qemu/linux-user-lseek-explicitly-cast-non-set.patch

From: Alexander Graf <agraf@suse.de>
Date: Thu, 13 Dec 2012 14:29:22 +0100
Subject: linux-user: lseek: explicitly cast non-set offsets to signed

When doing lseek, SEEK_SET indicates that the offset is an unsigned variable.
Other seek types have parameters that can be negative.

When converting from 32bit to 64bit parameters, we need to take this into
account and enable SEEK_END and SEEK_CUR to be negative, while SEEK_SET stays
absolute positioned which we need to maintain as unsigned.

Signed-off-by: Alexander Graf <agraf@suse.de>
---
 linux-user/syscall.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 4c178ceab8ac708e4ee4587f6589..72c10911d6773e1e53fa36a3e741 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -8563,8 +8563,13 @@ static abi_long do_syscall1(void *cpu_env, int num, abi_ulong arg1,
         return ret;
 #endif
 #ifdef TARGET_NR_lseek
-    case TARGET_NR_lseek:
-        return get_errno(lseek(arg1, arg2, arg3));
+    case TARGET_NR_lseek: {
+        off_t off = arg2;
+        if (arg3 != SEEK_SET) {
+            off = (abi_long)arg2;
+        }
+        return get_errno(lseek(arg1, off, arg3));
+    }
 #endif
 #if defined(TARGET_NR_getxpid) && defined(TARGET_ALPHA)
     /* Alpha specific */