memory stack problem Post: 80431

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Top Forums Programming memory stack problem Post 80431 by jkeagy on Monday 8th of August 2005 11:02:56 AM

08-08-2005

Registered User

memory stack problem

Hi, I am writing a C program under SCO Unix. I have a memory stack problem but do not know how to go about fixing it. I have tried running INSURE but that does not detect any problems.

Essentially the problem is that the memory address shifts on return from a routine. I pass a pointer to function "get_dsp_data" which passes a pointer to that pointer (AKA double pointer) to a database routine. In the db routine I fill in the double pointer structure after malloc'ing memory. The data is fine within the db routine. The data is fine in the "get_dsp_data" routine. However, when the data gets back to the first routine the memory location has shifted, see below.

*****************************************************
stbm.c 310 before: p_number_of_dsps is 0 and
&p_number_of_dsps is 2147481140
stbm.c 1052 In get_dsp_data, p_number_of_dsps is 16 and
&p_number_of_dsps is 2147481140

** memory shifts here but I don't know why or how **

stbm.c 312 after: p_number_of_dsps is 0 and
&p_number_of_dsps is 2147481034
*****************************************************

If I change things around so that the variable is a global then the program cores at the end of the last routine before exit. I am thinking that possibly memory is going past its bounds but I don't know how to verify or fix this.

One other bit of information, I ported my code over to LINUX and ran valgrind on it, but no problems were detected. But that could be because the memory did not shift when run on the LINUX system. Perhaps it is a difference in the way the compilers handle memory??

Please if anyone has any ideas for me on how to troubleshoot let me know.

Thanks, Jeanne

jkeagy

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xmfontlistgetnextfont

XmFontListGetNextFont(library call)									       XmFontListGetNextFont(library call)

NAME

       XmFontListGetNextFont -- A font list function that allows applications to access the fonts and character sets in a font list

SYNOPSIS

       #include <Xm/Xm.h>
       Boolean XmFontListGetNextFont(
       XmFontContext context,
       XmStringCharSet *charset,
       XFontStruct **font);

DESCRIPTION

       XmFontListGetNextFont  accesses	the  character set and font for the next entry of the font list. The application first uses the XmFontLis-
       tInitFontContext routine to create a font list context.	The application then calls XmFontListGetNextFont repeatedly with the same context.
       Each succeeding call accesses the next element of the font list. When finished, the application calls XmFontListFreeFontContext to free the
       allocated font list context.

       This routine allocates memory for the character set string that must be freed by  the  application.   The  function  allocates  memory  for
       charset.   The  application  is responsible for managing the allocated memory.  The application can recover the allocated memory by calling
       XtFree.

       This function is obsolete and exists for compatibility with previous releases. It is replaced by  XmFontListNextEntry.	If  XmFontListGet-
       NextFont  is  passed a context that contains a font set entry, it will return the first font of the font set. The next call to the function
       will move to the next entry in the font list.

       context	 Specifies the font list context

       charset	 Specifies a pointer to a character set string; the routine returns the character set for the current font list element

       font	 Specifies a pointer to a pointer to a font structure; the routine returns the font for the current font list element

RETURN

       Returns True if the returned values are valid; otherwise, returns False.

RELATED

       XmFontList(3) and XmFontListNextEntry(3).

													       XmFontListGetNextFont(library call)