Add new file include/share/safe_str.h.

New functions safe_strncat() and safe_strncpy() which always return
a NUL terminated string and do not overflow the destination buffer.

include/share/Makefile.am

@@ -12,4 +12,5 @@ EXTRA_DIST = \
 	private.h \
 	replaygain_analysis.h \
 	replaygain_synthesis.h \
+	safe_str.h \
 	utf8.h

include/share/safe_str.h

@@ -0,0 +1,69 @@
+/* libFLAC - Free Lossless Audio Codec library
+ * Copyright (C) 2013  Xiph.org Foundation
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * - Neither the name of the Xiph.org Foundation nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+/* Safe string handling functions to replace things like strcpy, strncpy,
+ * strcat, strncat etc.
+ * All of these functions guarantee a correctly NUL terminated string but
+ * the string may be truncated if the destination buffer was too short.
+ */
+
+#ifndef FLAC__SHARE_SAFE_STR_H
+#define FLAC__SHARE_SAFE_STR_H
+
+static inline char *
+safe_strncat(char *dest, const char *src, size_t dest_size)
+{
+	char * ret;
+
+	if (dest_size < 1)
+		return dest;
+
+	ret = strncat(dest, src, dest_size - strlen (dest));
+	dest [dest_size - 1] = 0;
+
+	return ret;
+}
+
+static inline char *
+safe_strncpy(char *dest, const char *src, size_t dest_size)
+{
+	char * ret;
+
+	if (dest_size < 1)
+		return dest;
+
+	ret = strncpy(dest, src, dest_size);
+	dest [dest_size - 1] = 0;
+
+	return ret;
+}
+
+#endif /* FLAC__SHARE_SAFE_STR_H */