Check for strlcat and strlcpy

This partially reverts commit 8005ca4 by moving the strlcat()
and strlcpy() compatibility implementations back to their original
location.

In addition, these two functions were added to the AC_CHECK_FUNCS
macro. When these functions are available from the C library,
HAVE_STRLCAT and HAVE_STRLCPY will be defined and library version
used. Otherwise the compatibility version is built.

Reviewed-by: Sebastian Gottschall <[email protected]>
Reviewed-by: Alek Pinchuk <[email protected]>
Signed-off-by: Brian Behlendorf <[email protected]>
Closes #8157 
Closes #8202 

1 files changed, 6 insertions, 49 deletions

diff --git a/lib/libspl/include/string.h b/lib/libspl/include/string.h
index 8908ce228..a7d40fa61 100644
--- a/lib/libspl/include/string.h
+++ b/lib/libspl/include/string.h
@@ -28,56 +28,13 @@
 #define	_LIBSPL_STRING_H
 
 #include_next <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.
- */
-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';
+#ifndef HAVE_STRLCAT
+extern size_t strlcat(char *dst, const char *src, size_t dstsize);
+#endif
 
-	return (slen);
-}
+#ifndef HAVE_STRLCPY
+extern size_t strlcpy(char *dst, const char *src, size_t len);
+#endif
 
 #endif