flua: Add wrappers for sys/utsname.h

This allows one to invoke uname from lua scripts.

Reviewed by:	bapt, kevans, emaste
MFC after:	1 month
Differential Revision:	https://reviews.freebsd.org/D42017

(cherry picked from commit 1726db7af6b3738eb04d962b351d7f4017e1fc77)

libexec/flua/linit_flua.c

@@ -58,6 +58,7 @@ static const luaL_Reg loadedlibs[] = {
   /* FreeBSD Extensions */
   {"lfs", luaopen_lfs},
   {"posix.sys.stat", luaopen_posix_sys_stat},
+  {"posix.sys.utsname", luaopen_posix_sys_utsname},
   {"posix.unistd", luaopen_posix_unistd},
   {"ucl", luaopen_ucl},
   {NULL, NULL}

libexec/flua/modules/lposix.c

@@ -24,8 +24,8 @@
  *
  */
 
-#include <sys/cdefs.h>
 #include <sys/stat.h>
+#include <sys/utsname.h>
 
 #include <errno.h>
 #include <grp.h>
@@ -130,12 +130,50 @@ lua_getpid(lua_State *L)
 	return 1;
 }
 
+static int
+lua_uname(lua_State *L)
+{
+	struct utsname name;
+	int error, n;
+
+	n = lua_gettop(L);
+	luaL_argcheck(L, n == 0, 1, "too many arguments");
+
+	error = uname(&name);
+	if (error != 0) {
+		error = errno;
+		lua_pushnil(L);
+		lua_pushstring(L, strerror(error));
+		lua_pushinteger(L, error);
+		return (3);
+	}
+
+	lua_newtable(L);
+#define	setkv(f) do {			\
+	lua_pushstring(L, name.f);	\
+	lua_setfield(L, -2, #f);	\
+} while (0)
+	setkv(sysname);
+	setkv(nodename);
+	setkv(release);
+	setkv(version);
+	setkv(machine);
+#undef setkv
+
+	return (1);
+}
+
 #define REG_SIMPLE(n)	{ #n, lua_ ## n }
 static const struct luaL_Reg sys_statlib[] = {
 	REG_SIMPLE(chmod),
 	{ NULL, NULL },
 };
 
+static const struct luaL_Reg sys_utsnamelib[] = {
+	REG_SIMPLE(uname),
+	{ NULL, NULL },
+};
+
 static const struct luaL_Reg unistdlib[] = {
 	REG_SIMPLE(getpid),
 	REG_SIMPLE(chown),
@@ -150,6 +188,13 @@ luaopen_posix_sys_stat(lua_State *L)
 	return 1;
 }
 
+int
+luaopen_posix_sys_utsname(lua_State *L)
+{
+	luaL_newlib(L, sys_utsnamelib);
+	return 1;
+}
+
 int
 luaopen_posix_unistd(lua_State *L)
 {

libexec/flua/modules/lposix.h

@@ -8,4 +8,5 @@
 #include <lua.h>
 
 int luaopen_posix_sys_stat(lua_State *L);
+int luaopen_posix_sys_utsname(lua_State *L);
 int luaopen_posix_unistd(lua_State *L);