| Re: call_external (IDL5.5) [message #29474] |
Tue, 26 February 2002 10:43  |
Craig Markwardt
Messages: 1869
Registered: November 1996
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Senior Member |
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Reimar Bauer <r.bauer@fz-juelich.de> writes:
> James Kuyper wrote:
...
>> Which points out he importance of using "#include export.h" to create
>> the typedef, rather than copying the typedef into your own code.
>
> I agree to this and sure this was the main problem.
>
> The second problem comes from this two lines.
>
> strcpy(buf,path.s);
> buf[path.slen]='\0';
>
> I have learned that I have to do:
>
> buf[path.slen]='\0';
> strcpy(buf,path.s);
Reimar, this does not sound right. The use of strcpy() is rather
unsafe, and you should prefer strncpy(). Also, there is the risk that
the "path" string is longer than buf[]. Then what do you do?
Safer approach:
char buf[NCHAR];
int len;
if (path.slen >= NCHAR) len = NCHAR-1; else len = path.slen;
if (len > 0) strncpy(buf, path.s, len);
buf[len] = 0;
If the "path" is too long for the buf[], then this code truncates it.
Cheers,
Craig
--
------------------------------------------------------------ --------------
Craig B. Markwardt, Ph.D. EMAIL: craigmnet@cow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
------------------------------------------------------------ --------------
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| Re: call_external (IDL5.5) [message #29494 is a reply to message #29493] |
Mon, 25 February 2002 06:56  |
Mark Rivers
Messages: 49
Registered: February 2000
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Member |
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Reimar Bauer <r.bauer@fz-juelich.de> wrote in message
news:3C7A252F.F64A3633@fz-juelich.de...
> Hi,
>
> I have a found a difference between CALL_EXTERNAL for IDL5.4.1 and
> IDL5.5. One of my routines crashes in idl5.5.
> Why? I don't know at the moment!
>
> I don't find a hint about changes for call_external.
>
> What is your experience?
There is one very important difference between CALL_EXTERNAL in IDL 5.5 and
previous versions, which has to do with how IDL strings are passed. The
following code is from "export.h" in IDL 5.5.
********************************************
typedef int IDL_STRING_SLEN_T;
#define IDL_STRING_MAX_SLEN 2147483647
typedef struct { /* Define string descriptor */
IDL_STRING_SLEN_T slen; /* Length of string, 0 for null */
short stype; /* type of string, static or dynamic */
char *s; /* Addr of string */
} IDL_STRING;
********************************************
Note that "slen" is of type "int". In previous versions it was of type
"short". Thus, if your external C code is being passed strings it needs to
be changed for IDL 5.5.
I worked around this problem, making a single DLL that will work for any IDL
version, by changing my IDL wrapper routines and C code to never pass
strings, but convert everything to byte arrays before CALL_EXTERNAL, and
back to strings after CALL_EXTERNAL.
Mark Rivers
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| Re: call_external (IDL5.5) [message #29497 is a reply to message #29496] |
Mon, 25 February 2002 05:19 |
R.Bauer
Messages: 1424
Registered: November 1998
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Senior Member |
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Reimar Bauer wrote:
>
Hi,
I give an example:
The following compiled and used by idl5.4.1 works fine and IDL5.5 got's
a memory fault.
IDL> PRINT,call_external('my_stat.so.linux','uid','file.txt',/i_v alue)
/*
Linux:
gcc -fPIC -Wall -g -c my_stat.c
gcc -g -shared -W1,-soname,my_stat.so.0 -o my_stat.so.linux my_stat.o
-lc
*/
#include <sys/stat.h>
#include <stdio.h>
#include <stdlib.h>
typedef struct {
unsigned short slen;
short stype;
char *s;
} IDL_STRING;
double uid(int argc, void *argv[])
{
/* returns the user-id of the file */
struct stat s;
int rcode;
IDL_STRING path;
char buf[1023];
long uid;
path=*(IDL_STRING *) argv[0];
strcpy(buf,path.s);
buf[path.slen]='\0';
rcode=stat(buf,&s);
uid=s.st_uid;
return(uid);
}
--
Reimar Bauer
Institut fuer Stratosphaerische Chemie (ICG-1)
Forschungszentrum Juelich
email: R.Bauer@fz-juelich.de
http://www.fz-juelich.de/icg/icg1/
============================================================ ======
a IDL library at ForschungsZentrum Juelich
http://www.fz-juelich.de/icg/icg1/idl_icglib/idl_lib_intro.h tml
http://www.fz-juelich.de/zb/text/publikation/juel3786.html
============================================================ ======
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| Re: call_external (IDL5.5) [message #29584 is a reply to message #29495] |
Wed, 06 March 2002 06:42 |
Gert Van de Wouwer
Messages: 21
Registered: January 2002
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Junior Member |
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>
> Under what conditions do you have to link in idl32.lib? I don't
> -think- I did that with my call_external .dll's under 5.4 (unless
> there was something horrible buried in the export.h file...)
>
you only need to link if you use stuff like IDL_Message(..) in your
c-code...
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