Calling a DLL from LabVIEW causes crash

Okay, this is an odd one. I have searched through various posts and have found several things that were close but not quite the same.
I have a DLL. I pass to the function in the DLL two strings, each one representing an absolute path to a pair of files. I use a path control to get the paths and then convert those paths to strings. The function also has about 13 other parameters, each of which are U8's passed by reference. I have attached my VI and the DLL. I had to zip the DLL to get it a valid extension.
The function opens the file pointed to by the first string and parses information out of it. It then tries to create some temporary files in a folder that W7 considers to be a safe temporary folder. The problem is that when I run this VI, LabVIEW crashes...hard. I get the message that LV needs to close. However, before it crashes, it successfully opens the file, parses the info out of it and creates one new file in the temp folder. So, the issue seems to happen after the function mostly finishes with everything it needs to do.
One interesting note: I replaced the outputs of the path2string conversions with string constants pointing to the exact same files. Now LV doesn't crash. Instead I get an unhandled exception error in the DLL.
Next interesting note: This same procedure called from another application written in C (on another system) works fine.
Finally, I do have one advantage that most others don't: the developer of the DLL is a coworker of mine. So I have access to the source code.
My coworker feels that the function is failing "between the lines" of code. He thinks it is some type of stack overrun but can't place it.
Any thoughts?
Thanks,
Joe
Attachments:
dll_LoadConstantsFile.vi ‏15 KB
gui_confread_dll.zip ‏40 KB

Rolf, if I understood you correctly, here is the portion of the header file that declares the function:
#define
DLL_EXPORT __declspec(dllexport)
BOOL WINAPI DLLMain(HINSTANCE hinstDLL,DWORD,LPVOID);
extern
"C" DLL_EXPORT void__cdecl LoadConstantsFile(char*filename,
char*patch,
uInt8 *load_status,
uInt8 *device_type,
uInt8 *multi_bom_available,
uInt8 *hires_gain_available,
uInt8 *dcdc_bom_option,
uInt8 *bat_rail_type,
uInt8 *num_mb_genconf,
uInt8 *num_ring_presets,
uInt8 *num_dcfeed_presets,
uInt8 *num_impedance_presets,
uInt8 *num_fsk_presets,
uInt8 *num_tone_presets,
uInt8 *num_pcm_presets);
Here is a description of the function:
Constants File Reader
This is the main function that parses the constants files, collects information, and creates temporary script files. Run this FIRST.
void LoadConstantsFile(char *filename,
char *patch,
uInt8 *load_status,
uInt8 *device_type,
uInt8 *multi_bom_available,
uInt8 *hires_gain_available,
uInt8 *dcdc_bom_option,
uInt8 *bat_rail_type,
uInt8 *num_mb_genconf,
uInt8 *num_ring_presets,
uInt8 *num_dcfeed_presets,
uInt8 *num_impedance_presets,
uInt8 *num_fsk_presets,
uInt8 *num_tone_presets,
uInt8 *num_pcm_presets);
Inputs
filename
Full path and filename of constants file to be read
patch
Full path and filename of patch file to be loaded
I/O
load_status
Updated with 0 if load successful, non-zero if unsuccessful (see codes table)
device_type
Updated with value representing device supported by the configuration file (see codes table)
multi_bom_available
Updated with 1 if configuration file supports the multi-bom format, 0 otherwise
hires_gain_available
Updated with 1 if configuration file supports the hires gain format, 0 otherwise
dcdc_bom_option
Updated with DCDC BOM Option of
default General Configuration detected (see codes table)
bat_rail_type
Updated with Battery Rail Type of
default General Configuration detected (see codes table)
num_mb_genconf
Number of general configuration presets detected (if multi-bom is supported)
The items marked as "inputs" are meant to have something passed in as a value. The parameters marked as I/O are meant to have a pointer to them passed so the function can modify the values (passed as reference).
The function simply opens the file at "filename" and parses out the info to update the other U8 parameters. The file pointed to by "patch" is simply opened to verify it exists and then closed.

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Problem about calling a DLL in LABVIEW

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Attachments:
mydll.txt ‏22 KB
callfunctionnode.vi ‏7 KB

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Message Edited by Ravens Fan on 07-20-2007 12:01 AM

Calling a DLL from LabVIEW causes crash

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