[Qemu-devel] ARM/system mode/stdin

[Christophe LYON]

Hello,

I am trying to use qemu-system-arm (0.12.3) to execute an ARM bare 
machine program (not a Linux kernel), and I have some trouble when the 
program in question tries to read from stdin.

The program does use ARM semihosting to communicate with the host.

Here is the sample code:
======================
#include <stdio.h>
int main() {
  int i, j;
  char tab[81];
  printf("enter a number\n");
  scanf("%d", &i);
  printf("enter a string (max: 80 char)\n");
  scanf("%80s", tab);
  printf("enter a number\n");
  scanf("%d", &j);

  printf("You entered:\n%d\n%s\n%d\n", i, tab, j);

  return 0;
}
=======================
(compiled with arm-none-eabi-gcc -O0 -mcpu=cortex-a9)

To execute it, I use:
$ qemu-system-arm -semihosting -cpu cortex-a9 -nographic -kernel ./input.exe
In this case, it does not wait for me to type something:
enter a number
enter a string (max: 80 char)
enter a number
You entered:
134217720

1

Now, if
$ cat data
4 hello 5
$ qemu-system-arm -semihosting -cpu cortex-a9 -nographic -kernel 
./input.exe < data
enter a number
enter a string (max: 80 char)
enter a number
You entered:
134217720
ello
5

as you can see, the first 3 chars of 'data' have been changed/swallowed.

If I remove
    fcntl(0, F_SETFL, O_NONBLOCK);
from term_init() (qemu-char.c), then I get expected behaviour when I 
don't redirect stdin, but this has no effect on the latter case.


What should I do/patch to achieve the behaviour I'd like?

Thanks!

Christophe.