[Qemu-devel] [PATCH] fix fcntl support in linux-user.

[Rtp]

The current code in do_fcntl is passing the target command as a host
command. This is introducing 2 problems:

- When building with "-D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE", we
  may end up passing commands like F_GETFL instead of F_GETFL64. This is
  likely to return an error.

- The F_*64 constants doesn't always have the same value between host
  and target.

Without this patch locking is not working (My test-case was pwck with arm as
target and mips as host).

Signed-off-by: Arnaud Patard <address@hidden>
---

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 2d51d6b..2d876c1 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -3126,7 +3141,7 @@ static abi_long do_fcntl(int fd, int cmd, abi_ulong arg)
         fl.l_len = tswapl(target_fl->l_len);
         fl.l_pid = tswapl(target_fl->l_pid);
         unlock_user_struct(target_fl, arg, 0);
-        ret = get_errno(fcntl(fd, cmd, &fl));
+        ret = get_errno(fcntl(fd, F_GETLK, &fl));
         if (ret == 0) {
             if (!lock_user_struct(VERIFY_WRITE, target_fl, arg, 0))
                 return -TARGET_EFAULT;
@@ -3149,7 +3164,7 @@ static abi_long do_fcntl(int fd, int cmd, abi_ulong arg)
         fl.l_len = tswapl(target_fl->l_len);
         fl.l_pid = tswapl(target_fl->l_pid);
         unlock_user_struct(target_fl, arg, 0);
-        ret = get_errno(fcntl(fd, cmd, &fl));
+        ret = get_errno(fcntl(fd, F_SETLK+(cmd-TARGET_F_SETLK), &fl));
         break;
 
     case TARGET_F_GETLK64:
@@ -3161,7 +3176,7 @@ static abi_long do_fcntl(int fd, int cmd, abi_ulong arg)
         fl64.l_len = tswapl(target_fl64->l_len);
         fl64.l_pid = tswap16(target_fl64->l_pid);
         unlock_user_struct(target_fl64, arg, 0);
-        ret = get_errno(fcntl(fd, cmd >> 1, &fl64));
+        ret = get_errno(fcntl(fd, F_GETLK64, &fl64));
         if (ret == 0) {
             if (!lock_user_struct(VERIFY_WRITE, target_fl64, arg, 0))
                 return -TARGET_EFAULT;
@@ -3183,7 +3198,7 @@ static abi_long do_fcntl(int fd, int cmd, abi_ulong arg)
         fl64.l_len = tswapl(target_fl64->l_len);
         fl64.l_pid = tswap16(target_fl64->l_pid);
         unlock_user_struct(target_fl64, arg, 0);
-        ret = get_errno(fcntl(fd, cmd >> 1, &fl64));
+        ret = get_errno(fcntl(fd, F_SETLK64+(cmd-TARGET_F_SETLK64), &fl64));
         break;
 
     case F_GETFL:
@@ -6022,7 +6039,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
             ret = get_errno(fcntl(arg1, cmd, &fl));
            break;
         default:
-            ret = do_fcntl(arg1, cmd, arg3);
+            ret = do_fcntl(arg1, arg2, arg3);
             break;
         }
        break;