2009/7/6 fang zhengshu <fangzhsh07@gmail.com>

hi all,

when I write a function in the IDL file, there is a problem:want to write a different-length string to a array and then read  parts of the array to another string like:

interface test{
        int write([string]char* str, int len);
        int read([out,prealloc_client, size_is(size), prealloc_server]char str[], int size);
       };

I have defined a fixed size array in the server like array[256].
In the write() function I write a different length string to the array, then I want to read parts or all of the array in the read() function, the process will be like the following:

string[len]                               str[size]
        |                                        ^
        |                                         |
        --------->array[256] -----------|

but when I put the function above and compile it, there are some error happen. I have change the size_is() with length_is() or max_is(), but there still error when I compile it. I know if I define a fix array str[256] the code can be work, but I just want to use a unfixed length array to get the string.
could someone please give me some advice?if I describe the problem clearly, please let me know.

thank you!

I don't know whether  I describe what I want to do clearly,so I put the simple code below:

read-client                                                                                 write-client
#define STR_TO 30                                                                  #define STR_FROM 30
...                                                                                              ...
char str_to[SRR_TO];                                                               char str_from[STR_FROM];
...                                                                                              ...
read(str_to, STR_TO);                                                              write(str_from, STR_FROM);
...                                                                                               ...

                                                      server
                                                     #define SIZE 256
                                                     ...
                                                    char string[SIZE];
                                                    ...
                                                    int write(char *str_from, int str_from)
                                                   {
                 //write str_from size chars of str_from array to the string array which is in server
                                                   }
                                                   int read(char *str_to, int str_to)
                                                  {
                //read str_to size chars from the string array which is in server to str_to
                                                   }

Then I define write functions as the above in a .idl file,but when I compile it,there will be the following error:

terminate called after throwing an instance of 'std::out_of_range'
  what():  CBEMsgBuffer::IsEarlier
make[1]: *** [test-server.c] Aborted
make[1]: *** [test-server.c] Deleting file `test-sys.h'
make[1]: *** [test-server.c] Deleting file `test-client.h'
make[1]: *** [test-server.c] Deleting file `test-client.c'

make: *** [/home/l4/tudos/build/pkg/

fifo/idl/OBJ-x86-l4v2] Error 2

must we use the format as the dice manual below?:

int read([out, prealloc_client, size_is(len)] char **str, [out,in]int *len)

and when I modify the function as

int read([out, prealloc_client, prealloc_server, size_is(len)] char *str, [out,in]int *len)

there is no error when compile it,but there will be another error called :fpage
could you give me some advice for the read function?
thank you.
--
fang,