hashcmd.c

   1 /* hashcmd.c - functions for managing a hash table mapping command names to
   2                full pathnames. */
   3
   4 /* Copyright (C) 1997-2009 Free Software Foundation, Inc.
   5
   6    This file is part of GNU Bash, the Bourne Again SHell.
   7
   8    Bash is free software: you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation, either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    Bash is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with Bash.  If not, see <http://www.gnu.org/licenses/>.
  20 */
  21
  22 #include <config.h>
  23
  24 #include "bashtypes.h"
  25 #include "posixstat.h"
  26
  27 #if defined (HAVE_UNISTD_H)
  28 #  include <unistd.h>
  29 #endif
  30
  31 #include "bashansi.h"
  32
  33 #include "shell.h"
  34 #include "findcmd.h"
  35 #include "hashcmd.h"
  36
  37 extern int hashing_enabled;
  38
  39 HASH_TABLE *hashed_filenames = (HASH_TABLE *)NULL;
  40
  41 static void phash_freedata __P((PTR_T));
  42
  43 void
  44 phash_create ()
  45 {
  46   if (hashed_filenames == 0)
  47     hashed_filenames = hash_create (FILENAME_HASH_BUCKETS);
  48 }
  49
  50 static void
  51 phash_freedata (data)
  52      PTR_T data;
  53 {
  54   free (((PATH_DATA *)data)->path);
  55   free (data);
  56 }
  57
  58 void
  59 phash_flush ()
  60 {
  61   if (hashed_filenames)
  62     hash_flush (hashed_filenames, phash_freedata);
  63 }
  64
  65 /* Remove FILENAME from the table of hashed commands. */
  66 int
  67 phash_remove (filename)
  68      const char *filename;
  69 {
  70   register BUCKET_CONTENTS *item;
  71
  72   if (hashing_enabled == 0 || hashed_filenames == 0)
  73     return 0;
  74
  75   item = hash_remove (filename, hashed_filenames, 0);
  76   if (item)
  77     {
  78       if (item->data)
  79         phash_freedata (item->data);
  80       free (item->key);
  81       free (item);
  82       return 0;
  83     }
  84   return 1;
  85 }
  86
  87 /* Place FILENAME (key) and FULL_PATH (data->path) into the
  88    hash table.  CHECK_DOT if non-null is for future calls to
  89    phash_search (); it means that this file was found
  90    in a directory in $PATH that is not an absolute pathname.
  91    FOUND is the initial value for times_found. */
  92 void
  93 phash_insert (filename, full_path, check_dot, found)
  94      char *filename, *full_path;
  95      int check_dot, found;
  96 {
  97   register BUCKET_CONTENTS *item;
  98
  99   if (hashing_enabled == 0)
 100     return;
 101
 102   if (hashed_filenames == 0)
 103     phash_create ();
 104
 105   item = hash_insert (filename, hashed_filenames, 0);
 106   if (item->data)
 107     free (pathdata(item)->path);
 108   else
 109     {
 110       item->key = savestring (filename);
 111       item->data = xmalloc (sizeof (PATH_DATA));
 112     }
 113   pathdata(item)->path = savestring (full_path);
 114   pathdata(item)->flags = 0;
 115   if (check_dot)
 116     pathdata(item)->flags |= HASH_CHKDOT;
 117   if (*full_path != '/')
 118     pathdata(item)->flags |= HASH_RELPATH;
 119   item->times_found = found;
 120 }
 121
 122 /* Return the full pathname that FILENAME hashes to.  If FILENAME
 123    is hashed, but (data->flags & HASH_CHKDOT) is non-zero, check
 124    ./FILENAME and return that if it is executable.  This always
 125    returns a newly-allocated string; the caller is responsible
 126    for freeing it. */
 127 char *
 128 phash_search (filename)
 129      const char *filename;
 130 {
 131   register BUCKET_CONTENTS *item;
 132   char *path, *dotted_filename, *tail;
 133   int same;
 134
 135   if (hashing_enabled == 0 || hashed_filenames == 0)
 136     return ((char *)NULL);
 137
 138   item = hash_search (filename, hashed_filenames, 0);
 139
 140   if (item == NULL)
 141     return ((char *)NULL);
 142
 143   /* If this filename is hashed, but `.' comes before it in the path,
 144      see if ./filename is executable.  If the hashed value is not an
 145      absolute pathname, see if ./`hashed-value' exists. */
 146   path = pathdata(item)->path;
 147   if (pathdata(item)->flags & (HASH_CHKDOT|HASH_RELPATH))
 148     {
 149       tail = (pathdata(item)->flags & HASH_RELPATH) ? path : (char *)filename;  /* XXX - fix const later */
 150       /* If the pathname does not start with a `./', add a `./' to it. */
 151       if (tail[0] != '.' || tail[1] != '/')
 152         {
 153           dotted_filename = (char *)xmalloc (3 + strlen (tail));
 154           dotted_filename[0] = '.'; dotted_filename[1] = '/';
 155           strcpy (dotted_filename + 2, tail);
 156         }
 157       else
 158         dotted_filename = savestring (tail);
 159
 160       if (executable_file (dotted_filename))
 161         return (dotted_filename);
 162
 163       free (dotted_filename);
 164
 165 #if 0
 166       if (pathdata(item)->flags & HASH_RELPATH)
 167         return ((char *)NULL);
 168 #endif
 169
 170       /* Watch out.  If this file was hashed to "./filename", and
 171          "./filename" is not executable, then return NULL. */
 172
 173       /* Since we already know "./filename" is not executable, what
 174          we're really interested in is whether or not the `path'
 175          portion of the hashed filename is equivalent to the current
 176          directory, but only if it starts with a `.'.  (This catches
 177          ./. and so on.)  same_file () tests general Unix file
 178          equivalence -- same device and inode. */
 179       if (*path == '.')
 180         {
 181           same = 0;
 182           tail = (char *)strrchr (path, '/');
 183
 184           if (tail)
 185             {
 186               *tail = '\0';
 187               same = same_file (".", path, (struct stat *)NULL, (struct stat *)NULL);
 188               *tail = '/';
 189             }
 190
 191           return same ? (char *)NULL : savestring (path);
 192         }
 193     }
 194
 195   return (savestring (path));
 196 }