Provide fallback strnlen implementation

1 files changed, 30 insertions, 0 deletions

diff --git a/util.c b/util.c
index 087c918faa..244d9368a8 100644
--- a/util.c
+++ b/util.c
@@ -5480,6 +5480,36 @@ Perl_my_strlcpy(char *dst, const char *src, Size_t size)
 }
 #endif
 
+/*
+=for apidoc my_strnlen
+
+The C library C<strnlen> if available, or a Perl implementation of it.
+
+C<my_strnlen()> computes the length of the string, up to C<maxlen>
+characters.  It will will never attempt to address more than C<maxlen>
+characters, making it suitable for use with strings that are not
+guaranteed to be NUL-terminated.
+
+=cut
+
+Description stolen from http://man.openbsd.org/strnlen.3,
+implementation stolen from PostgreSQL.
+*/
+#ifndef HAS_STRNLEN
+Size_t
+Perl_my_strnlen(const char *str, Size_t maxlen)
+{
+    const char *p = str;
+
+    PERL_ARGS_ASSERT_MY_STRNLEN;
+
+    while(maxlen-- && *p)
+        p++;
+
+    return p - str;
+}
+#endif
+
 #if defined(_MSC_VER) && (_MSC_VER >= 1300) && (_MSC_VER < 1400) && (WINVER < 0x0500)
 /* VC7 or 7.1, building with pre-VC7 runtime libraries. */
 long _ftol( double ); /* Defined by VC6 C libs. */