FindFirstFile and FindNextFile crash my program in assembly. Why?

Question

I am writing a program that looking for files with the extension ".fly". It displays the names of the founded files, but when I try to use FindFirstFile and FindNextFile, my program crashes. I have tried with FindFirstFileA (ANSI Version of the function) , but my code crashes too. Please, give me a example of code if it's possible.

Please, thanks for your answers. Here's my source code written in FASM Assembly

format pe console 4.0
include 'C:\fasm\INCLUDE\WIN32AX.INC'

; Declare a macro to make buffers
macro dup label,lcount
 { forward
   label#:
   common
    repeat lcount
   forward
    db      0
   common
    end repeat }


.code

main:

explore_directoy:
    invoke      FindFirstFile,file_extension, FIND_STRUCT   ; find the first *.fly
    mov dword [find_handle], eax

find_more_files:
    cmp eax, 0
    je exit
    call show_file

findnextfile:
    invoke FindNextFile, dword [find_handle], FIND_STRUCT
    jmp find_more_files

show_file:
    invoke MessageBox, NULL, addr msg, addr msg_caption, MB_OK ; Easy way of outputing               the text
    ;invoke MessageBox, NULL, addr cFileName, addr msg_caption, MB_OK
    ret

exit:
    invoke ExitProcess, 0

datazone:
    end_msg     db      'End of program', 0
    msg         db      'File founded', 0
    msg_caption db      'Assembly program...', 0
    file_extension db '*.fly', 0
    find_handle     dd 0              ; handles/other stuff..
    FIND_STRUCT:                      ; find structure used with searching
        dwFileAttributes    dd 0
        ftCreationTime      dd 0,0
        ftLastAccessTime    dd 0,0
        ftLastWriteTime     dd 0,0
        nFileSizeHigh       dd 0
        nFileSizeLow        dd 0
        dwReserved0         dd 0
        dwReserved1         dd 0
        dup         cFileName, 256        ; found file buffer
        dup         cAlternate, 14

.end main

Are you calling `FindFirstFileA` or `FindFirstFileW`? Because if it's `FindFirstFileW`, I would expect a crash. — Gabe, Aug 15 '14 at 20:38
I have tried with the FindFirstFileA (ANSI function) but don't works. — jhonny6721, Aug 15 '14 at 20:40

score 2 · Accepted Answer · answered Aug 16 '14 at 01:16

2

Your .text section isn't writable. Change

.code

to

section '.text' readable writable executable

answered Aug 16 '14 at 01:16

Jens Björnhager

5,632
3
27
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Bjornhager, thanks for your answer. Your answer was very useful to fix my problem. – jhonny6721 Aug 18 '14 at 02:13

rcgldr · Answer 2 · 2014-08-16T20:37:43.103

0

Data should go into the .data section, not the .code section. If your assembler supports uninitialized data (all values defined as ?), then it should go into the .data? section (this is the equivalent of a bss (block started by symbol) section used in some other assemblers).

edited Aug 16 '14 at 20:37

answered Aug 16 '14 at 07:09

rcgldr

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FindFirstFile and FindNextFile crash my program in assembly. Why?

2 Answers2