[Qemu-devel] [PATCH v2 1/2] linux-user: added support for preadv() system call.

[Dejan Jovicevic]

v1 -> v2:
        - Using safe_preadv() instead of calling preadv() directly.

This system call performs the same task as the readv system call,
with the exception of having the fourth argument, offset, which
specifes the file offset at which the input operation is to be performed.

This implementation is based on the existing readv implementation.

Signed-off-by: Dejan Jovicevic <address@hidden>
---
 linux-user/syscall.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 0815f30..c7619f6 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -908,6 +908,8 @@ safe_syscall2(int, tkill, int, tid, int, sig)
 safe_syscall3(int, tgkill, int, tgid, int, pid, int, sig)
 safe_syscall3(ssize_t, readv, int, fd, const struct iovec *, iov, int, iovcnt)
 safe_syscall3(ssize_t, writev, int, fd, const struct iovec *, iov, int, iovcnt)
+safe_syscall4(ssize_t, preadv, int, fd, const struct iovec *, iov, int, iovcnt,
+              off_t, offset)
 safe_syscall3(int, connect, int, fd, const struct sockaddr *, addr,
               socklen_t, addrlen)
 safe_syscall6(ssize_t, sendto, int, fd, const void *, buf, size_t, len,
@@ -9894,6 +9896,19 @@ abi_long do_syscall(void *cpu_env, int num, abi_long 
arg1,
             }
         }
         break;
+#if defined(TARGET_NR_preadv)
+    case TARGET_NR_preadv:
+        {
+            struct iovec *vec = lock_iovec(VERIFY_WRITE, arg2, arg3, 0);
+            if (vec != NULL) {
+                ret = get_errno(safe_preadv(arg1, vec, arg3, arg4));
+                unlock_iovec(vec, arg2, arg3, 1);
+            } else {
+                ret = -host_to_target_errno(errno);
+           }
+        }
+        break;
+#endif
     case TARGET_NR_getsid:
         ret = get_errno(getsid(arg1));
         break;
-- 
1.9.1