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fgdata/Nasal/io.nas
mfranz caca942012 revert last change: don't append cwd to relative paths for now. There's
no way yet to safely detect absolute paths, so this would break on MS Windows.
This will only mean that relative paths will always fail, as they don't
match any pattern. These are all absolute.
2008-06-22 13:54:36 +00:00

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# Reads and returns a complete file as a string
var readfile = func(file) {
if((var st = stat(file)) == nil) die("Cannot stat file: " ~ file);
var sz = st[7];
var buf = bits.buf(sz);
read(open(file), buf, sz);
return buf;
}
# Generates a stat() test routine that is passed the "mode" field
# (stat(...)[2]) from a stat() call (index 2), extracts the IFMT
# subfield and compares it with the given type, assumes S_IFMT ==
# 0xf000.
var _gen_ifmt_test = func(ifmt) {
func(stat_mode) {
var buf = bits.buf(2);
bits.setfld(buf, 0, 16, stat_mode);
return ifmt == bits.fld(buf, 12, 4);
}
}
# Generate file type test predicates isdir(), isreg(), islnk(), etc.
# Usage: var s = io.stat(filename); # nil -> doesn't exist, broken link
# if (s != nil and io.isdir(s[2])) { ... }
var ifmts = {dir:4, reg:8, lnk:10, sock:12, fifo:1, blk:6, chr:2};
foreach(fmt; keys(ifmts))
caller(0)[0]["is" ~ fmt] = _gen_ifmt_test(ifmts[fmt]);
# Loads Nasal file into namespace and executes it. The namespace
# (module name) is taken from the optional second argument, or
# derived from the Nasal file's name.
#
# Usage: io.load_nasal(<filename> [, <modulename>]);
#
# Example:
#
# io.load_nasal(getprop("/sim/fg-root") ~ "/Local/test.nas");
# io.load_nasal("/tmp/foo.nas", "test");
#
var load_nasal = func(file, module = nil) {
if(module == nil)
module = split(".", split("/", file)[-1])[0];
if(!contains(globals, module))
globals[module] = {};
var err = [];
printlog("info", "loading ", file, " into namespace ", module);
var code = call(func compile(readfile(file), file), nil, err);
if(size(err))
return !!print(file ~ ": " ~ err[0]);
call(bind(code, globals), nil, nil, globals[module], err);
debug.printerror(err);
return !!size(err);
}
# The following two functions are for reading generic XML files into
# the property tree and for writing them from there to the disk. The
# built-in fgcommands (load, save, loadxml, savexml) are for FlightGear's
# own <PropertyList> XML files only, as they only handle a limited
# number of very specific attributes. The io.readxml() loader turns
# attributes into regular children with a configurable prefix prepended
# to their name, while io.writexml() turns such nodes back into
# attributes. The two functions have their own limitations, but can
# easily get extended to whichever needs. The underlying parsexml()
# command will handle any XML file.
# Reads an XML file from an absolute path and returns it as property
# tree. All nodes will be of type STRING. Data are only written to
# leafs. Attributes are written as regular nodes with the optional
# prefix prepended to the name. If the prefix is nil, then attributes
# are ignored. Returns nil on error.
#
var readxml = func(path, prefix = "___") {
var stack = [[{}, ""]];
var node = props.Node.new();
var tree = node; # prevent GC
var start = func(name, attr) {
var index = stack[-1][0];
if(!contains(index, name))
index[name] = 0;
node = node.getChild(name, index[name], 1);
if(prefix != nil)
foreach(var n; keys(attr))
node.getNode(prefix ~ n, 1).setValue(attr[n]);
index[name] += 1;
append(stack, [{}, ""]);
}
var end = func(name) {
var buf = pop(stack);
if(!size(buf[0]) and size(buf[1]))
node.setValue(buf[1]);
node = node.getParent();
}
var data = func(d) {
stack[-1][1] ~= d;
}
return parsexml(path, start, end, data) == nil ? nil : tree;
}
# Writes a property tree as returned by readxml() to a file. Children
# with name starting with <prefix> are again turned into attributes of
# their parent. <node> must contain exactly one child, which will
# become the XML file's outermost element.
#
var writexml = func(path, node, indent = "\t", prefix = "___") {
var root = node.getChildren();
if(!size(root))
die("writexml(): tree doesn't have a root node");
if(substr(path, -4) != ".xml")
path ~= ".xml";
var file = open(path, "w");
write(file, "<?xml version=\"1.0\"?>\n\n");
var writenode = func(n, ind = "") {
var name = n.getName();
var name_attr = name;
var children = [];
foreach(var c; n.getChildren()) {
var a = c.getName();
if(substr(a, 0, size(prefix)) == prefix)
name_attr ~= " " ~ substr(a, size(prefix)) ~ '="' ~ c.getValue() ~ '"';
else
append(children, c);
}
if(size(children)) {
write(file, ind ~ "<" ~ name_attr ~ ">\n");
foreach(var c; children)
writenode(c, ind ~ indent);
write(file, ind ~ "</" ~ name ~ ">\n");
} elsif((var value = n.getValue()) != nil) {
write(file, ind ~ "<" ~ name_attr ~ ">" ~ value ~ "</" ~ name ~ ">\n");
} else {
write(file, ind ~ "<" ~ name_attr ~ "/>\n");
}
}
writenode(root[0]);
close(file);
if(size(root) != 1)
die("writexml(): tree has more than one root node");
}
# Redefine io.open() such that files can only be opened under authorized directories.
#
_setlistener("/sim/signals/nasal-dir-initialized", func {
var _open = open;
var root = string.fixpath(getprop("/sim/fg-root"));
var home = string.fixpath(getprop("/sim/fg-home"));
var config = "Nasal/IOrules";
var read_rules = [];
var write_rules = [];
var load_rules = func(path) {
if(stat(path) == nil)
return 0;
printlog("info", "using io.open() rules from ", path);
read_rules = [];
write_rules = [];
var file = open(path, "r");
for(var no = 1; (var line = readln(file)) != nil; no += 1) {
if(!size(line) or line[0] == `#`)
continue;
var f = split(" ", line);
if(size(f) < 3 or f[0] != "READ" and f[0] != "WRITE" or f[1] != "DENY" and f[1] != "ALLOW") {
printlog("alert", "ERROR: invalid io.open() rule in ", path, ", line ", no, ": ", line);
read_rules = write_rules = [];
break; # don't use die(), as io.open() has yet to be redefined
}
var pattern = f[2];
foreach(var p; subvec(f, 3))
pattern ~= " " ~ p;
if(substr(pattern, 0, 9) == "$FG_ROOT/")
pattern = root ~ "/" ~ substr(pattern, 9);
elsif(substr(pattern, 0, 9) == "$FG_HOME/")
pattern = home ~ "/" ~ substr(pattern, 9);
append(f[0] == "READ" ? read_rules : write_rules, [pattern, f[1] == "ALLOW"]);
}
close(file);
return 1;
}
# catch exceptions so that a die() doesn't ruin everything
call(func load_rules(home ~ "/" ~ config) or load_rules(root ~ "/" ~ config), nil, var err = []);
if(curr == "" or size(err)) {
debug.printerror(err);
read_rules = write_rules = [];
}
read_rules = [["*/" ~ config, 0]] ~ read_rules;
write_rules = [["*/" ~ config, 0]] ~ write_rules;
if(getprop("/sim/logging/priority") == "info") {
print("READ: ", debug.string(read_rules));
print("WRITE: ", debug.string(write_rules));
}
open = func(path, mode = "rb") {
var rules = write_rules;
if(mode == "r" or mode == "rb" or mode == "br")
rules = read_rules;
var fpath = string.fixpath(path);
foreach(var d; rules) {
if(string.match(fpath, d[0])) {
if(d[1])
return _open(fpath, mode);
break;
}
}
die("io.open(): opening file '" ~ path ~ "' denied (unauthorized directory)\n ");
}
});