Hi Simon,
Only two documented reasons for malloc() to return NULL:
1) Insufficient storage available
2) Requested allocation size is zero
Neither, it seems one of the procedures failed and subsequently several
other procedures ended abnormally then the error was trapped, but the
allocated storage not freed and the program seemed to end normally. I need
to do some more tests, but if everything runs ok, malloc works correctly.
Mit freundlichen Grüßen / Best regards
Birgitta Hauser
"Shoot for the moon, even if you miss, you'll land among the stars." (Les
Brown)
"If you think education is expensive, try ignorance." (Derek Bok)
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-----Ursprüngliche Nachricht-----
Von: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx] Im
Auftrag von Simon Coulter
Gesendet: Thursday, 17. September 2009 15:43
An: RPG programming on the IBM i / System i
Betreff: Re: C-function returns *NULL when executing malloc
On 16/09/2009, at 10:28 PM, Birgitta Hauser wrote:
In an specific environment it works the first time I call the
procedure, but
for all subsequent calls MyDS_p is returned as *NULL-Value (and I
have no
idea why, there is no joblog entry either ).
Only two documented reasons for malloc() to return NULL:
1) Insufficient storage available
2) Requested allocation size is zero
Reason 1 is possible but unlikely unless previous allocations are not
being released (i.e., memory leak) especially on only the second call,
reason 2 would also be unlikely because the code uses %SIZE to
calculate the requested allocation however I think the compiler
calculates the result of %SIZE once and stores it so perhaps the
storage is being trashed and set to a nonsense value?
If I call the same procedure from an other program within the same
job it
works without problems, even for repeated calls.
Suggests the problem is in the calling program.
I know it would be easier to define the data structure directly
without
based, but it is an old procedure and I cannot change it.
Someone has an idea what happened.
My colleague assumes it is because I?m using named activation
groups, while
all other programs and service program (also this one where the
procedure is
located) run in the QILE default activation group.
Hmm, terminology check. QILE isn't the default activation group. There
is no difference between the QILE activation group and any other named
activation group.
But I cannot imagine that different activation groups may cause this
problem.
I doubt it too. Given what you describe I suspect the calling program
is doing something to trash storage which results in this effect.
Regards,
Simon Coulter.
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