hurd/path-lookup.c

   1 /* Filename lookup using a search path
   2    Copyright (C) 1995-2017 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Written by Miles Bader <miles@gnu.ai.mit.edu>
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, see
  18    <http://www.gnu.org/licenses/>.  */
  19
  20 #include <string.h>
  21 #include <hurd.h>
  22 #include <hurd/lookup.h>
  23
  24 /* If FILE_NAME contains a '/', or PATH is NULL, call FUN with FILE_NAME, and
  25    return the result (if PREFIXED_NAME is non-NULL, setting *PREFIXED_NAME to
  26    NULL).  Otherwise, call FUN repeatedly with FILE_NAME prefixed with each
  27    successive `:' separated element of PATH, returning whenever FUN returns
  28    0 (if PREFIXED_NAME is non-NULL, setting *PREFIXED_NAME to the resulting
  29    prefixed path).  If FUN never returns 0, return the first non-ENOENT
  30    return value, or ENOENT if there is none.  */
  31 error_t
  32 file_name_path_scan (const char *file_name, const char *path,
  33                      error_t (*fun)(const char *name),
  34                      char **prefixed_name)
  35 {
  36   if (path == NULL || strchr (file_name, '/'))
  37     {
  38       if (prefixed_name)
  39         *prefixed_name = 0;
  40       return (*fun)(file_name);
  41     }
  42   else
  43     {
  44       error_t real_err = 0;
  45       size_t file_name_len = strlen (file_name);
  46
  47       for (;;)
  48         {
  49           error_t err;
  50           const char *next = strchr (path, ':') ?: path + strlen (path);
  51           size_t pfx_len = next - path;
  52           char pfxed_name[pfx_len + 2 + file_name_len + 1];
  53
  54           if (pfx_len == 0)
  55             pfxed_name[pfx_len++] = '.';
  56           else
  57             memcpy (pfxed_name, path, pfx_len);
  58           if (pfxed_name[pfx_len - 1] != '/')
  59             pfxed_name[pfx_len++] = '/';
  60           memcpy (pfxed_name + pfx_len, file_name, file_name_len + 1);
  61
  62           err = (*fun)(pfxed_name);
  63           if (err == 0)
  64             {
  65               if (prefixed_name)
  66                 *prefixed_name = strdup (pfxed_name);
  67               return 0;
  68             }
  69           if (!real_err && err != ENOENT)
  70             real_err = err;
  71
  72           if (*next == '\0')
  73             return real_err ?: ENOENT;
  74           else
  75             path = next + 1;
  76         }
  77     }
  78 }
  79
  80 /* Lookup FILE_NAME and return the node opened with FLAGS & MODE in result
  81    (see hurd_file_name_lookup for details), but a simple filename (without
  82    any directory prefixes) will be consecutively prefixed with the pathnames
  83    in the `:' separated list PATH until one succeeds in a successful lookup.
  84    If none succeed, then the first error that wasn't ENOENT is returned, or
  85    ENOENT if no other errors were returned.  If PREFIXED_NAME is non-NULL,
  86    then if RESULT is looked up directly, *PREFIXED_NAME is set to NULL, and
  87    if it is looked up using a prefix from PATH, *PREFIXED_NAME is set to
  88    malloced storage containing the prefixed name.  */
  89 error_t
  90 hurd_file_name_path_lookup (error_t (*use_init_port)
  91                               (int which, error_t (*operate) (mach_port_t)),
  92                             file_t (*get_dtable_port) (int fd),
  93                             error_t (*lookup)
  94                               (file_t dir, char *name, int flags, mode_t mode,
  95                                retry_type *do_retry, string_t retry_name,
  96                                mach_port_t *result),
  97                             const char *file_name, const char *path,
  98                             int flags, mode_t mode,
  99                             file_t *result, char **prefixed_name)
 100 {
 101   error_t scan_lookup (const char *name)
 102     {
 103       return
 104         __hurd_file_name_lookup (use_init_port, get_dtable_port, lookup,
 105                                  name, flags, mode, result);
 106     }
 107   return file_name_path_scan (file_name, path, scan_lookup, prefixed_name);
 108 }
 109
 110 file_t
 111 file_name_path_lookup (const char *file_name, const char *path,
 112                        int flags, mode_t mode, char **prefixed_name)
 113 {
 114   error_t err;
 115   file_t result;
 116
 117   err = hurd_file_name_path_lookup (&_hurd_ports_use, &__getdport, 0,
 118                                     file_name, path, flags, mode,
 119                                     &result, prefixed_name);
 120
 121   return err ? (__hurd_fail (err), MACH_PORT_NULL) : result;
 122 }