Add access(2) constants to the constants table

[rpigott]

fs_access is equivalent to access(2), but this function is useless without the corresponsing access mode constants F_OK, R_OK, W_OK, and X_OK. Let's add these constants to the table.

[squeek502]

Seems fine to add these, but note that the mode can be specified as a string:

luv/docs.md

Lines 2844 to 2846 in 16bbffd

	Equivalent to `access(2)` on Unix. Windows uses `GetFileAttributesW()`. Access
	`mode` can be an integer or a string containing `"R"` or `"W"` or `"X"`.
	Returns `true` or `false` indicating access permission.

which is usually how it's used, e.g. here

Implementation is here for reference:

luv/src/fs.c

Lines 179 to 207 in 16bbffd

	static int luv_check_amode(lua_State* L, int index) {
	size_t i;
	int mode;
	const char* string;
	if (lua_isnumber(L, index)) {
	return lua_tointeger(L, index);
	}
	else if (!lua_isstring(L, index)) {
	return luaL_argerror(L, index, "Expected string or integer for file access mode check");
	}
	string = lua_tostring(L, index);
	mode = 0;
	for (i = 0; i < strlen(string); ++i) {
	switch (string[i]) {
	case 'r': case 'R':
	mode |= R_OK;
	break;
	case 'w': case 'W':
	mode |= W_OK;
	break;
	case 'x': case 'X':
	mode |= X_OK;
	break;
	default:
	return luaL_argerror(L, index, "Unknown character in access mode string");
	}
	}
	return mode;
	}

[squeek502]

Thanks!

[rpigott]

mode can be specified as a string

I didn't know that! TYVM for the info.