How to malloc a char ** from C to Perl (btw, $! now works, thanks!)

[Daniel Shane]

Hi,

With the help of this group I got $! to work, now here is another problem...

I would like to make this work in perl XS:

void init(str)
        char *   &str

void fill(str, str2)
        char *    str
        char *    str2

void free(str)
        char *    str

void init(char *str) {
        *str = (char *)calloc(20, sizeof(char));
}

void fill(char *str, char *str2) {
        strcpy(str, str2);
}

void free(char *str) {
        free(str);
}

Now in perl I could simply do:

my $test_string;           # $test_string is undefined...

init(\$test_string);       # now $test_string should be defined but empty...
print "$test_string \n";   # Should print nothing...

fill($test_string, "Hello World!");
print "$test_string \n";   # Should print "Hello World!"

free($test_string);        # Now $test_string should be undefined

The char ** is to be considered as a pointer to a string and not a table of
strings (hence the char * &str in init()).

I'm not sure if I \$test_string is sufficient or if I should rather do $tmp;
$test_string = \$tmp;

What would I put in my typemap file to handle freely the conversion between
char ** and perl in this special case, would T_PACKED work? I would
especialy like to "undefine" a perl variable in C. Is this possible?

Thanks!

Daniel Shane