Move strlcat, strlcpy, and strnlen

Move strlcat() and strlcpy() from .c source files in to the libspl
string.h header.  By changing these compatibility functions to static
inline functions they can included as needed without requiring linking
with the libspl.so library.

Remove strnlen() which is barely used in the source, and has been
provided by glibc since v2.10.

Finally, convert four instances of strncpy() to strlcpy() in
libzfs_input_check.c which were causing build warnings when compiling
with gcc 8.2.1.  For example:

  libzfs_input_check.c: In function ‘zfs_destroy’:
  libzfs_input_check.c:651:9: error: ‘strncpy’ specified bound \
      4096 equals destination size [-Werror=stringop-truncation]
    (void) strncpy(zc.zc_name, dataset, sizeof (zc.zc_name));
         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Reviewed-by: Olaf Faaland <[email protected]>
Reviewed-by: Richard Laager <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Closes #8116 

5 files changed, 50 insertions, 158 deletions

diff --git a/lib/libspl/Makefile.am b/lib/libspl/Makefile.am
index b7fa795d5..8d0d4d038 100644
--- a/lib/libspl/Makefile.am
+++ b/lib/libspl/Makefile.am
@@ -22,9 +22,6 @@ USER_C = \
 	list.c \
 	mkdirp.c \
 	page.c \
-	strlcat.c \
-	strlcpy.c \
-	strnlen.c \
 	timestamp.c \
 	zone.c \
 	include/sys/list.h \
diff --git a/lib/libspl/include/string.h b/lib/libspl/include/string.h
index 9e5133e0e..8908ce228 100644
--- a/lib/libspl/include/string.h
+++ b/lib/libspl/include/string.h
@@ -28,9 +28,56 @@
 #define	_LIBSPL_STRING_H
 
 #include_next <string.h>
+#include <sys/types.h>
 
-extern size_t strlcat(char *dst, const char *src, size_t dstsize);
-extern size_t strlcpy(char *dst, const char *src, size_t len);
-extern size_t strnlen(const char *str, size_t maxlen);
+/*
+ * Appends src to the dstsize buffer at dst. The append will never
+ * overflow the destination buffer and the buffer will always be null
+ * terminated. Never reference beyond &dst[dstsize-1] when computing
+ * the length of the pre-existing string.
+ */
+static inline size_t
+strlcat(char *dst, const char *src, size_t dstsize)
+{
+	char *df = dst;
+	size_t left = dstsize;
+	size_t l1;
+	size_t l2 = strlen(src);
+	size_t copied;
+
+	while (left-- != 0 && *df != '\0')
+		df++;
+
+	l1 = df - dst;
+
+	if (dstsize == l1)
+		return (l1 + l2);
+
+	copied = l1 + l2 >= dstsize ? dstsize - l1 - 1 : l2;
+	(void) memcpy(dst + l1, src, copied);
+	dst[l1+copied] = '\0';
+
+	return (l1 + l2);
+}
+
+/*
+ * Copies src to the dstsize buffer at dst. The copy will never
+ * overflow the destination buffer and the buffer will always be null
+ * terminated.
+ */
+static inline size_t
+strlcpy(char *dst, const char *src, size_t len)
+{
+	size_t slen = strlen(src);
+
+	if (len == 0)
+		return (slen);
+
+	size_t copied = (slen >= len) ? len - 1 : slen;
+	(void) memcpy(dst, src, copied);
+	dst[copied] = '\0';
+
+	return (slen);
+}
 
 #endif
diff --git a/lib/libspl/strlcat.c b/lib/libspl/strlcat.c
deleted file mode 100644
index a001df7b1..000000000
--- a/lib/libspl/strlcat.c
+++ /dev/null
@@ -1,56 +0,0 @@
-/*
- * CDDL HEADER START
- *
- * The contents of this file are subject to the terms of the
- * Common Development and Distribution License (the "License").
- * You may not use this file except in compliance with the License.
- *
- * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
- * or http://www.opensolaris.org/os/licensing.
- * See the License for the specific language governing permissions
- * and limitations under the License.
- *
- * When distributing Covered Code, include this CDDL HEADER in each
- * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
- * If applicable, add the following below this CDDL HEADER, with the
- * fields enclosed by brackets "[]" replaced with your own identifying
- * information: Portions Copyright [yyyy] [name of copyright owner]
- *
- * CDDL HEADER END
- */
-
-/*
- * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
- * Use is subject to license terms.
- */
-
-#include <string.h>
-#include <sys/types.h>
-
-/*
- * Appends src to the dstsize buffer at dst. The append will never
- * overflow the destination buffer and the buffer will always be null
- * terminated. Never reference beyond &dst[dstsize-1] when computing
- * the length of the pre-existing string.
- */
-
-size_t
-strlcat(char *dst, const char *src, size_t dstsize)
-{
-	char *df = dst;
-	size_t left = dstsize;
-	size_t l1;
-	size_t l2 = strlen(src);
-	size_t copied;
-
-	while (left-- != 0 && *df != '\0')
-		df++;
-	l1 = df - dst;
-	if (dstsize == l1)
-		return (l1 + l2);
-
-	copied = l1 + l2 >= dstsize ? dstsize - l1 - 1 : l2;
-	(void) memcpy(dst + l1, src, copied);
-	dst[l1+copied] = '\0';
-	return (l1 + l2);
-}
diff --git a/lib/libspl/strlcpy.c b/lib/libspl/strlcpy.c
deleted file mode 100644
index 2d0daae05..000000000
--- a/lib/libspl/strlcpy.c
+++ /dev/null
@@ -1,52 +0,0 @@
-/*
- * CDDL HEADER START
- *
- * The contents of this file are subject to the terms of the
- * Common Development and Distribution License (the "License").
- * You may not use this file except in compliance with the License.
- *
- * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
- * or http://www.opensolaris.org/os/licensing.
- * See the License for the specific language governing permissions
- * and limitations under the License.
- *
- * When distributing Covered Code, include this CDDL HEADER in each
- * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
- * If applicable, add the following below this CDDL HEADER, with the
- * fields enclosed by brackets "[]" replaced with your own identifying
- * information: Portions Copyright [yyyy] [name of copyright owner]
- *
- * CDDL HEADER END
- */
-
-/*
- * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
- * Use is subject to license terms.
- */
-
-#include <string.h>
-#include <sys/types.h>
-
-/*
- * Copies src to the dstsize buffer at dst. The copy will never
- * overflow the destination buffer and the buffer will always be null
- * terminated.
- */
-
-size_t
-strlcpy(char *dst, const char *src, size_t len)
-{
-	size_t slen = strlen(src);
-	size_t copied;
-
-	if (len == 0)
-		return (slen);
-
-	if (slen >= len)
-		copied = len - 1;
-	else
-		copied = slen;
-	(void) memcpy(dst, src, copied);
-	dst[copied] = '\0';
-	return (slen);
-}
diff --git a/lib/libspl/strnlen.c b/lib/libspl/strnlen.c
deleted file mode 100644
index 9fb8227b9..000000000
--- a/lib/libspl/strnlen.c
+++ /dev/null
@@ -1,44 +0,0 @@
-/*
- * CDDL HEADER START
- *
- * The contents of this file are subject to the terms of the
- * Common Development and Distribution License (the "License").
- * You may not use this file except in compliance with the License.
- *
- * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
- * or http://www.opensolaris.org/os/licensing.
- * See the License for the specific language governing permissions
- * and limitations under the License.
- *
- * When distributing Covered Code, include this CDDL HEADER in each
- * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
- * If applicable, add the following below this CDDL HEADER, with the
- * fields enclosed by brackets "[]" replaced with your own identifying
- * information: Portions Copyright [yyyy] [name of copyright owner]
- *
- * CDDL HEADER END
- */
-
-/*
- * Copyright 2008 Sun Microsystems, Inc.
- * All rights reserved.  Use is subject to license terms.
- */
-
-#include <string.h>
-#include <sys/types.h>
-
-/*
- * Returns the number of non-NULL bytes in string argument,
- * but not more than maxlen.  Does not look past str + maxlen.
- */
-size_t
-strnlen(const char *str, size_t maxlen)
-{
-	const char *ptr;
-
-	ptr = memchr(str, 0, maxlen);
-	if (ptr == NULL)
-		return (maxlen);
-
-	return (ptr - str);
-}