemcpy_s``, ``memchr``, ``wmemchr``, ``memmove``, ``wmemmove``,
+``memmove_s``, ``wmemmove_s``, ``memset``, ``wmemset``, ``strerror_s``,
+``strncmp``, ``wcsncmp``, ``strxfrm``, ``wcsxfrm``
+
+The following is a real-world example where the programmer forgot to increase
+the passed third argument, which is ``size_t length``. The proper length is
+``strlen(src) + 1`` because the null-terminator need an extra space. The result
+is badly not-null-terminated:
+
+.. code-block:: c
+
+  void bad_memcpy(char *dest, const char *src) {
+    memcpy(dest, src, strlen(src));
+  }
+
+In addition to issuing warnings, fix-it rewrites all the necessary code
+depending on the version number. The upper code would be the following:
+
+- If C++11 is the target fix-it will rewrite it to the most safe function:
+
+.. code-block:: c++
+
+  void good_memcpy_cxx11(char *dest, const char *src) {
+    strncpy_s(dest, src, strlen(src));
+  }
+
+- otherwise fix-it will rewrite it to a safer function, that born before C++11:
+
+.. code-block:: c
+
+  void good_memcpy_not_cxx11(char *dest, const char *src) {
+    strncpy(dest, src, (strlen(src) + 1));
+  }
+
+In general, the following transformations are could happen:
+
+**Memory allocation functions**
+
+- ``alloca`` function's argument gets a ``+ 1`` operation.
+
+- ``calloc`` function's first argument gets a ``+ 1`` operation.
+
+- ``malloc`` function's argument gets a ``+ 1`` operation.
+
+- ``realloc`` function's second argument gets a ``+ 1`` operation.
+
+**Memory handler functions**
+
+- ``memcpy``, ``wmemcpy``:
+  - C++11: New function is ``strncpy_s``/``wcsncpy_s``, where no ``+ 1`` needed.
+  
+  - Not C++11: New function is ``strncpy``, where ``+ 1`` needed.
+
+- ``memchr``, ``wmemchr``:
+  - Usually there is a C-style cast, and it is needed to be removed, because the
+    new function ``strchr``/``wcschr``'s return type is correct.
+  - Also the third argument is not needed.
+
+- ``memmove``, ``wmemmove``:
+  - C++11: New function is ``memmmove_s``/``wmemmove_s``, it has four arguments,
+  - the new second argument is the first argument's length, and
+  - the third argument will be moved as the fourth, where ``+ 1`` needed.
+
+  - Not C++11: The third argument gets a ``+ 1`` operation.
+
+- ``memmove_s``/``wmemmove_s``:
+  - The function's fourth argument gets a ``+ 1`` operation.
+
+- ``memset``/``wmemset``:
+  - The function's third argument has to be truncated without the ``+ 1`` part.
+
+**Character functions**
+
+- ``strerror_s`` functions's second argument get a ``+ 1`` operation.
+
+- ``strncmp``/``wcsncmp``:
+  - If the third argument is the first or the second argument's ``length + 1``,
+    then it has to be truncated without the ``+ 1`` operation.
+
+- ``strxfrm``/``wcsxfrm`` function's third argument gets a ``+ 1`` operation.
+
Index: docs/ReleaseNotes.rst
===================================================================
--- docs/ReleaseNotes.rst
+++ docs/ReleaseNotes.rst
@@ -57,126 +57,144 @@
 Improvements to clang-tidy
 --------------------------
 
+- New module `abseil` for checks related to the `Abseil <https://abseil.io>`_
+  library.
+
 - New module ``portability``.
 
 - New module ``zircon`` for checks related to Fuchsia's Zircon kernel.
 
-- New `bugprone-throw-keyword-missing
-  <http://clang.llvm.org/extra/clang-tidy/checks/bugprone-throw-keyword-missing.html>`_ check
+- New :doc:`bugprone-not-null-terminated-result
+  <clang-tidy/checks/bugprone-not-null-terminated-result>` check
+
+  Finds function calls where ``strlen`` or ``wcslen`` function is passed as an
+  argument and caused a not null-terminated result. Depending on the case of
+  use, it may insert or remove the increase operation to ensure the result is
+  null-terminated.
+
+- New :doc:`bugprone-throw-keyword-missing
+  <clang-tidy/checks/bugprone-throw-keyword-missing>` check
 
   Diagnoses when a temporary object that appears to be an exception is
   constructed but not thrown.
 
-- New `cppcoreguidelines-avoid-goto
-  <http://clang.llvm.org/extra/clang-tidy/checks/cppcoreguidelines-avoid-goto.html>`_ check
+- New :doc:`bugprone-unused-return-value
+  <clang-tidy/checks/bugprone-unused-return-value>` check
+
+  Warns on unused function return values.
+
+- New :doc:`cppcoreguidelines-avoid-goto
+  <clang-tidy/checks/cppcoreguidelines-avoid-goto>` check
 
   The usage of ``goto`` for control flow is error prone and should be replaced
   with looping constructs. Every backward jump is rejected. Forward jumps are
   only allowed in nested loops.
 
-- New `fuchsia-multiple-inheritance
-  <http://clang.llvm.org/extra/clang-tidy/checks/fuchsia-multiple-inheritance.html>`_ check
+- New :doc:`fuchsia-multiple-inheritance
+  <clang-tidy/checks/fuchsia-multiple-inheritance>` check
 
   Warns if a class inherits from multiple classes that are not pure virtual.
 
-- New `abseil` module for checks related to the `Abseil <https://abseil.io>`_
-  library.
-
-- New `abseil-string-find-startswith
-  <http://clang.llvm.org/extra/clang-tidy/checks/abseil-string-find-startswith.html>`_ check
+- New :doc:`abseil-string-find-startswith
+  <clang-tidy/checks/abseil-string-find-startswith>` check
 
   Checks whether a ``std::string::find()`` result is compared with 0, and
   suggests replacing with ``absl::StartsWith()``.
 
-- New `fuchsia-statically-constructed-objects
-  <http://clang.llvm.org/extra/clang-tidy/checks/fuchsia-statically-constructed-objects.html>`_ check
+- New :doc:`fuchsia-statically-constructed-objects
+  <clang-tidy/checks/fuchsia-statically-constructed-objects>` check
 
   Warns if global, non-trivial objects with static storage are constructed,
   unless the object is statically initialized with a ``constexpr`` constructor
   or has no explicit constructor.
 
-- New `fuchsia-trailing-return
-  <http://clang.llvm.org/extra/clang-tidy/checks/fuchsia-trailing-return.html>`_ check
+- New :doc:`fuchsia-trailing-return
+  <clang-tidy/checks/fuchsia-trailing-return>` check
 
   Functions that have trailing returns are disallowed, except for those
   using ``decltype`` specifiers and lambda with otherwise unutterable
   return types.
 
-- New `modernize-use-uncaught-exceptions
-  <http://clang.llvm.org/extra/clang-tidy/checks/modernize-use-uncaught-exceptions.html>`_ check
+- New :doc:`hicpp-multiway-paths-covered
+  <clang-tidy/checks/hicpp-multiway-paths-covered>` check
+
+  Checks on ``switch`` and ``if`` - ``else if`` constructs that do not cover all possible code paths.
+
+- New :doc:`modernize-use-uncaught-exceptions
+  <clang-tidy/checks/modernize-use-uncaught-exceptions>` check
 
   Finds and replaces deprecated uses of ``std::uncaught_exception`` to
   ``std::uncaught_exceptions``.
 
-- New `portability-simd-intrinsics
-  <http://clang.llvm.org/extra/clang-tidy/checks/portability-simd-intrinsics.html>`_ check
+- New :doc:`portability-simd-intrinsics
+  <clang-tidy/checks/portability-simd-intrinsics>` check
 
   Warns or suggests alternatives if SIMD intrinsics are used which can be replaced by
   ``std::experimental::simd`` operations.
 
-- New `zircon-temporary-objects
-  <http://clang.llvm.org/extra/clang-tidy/checks/zircon-temporary-objects.html>`_ check
+- New :doc:`zircon-temporary-objects
+  <clang-tidy/checks/zircon-temporary-objects>` check
 
   Warns on construction of specific temporary objects in the Zircon kernel.
 
-- New alias `hicpp-avoid-goto
-  <http://clang.llvm.org/extra/clang-tidy/checks/hicpp-avoid-goto.html>`_ to
-  `cppcoreguidelines-avoid-goto <http://clang.llvm.org/extra/clang-tidy/checks/cppcoreguidelines-avoid-goto.html>`_
+- New alias :doc:`hicpp-avoid-goto
+  <clang-tidy/checks/hicpp-avoid-goto>` to :doc:`cppcoreguidelines-avoid-goto
+  <clang-tidy/checks/cppcoreguidelines-avoid-goto>`
   added.
 
-- The 'misc-forwarding-reference-overload' check was renamed to `bugprone-forwarding-reference-overload
-  <http://clang.llvm.org/extra/clang-tidy/checks/bugprone-forwarding-reference-overload.html>`_
+- The 'misc-forwarding-reference-overload' check was renamed to :doc:`bugprone-forwarding-reference-overload
+  <clang-tidy/checks/bugprone-forwarding-reference-overload>`
 
-- The 'misc-incorrect-roundings' check was renamed to `bugprone-incorrect-roundings
-  <http://clang.llvm.org/extra/clang-tidy/checks/bugprone-incorrect-roundings.html>`_
+- The 'misc-incorrect-roundings' check was renamed to :doc:`bugprone-incorrect-roundings
+  <clang-tidy/checks/bugprone-incorrect-roundings>`
 
-- The 'misc-lambda-function-name' check was renamed to `bugprone-lambda-function-name
-  <http://clang.llvm.org/extra/clang-tidy/checks/bugprone-lambda-function-name.html>`_
+- The 'misc-lambda-function-name' check was renamed to :doc:`bugprone-lambda-function-name
+  <clang-tidy/checks/bugprone-lambda-function-name>`
 
-- The 'misc-macro-parentheses' check was renamed to `bugprone-macro-parentheses
-  <http://clang.llvm.org/extra/clang-tidy/checks/bugprone-macro-parentheses.html>`_
+- The 'misc-macro-parentheses' check was renamed to :doc:`bugprone-macro-parentheses
+  <clang-tidy/checks/bugprone-macro-parentheses>`
 
-- The 'misc-macro-repeated-side-effects' check was renamed to `bugprone-macro-repeated-side-effects
-  <http://clang.llvm.org/extra/clang-tidy/checks/bugprone-macro-repeated-side-effects.html>`_
+- The 'misc-macro-repeated-side-effects' check was renamed to :doc:`bugprone-macro-repeated-side-effects
+  <clang-tidy/checks/bugprone-macro-repeated-side-effects>`
 
-- The 'misc-misplaced-widening-cast' check was renamed to `bugprone-misplaced-widening-cast
-  <http://clang.llvm.org/extra/clang-tidy/checks/bugprone-misplaced-widening-cast.html>`_
+- The 'misc-misplaced-widening-cast' check was renamed to :doc:`bugprone-misplaced-widening-cast
+  <clang-tidy/checks/bugprone-misplaced-widening-cast>`
 
-- The 'misc-sizeof-container' check was renamed to `bugprone-sizeof-container
-  <http://clang.llvm.org/extra/clang-tidy/checks/bugprone-sizeof-container.html>`_
+- The 'misc-sizeof-container' check was renamed to :doc:`bugprone-sizeof-container
+  <clang-tidy/checks/bugprone-sizeof-container>`
 
-- The 'misc-sizeof-expression' check was renamed to `bugprone-sizeof-expression
-  <http://clang.llvm.org/extra/clang-tidy/checks/bugprone-sizeof-expression.html>`_
+- The 'misc-sizeof-expression' check was renamed to :doc:`bugprone-sizeof-expression
+  <clang-tidy/checks/bugprone-sizeof-expression>`
 
-- The 'misc-string-compare' check was renamed to `readability-string-compare
-  <http://clang.llvm.org/extra/clang-tidy/checks/readability-string-compare.html>`_
+- The 'misc-string-compare' check was renamed to :doc:`readability-string-compare
+  <clang-tidy/checks/readability-string-compare>`
 
-- The 'misc-string-integer-assignment' check was renamed to `bugprone-string-integer-assignment
-  <http://clang.llvm.org/extra/clang-tidy/checks/bugprone-string-integer-assignment.html>`_
+- The 'misc-string-integer-assignment' check was renamed to :doc:`bugprone-string-integer-assignment
+  <clang-tidy/checks/bugprone-string-integer-assignment>`
 
-- The 'misc-string-literal-with-embedded-nul' check was renamed to `bugprone-string-literal-with-embedded-nul
-  <http://clang.llvm.org/extra/clang-tidy/checks/bugprone-string-literal-with-embedded-nul.html>`_
+- The 'misc-string-literal-with-embedded-nul' check was renamed to :doc:`bugprone-string-literal-with-embedded-nul
+  <clang-tidy/checks/bugprone-string-literal-with-embedded-nul>`
 
-- The 'misc-suspicious-enum-usage' check was renamed to `bugprone-suspicious-enum-usage
-  <http://clang.llvm.org/extra/clang-tidy/checks/bugprone-suspicious-enum-usage.html>`_
+- The 'misc-suspicious-enum-usage' check was renamed to :doc:`bugprone-suspicious-enum-usage
+  <clang-tidy/checks/bugprone-suspicious-enum-usage>`
 
-- The 'misc-suspicious-missing-comma' check was renamed to `bugprone-suspicious-missing-comma
-  <http://clang.llvm.org/extra/clang-tidy/checks/bugprone-suspicious-missing-comma.html>`_
+- The 'misc-suspicious-missing-comma' check was renamed to :doc:`bugprone-suspicious-missing-comma
+  <clang-tidy/checks/bugprone-suspicious-missing-comma>`
 
-- The 'misc-suspicious-semicolon' check was renamed to `bugprone-suspicious-semicolon
-  <http://clang.llvm.org/extra/clang-tidy/checks/bugprone-suspicious-semicolon.html>`_
+- The 'misc-suspicious-semicolon' check was renamed to :doc:`bugprone-suspicious-semicolon
+  <clang-tidy/checks/bugprone-suspicious-semicolon>`
 
-- The 'misc-suspicious-string-compare' check was renamed to `bugprone-suspicious-string-compare
-  <http://clang.llvm.org/extra/clang-tidy/checks/bugprone-suspicious-string-compare.html>`_
+- The 'misc-suspicious-string-compare' check was renamed to :doc:`bugprone-suspicious-string-compare
+  <clang-tidy/checks/bugprone-suspicious-string-compare>`
 
-- The 'misc-swapped-arguments' check was renamed to `bugprone-swapped-arguments
-  <http://clang.llvm.org/extra/clang-tidy/checks/bugprone-swapped-arguments.html>`_
+- The 'misc-swapped-arguments' check was renamed to :doc:`bugprone-swapped-arguments
+  <clang-tidy/checks/bugprone-swapped-arguments>`
 
-- The 'misc-undelegated-constructor' check was renamed to `bugprone-undelegated-constructor
-  <http://clang.llvm.org/extra/clang-tidy/checks/bugprone-undelegated-constructor.html>`_
+- The 'misc-undelegated-constructor' check was renamed to :doc:`bugprone-undelegated-constructor
+  <clang-tidy/checks/bugprone-undelegated-constructor>`
 
-- The 'misc-unused-raii' check was renamed to `bugprone-unused-raii
-  <http://clang.llvm.org/extra/clang-tidy/checks/bugprone-unused-raii.html>`_
+- The 'misc-unused-raii' check was renamed to :doc:`bugprone-unused-raii
+  <clang-tidy/checks/bugprone-unused-raii>`
 
 Improvements to include-fixer
 -----------------------------
Index: clang-tidy/bugprone/NotNullTerminatedResultCheck.h
===================================================================
--- /dev/null
+++ clang-tidy/bugprone/NotNullTerminatedResultCheck.h
@@ -0,0 +1,77 @@
+//===--------------- NotNullTerminatedResultCheck.h - clang-tidy-*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_NOT_NULL_TERMINATED_RESULT_H
+#define LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_NOT_NULL_TERMINATED_RESULT_H
+
+#include "../ClangTidy.h"
+
+namespace clang {
+namespace tidy {
+namespace bugprone {
+
+/// Finds function calls where ``strlen`` or ``wcslen`` function is passed as an
+/// argument and caused a not null-terminated result. Depending on the case of
+/// use, it may insert or remove the increase operation to ensure the result is
+/// null-terminated.
+///
+/// For the user-facing documentation see:
+/// http://clang.llvm.org/extra/clang-tidy/checks/bugprone-not-null-terminated-result.html
+class NotNullTerminatedResultCheck : public ClangTidyCheck {
+public:
+  NotNullTerminatedResultCheck(StringRef Name, ClangTidyContext *Context)
+      : ClangTidyCheck(Name, Context) {}
+  void registerMatchers(ast_matchers::MatchFinder *Finder) override;
+  void check(const ast_matchers::MatchFinder::MatchResult &Result) override;
+
+private:
+  void memAllocFuncFix(StringRef Name,
+                       const ast_matchers::MatchFinder::MatchResult &Result);
+  void memHandlerFuncFix(StringRef Name,
+                         const ast_matchers::MatchFinder::MatchResult &Result);
+  void memcpyFix(StringRef Name,
+                 const ast_matchers::MatchFinder::MatchResult &Result,
+                 DiagnosticBuilder &Diag);
+  void memcpy_sFix(StringRef Name,
+                   const ast_matchers::MatchFinder::MatchResult &Result,
+                   DiagnosticBuilder &Diag);
+  void memchrFix(StringRef Name,
+                 const ast_matchers::MatchFinder::MatchResult &Result,
+                 DiagnosticBuilder &Diag);
+  void memmoveFix(StringRef Name,
+                  const ast_matchers::MatchFinder::MatchResult &Result);
+  void memmove_sFix(StringRef Name,
+                    const ast_matchers::MatchFinder::MatchResult &Result);
+  void characterFuncFix(StringRef Name,
+                        const ast_matchers::MatchFinder::MatchResult &Result);
+  void strerror_sFix(const ast_matchers::MatchFinder::MatchResult &Result);
+  void ncmpFix(StringRef Name,
+               const ast_matchers::MatchFinder::MatchResult &Result);
+  void xfrmFix(StringRef Name,
+               const ast_matchers::MatchFinder::MatchResult &Result);
+  void
+  lengthArgInsertIncByOne(const int ArgPos,
+                          const ast_matchers::MatchFinder::MatchResult &Result,
+                          DiagnosticBuilder &Diag);
+  void
+  lengthArgRemoveIncByOne(const ast_matchers::MatchFinder::MatchResult &Result,
+                          DiagnosticBuilder &Diag);
+  void removeArg(const int ArgPos,
+                 const ast_matchers::MatchFinder::MatchResult &Result,
+                 DiagnosticBuilder &Diag);
+  void renameFunc(StringRef NewFuncName,
+                  const ast_matchers::MatchFinder::MatchResult &Result,
+                  DiagnosticBuilder &Diag);
+};
+
+} // namespace bugprone
+} // namespace tidy
+} // namespace clang
+
+#endif // LLVM_CLANG_TOOLS_EXTRA_CLANG_TIDY_BUGPRONE_NOT_NULL_TERMINATED_RESULT_H
Index: clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp
===================================================================
--- /dev/null
+++ clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp
@@ -0,0 +1,435 @@
+//===------------- NotNullTerminatedResultCheck.cpp - clang-tidy-*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "NotNullTerminatedResultCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Lex/Lexer.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace bugprone {
+
+static std::string exprToStr(const Expr *Expr,
+                             const MatchFinder::MatchResult &Result) {
+  return Lexer::getSourceText(
+      CharSourceRange::getTokenRange(Expr->getSourceRange()),
+      *Result.SourceManager, Result.Context->getLangOpts(), 0);
+}
+
+static SourceLocation exprLocEnd(const Expr *Expr,
+                                 const MatchFinder::MatchResult &Result) {
+  return Lexer::getLocForEndOfToken(Expr->getLocEnd(), 0, *Result.SourceManager,
+                                    Result.Context->getLangOpts());
+}
+
+static bool isInsideParentheses(const Expr *Expr,
+                                const MatchFinder::MatchResult &Result) {
+  auto NewExpr = const_cast<clang::Expr *>(Expr);
+  ParenExpr *PE = new (Result.Context)
+      ParenExpr(NewExpr->getLocStart().getLocWithOffset(-1),
+                NewExpr->getLocEnd().getLocWithOffset(1), NewExpr);
+  return Expr == PE->getSubExpr();
+}
+
+/// Sometimes the 'memmove' function is in use to trim the text until it matches
+/// to a specific condition. For example a .CSV file's line would be trimmed
+/// from ' "data_name", "data", ' to just 'data' by "memmoving" it char-by-char.
+bool isTrimFunc(const MatchFinder::MatchResult &Result) {
+  const auto *FuncExpr = Result.Nodes.getNodeAs<CallExpr>("expr");
+  const int ArgPos = FuncExpr->getNumArgs() - 2;
+
+  // This is the following structure: (dest, (src + 1), strlen(src))
+  //                          LHSStr:         ~~~
+  //                          RHSStr:               ~
+  //                    StrLenArgStr:                          ~~~
+  if (const auto *BinOp = dyn_cast<BinaryOperator>(
+          FuncExpr->getArg(ArgPos)->IgnoreParenCasts())) {
+    std::string LHSStr = exprToStr(BinOp->getLHS()->IgnoreParens(), Result);
+    std::string RHSStr = exprToStr(BinOp->getRHS()->IgnoreParens(), Result);
+    std::string StrLenArgStr = exprToStr(
+        Result.Nodes.getNodeAs<CallExpr>("length-call")->getArg(0), Result);
+
+    return StrLenArgStr == LHSStr || StrLenArgStr == RHSStr;
+  }
+  return false;
+}
+
+void NotNullTerminatedResultCheck::registerMatchers(MatchFinder *Finder) {
+  // The following function's expression binding is necessary because some of
+  // the functions create double binding on the same function call.
+  const auto LengthCall =
+      callExpr(callee(functionDecl(hasAnyName("strlen", "wcslen"))),
+               expr().bind("length-call"));
+
+  const auto IsNotPlusOperator = unless(hasOperatorName("+"));
+
+  const auto HasIntOperand =
+      hasEitherOperand(ignoringParenImpCasts(integerLiteral()));
+
+  const auto HasInc = binaryOperator(hasOperatorName("+"), HasIntOperand);
+
+  // The following 3 case match 'strlen' or 'wcslen' function calls where no
+  // increase by one operation found.
+  //- Simple case: strlen(src) or wcslen(src)
+  const auto SimpleWithoutInc = LengthCall.bind("length-wout-inc-simp");
+
+  //- Complex case: (strlen(src) * 2) or (wcslen(src) * 2)
+  const auto ComplexWithoutInc =
+      binaryOperator(IsNotPlusOperator, hasEitherOperand(LengthCall))
+          .bind("length-wout-inc-comp");
+
+  //- Complex case: (strlen(dest) + strlen(src)) or (wcslen(dest) + wcslen(src))
+  const auto ComplexTwoWithoutInc =
+      allOf(binaryOperator(hasOperatorName("+"), unless(HasIntOperand)),
+            binaryOperator(hasOperatorName("+"), hasLHS(LengthCall),
+                           hasRHS(LengthCall))
+                .bind("length-wout-inc-comp"));
+
+  const auto LengthWithoutInc =
+      anyOf(SimpleWithoutInc, ComplexWithoutInc, ComplexTwoWithoutInc);
+
+  // The following 2 case match 'strlen' or 'wcslen' function calls where
+  // increase by one operation found.
+  //- Simple case: (strlen(src) + 1) or (wcslen(src) + 1)
+  const auto SimpleWithInc =
+      allOf(HasInc,
+            binaryOperator(hasEitherOperand(LengthCall.bind("inner-operator")))
+                .bind("outer-operator"));
+
+  //- Complex case: ((strlen(src) / 2) + 1) or ((wcslen(src) / 2) + 1)
+  const auto ComplexWithInc = allOf(
+      HasInc, binaryOperator(has(binaryOperator(unless(hasOperatorName("+")),
+                                                hasEitherOperand(LengthCall))
+                                     .bind("inner-operator")))
+                  .bind("outer-operator"));
+
+  const auto LengthWithInc = anyOf(SimpleWithInc, ComplexWithInc);
+
+  enum StrLenKind { WithInc, WithoutInc };
+
+  const auto Matcher = [=](StringRef Name, const int ArgCount, const int ArgPos,
+                           StrLenKind Kind) {
+    if (Kind == StrLenKind::WithoutInc) {
+      return allOf(callee(functionDecl(hasName(Name))),
+                   argumentCountIs(ArgCount),
+                   hasArgument(ArgPos, LengthWithoutInc));
+    } else {
+      return allOf(callee(functionDecl(hasName(Name))),
+                   argumentCountIs(ArgCount),
+                   hasArgument(ArgPos, LengthWithInc));
+    }
+  };
+
+  // clang-format off
+  const auto Alloca =     Matcher("alloca",     1, 0, StrLenKind::WithoutInc);
+  const auto Calloc =     Matcher("calloc",     2, 0, StrLenKind::WithoutInc);
+  const auto Malloc =     Matcher("malloc",     1, 0, StrLenKind::WithoutInc);
+  const auto Realloc =    Matcher("realloc",    2, 1, StrLenKind::WithoutInc);
+  const auto Memcpy =     Matcher("memcpy",     3, 2, StrLenKind::WithoutInc);
+  const auto Wmemcpy =    Matcher("wmemcpy",    3, 2, StrLenKind::WithoutInc);
+  const auto Memcpy_s =   Matcher("memcpy_s",   4, 3, StrLenKind::WithoutInc);
+  const auto Wmemcpy_s =  Matcher("wmemcpy_s",  4, 3, StrLenKind::WithoutInc);
+  const auto Memchr =     Matcher("memchr",     3, 2, StrLenKind::WithoutInc);
+  const auto Wmemchr =    Matcher("wmemchr",    3, 2, StrLenKind::WithoutInc);
+  const auto Memmove =    Matcher("memmove",    3, 2, StrLenKind::WithoutInc);
+  const auto Wmemmove =   Matcher("wmemmove",   3, 2, StrLenKind::WithoutInc);
+  const auto Memmove_s =  Matcher("memmove_s",  4, 3, StrLenKind::WithoutInc);
+  const auto Wmemmove_s = Matcher("wmemmove_s", 4, 3, StrLenKind::WithoutInc);
+  const auto Memset =     Matcher("memset",     3, 2, StrLenKind::WithInc);
+  const auto Wmemset =    Matcher("wmemset",    3, 2, StrLenKind::WithInc);
+  const auto Strerror_s = Matcher("strerror_s", 3, 1, StrLenKind::WithoutInc);
+  const auto Strncmp =    Matcher("strncmp",    3, 2, StrLenKind::WithInc);
+  const auto Wcsncmp =    Matcher("wcsncmp",    3, 2, StrLenKind::WithInc);
+  const auto Strxfrm =    Matcher("strxfrm",    3, 2, StrLenKind::WithoutInc);
+  const auto Wcsxfrm =    Matcher("wcsxfrm",    3, 2, StrLenKind::WithoutInc);
+  // clang-format on
+
+  const auto AnyOfExpressions = anyOf(
+      Alloca, Calloc, Malloc, Realloc, Memcpy, Wmemcpy, Memcpy_s, Wmemcpy_s,
+      Memchr, Wmemchr, Memmove, Wmemmove, Memmove_s, Wmemmove_s, Memset,
+      Wmemset, Strerror_s, Strncmp, Wcsncmp, Strxfrm, Wcsxfrm);
+
+  Finder->addMatcher(callExpr(AnyOfExpressions).bind("expr"), this);
+  Finder->addMatcher(
+      binaryOperator(
+          has(cStyleCastExpr(has(callExpr(anyOf(Memchr, Wmemchr)).bind("expr")))
+                  .bind("cast"))),
+      this);
+}
+
+void NotNullTerminatedResultCheck::check(
+    const MatchFinder::MatchResult &Result) {
+  const auto *FuncExpr = Result.Nodes.getNodeAs<CallExpr>("expr");
+
+  if (FuncExpr->getLocStart().isMacroID())
+    return;
+
+  if (!FuncExpr->getDirectCallee())
+    return;
+
+  StringRef Name = FuncExpr->getDirectCallee()->getName();
+
+  if (Name.contains("alloc"))
+    memAllocFuncFix(Name, Result);
+  else if (Name.startswith("mem") || Name.startswith("wmem"))
+    memHandlerFuncFix(Name, Result);
+  else if (Name.startswith("str") || Name.startswith("wcs"))
+    characterFuncFix(Name, Result);
+}
+
+void NotNullTerminatedResultCheck::memAllocFuncFix(
+    StringRef Name, const MatchFinder::MatchResult &Result) {
+  auto Diag =
+      diag(Result.Nodes.getNodeAs<CallExpr>("expr")->getLocStart(),
+           "'%0' function's allocated memory cannot hold the null-terminator")
+      << Name;
+
+  if (Name == "alloca" || Name == "calloc" || Name == "malloc")
+    lengthArgInsertIncByOne(0, Result, Diag);
+  else if (Name == "realloc")
+    lengthArgInsertIncByOne(1, Result, Diag);
+}
+
+void NotNullTerminatedResultCheck::memHandlerFuncFix(
+    StringRef Name, const MatchFinder::MatchResult &Result) {
+  if (Name == "memmove" || Name == "wmemmove")
+    memmoveFix(Name, Result);
+  else if (Name == "memmove_s" || Name == "wmemmove_s")
+    memmove_sFix(Name, Result);
+  else {
+    auto Diag = diag(Result.Nodes.getNodeAs<CallExpr>("expr")->getLocStart(),
+                     "'%0' function's result is not null-terminated")
+                << Name;
+    if (Name == "memcpy" || Name == "wmemcpy")
+      memcpyFix(Name, Result, Diag);
+    else if (Name == "memcpy_s" || Name == "wmemcpy_s")
+      memcpy_sFix(Name, Result, Diag);
+    else if (Name == "memchr" || Name == "wmemchr")
+      memchrFix(Name, Result, Diag);
+    else if (Name == "memset" || Name == "wmemset")
+      lengthArgRemoveIncByOne(Result, Diag);
+  }
+}
+
+void NotNullTerminatedResultCheck::memcpyFix(
+    StringRef Name, const MatchFinder::MatchResult &Result,
+    DiagnosticBuilder &Diag) {
+  if (getLangOpts().CPlusPlus11) {
+    StringRef NewFuncName = (Name[0] != 'w') ? "strncpy_s" : "wcsncpy_s";
+    renameFunc(NewFuncName, Result, Diag);
+  } else {
+    StringRef NewFuncName = (Name[0] != 'w') ? "strncpy" : "wcsncpy";
+    renameFunc(NewFuncName, Result, Diag);
+    lengthArgInsertIncByOne(2, Result, Diag);
+  }
+}
+
+void NotNullTerminatedResultCheck::memcpy_sFix(
+    StringRef Name, const MatchFinder::MatchResult &Result,
+    DiagnosticBuilder &Diag) {
+  StringRef NewFuncName = (Name[0] != 'w') ? "strncpy_s" : "wcsncpy_s";
+  renameFunc(NewFuncName, Result, Diag);
+  removeArg(1, Result, Diag);
+}
+
+void NotNullTerminatedResultCheck::memchrFix(
+    StringRef Name, const MatchFinder::MatchResult &Result,
+    DiagnosticBuilder &Diag) {
+  if (const auto *CastExpr = Result.Nodes.getNodeAs<CStyleCastExpr>("cast")) {
+    const auto *FuncExpr = Result.Nodes.getNodeAs<CallExpr>("expr");
+    const auto CastRemoveFix = FixItHint::CreateRemoval(SourceRange(
+        CastExpr->getLocStart(), FuncExpr->getLocStart().getLocWithOffset(-1)));
+    Diag << CastRemoveFix;
+  }
+  StringRef NewFuncName = (Name[0] != 'w') ? "strchr" : "wcschr";
+  renameFunc(NewFuncName, Result, Diag);
+  removeArg(2, Result, Diag);
+}
+
+void NotNullTerminatedResultCheck::memmoveFix(
+    StringRef Name, const MatchFinder::MatchResult &Result) {
+  if (isTrimFunc(Result))
+    return;
+
+  const auto *FuncExpr = Result.Nodes.getNodeAs<CallExpr>("expr");
+  auto Diag = diag(FuncExpr->getLocStart(),
+                   "'%0' function's result is not null-terminated")
+              << Name;
+
+  if (getLangOpts().CPlusPlus11) {
+    StringRef NewFuncName = (Name[0] != 'w') ? "memmove_s" : "wmemmove_s";
+    renameFunc(NewFuncName, Result, Diag);
+
+    const auto FirstArg = FuncExpr->getArg(0);
+    std::string NewSecondArg = " strlen(" + exprToStr(FirstArg, Result) + "),";
+
+    const auto InsertNewArgFix = FixItHint::CreateInsertion(
+        exprLocEnd(FirstArg, Result).getLocWithOffset(1), NewSecondArg);
+    Diag << InsertNewArgFix;
+  }
+  lengthArgInsertIncByOne(2, Result, Diag);
+}
+
+void NotNullTerminatedResultCheck::memmove_sFix(
+    StringRef Name, const MatchFinder::MatchResult &Result) {
+  if (isTrimFunc(Result))
+    return;
+
+  auto Diag = diag(Result.Nodes.getNodeAs<CallExpr>("expr")->getLocStart(),
+                   "'%0' function's result is not null-terminated")
+              << Name;
+  lengthArgInsertIncByOne(3, Result, Diag);
+}
+
+void NotNullTerminatedResultCheck::characterFuncFix(
+    StringRef Name, const MatchFinder::MatchResult &Result) {
+  if (Name == "strerror_s")
+    strerror_sFix(Result);
+  else if (Name == "strncmp" || Name == "wcsncmp")
+    ncmpFix(Name, Result);
+  else if (Name == "strxfrm" || Name == "wcsxfrm")
+    xfrmFix(Name, Result);
+}
+
+void NotNullTerminatedResultCheck::strerror_sFix(
+    const MatchFinder::MatchResult &Result) {
+  auto Diag = diag(Result.Nodes.getNodeAs<CallExpr>("expr")->getLocStart(),
+                   "'strerror_s' function's result is not null-terminated and "
+                   "missing the last character of the error message");
+  lengthArgInsertIncByOne(1, Result, Diag);
+}
+
+void NotNullTerminatedResultCheck::ncmpFix(
+    StringRef Name, const MatchFinder::MatchResult &Result) {
+  const auto *FuncExpr = Result.Nodes.getNodeAs<CallExpr>("expr");
+  std::string FirstArg = exprToStr(FuncExpr->getArg(0), Result);
+  std::string SecondArg = exprToStr(FuncExpr->getArg(1), Result);
+  std::string StrLenArg = exprToStr(
+      Result.Nodes.getNodeAs<CallExpr>("length-call")->getArg(0), Result);
+
+  if (StrLenArg == FirstArg || StrLenArg == SecondArg) {
+    auto Diag = diag(FuncExpr->getLocStart(),
+                     "'%0' function's comparison's length is too long")
+                << Name;
+    lengthArgRemoveIncByOne(Result, Diag);
+  }
+}
+
+void NotNullTerminatedResultCheck::xfrmFix(
+    StringRef Name, const MatchFinder::MatchResult &Result) {
+  auto Diag = diag(Result.Nodes.getNodeAs<CallExpr>("expr")->getLocStart(),
+                   "'%0' function's result is not null-terminated")
+              << Name;
+  lengthArgInsertIncByOne(2, Result, Diag);
+}
+
+/// FIXME: It is probably a false-positive factory because of the complex cases.
+void NotNullTerminatedResultCheck::lengthArgInsertIncByOne(
+    const int ArgPos, const MatchFinder::MatchResult &Result,
+    DiagnosticBuilder &Diag) {
+  bool isComplexCase = false;
+  const Expr *StrLenExpr = nullptr;
+  if (const auto *StrLen = Result.Nodes.getNodeAs<Expr>("length-wout-inc-simp"))
+    StrLenExpr = StrLen;
+  else {
+    StrLenExpr = Result.Nodes.getNodeAs<Expr>("length-wout-inc-comp");
+    isComplexCase = true;
+  }
+
+  bool NeedInnerParen = false, NeedOuterParen = false;
+  if (isComplexCase) {
+    if (const auto *BinOp =
+            Result.Nodes.getNodeAs<BinaryOperator>("length-wout-inc-comp")) {
+      NeedInnerParen = BinOp->getOpcode() != BO_Add;
+    }
+  }
+  if (!isInsideParentheses(StrLenExpr, Result)) {
+    const auto *FuncExpr = Result.Nodes.getNodeAs<CallExpr>("expr");
+    NeedOuterParen = FuncExpr->getNumArgs() > 1;
+  }
+
+  std::string LHSPartStr = NeedOuterParen ? "(" : "";
+  LHSPartStr += NeedInnerParen ? "(" : "";
+  std::string RHSPartStr = NeedInnerParen ? ")" : "";
+  RHSPartStr += " + 1";
+  RHSPartStr += NeedOuterParen ? ")" : "";
+
+  const auto InsertFirstParenFix =
+      FixItHint::CreateInsertion(StrLenExpr->getLocStart(), LHSPartStr);
+  const auto InsertPlusOneAndSecondParenFix = FixItHint::CreateInsertion(
+      StrLenExpr->getLocEnd().getLocWithOffset(1), RHSPartStr);
+  Diag << InsertFirstParenFix << InsertPlusOneAndSecondParenFix;
+}
+
+void NotNullTerminatedResultCheck::lengthArgRemoveIncByOne(
+    const MatchFinder::MatchResult &Result, DiagnosticBuilder &Diag) {
+  // This is the following structure: ((strlen(src) * 2) + 1)
+  //               InnerOperatorExpr:   ~~~~~~~~~~~~^~~
+  //               OuterOperatorExpr:  ~~~~~~~~~~~~~~~~~~^~~
+  const auto InnerOperatorExpr = Result.Nodes.getNodeAs<Expr>("inner-operator");
+  const auto OuterOperatorExpr = Result.Nodes.getNodeAs<Expr>("outer-operator");
+  int OuterOperatorOffset = 0;
+
+  if (isInsideParentheses(OuterOperatorExpr, Result))
+    ++OuterOperatorOffset;
+
+  // This is the following structure: ((strlen(src) * 2) + 1)
+  //                  LHSRemoveRange: ~~
+  //                  RHSRemoveRange:                  ~~~~~~
+  const auto LHSRemoveRange = SourceRange(
+      OuterOperatorExpr->getLocStart().getLocWithOffset(-OuterOperatorOffset),
+      InnerOperatorExpr->getLocStart().getLocWithOffset(-1));
+
+  const auto RHSRemoveRange = SourceRange(
+      InnerOperatorExpr->getLocEnd().getLocWithOffset(1),
+      OuterOperatorExpr->getLocEnd().getLocWithOffset(OuterOperatorOffset));
+
+  const auto LHSRemoveFix = FixItHint::CreateRemoval(LHSRemoveRange);
+  const auto RHSRemoveFix = FixItHint::CreateRemoval(RHSRemoveRange);
+  Diag << LHSRemoveFix << RHSRemoveFix;
+}
+
+void NotNullTerminatedResultCheck::removeArg(
+    const int ArgPos, const MatchFinder::MatchResult &Result,
+    DiagnosticBuilder &Diag) {
+  // This is the following structure: (src, '\0', strlen(src))
+  //                     ArgToRemove:             ~~~~~~~~~~~
+  //                          LHSArg:       ~~~~
+  //                    RemoveArgFix:           ~~~~~~~~~~~~~
+  const auto *FuncExpr = Result.Nodes.getNodeAs<CallExpr>("expr");
+  const auto ArgToRemove = FuncExpr->getArg(ArgPos);
+  const auto LHSArg = FuncExpr->getArg(ArgPos - 1);
+  const auto RemoveArgFix = FixItHint::CreateRemoval(
+      SourceRange(exprLocEnd(LHSArg, Result),
+                  exprLocEnd(ArgToRemove, Result).getLocWithOffset(-1)));
+  Diag << RemoveArgFix;
+}
+
+void NotNullTerminatedResultCheck::renameFunc(
+    StringRef NewFuncName, const MatchFinder::MatchResult &Result,
+    DiagnosticBuilder &Diag) {
+  const auto *FuncExpr = Result.Nodes.getNodeAs<CallExpr>("expr");
+  const auto FuncNameLength =
+      FuncExpr->getDirectCallee()->getIdentifier()->getLength();
+  const auto FirstArgLoc = FuncExpr->getArg(0)->getExprLoc();
+  const auto FuncNameRange = CharSourceRange::getCharRange(
+      FirstArgLoc.getLocWithOffset(-FuncNameLength - 1),
+      FirstArgLoc.getLocWithOffset(-1));
+
+  const auto FuncNameFix =
+      FixItHint::CreateReplacement(FuncNameRange, NewFuncName);
+  Diag << FuncNameFix;
+}
+
+} // namespace bugprone
+} // namespace tidy
+} // namespace clang
Index: clang-tidy/bugprone/CMakeLists.txt
===================================================================
--- clang-tidy/bugprone/CMakeLists.txt
+++ clang-tidy/bugprone/CMakeLists.txt
@@ -20,6 +20,7 @@
   MisplacedWideningCastCheck.cpp
   MoveForwardingReferenceCheck.cpp
   MultipleStatementMacroCheck.cpp
+  NotNullTerminatedResultCheck.cpp
   SizeofContainerCheck.cpp
   SizeofExpressionCheck.cpp
   StringConstructorCheck.cpp
Index: clang-tidy/bugprone/BugproneTidyModule.cpp
===================================================================
--- clang-tidy/bugprone/BugproneTidyModule.cpp
+++ clang-tidy/bugprone/BugproneTidyModule.cpp
@@ -28,6 +28,7 @@
 #include "MisplacedWideningCastCheck.h"
 #include "MoveForwardingReferenceCheck.h"
 #include "MultipleStatementMacroCheck.h"
+#include "NotNullTerminatedResultCheck.h"
 #include "SizeofContainerCheck.h"
 #include "SizeofExpressionCheck.h"
 #include "StringConstructorCheck.h"
@@ -89,6 +90,8 @@
         "bugprone-move-forwarding-reference");
     CheckFactories.registerCheck<MultipleStatementMacroCheck>(
         "bugprone-multiple-statement-macro");
+    CheckFactories.registerCheck<NotNullTerminatedResultCheck>(
+        "bugprone-not-null-terminated-result");
     CheckFactories.registerCheck<SizeofContainerCheck>(
         "bugprone-sizeof-container");
     CheckFactories.registerCheck<SizeofExpressionCheck>(
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