kernel-doc: core-api: include string.h into core-api

core-api should show all the various string functions including the newly
added stracpy and stracpy_pad.

Miscellanea:

o Update the Returns: value for strscpy
o fix a defect with %NUL)

Link: http://lkml.kernel.org/r/224a6ebf39955f4107c0c376d66155d970e46733.1563841972.git.joe@perches.com
Signed-off-by: Joe Perches <joe@perches.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Stephen Kitt <steve@sk2.org>
Cc: Nitin Gote <nitin.r.gote@intel.com>
Cc: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Cc: Jann Horn <jannh@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
diff --git a/Documentation/core-api/kernel-api.rst b/Documentation/core-api/kernel-api.rst
index 08af5ca..f77de49 100644
--- a/Documentation/core-api/kernel-api.rst
+++ b/Documentation/core-api/kernel-api.rst
@@ -42,6 +42,9 @@
 .. kernel-doc:: lib/string.c
    :export:
 
+.. kernel-doc:: include/linux/string.h
+   :internal:
+
 .. kernel-doc:: mm/util.c
    :functions: kstrdup kstrdup_const kstrndup kmemdup kmemdup_nul memdup_user
                vmemdup_user strndup_user memdup_user_nul
diff --git a/include/linux/string.h b/include/linux/string.h
index 7572cd7..3cf684d 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -519,8 +519,9 @@
  * But this can lead to bugs due to typos, or if prefix is a pointer
  * and not a constant. Instead use str_has_prefix().
  *
- * Returns: 0 if @str does not start with @prefix
-         strlen(@prefix) if @str does start with @prefix
+ * Returns:
+ * * strlen(@prefix) if @str starts with @prefix
+ * * 0 if @str does not start with @prefix
  */
 static __always_inline size_t str_has_prefix(const char *str, const char *prefix)
 {
diff --git a/lib/string.c b/lib/string.c
index 461fb62..53582b6 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -173,8 +173,9 @@
  * doesn't unnecessarily force the tail of the destination buffer to be
  * zeroed.  If zeroing is desired please use strscpy_pad().
  *
- * Return: The number of characters copied (not including the trailing
- *         %NUL) or -E2BIG if the destination buffer wasn't big enough.
+ * Returns:
+ * * The number of characters copied (not including the trailing %NUL)
+ * * -E2BIG if count is 0.
  */
 ssize_t strscpy(char *dest, const char *src, size_t count)
 {
@@ -253,8 +254,9 @@
  * For full explanation of why you may want to consider using the
  * 'strscpy' functions please see the function docstring for strscpy().
  *
- * Return: The number of characters copied (not including the trailing
- *         %NUL) or -E2BIG if the destination buffer wasn't big enough.
+ * Returns:
+ * * The number of characters copied (not including the trailing %NUL)
+ * * -E2BIG if count is 0.
  */
 ssize_t strscpy_pad(char *dest, const char *src, size_t count)
 {