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Diffstat (limited to 'sutils/clookup.c')
| -rw-r--r-- | sutils/clookup.c | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/sutils/clookup.c b/sutils/clookup.c new file mode 100644 index 00000000..d0f69d9b --- /dev/null +++ b/sutils/clookup.c @@ -0,0 +1,168 @@ +/* Careful filename lookup + + Copyright (C) 1996, 1998, 1999 Free Software Foundation, Inc. + + Written by Miles Bader <miles@gnu.ai.mit.edu> + + This file is part of the GNU Hurd. + + The GNU Hurd is free software; you can redistribute it and/or + modify it under the terms of the GNU General Public License as + published by the Free Software Foundation; either version 2, or (at + your option) any later version. + + The GNU Hurd is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software + Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ + +#include <unistd.h> +#include <stdlib.h> +#include <string.h> +#include <errno.h> +#include <fcntl.h> +#include <sys/mman.h> +#include <hurd.h> +#include <hurd/lookup.h> +#include <hurd/id.h> +#include <hurd/fsys.h> + + +/* This function is like file_name_lookup, but tries hard to avoid starting + any passive translators. If a node with an unstarted passive translator + is encountered, ENXIO is returned in ERRNO; other errors are as for + file_name_lookup. Note that checking for an active translator currently + requires fetching the control port, which is a priveleged operation. */ +file_t +file_name_lookup_carefully (const char *name, int flags, mode_t mode) +{ + error_t err; + file_t node; + uid_t *uids; /* Authentication of the current process. */ + gid_t *gids; + size_t num_uids, num_gids; + + /* Do the actual directory lookup. We only do the first pathname element + of NAME, appending the rest to any RETRY_NAME returned. We then make + sure the result node doesn't have a passive translator with no active + translator started (but we make an exception for symlinks) -- if it + does, we just return ENXIO. */ + error_t lookup (file_t dir, char *name, int flags, mode_t mode, + retry_type *retry, string_t retry_name, + mach_port_t *node) + { + error_t err; + char *head, *tail; + char *slash = index (name, '/'); + + if (slash) + { + *stpncpy (head = alloca (slash - name + 1), name, slash - name) = 0; + tail = slash + 1; + } + else + { + head = name; + tail = 0; + } + + err = dir_lookup (dir, head, flags | O_NOTRANS, mode, + retry, retry_name, node); + if (err) + return err; + + if (*node != MACH_PORT_NULL + && (!(flags & O_NOTRANS) || tail || *retry_name)) + /* The dir_lookup has returned a node to use for the next stage of + the lookup. Unless it's the last element of the path and FLAGS + has O_NOTRANS set (in which case we just return what we got as + is), we have to simulate the above lookup being done without + O_NOTRANS. Do this being careful not to start any translators. */ + { + char _ptrans[1024], *ptrans = _ptrans; + size_t ptrans_len = sizeof _ptrans; + + err = file_get_translator (*node, &ptrans, &ptrans_len); + if (! err) + /* Has a passive translator, see if there's an active one too. */ + { + fsys_t fsys; /* Active translator control port. */ + + if (ptrans != _ptrans) + /* Deallocate out-of-line memory from file_get_translator. */ + munmap (ptrans, ptrans_len); + + err = file_get_translator_cntl (*node, &fsys); + if (! err) + /* There is! Get its root node to use as the actual file. */ + { + file_t unauth_dir; /* DIR unauthenticated. */ + err = io_restrict_auth (dir, &unauth_dir, 0, 0, 0, 0); + if (! err) + { + file_t old_node = *node; + err = fsys_getroot (fsys, + unauth_dir, MACH_MSG_TYPE_MOVE_SEND, + uids, num_uids, gids, num_gids, + flags & ~O_NOTRANS, retry, + retry_name, node); + if (! err) + mach_port_deallocate (mach_task_self (), old_node); + } + mach_port_deallocate (mach_task_self (), fsys); + } + } + else if (err == EINVAL) + /* No passive translator. */ + err = 0; + + if (!err && tail) + /* Append TAIL to RETRY_NAME. */ + { + size_t rtn_len = strlen (retry_name); + if (rtn_len + 1 + strlen (tail) + 1 > sizeof (string_t)) + err = ENAMETOOLONG; /* Argh. Lovely string_t. */ + else + { + if (rtn_len > 0 && retry_name[rtn_len - 1] != '/') + retry_name[rtn_len++] = '/'; + strcpy (retry_name + rtn_len, tail); + } + } + + if (err) + mach_port_deallocate (mach_task_self (), *node); + } + + return err; + } + + /* Fetch uids for use with fsys_getroot. */ + num_uids = geteuids (0, 0); + if (num_uids < 0) + return errno; + uids = alloca (num_uids * sizeof (uid_t)); + num_uids = geteuids (num_uids, uids); + if (num_uids < 0) + return errno; + + /* ... and gids. */ + num_gids = getgroups (0, 0); + if (num_gids < 0) + return errno; + gids = alloca (num_gids * sizeof (gid_t)); + num_gids = getgroups (num_gids, gids); + if (num_gids < 0) + return errno; + + /* Look things up ... */ + err = hurd_file_name_lookup (&_hurd_ports_use, &getdport, lookup, + name, flags, mode & ~getumask (), + &node); + + return err ? (__hurd_fail (err), MACH_PORT_NULL) : node; +} |