Re: [Qemu-devel] [PATCH] linux-user: identify running binary in /proc/self/exe

[Aurelien Jarno <aurelien@aurel32.net>]

On Mon, Jan 26, 2009 at 09:07:11PM +0200, Riku Voipio wrote:
> Some applications like to test /proc/self/exe to find
> out who they are. Fake the result of readlink() for
> them. Use realpath() to return full path to binary
> (which the links /proc/self/exe are)
> 
> updated version - fix ret/errno in the /proc/self/exe case.
> 
> Signed-off-by: Riku Voipio <riku.voipio@iki.fi>

Thanks, applied.

> ---
>  linux-user/main.c    |    3 +++
>  linux-user/qemu.h    |    1 +
>  linux-user/syscall.c |   15 ++++++++++++---
>  3 files changed, 16 insertions(+), 3 deletions(-)
> 
> diff --git a/linux-user/main.c b/linux-user/main.c
> index cb10173..3418ca6 100644
> --- a/linux-user/main.c
> +++ b/linux-user/main.c
> @@ -37,6 +37,8 @@
>  
>  #define DEBUG_LOGFILE "/tmp/qemu.log"
>  
> +char *exec_path;
> +
>  static const char *interp_prefix = CONFIG_QEMU_PREFIX;
>  const char *qemu_uname_release = CONFIG_UNAME_RELEASE;
>  
> @@ -2354,6 +2356,7 @@ int main(int argc, char **argv, char **envp)
>      if (optind >= argc)
>          usage();
>      filename = argv[optind];
> +    exec_path = argv[optind];
>  
>      /* Zero out regs */
>      memset(regs, 0, sizeof(struct target_pt_regs));
> diff --git a/linux-user/qemu.h b/linux-user/qemu.h
> index 9fddd05..4137567 100644
> --- a/linux-user/qemu.h
> +++ b/linux-user/qemu.h
> @@ -120,6 +120,7 @@ typedef struct TaskState {
>      uint8_t stack[0];
>  } __attribute__((aligned(16))) TaskState;
>  
> +extern char *exec_path;
>  void init_task_state(TaskState *ts);
>  extern const char *qemu_uname_release;
>  
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 690df14..2903bf3 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -4877,13 +4877,22 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
>  #endif
>      case TARGET_NR_readlink:
>          {
> -            void *p2;
> +            void *p2, *temp;
>              p = lock_user_string(arg1);
>              p2 = lock_user(VERIFY_WRITE, arg2, arg3, 0);
>              if (!p || !p2)
>                  ret = -TARGET_EFAULT;
> -            else
> -                ret = get_errno(readlink(path(p), p2, arg3));
> +            else {
> +                if (strncmp((const char *)p, "/proc/self/exe", 14) == 0) {
> +                    char real[PATH_MAX];
> +                    temp = realpath(exec_path,real);
> +                    ret = (temp==NULL) ? get_errno(-1) : strlen(real) ;
> +                    snprintf((char *)p2, arg3, "%s", real);
> +                    }
> +                else
> +                    ret = get_errno(readlink(path(p), p2, arg3));
> +                break;
> +            }
>              unlock_user(p2, arg2, ret);
>              unlock_user(p, arg1, 0);
>          }
> -- 
> 1.5.6.5
> 
> 
> 
> 

-- 
Aurelien Jarno	                        GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net