[fpc-pascal] More memory leaks and other problems: request for review of probably stupid mistake

[Jim]

Hi all,

I'm trying to learn FreePascal by writing a file indexer a la locate and
I'm hitting more walls after receiving quick and clear help from Michael
Van Canneyt  regarding memory leaks.

In the last couple of hours I've seen memory leaks cropping up in the
main LPR file, invalid pointer problems (=> think I was too aggressive
cleaning up memory),  list index out of bounds, reading past end of file
errors (faulty "improvement" of data types in exif code?).

1. Could some kind soul tell me what I've been doing wrong if possible?
It's probably in the search as well as in the exif code.
I'd love to start with something that I can understand and work up from
there - at this moment I feel like I'm chasing smoke.
The code is at:
http://bitbucket.org/jb/flocate/downloads/

... but I'd rather prefer getting better at figuring out what I did
wrong, however, when setting some breakpoints on my
Lazarus 0.9.29 r23972 FPC 2.4.1 x86_64-win64-win32/win64
Free Pascal Compiler version 2.4.1 [2010/03/13] for x86_64
system, every time the IDE would inform me that the debugger had crashed.
I didn't see instructions for debugging with Lazarus x64 on Windows.
(I've also been running the fpc compiler only on Linux to see the
effects of the compiler conditionals).

2. Is there anything I need to do to get visual debugging working? Some
project options? I've fiddled with dwarf output etc but am not sure what
should be enable and disabled? Should I switch to Lazarus 32bit?
Please see heaptrc dump as well as last part of my debug output below.

Seems like I still need to get some basic details about the language
regardless of checking the fpc reference manual, Marco Cantu's Essential
Pascal/Delphi and the Delphi basics website...

Thanks in advance,
jb

stdout message:
exception at 000000010003EFE3:
Read past end of file.

stderr output snipped:
Debug: 31-3-2010 19:38:37: starting exif info
for:C:\Windows\Microsoft.NET\Framework64\v2.0.50727\ASP.NETWebAdminFiles\Images\ASPdotNET_logo.jpg
Heap dump by heaptrc unit
156639 memory blocks allocated : 13406733/14127240
156636 memory blocks freed     : 13406173/14126672
3 unfreed memory blocks : 560
True heap size : 1343488 (224 used in System startup)
True free heap : 1342208
Should be : 1342312
Call trace for block $00000000035662A0 size 432
  $0000000100038E2D  TFILESEARCH__SEARCHPERFILTER,  line 659 of search.pp
  $0000000100038CCF  TFILESEARCH__SEARCHPERFILTER,  line 638 of search.pp
  $0000000100038CCF  TFILESEARCH__SEARCHPERFILTER,  line 638 of search.pp
  $0000000100038CCF  TFILESEARCH__SEARCHPERFILTER,  line 638 of search.pp
  $0000000100038CCF  TFILESEARCH__SEARCHPERFILTER,  line 638 of search.pp
  $0000000100038CCF  TFILESEARCH__SEARCHPERFILTER,  line 638 of search.pp
  $000000010003915B  TFILESEARCH__SEARCH,  line 714 of search.pp
  $0000000100001AF5  FLOCATE__DORUN,  line 140 of flocate.lpr
Call trace for block $00000000035CAEF0 size 35
  $0000000100030659
  $00000001000324B1
  $0000000100032616
  $0000000100038CCF  TFILESEARCH__SEARCHPERFILTER,  line 638 of search.pp
  $0000000100038CCF  TFILESEARCH__SEARCHPERFILTER,  line 638 of search.pp
  $0000000100038CCF  TFILESEARCH__SEARCHPERFILTER,  line 638 of search.pp
  $0000000100038CCF  TFILESEARCH__SEARCHPERFILTER,  line 638 of search.pp
  $0000000100038CCF  TFILESEARCH__SEARCHPERFILTER,  line 638 of search.pp
Call trace for block $00000000011A5340 size 93
  $0000000100038CBB  TFILESEARCH__SEARCHPERFILTER,  line 638 of search.pp
  $0000000100038CCF  TFILESEARCH__SEARCHPERFILTER,  line 638 of search.pp
  $0000000100038CCF  TFILESEARCH__SEARCHPERFILTER,  line 638 of search.pp
  $0000000100038CCF  TFILESEARCH__SEARCHPERFILTER,  line 638 of search.pp
  $0000000100038CCF  TFILESEARCH__SEARCHPERFILTER,  line 638 of search.pp
  $000000010003915B  TFILESEARCH__SEARCH,  line 714 of search.pp
  $0000000100001AF5  FLOCATE__DORUN,  line 140 of flocate.lpr
  $0000000100034148