I'm try to create std.c.setjmp from <setjmp.h> (on Linux, gcc 3.3.1)

The following simple program seg faults:

[d] dmd -g sj.d
gcc sj.o -o sj -g -lphobos -lpthread -lm
[d] ./sj
Segmentation fault
------------------------------------------------ sj.d ---------------------
import std.c.setjmp;

jmp_buf env;

void main()
{
if(setjmp(env)) {
printf("0\n");
}
else {
printf("1\n");
}
}
---------------------------------------------------------------------------

Can anybody tell me why? thanks!

Also, if I change "env" to be a local var inside "main()", I cannot link sj:

[d] dmd -g sj.d
gcc sj.o -o sj -g -lphobos -lpthread -lm
sj.o(.gnu.linkonce.t_Dmain+0x8): In function `_Dmain':
: undefined reference to `_init_3std1c6setjmp13__jmp_buf_tag'
collect2: ld returned 1 exit status
--- errorlevel 256
------------------------------------------------ sj.d ---------------------
import std.c.setjmp;

void main()
{
jmp_buf env;

if(setjmp(env)) {
printf("0\n");
}
else {
printf("1\n");
}
}
---------------------------------------------------------------------------

So what's the problem with linking?

Thanks.

The generated setjmp.d is here (also attached):
---------------------------------------------------------- setjmp.d -------
odule std.c.setjmp;

extern (C)
{

alias int __jmp_buf[6];
alias int __sig_atomic_t;

struct __sigset_t
{
uint __val[(1024 / (8 * uint.sizeof))];
}

struct __jmp_buf_tag
{

__jmp_buf __jmpbuf;
int __mask_was_saved;
__sigset_t __saved_mask;
}

alias __jmp_buf_tag jmp_buf;

extern int setjmp (jmp_buf __env) ;

extern int __sigsetjmp  (__jmp_buf_tag __env, int __savemask) ;

extern int _setjmp      (__jmp_buf_tag __env) ;

extern void longjmp     (__jmp_buf_tag __env, int __val) ;

extern void _longjmp    (__jmp_buf_tag __env, int __val) ;

alias __jmp_buf_tag sigjmp_buf;
extern void siglongjmp  (sigjmp_buf __env, int __val) ;

}
---------------------------------------------------------------------------

Try &jmp_buf.

<some@where.com> wrote in message news:c6t0e4$1bc8$1@digitaldaemon.com...
> I'm try to create std.c.setjmp from <setjmp.h> (on Linux, gcc 3.3.1)
>
> The following simple program seg faults:
>
> [d] dmd -g sj.d
> gcc sj.o -o sj -g -lphobos -lpthread -lm
> [d] ./sj
> Segmentation fault
> ------------------------------------------------ 
sj.d ---------------------
> import std.c.setjmp;
>
> jmp_buf env;
>
> void main()
> {
> if(setjmp(env)) {
> printf("0\n");
> }
> else {
> printf("1\n");
> }
> }
> --------------------------------------------------------------------------
-
>
> Can anybody tell me why? thanks!
>
> Also, if I change "env" to be a local var inside "main()", I cannot link
sj:
>
> [d] dmd -g sj.d
> gcc sj.o -o sj -g -lphobos -lpthread -lm
> sj.o(.gnu.linkonce.t_Dmain+0x8): In function `_Dmain':
> : undefined reference to `_init_3std1c6setjmp13__jmp_buf_tag'
> collect2: ld returned 1 exit status
> --- errorlevel 256
> ------------------------------------------------ 
sj.d ---------------------
> import std.c.setjmp;
>
> void main()
> {
> jmp_buf env;
>
> if(setjmp(env)) {
> printf("0\n");
> }
> else {
> printf("1\n");
> }
> }
> --------------------------------------------------------------------------
-
>
> So what's the problem with linking?
>
> Thanks.
>
> The generated setjmp.d is here (also attached):
> ---------------------------------------------------------- 
setjmp.d -------
> odule std.c.setjmp;
>
> extern (C)
> {
>
> alias int __jmp_buf[6];
> alias int __sig_atomic_t;
>
> struct __sigset_t
> {
> uint __val[(1024 / (8 * uint.sizeof))];
> }
>
> struct __jmp_buf_tag
> {
>
> __jmp_buf __jmpbuf;
> int __mask_was_saved;
> __sigset_t __saved_mask;
> }
>
> alias __jmp_buf_tag jmp_buf;
>
> extern int setjmp (jmp_buf __env) ;
>
> extern int __sigsetjmp  (__jmp_buf_tag __env, int __savemask) ;
>
> extern int _setjmp      (__jmp_buf_tag __env) ;
>
> extern void longjmp     (__jmp_buf_tag __env, int __val) ;
>
> extern void _longjmp    (__jmp_buf_tag __env, int __val) ;
>
> alias __jmp_buf_tag sigjmp_buf;
> extern void siglongjmp  (sigjmp_buf __env, int __val) ;
>
> }
> --------------------------------------------------------------------------
-
>
>
>
>

In article <c6tsrh$2r2d$1@digitaldaemon.com>, Walter says...
>
>Try &jmp_buf.

What do you mean?

I tried to put "&" before/after "jmp_buf", the file is not compiling:

[d] dmd sj.d
sj.d(3): no identifier for declarator
sj.d(3): semicolon expected, not '&'
sj.d(3): Declaration expected, not '&'

If I try to put "&" before "env", it says:

[d] dmd sj.d
sj.d(6): function setjmp (__jmp_buf_tag __env) does not match argument types
(__jmp_buf_tag *)


[d] cat sj.d
------------------------------------------------------------------
import std.c.setjmp;

jmp_buf env;
void main()
{
if(setjmp(&env))  { printf("0\n"); }
else              { printf("1\n"); }
}
------------------------------------------------------------------

This is a very tiny example, can you be more verbose in your response?

Thanks.

C's setjmp() takes a pointer to a struct, not the struct itself. Just as you
would in C.

<some@where.com> wrote in message news:c6tu09$2t7e$1@digitaldaemon.com...
> In article <c6tsrh$2r2d$1@digitaldaemon.com>, Walter says...
> >
> >Try &jmp_buf.
>
> What do you mean?
>
> I tried to put "&" before/after "jmp_buf", the file is not compiling:
>
> [d] dmd sj.d
> sj.d(3): no identifier for declarator
> sj.d(3): semicolon expected, not '&'
> sj.d(3): Declaration expected, not '&'
>
> If I try to put "&" before "env", it says:
>
> [d] dmd sj.d
> sj.d(6): function setjmp (__jmp_buf_tag __env) does not match argument
types
> (__jmp_buf_tag *)
>
>
> [d] cat sj.d
> ------------------------------------------------------------------
> import std.c.setjmp;
>
> jmp_buf env;
> void main()
> {
> if(setjmp(&env))  { printf("0\n"); }
> else              { printf("1\n"); }
> }
> ------------------------------------------------------------------
>
> This is a very tiny example, can you be more verbose in your response?
>
> Thanks.
>
>
>

Forgot to mention, you'll also need to fix your declaration of setjmp() in setjmp.d to take a pointer to the struct. Otherwise, you'll get the message you did in the second example.

"Walter" <newshound@digitalmars.com> wrote in message news:c6uja9$sqg$1@digitaldaemon.com...
> C's setjmp() takes a pointer to a struct, not the struct itself. Just as
you
> would in C.
>
> <some@where.com> wrote in message news:c6tu09$2t7e$1@digitaldaemon.com...
> > In article <c6tsrh$2r2d$1@digitaldaemon.com>, Walter says...
> > >
> > >Try &jmp_buf.
> >
> > What do you mean?
> >
> > I tried to put "&" before/after "jmp_buf", the file is not compiling:
> >
> > [d] dmd sj.d
> > sj.d(3): no identifier for declarator
> > sj.d(3): semicolon expected, not '&'
> > sj.d(3): Declaration expected, not '&'
> >
> > If I try to put "&" before "env", it says:
> >
> > [d] dmd sj.d
> > sj.d(6): function setjmp (__jmp_buf_tag __env) does not match argument
> types
> > (__jmp_buf_tag *)
> >
> >
> > [d] cat sj.d
> > ------------------------------------------------------------------
> > import std.c.setjmp;
> >
> > jmp_buf env;
> > void main()
> > {
> > if(setjmp(&env))  { printf("0\n"); }
> > else              { printf("1\n"); }
> > }
> > ------------------------------------------------------------------
> >
> > This is a very tiny example, can you be more verbose in your response?
> >
> > Thanks.
> >
> >
> >
>
>

I also have *thought* that setjmp() should take a pointer.  And the calling
function should hold the actual struct.  But ... (Digital Mars Compiler Version
8.38n)

c:\> dmc sj.c
link sj,,,user32+kernel32/noi;

c:\> sj.exe
sizeof(jmp_buf) = 64

----------------------------------------------------------------- sj.c -----
#include <setjmp.h>
#include <stdio.h>

int main()
{
printf("sizeof(jmp_buf) = %d\n", sizeof(jmp_buf));
return 0;
}
----------------------------------------------------------------- sj.c -----

And on Linux:

[d] ./sj
sizeof(jmp_buf) = 156

I'm totally confused.  Can you try my example?  and what's your explanation?

Thanks.


In article <c6uk14$ts0$1@digitaldaemon.com>, Walter says...
>
>Forgot to mention, you'll also need to fix your declaration of setjmp() in setjmp.d to take a pointer to the struct. Otherwise, you'll get the message you did in the second example.
>
>"Walter" <newshound@digitalmars.com> wrote in message news:c6uja9$sqg$1@digitaldaemon.com...
>> C's setjmp() takes a pointer to a struct, not the struct itself. Just as
>you
>> would in C.

You're falling victim to the C rule of implicitly converting arrays to pointers, *EXCEPT* if they are the argument to sizeof. Thus, setjmp(jmp_buf) passes a pointer to setjmp, but sizeof(jmp_buf) gives the size of the jmp_buf array, not the size of a pointer.

<some@where.com> wrote in message news:c6ull3$104i$1@digitaldaemon.com...
> I also have *thought* that setjmp() should take a pointer.  And the
calling
> function should hold the actual struct.  But ... (Digital Mars Compiler
Version
> 8.38n)
>
> c:\> dmc sj.c
> link sj,,,user32+kernel32/noi;
>
> c:\> sj.exe
> sizeof(jmp_buf) = 64
>
> ----------------------------------------------------------------- 
sj.c -----
> #include <setjmp.h>
> #include <stdio.h>
>
> int main()
> {
> printf("sizeof(jmp_buf) = %d\n", sizeof(jmp_buf));
> return 0;
> }
> ----------------------------------------------------------------- 
sj.c -----
>
> And on Linux:
>
> [d] ./sj
> sizeof(jmp_buf) = 156
>
> I'm totally confused.  Can you try my example?  and what's your
explanation?
>
> Thanks.
>
>
> In article <c6uk14$ts0$1@digitaldaemon.com>, Walter says...
> >
> >Forgot to mention, you'll also need to fix your declaration of setjmp()
in
> >setjmp.d to take a pointer to the struct. Otherwise, you'll get the
message
> >you did in the second example.
> >
> >"Walter" <newshound@digitalmars.com> wrote in message news:c6uja9$sqg$1@digitaldaemon.com...
> >> C's setjmp() takes a pointer to a struct, not the struct itself. Just
as
> >you
> >> would in C.
>
>