I tried to read an input into a buffer with fgets. I pushed the 3 parameters, but got segmentation fault. I tried to see the problem with GDB, but I didn't understand the message that I got there.
This is the code:
section .rodata
buffer: db 10
section .text
align 16
global main
extern fgets
extern stdin
main:
push ebp
mov ebp, esp
pushad
push dword[stdin];
push 10;
push buffer;
call fgets;
add esp, 12;
popad ; Restore registers
mov esp, ebp ; Function exit code
pop ebp
ret
And this is the message that I got:
Program received signal SIGSEGV, Segmentation fault.
__GI__IO_getline_info (fp=fp@entry=0xf7fb1c20 <_IO_2_1_stdin_>,
buf=buf@entry=0x80484f0 "\n", n=8, n@entry=9, delim=delim@entry=10,
extract_delim=extract_delim@entry=1, eof=eof@entry=0x0) at iogetline.c:86
86 iogetline.c: No such file or directory.
What is wrong with my code?
Probably the library you were using.
It's 25 years since I bothered mixing C with asm... but a question.
It is correct to put C function declarations in a .text segment ?
That read buffer size was only 1 byte in readonly section?
section .bss
buffer: resb 15
Hi johny23,
Here is an example for you. The application receives keyboard input using the function fgets and displays the text in the console :
include fgets.inc
_iobuf STRUCT
_ptr DWORD ?
_cnt DWORD ?
_base DWORD ?
_flag DWORD ?
_file DWORD ?
_charbuf DWORD ?
_bufsiz DWORD ?
_tmpfname DWORD ?
_iobuf ENDS
FILE TYPEDEF _iobuf
BUFF_SIZE equ 256
.data
format db 13,10,'%s',0
msg db 'Type some text and hit RETURN',13,10,0
.data?
stdout dd ?
stdin dd ?
stderr dd ?
buffer db BUFF_SIZE dup(?)
.code
start:
call crt___p__iob
mov stdin,eax ; #define stdin (&__iob_func()[0])
mov ecx,SIZEOF(FILE)
add eax,ecx
mov stdout,eax ; #define stdout (&__iob_func()[1])
add eax,ecx
mov stderr,eax ; #define stderr (&__iob_func()[2])
invoke crt_printf,ADDR msg
invoke crt_fgets,ADDR buffer,BUFF_SIZE,stdin
invoke crt_printf,ADDR format,ADDR buffer
invoke ExitProcess,0
END start