[REBOL] Re: Accesing struct! after routine! exec
From: nitsch-lists:netcologne at: 3-Jun-2003 3:54
Jaime Vargas wrote:
>Hello All. I've been having problems with the following script
>when trying to access a subroutine in libc. I am using openbsd.
>
>Everything executes well but rebol crashes with a coredump
>when I try to access the fields of the struct! after calling the
>external function.
>
>REBOL[]
>stdclib: %/usr/lib/libc.so.29.0
>clib: load/library stdclib
>
>c-string: func [
> "Returns a null terminated c-string of size strsize"
> strsize [integer!] "The size of the string"
> /fill blank [char!] "Character to fill the blanks"
> /local str
>][
> if none? fill [ blank: #"." ]
>
> ; fill the blancs
> str: make string! strsize
> loop strsize [
> insert str blank
> ]
>
> ; insert null to terminate the c-string
> poke str strsize #"^(null)"
>
> return str
>]
>
>utsname: make struct! [
> sysname [string!]
> nodename [string!]
> release [string!]
> version [string!]
> machine [string!]
>] reduce [
> c-string 256
> c-string 256
> c-string 256
> c-string 256
> c-string 256
> c-string 256
>]
>
>uname: make routine! compose/deep [
> name [struct! [(first utsname)]]
> return: [integer!]
>] clib "_uname"
>
>uname utsname
>
>probe utsname
>
>Here are the c definitions:
>
>int uname (struct utsname *name );
>#define SYS_NMLN 256
>
>struct utsname {
> char
sysname[SYS_NMLN];
/* Name of this OS. */
> char
nodename[SYS_NMLN];
/* Name of this network node. */
> char
release[SYS_NMLN];
/* Release level. */
> char
version[SYS_NMLN];
/* Version level. */
> char
machine[SYS_NMLN];
/* Hardware type. */
>};
>
Trying to remember c,
the rebol-definition means
struct utsname {
char * sysname;
/* Name of this OS. */
char * nodename;
/* Name of this network node. */
char * release;
/* Release level. */
char * version;
/* Version level. */
char * machine;
/* Hardware type. */
};
which means a struct with pointers.
while the c-defenition is a struct with char-arrays.
if i am right, eventually this works:
string: insert/dup "" " " 5 * SYS_NMLN ; make a filled string
sysname: string
nodename: skip string SYS_NMLN
release: skip nodename SYS_NMLN
...
and pass the string as argument.
sysname: copy/part sysname find sysname #"^(null)"
to get it back.
>Ideas anyone??? Thanks for your help, Jaime
>
>-- The best way to predict the future is to invent it -- Steve Jobs
>
-Volker
