linux-user: identify running binary in /proc/self/exe

Some applications like to test /proc/self/exe to find
out who they are. Fake the result of readlink() for
them. Use realpath() to return full path to binary
(which the links /proc/self/exe are)

Signed-off-by: Riku Voipio <riku.voipio@iki.fi>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6485 c046a42c-6fe2-441c-8c8c-71466251a162

1 files changed, 12 insertions, 3 deletions

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 3e21bb311c..8d52099cb9 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -4410,13 +4410,22 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
 #endif
     case TARGET_NR_readlink:
         {
-            void *p2;
+            void *p2, *temp;
             p = lock_user_string(arg1);
             p2 = lock_user(VERIFY_WRITE, arg2, arg3, 0);
             if (!p || !p2)
                 ret = -TARGET_EFAULT;
-            else
-                ret = get_errno(readlink(path(p), p2, arg3));
+            else {
+                if (strncmp((const char *)p, "/proc/self/exe", 14) == 0) {
+                    char real[PATH_MAX];
+                    temp = realpath(exec_path,real);
+                    ret = (temp==NULL) ? get_errno(-1) : strlen(real) ;
+                    snprintf((char *)p2, arg3, "%s", real);
+                    }
+                else
+                    ret = get_errno(readlink(path(p), p2, arg3));
+                break;
+            }
             unlock_user(p2, arg2, ret);
             unlock_user(p, arg1, 0);
         }