perf tools: Move strlcpy() from perf to tools/lib/string.c

strlcpy() will be needed by the subcmd library.  Move it to the shared
tools/lib/string.c file which can be used by other tools.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/71e2804b973bf39ad3d3b9be10f99f2ea630be46.1450193761.git.jpoimboe@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/lib/string.c

@@ -16,6 +16,7 @@
 #include <string.h>
 #include <errno.h>
 #include <linux/string.h>
+#include <linux/compiler.h>
 
 /**
  * memdup - duplicate region of memory
@@ -60,3 +61,29 @@ int strtobool(const char *s, bool *res)
 	}
 	return 0;
 }
+
+/**
+ * strlcpy - Copy a C-string into a sized buffer
+ * @dest: Where to copy the string to
+ * @src: Where to copy the string from
+ * @size: size of destination buffer
+ *
+ * Compatible with *BSD: the result is always a valid
+ * NUL-terminated string that fits in the buffer (unless,
+ * of course, the buffer size is zero). It does not pad
+ * out the result like strncpy() does.
+ *
+ * If libc has strlcpy() then that version will override this
+ * implementation:
+ */
+size_t __weak strlcpy(char *dest, const char *src, size_t size)
+{
+	size_t ret = strlen(src);
+
+	if (size) {
+		size_t len = (ret >= size) ? size - 1 : ret;
+		memcpy(dest, src, len);
+		dest[len] = '\0';
+	}
+	return ret;
+}