source: MondoRescue/branches/2.2.9/mindi-busybox/examples/linux-2.6.30_proc_self_exe.patch@ 3320

This patch makes /proc/self/exe executable even if proc
is not mounted. It is especially useful on NOMMU arches.

diff -urp ../linux-2.6.30.org/fs/exec.c linux-2.6.30/fs/exec.c
--- ../linux-2.6.30.org/fs/exec.c   2009-06-10 05:05:27.000000000 +0200
+++ linux-2.6.30/fs/exec.c  2009-06-25 00:20:13.000000000 +0200
@@ -652,9 +652,25 @@ struct file *open_exec(const char *name)
    file = do_filp_open(AT_FDCWD, name,
                O_LARGEFILE | O_RDONLY | FMODE_EXEC, 0,
                MAY_EXEC | MAY_OPEN);
-   if (IS_ERR(file))
-       goto out;
+   if (IS_ERR(file)) {
+       if ((PTR_ERR(file) == -ENOENT || PTR_ERR(file) == -EACCES)
+        && strcmp(name, "/proc/self/exe") == 0
+       ) {
+           struct file *sv = file;
+           struct mm_struct *mm;
 
+           mm = get_task_mm(current);
+           if (!mm)
+               goto out;
+           file = get_mm_exe_file(mm);
+           mmput(mm);
+           if (file)
+               goto ok;
+           file = sv;
+       }
+       goto out;
+   }
+ok:
    err = -EACCES;
    if (!S_ISREG(file->f_path.dentry->d_inode->i_mode))
        goto exit;