linux-user linkat() syscall, by Thayne Harbaugh.

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@3223 c046a42c-6fe2-441c-8c8c-71466251a162

linux-user/syscall.c

@@ -143,6 +143,7 @@ type name (type1 arg1,type2 arg2,type3 arg3,type4 arg4,type5 arg5,type6 arg6)	\
 #define __NR_sys_getcwd1 __NR_getcwd
 #define __NR_sys_getdents __NR_getdents
 #define __NR_sys_getdents64 __NR_getdents64
+#define __NR_sys_linkat __NR_linkat
 #define __NR_sys_mkdirat __NR_mkdirat
 #define __NR_sys_mknodat __NR_mknodat
 #define __NR_sys_openat __NR_openat
@@ -176,6 +177,10 @@ _syscall3(int, sys_getdents64, uint, fd, struct dirent64 *, dirp, uint, count);
 #endif
 _syscall5(int, _llseek,  uint,  fd, ulong, hi, ulong, lo,
           loff_t *, res, uint, wh);
+#if defined(TARGET_NR_linkat) && defined(__NR_linkat)
+_syscall5(int,sys_linkat,int,olddirfd,const char *,oldpath,
+	  int,newdirfd,const char *,newpath,int,flags)
+#endif
 #if defined(TARGET_NR_mkdirat) && defined(__NR_mkdirat)
 _syscall3(int,sys_mkdirat,int,dirfd,const char *,pathname,mode_t,mode)
 #endif
@@ -2581,6 +2586,28 @@ long do_syscall(void *cpu_env, int num, long arg1, long arg2, long arg3,
             unlock_user(p, arg1, 0);
         }
         break;
+#if defined(TARGET_NR_linkat) && defined(__NR_linkat)
+    case TARGET_NR_linkat:
+        if (!arg2 || !arg4) {
+            ret = -EFAULT;
+            goto fail;
+	}
+        {
+            void * p2 = NULL;
+            p  = lock_user_string(arg2);
+            p2 = lock_user_string(arg4);
+            if (!access_ok(VERIFY_READ, p, 1)
+                || !access_ok(VERIFY_READ, p2, 1))
+                ret = -EFAULT;
+            else
+                ret = get_errno(sys_linkat(arg1, p, arg3, p2, arg5));
+            if (p2)
+                unlock_user(p, arg2, 0);
+            if (p)
+                unlock_user(p2, arg4, 0);
+        }
+        break;
+#endif
     case TARGET_NR_unlink:
         p = lock_user_string(arg1);
         ret = get_errno(unlink(p));