strlcpy: add strlcpy() implementation

configure.ac

@@ -672,6 +672,10 @@ AC_CHECK_FUNCS([fgetln],
 	AM_CONDITIONAL(HAVE_FGETLN, true)
 	AC_DEFINE(HAVE_FGETLN,1,[Have fgetln]),
 	AM_CONDITIONAL(HAVE_FGETLN, false))
+AC_CHECK_FUNCS([strlcpy],
+	AM_CONDITIONAL(HAVE_STRLCPY, true)
+	AC_DEFINE(HAVE_STRLCPY,1,[Have strlcpy]),
+	AM_CONDITIONAL(HAVE_STRLCPY, false))
 
 # Check for some libraries
 AX_PTHREAD

src/include/strlcpy.c

+/* liblxcapi
+ *
+ * Copyright © 2018 Christian Brauner <christian@brauner.io>.
+ * Copyright © 2018 Canonical Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * This function has been copied from musl.
+ */
+
+#include <limits.h>
+#include <stdint.h>
+#include <string.h>
+
+#define ALIGN (sizeof(size_t) - 1)
+#define ONES ((size_t)-1 / UCHAR_MAX)
+#define HIGHS (ONES * (UCHAR_MAX / 2 + 1))
+#define HASZERO(x) (((x)-ONES) & ~(x)&HIGHS)
+
+size_t strlcpy(char *d, const char *s, size_t n)
+{
+	char *d0 = d;
+	size_t *wd;
+	const size_t *ws;
+
+	if (!n--)
+		goto finish;
+
+	if (((uintptr_t)s & ALIGN) == ((uintptr_t)d & ALIGN)) {
+		for (; ((uintptr_t)s & ALIGN) && n && (*d = *s); n--, s++, d++)
+			;
+		if (n && *s) {
+			wd = (void *)d;
+			ws = (const void *)s;
+			for (; n >= sizeof(size_t) && !HASZERO(*ws);
+			     n -= sizeof(size_t), ws++, wd++)
+				*wd = *ws;
+			d = (void *)wd;
+			s = (const void *)ws;
+		}
+	}
+
+	for (; n && (*d = *s); n--, s++, d++)
+		;
+
+	*d = 0;
+
+finish:
+	return d - d0 + strlen(s);
+}

src/include/strlcpy.h

+/* liblxcapi
+ *
+ * Copyright © 2018 Christian Brauner <christian@brauner.io>.
+ * Copyright © 2018 Canonical Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * This function has been copied from musl.
+ */
+
+#ifndef _STRLCPY_H
+#define _STRLCPY_H
+
+#include <stdio.h>
+
+extern size_t strlcpy(char *, const char *, size_t);
+
+#endif

src/lxc/Makefile.am

@@ -144,6 +144,10 @@ liblxc_la_SOURCES += ../include/getline.c ../include/getline.h
 endif
 endif
 
+if !HAVE_STRLCPY
+liblxc_la_SOURCES += ../include/strlcpy.c ../include/strlcpy.h
+endif
+
 AM_CFLAGS=-DLXCROOTFSMOUNT=\"$(LXCROOTFSMOUNT)\" \
 	-DLXCPATH=\"$(LXCPATH)\" \
 	-DLXC_GLOBAL_CONF=\"$(LXC_GLOBAL_CONF)\" \
@@ -296,6 +300,10 @@ init_lxc_static_SOURCES += ../include/getline.c
 endif
 endif
 
+if !HAVE_STRLCPY
+init_lxc_static_SOURCES += ../include/strlcpy.c ../include/strlcpy.h
+endif
+
 init_lxc_static_LDFLAGS = -all-static
 init_lxc_static_LDADD = @CAP_LIBS@
 init_lxc_static_CFLAGS = $(AM_CFLAGS) -DNO_LXC_CONF