bsd/man/man2/chroot.2

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  34 .\"     @(#)chroot.2    8.1 (Berkeley) 6/4/93
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  36 .Dd June 4, 1993
  37 .Dt CHROOT 2
  38 .Os BSD 4.2
  39 .Sh NAME
  40 .Nm chroot
  41 .Nd change root directory
  42 .Sh SYNOPSIS
  43 .Fd #include <unistd.h>
  44 .Ft int
  45 .Fn chroot "const char *dirname"
  46 .Sh DESCRIPTION
  47 .Fa Dirname
  48 is the address of the pathname of a directory, terminated by an ASCII NUL.
  49 .Fn Chroot
  50 causes
  51 .Fa dirname
  52 to become the root directory,
  53 that is, the starting point for path searches of pathnames
  54 beginning with
  55 .Ql / .
  56 .Pp
  57 In order for a directory to become the root directory
  58 a process must have execute (search) access for that directory.
  59 .Pp
  60 If the program is not currently running with an altered root directory,
  61 it should be noted that
  62 .Fn chroot
  63 has no effect on the process's current directory.
  64 .Pp
  65 If the program is already running with an altered root directory, the
  66 process's current directory is changed to the same new root directory.
  67 This prevents the current directory from being further up the directory
  68 tree than the altered root directory.
  69 .Pp
  70 This call is restricted to the super-user.
  71 .Sh RETURN VALUES
  72 Upon successful completion, a value of 0 is returned.  Otherwise,
  73 a value of -1 is returned and
  74 .Va errno
  75 is set to indicate an error.
  76 .Sh ERRORS
  77 .Fn Chroot
  78 will fail and the root directory will be unchanged if:
  79 .Bl -tag -width Er
  80 .It Bq Er ENOTDIR
  81 A component of the path name is not a directory.
  82 .It Bq Er ENAMETOOLONG
  83 A component of a pathname exceeded
  84 .Dv {NAME_MAX}
  85 characters, or an entire path name exceeded
  86 .Dv {PATH_MAX}
  87 characters.
  88 .It Bq Er ENOENT
  89 The named directory does not exist.
  90 .It Bq Er EACCES
  91 Search permission is denied for any component of the path name.
  92 .It Bq Er ELOOP
  93 Too many symbolic links were encountered in translating the pathname.
  94 .It Bq Er EFAULT
  95 .Fa Path
  96 points outside the process's allocated address space.
  97 .It Bq Er EIO
  98 An I/O error occurred while reading from or writing to the file system.
  99 .El
 100 .Sh SEE ALSO
 101 .Xr chdir 2
 102 .Sh WARNINGS
 103 There are ways for a root process to escape from the chroot jail.
 104 .Sh HISTORY
 105 The
 106 .Fn chroot
 107 function call appeared in
 108 .Bx 4.2 .