[Qemu-devel] Small patch for getdents syscall

[Henry Wertz]

I have a trivial, 1-line patch for getdents function; due to use of
unsigned long, the struct on 64-bit and 32-bit systems is not the same.
qemu is aware of this, however it currently only checks for a 32-bit target
on 64-bit host case; in my case, I'm running 64-bit target on 32-bit host
(x86-64 binaries on a 32-bit ARM).

My use case for this patch, I have Android Studio on my (32-bit ARM)
chromebook -- thank goodness I got the 4GB model!  Since Android Studio is
java, that worked; but it calls aapt from build tools.  Up through 23.x.x
(which is build for 32-bit x86) it worked.  With 25.0.0 (and 24.x.x
version) aapt is now built for 64-bit x86-64; it would give an odd error
about a directory being invalid.  By comparing strace between qemu and real
x86-64, I found getdents was behaving differently.  WIth this patch aapt
completes.

I really wasn't sure if this would be better this way ("if target != host")
or if something like  "if (target==32 && host==64) || (target==64 &&
host==32)" would be preferrable.
---------------------------------------------------

Signed-off-by: Henry Wertz <address@hidden>


*** linux-user/syscall.c~       2017-03-04 10:31:14.000000000 -0600
--- linux-user/syscall.c        2017-03-07 17:08:24.615399116 -0600
***************
*** 9913,9921 ****
  #endif
  #ifdef TARGET_NR_getdents
      case TARGET_NR_getdents:
  #ifdef __NR_getdents
! #if TARGET_ABI_BITS == 32 && HOST_LONG_BITS == 64
          {
              struct target_dirent *target_dirp;
              struct linux_dirent *dirp;
              abi_long count = arg3;
--- 9913,9921 ----
  #endif
  #ifdef TARGET_NR_getdents
      case TARGET_NR_getdents:
  #ifdef __NR_getdents
! #if TARGET_ABI_BITS != HOST_LONG_BITS
          {
              struct target_dirent *target_dirp;
              struct linux_dirent *dirp;
              abi_long count = arg3;