[PATCH] Fix ioctl() wrappers for 64-bit systems

[Nate Case]

On Fri, 2008-04-11 at 02:14 +0200, Denys Vlasenko wrote:
> I want to understand the failure. Please apply this patch,
> run failing getty and let us know what did you see.

Here is the output with your debug patch applied:

  # ./busybox getty -L ttyS0 115200 vt100
  getty: getty_main: request 403c7413 argp 0xfffffafec30                                                                           
  getty: request 403c7413 argp 0xfffffafec30                                      
                                                                                
  xpedite8000 login: root                                                         
  getty: termios_final: request 803c7414 argp 0xfffffafec30                                                                    
  getty: request 803c7414 argp 0xfffffafec30                                      
  getty: ttyS0: TCSETS: Invalid argument   

>From this output, everything looks fine.  It's the actual system call
that gets the bogus argument.  I made a simple standalone test case that
demonstrates this same weird behavior:

---[snip]---
#include <stdio.h>
#include <stdlib.h>                                                             
#include <stdarg.h>                                                             
#include <termios.h>                                                            
#include <errno.h>                                                              
#include <asm/ioctls.h>                                                         
                                                                                
void ioctl_wrapper(int fd, int request, void *argp)               
{                                                                               
        printf("ioctl_wrapper: req = %x, argp = %p\n", request, argp);        
        if (ioctl(fd, request, argp) < 0) {                                     
                printf("ioctl_wrapper() failed!\n");                          
                exit(-2);                                                       
        }                                                                       
        printf("ioctl_wrapper() success!\n");                                 
}                            

int main(void)                                                                  
{                                                                               
        int res;                                                                
        struct termios termios;                                                 
                                                                                
        printf("main TCGETS: req = %x, argp = %p\n", TCGETS, &termios);       
        ioctl_wrapper(0, TCGETS, &termios);                                     
        printf("main TCSETS: req = %x, argp = %p\n", TCSETS, &termios);       
        ioctl_wrapper(0, TCSETS, &termios);                                     
}         
---[snip]---

Running on i386:

    $ ./ioctl-bug 
    main TCGETS: req = 5401, argp = 0xbff9da84
    ioctl_wrapper: req = 5401, argp = 0xbff9da84
    ioctl_wrapper() success!
    main TCSETS: req = 5402, argp = 0xbff9da84
    ioctl_wrapper: req = 5402, argp = 0xbff9da84
    ioctl_wrapper() success!

Running on ppc64:

    $ ./ioctl-bug 
    main TCGETS: req = 403c7413, argp = 0xfffffebf640                               
    ioctl_wrapper: req = 403c7413, argp = 0xfffffebf640                             
    ioctl_wrapper() success!                                                        
    main TCSETS: req = 803c7414, argp = 0xfffffebf640                               
    ioctl_wrapper: req = 803c7414, argp = 0xfffffebf640                             
    ioctl_wrapper() failed!     

Running on AMD64:

    $ ./ioctl-bug.amd64 
    main TCGETS: req = 5401, argp = 0x7fff956cd5d0
    ioctl_wrapper: req = 5401, argp = 0x7fff956cd5d0
    ioctl_wrapper() success!
    main TCSETS: req = 5402, argp = 0x7fff956cd5d0
    ioctl_wrapper: req = 5402, argp = 0x7fff956cd5d0
    ioctl_wrapper() success!

So it doesn't appear to really affect all 64-bit systems since it worked
on x86-64.  It's also interesting that it seems to specifically affect
TCSETS and not TCGETS.

- Nate Case <ncase at xes-inc.com>