Re: exec problem is JDK 1.7.0_21
On 20/04/13 22:40, Sven K?hler wrote:
Oh, and of course the ProcessBuilder doesn't behave as it is supposed
to. As mentioned in my first post, the String "\"a b\"" would be passed
unmodified to the program invoked. However, clearly, the string passed
to the program should have been
"\"\\\"a b\\\"\""
Only with the quotes and backslashes added, CommandLineToArgv would
decode it to "\"a b\"". With the current ProcessBuilder implementation,
a Windows program will see the parameter "a b" while on UNIX the program
will see "\"a b\"".
See
http://msdn.microsoft.com/en-us/library/windows/desktop/bb776391%28v=vs.85%29.aspx
for details.
You're expecting Java to build its Windows command string something like
this?:
import java.util.*;
import java.util.regex.*;
public final class WindowsArgumentGenerator {
private WindowsArgumentGenerator() { }
private static final Pattern slashSequence =
Pattern.compile("\\\\*\"");
private static boolean needsQuotes(String arg) {
return arg.indexOf(' ') > -1;
}
public static String generateWindowsArgument(List<? extends String> args) {
StringBuilder out = new StringBuilder();
String sep = "";
for (String arg : args) {
out.append(sep);
sep = " ";
final boolean quoted = needsQuotes(arg);
if (quoted)
out.append('"');
Matcher m = slashSequence.matcher(arg);
int lastEnd = 0;
while (m.find()) {
out.append(arg.substring(lastEnd, m.start()));
final String slashes = m.group();
final int len = slashes.length() - 1;
out.append(slashes.substring(0, len))
.append('\\')
.append(slashes);
lastEnd = m.end();
}
out.append(arg.substring(lastEnd));
if (quoted)
out.append('"');
}
return out.toString();
}
public static void main(String[] args) throws Exception {
for (int i = 0; i < args.length; i++)
System.out.printf("argv[%d]=[%s]%n", i, args[i]);
System.out.println(generateWindowsArgument(Arrays.asList(args)));
}
}
Does that work correctly for anything to be thrown at CommandLineToArgvW?
Note, that I assume that the program invoked uses CommandLineToArgv to
decode the command line. Which is by no means clear, as any program can
implement their own tokenizer.
Don't you find that a bit strange?
Perhaps that assumption is too risky for Java to make, e.g. there are
enough 'native' Windows/DOS commands around that the programmer is
likely to want to invoke, but don't use CommandLineToArgvW, and so would
be confused if they received a string escaped as above. Not a very
satisfactory situation.
--
ss at comp dot lancs dot ac dot uk