I'm not sure why you're seeing garbage starting at the 22nd character
instead of the 25th. But keep in mind that StrNCopy -- like strncpy -- does
NOT terminate the string if there are at least "n" characters in the source
(where "n" is the third parameter passed to the function). When you then
pass an unterminated string to FrmCopyLabel, it will walk off then end of
the buffer allocated by MemPtrNew, resulting in the error message you see.
-- Keith Rollin
-- Palm OS Emulator engineer
Derek Kite <[EMAIL PROTECTED]> wrote in message
news:27396@palm-dev-forum...
>
> static void DetailsHeaderInit(MemHandle * LH)
> {
> I have this routine which I use to initialize some labels on a form. I am
> getting an this error in Pose, running gremlin 0.
>
> 3352.192 (7901): === ERROR: Gremlin #0 Event 7900
> 3352.193 (7901): === ERROR:
****************************************************************************
****
> 3352.193 (7901): === ERROR: "Job Tracker" 0.5.0 has just read directly
from memory manager data structures.
>
> This problem indicates an error in the application. Users should upgrade
this product immediately to safeguard their data.
> 3352.193 (7901): === ERROR:
****************************************************************************
****
> 3354.039 (7901): === ERROR: Gremlin #0 terminated in error at event #7900
>
> The error occurs as marked below in this routine...
>
> AccessArrayPtr lap;
> FormPtr frm;
> Char * tmpstr = NULL;
> MemHandle jhandle;
>
>
> lap = MemHandleLock(*LH);
> JobDataGetRecord(JobListDB,lap->jobrecnum,&lap->jobdata,&jhandle);
>
> frm = FrmGetFormPtr(jobdetailsform);
>
> // copy job number to top label
> FrmCopyLabel(frm,detailsjobnumlabel,lap->jobdata.fields[inumber]);
> if (StrLen(lap->jobdata.fields[icustomer]) > 24)
> tmpstr = MemPtrNew(26);
> tmpstr = StrNCopy(tmpstr,lap->jobdata.fields[icustomer],24);
> >>>>> FrmCopyLabel(frm,detailcustlabel,tmpstr);
> MemPtrFree(tmpstr);
>
> It blows up on FrmCopyLabel. The detailcustlabel is defined in the rcp
file as
> xx... 26 times. I am attempting to truncate the string to fit into the
label.
> 24 should work, and in fact does work if I test the routine with a long
string.
>
> In the debugger, If I look at lap->jobdata.fields[icustomer], it is as
> expected. After I do the StrNCopy into tmpstr, tmpstr is a copy for the
first
> 21 letters, then corrupted characters. 22 nd char is different, 23 is
/002, 24
> is /000. I suspect FrmCopyLabel is blowing up on the /002, or ??. Each
time I
> run it, the corrupted characters are the same. I have tried to get it to
do the
> same outside of the gremlins, with no success.
>
> I don't know what is happening here. tmpstr is initialized as NULL,
MemPtrNew
> succeeds, ie. tmpstr is not NULL. lap->jobdata.fields[icustomer] is a
struct
> which contains the jobdata struct into which is unpacked the database
packed
> record, with an array of charptrs. The data is locked, then unlocked at
the end
> of the routine.
>
> Why is StrNCopy not faithfully copying the string?
>
> Linux, prctools 2.0, 3.5 sdk, pose 3.07 for linux,
> palmos35-dr4-en-nonezdbg.rom, palmIII device, 1024K.
>
> Thanks
>
> Derek (I hope this gets on the somewhat intermittant list)
>
>
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