libextractor

extractor_plugpath.c (15707B)

---

 /*
      This file is part of libextractor.
      Copyright (C) 2002, 2003, 2004, 2005, 2006, 2009, 2012 Vidyut Samanta and Christian Grothoff
 
      libextractor 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 3, or (at your
      option) any later version.
 
      libextractor 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 libextractor; see the file COPYING.  If not, write to the
      Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
      Boston, MA 02110-1301, USA.
  */
 /**
  * @file main/extractor_plugpath.c
  * @brief determine path where plugins are installed
  * @author Christian Grothoff
  */
 
 #include "platform.h"
 #include "extractor.h"
 #include <dirent.h>
 #include <sys/types.h>
 #include <signal.h>
 #include <ltdl.h>
 #include <stdbool.h>
 
 #include "extractor_plugpath.h"
 #include "extractor_logging.h"
 
 /**
  * Function to call on paths.
  *
  * @param cls closure
  * @param path a directory path
  */
 typedef void (*EXTRACTOR_PathProcessor) (void *cls,
                                          const char *path);
 
 
 /**
  * Remove a trailing '/bin/' from 'in' (if present).
  *
  * @param in input string, modified
  * @return NULL if 'in' is NULL, otherwise 'in' with '/bin/' removed
  */
 static char *
 cut_bin (char *in)
 {
   size_t p;
 
   if (NULL == in)
     return NULL;
   p = strlen (in);
   if (p < 4)
     return in;
   if ( ('/' == in[p - 1]) ||
        ('\\' == in[p - 1]) )
     in[--p] = '\0';
   if (0 == strcmp (&in[p - 4],
                    "/bin"))
   {
     in[p - 4] = '\0';
     p -= 4;
   }
   else if (0 == strcmp (&in[p - 4],
                         "\\bin"))
   {
     in[p - 4] = '\0';
     p -= 4;
   }
   return in;
 }
 
 
 #if GNU_LINUX
 /**
  * Try to determine path by reading /proc/PID/exe or
  * /proc/PID/maps.
  *
  * Note that this may fail if LE is installed in one directory
  * and the binary linking against it sits elsewhere.
  */
 static char *
 get_path_from_proc_exe ()
 {
   char fn[64];
   char line[1024];
   char dir[1024];
   char *lnk;
   char *ret;
   char *lestr;
   ssize_t size;
   FILE *f;
 
   snprintf (fn,
             sizeof (fn),
             "/proc/%u/maps",
             getpid ());
   if (NULL != (f = fopen (fn, "r")))
   {
     while (NULL != fgets (line, 1024, f))
     {
       if ( (1 == sscanf (line,
                          "%*x-%*x %*c%*c%*c%*c %*x %*2x:%*2x %*u%*[ ]%1023s",
                          dir)) &&
            (NULL != (lestr = strstr (dir,
                                      "libextractor")) ) )
       {
         lestr[0] = '\0';
         fclose (f);
         return strdup (dir);
       }
     }
     fclose (f);
   }
   snprintf (fn,
             sizeof (fn),
             "/proc/%u/exe",
             getpid ());
   if (NULL == (lnk = malloc (1029))) /* 1024 + 6 for "/lib/" catenation */
     return NULL;
   size = readlink (fn, lnk, 1023);
   if ( (size <= 0) || (size >= 1024) )
   {
     free (lnk);
     return NULL;
   }
   lnk[size] = '\0';
   while ( ('/' != lnk[size]) &&
           (size > 0) )
     size--;
   if ( (size < 4) ||
        ('/' != lnk[size - 4]) )
   {
     /* not installed in "/bin/" -- binary path probably useless */
     free (lnk);
     return NULL;
   }
   lnk[size] = '\0';
   lnk = cut_bin (lnk);
   if (NULL == (ret = realloc (lnk, strlen (lnk) + 6)))
   {
     LOG_STRERROR ("realloc");
     free (lnk);
     return NULL;
   }
   strcat (ret, "/lib/"); /* guess "lib/" as the library dir */
   return ret;
 }
 
 
 #endif
 
 
 #if WINDOWS
 static HMODULE le_dll = NULL;
 
 BOOL WINAPI
 DllMain (HINSTANCE hinstDLL,
          DWORD fdwReason,
          LPVOID lpvReserved)
 {
   switch (fdwReason)
   {
   case DLL_PROCESS_ATTACH:
     le_dll = (HMODULE) hinstDLL;
     break;
   }
 
   return TRUE;
 }
 
 
 /**
  * Try to determine path with win32-specific function
  */
 static char *
 get_path_from_module_filename ()
 {
   char *path;
   char *ret;
   char *idx;
 
   if (NULL == (path = malloc (4103))) /* 4096+nil+6 for "/lib/" catenation */
     return NULL;
   GetModuleFileName (le_dll, path, 4096);
   idx = path + strlen (path);
   while ( (idx > path) &&
           ('\\' != *idx) &&
           ('/' != *idx) )
     idx--;
   *idx = '\0';
   path = cut_bin (path);
   if (NULL == (ret = realloc (path, strlen (path) + 6)))
   {
     LOG_STRERROR ("realloc");
     free (path);
     return NULL;
   }
   strcat (ret, "/lib/"); /* guess "lib/" as the library dir */
   return ret;
 }
 
 
 #endif
 
 
 #if DARWIN
 #include <dlfcn.h>
 #include <mach-o/dyld.h>
 
 /**
  * Signature of the '_NSGetExecutablePath" function.
  *
  * @param buf where to write the path
  * @param number of bytes available in 'buf'
  * @return 0 on success, otherwise desired number of bytes is stored in 'bufsize'
  */
 typedef int
 (*MyNSGetExecutablePathProto) (char *buf,
                                size_t *bufsize);
 
 
 /**
  * Try to obtain the path of our executable using '_NSGetExecutablePath'.
  *
  * @return NULL on error
  */
 static char *
 get_path_from_NSGetExecutablePath ()
 {
   static char zero;
   char *path;
   char *ret;
   size_t len;
   MyNSGetExecutablePathProto func;
 
   path = NULL;
   if (NULL == (func =
                  (MyNSGetExecutablePathProto) dlsym (RTLD_DEFAULT,
                                                      "_NSGetExecutablePath")))
     return NULL;
   path = &zero;
   len = 0;
   /* get the path len, including the trailing \0 */
   (void) func (path, &len);
   if (0 == len)
     return NULL;
   if (NULL == (path = malloc (len)))
   {
     LOG_STRERROR ("malloc");
     return NULL;
   }
   if (0 != func (path, &len))
   {
     free (path);
     return NULL;
   }
   len = strlen (path);
   while ((path[len] != '/') && (len > 0))
     len--;
   path[len] = '\0';
   if (NULL != strstr (path, "/lib"))
     return path;
   path = cut_bin (path);
   if (NULL == (ret = realloc (path, strlen (path) + 5)))
   {
     LOG_STRERROR ("realloc");
     free (path);
     return NULL;
   }
   strcat (ret, "/lib/");
   return ret;
 }
 
 
 /**
  * Try to obtain the path of our executable using '_dyld_image' API.
  *
  * @return NULL on error
  */
 static char *
 get_path_from_dyld_image ()
 {
   const char *path;
   char *s;
   char *p;
   unsigned int i;
   int c;
 
   c = _dyld_image_count ();
   for (i = 0; i < c; i++)
   {
     if (((void *) _dyld_get_image_header (i)) != (void *) &_mh_dylib_header)
       continue;
     path = _dyld_get_image_name (i);
     if ( (NULL == path) || (0 == strlen (path)) )
       continue;
     if (NULL == (p = strdup (path)))
     {
       LOG_STRERROR ("strdup");
       return NULL;
     }
     s = p + strlen (p);
     while ( (s > p) && ('/' != *s) )
       s--;
     s++;
     *s = '\0';
     return p;
   }
   return NULL;
 }
 
 
 #endif
 
 
 /**
  * Return the actual path to a file found in the current
  * PATH environment variable.
  *
  * @return path to binary, NULL if not found
  */
 static char *
 get_path_from_PATH ()
 {
   struct stat sbuf;
   char *path;
   char *pos;
   char *end;
   char *buf;
   char *ret;
   const char *p;
 
   if (NULL == (p = getenv ("PATH")))
     return NULL;
   if (NULL == (path = strdup (p))) /* because we write on it */
   {
     LOG_STRERROR ("strdup");
     return NULL;
   }
   if (NULL == (buf = malloc (strlen (path) + 20)))
   {
     LOG_STRERROR ("malloc");
     free (path);
     return NULL;
   }
   pos = path;
   while (NULL != (end = strchr (pos, ':')))
   {
     *end = '\0';
     sprintf (buf, "%s/%s", pos, "extract");
     if (0 == stat (buf, &sbuf))
     {
       free (buf);
       if (NULL == (pos = strdup (pos)))
       {
         LOG_STRERROR ("strdup");
         free (path);
         return NULL;
       }
       free (path);
       pos = cut_bin (pos);
       if (NULL == (ret = realloc (pos, strlen (pos) + 6)))
       {
         LOG_STRERROR ("realloc");
         free (pos);
         return NULL;
       }
       strcat (ret, "/lib/");
       return ret;
     }
     pos = end + 1;
   }
   sprintf (buf, "%s/%s", pos, "extract");
   if (0 == stat (buf, &sbuf))
   {
     pos = strdup (pos);
     free (buf);
     free (path);
     if (NULL == pos)
       return NULL;
     pos = cut_bin (pos);
     if (NULL == (ret = realloc (pos, strlen (pos) + 6)))
     {
       LOG_STRERROR ("realloc");
       free (pos);
       return NULL;
     }
     strcat (ret, "/lib/");
     return ret;
   }
   free (buf);
   free (path);
   return NULL;
 }
 
 
 /**
  * Create a filename by appending 'fname' to 'path'.
  *
  * @param path the base path
  * @param fname the filename to append
  * @return '$path/$fname', NULL on error
  */
 static char *
 append_to_dir (const char *path,
                const char *fname)
 {
   char *ret;
   size_t slen;
 
   if (0 == (slen = strlen (path)))
     return NULL;
   if ('/' == fname[0])
     fname++;
   ret = malloc (slen + strlen (fname) + 2);
   if (NULL == ret)
     return NULL;
 #ifdef MINGW
   if ('\\' == path[slen - 1])
     sprintf (ret,
              "%s%s",
              path,
              fname);
   else
     sprintf (ret,
              "%s\\%s",
              path,
              fname);
 #else
   if ('/' == path[slen - 1])
     sprintf (ret,
              "%s%s",
              path,
              fname);
   else
     sprintf (ret,
              "%s/%s",
              path,
              fname);
 #endif
   return ret;
 }
 
 
 /**
  * Iterate over all paths where we expect to find GNU libextractor
  * plugins.
  *
  * @param pp function to call for each path
  * @param pp_cls cls argument for pp.
  */
 static void
 get_installation_paths (EXTRACTOR_PathProcessor pp,
                         void *pp_cls)
 {
   const char *p;
   char *path;
   char *prefix;
   char *d;
   char *saveptr;
   bool skip; /* true if we should skip GETENV */
 
   prefix = NULL;
 #ifdef HAVE_SECURE_GETENV
   /* secure_getenv() already ignores the environment in secure execution
      mode, so we never have to suppress the lookup ourselves */
   #define GETENV secure_getenv
     skip = false;
 #elif WINDOWS
   /* no set-user-ID/set-group-ID notion to worry about */
   #define GETENV getenv
     skip = false;
 #elif defined(HAVE_ISSETUGID)
   #define GETENV getenv
     skip = (0 != issetugid ());
 #else
   /* poor man's approximation of the secure execution mode test
      that secure_getenv() would do for us */
   #define GETENV getenv
     skip = ( (getuid () != geteuid ()) ||
              (getgid () != getegid ()) );
 #endif
 
   if ( (! skip) &&
        (NULL != (p = GETENV ("LIBEXTRACTOR_PREFIX"))) )
   {
     if (NULL == (d = strdup (p)))
     {
       LOG_STRERROR ("strdup");
       return;
     }
     for (prefix = strtok_r (d, ":", &saveptr);
          NULL != prefix;
          prefix = strtok_r (NULL, ":", &saveptr))
       pp (pp_cls, prefix);
     free (d);
     return;
   }
 #if GNU_LINUX
   if (NULL == prefix)
     prefix = get_path_from_proc_exe ();
 #endif
 #if WINDOWS
   if (NULL == prefix)
     prefix = get_path_from_module_filename ();
 #endif
 #if DARWIN
   if (NULL == prefix)
     prefix = get_path_from_NSGetExecutablePath ();
   if (NULL == prefix)
     prefix = get_path_from_dyld_image ();
 #endif
   if (NULL == prefix)
     prefix = get_path_from_PATH ();
   pp (pp_cls, PLUGININSTDIR);
   if (NULL == prefix)
     return;
   path = append_to_dir (prefix, PLUGINDIR);
   if (NULL != path)
   {
     if (0 != strcmp (path,
                      PLUGININSTDIR))
       pp (pp_cls, path);
     free (path);
   }
   free (prefix);
 }
 
 
 /**
  * Closure for #find_plugin_in_path().
  */
 struct SearchContext
 {
   /**
    * Name of the plugin we are looking for.
    */
   const char *short_name;
 
   /**
    * Location for storing the path to the plugin upon success.
    */
   char *path;
 };
 
 
 /**
  * Load all plugins from the given directory.
  *
  * @param cls pointer to the "struct EXTRACTOR_PluginList*" to extend
  * @param path path to a directory with plugins
  */
 static void
 find_plugin_in_path (void *cls,
                      const char *path)
 {
   struct SearchContext *sc = cls;
   DIR *dir;
   struct dirent *ent;
   const char *sym_name;
   char *sym;
   char *dot;
   size_t dlen;
 
   if (NULL != sc->path)
     return;
   if (NULL == (dir = opendir (path)))
     return;
   while (NULL != (ent = readdir (dir)))
   {
     if ('.' == ent->d_name[0])
       continue;
     dlen = strlen (ent->d_name);
     if ( (dlen < 4) ||
          ( (0 != strcmp (&ent->d_name[dlen - 3], ".so")) &&
            (0 != strcasecmp (&ent->d_name[dlen - 4], ".dll")) ) )
       continue; /* only load '.so' and '.dll' */
     if (NULL == (sym_name = strrchr (ent->d_name, '_')))
       continue;
     sym_name++;
     if (NULL == (sym = strdup (sym_name)))
     {
       LOG_STRERROR ("strdup");
       closedir (dir);
       return;
     }
     dot = strchr (sym, '.');
     if (NULL != dot)
       *dot = '\0';
     if (0 == strcmp (sym, sc->short_name))
     {
       sc->path = append_to_dir (path, ent->d_name);
       free (sym);
       break;
     }
     free (sym);
   }
   closedir (dir);
 }
 
 
 /**
  * Given a short name of a library (i.e. "mime"), find
  * the full path of the respective plugin.
  */
 char *
 EXTRACTOR_find_plugin_ (const char *short_name)
 {
   struct SearchContext sc;
 
   sc.path = NULL;
   sc.short_name = short_name;
   get_installation_paths (&find_plugin_in_path,
                           &sc);
   return sc.path;
 }
 
 
 /**
  * Closure for #load_plugins_from_dir().
  */
 struct DefaultLoaderContext
 {
   /**
    * Accumulated result list.
    */
   struct EXTRACTOR_PluginList *res;
 
   /**
    * Flags to use for all plugins.
    */
   enum EXTRACTOR_Options flags;
 };
 
 
 /**
  * Load all plugins from the given directory.
  *
  * @param cls pointer to the "struct EXTRACTOR_PluginList*" to extend
  * @param path path to a directory with plugins
  */
 static void
 load_plugins_from_dir (void *cls,
                        const char *path)
 {
   struct DefaultLoaderContext *dlc = cls;
   DIR *dir;
   struct dirent *ent;
   const char *sym_name;
   char *sym;
   char *dot;
   size_t dlen;
 
   if (NULL == (dir = opendir (path)))
     return;
   while (NULL != (ent = readdir (dir)))
   {
     if (ent->d_name[0] == '.')
       continue;
     dlen = strlen (ent->d_name);
     if ( (dlen < 4) ||
          ( (0 != strcmp (&ent->d_name[dlen - 3], ".so")) &&
            (0 != strcasecmp (&ent->d_name[dlen - 4], ".dll")) ) )
       continue; /* only load '.so' and '.dll' */
     if (NULL == (sym_name = strrchr (ent->d_name, '_')))
       continue;
     sym_name++;
     if (NULL == (sym = strdup (sym_name)))
     {
       LOG_STRERROR ("strdup");
       closedir (dir);
       return;
     }
     if (NULL != (dot = strchr (sym, '.')))
       *dot = '\0';
     dlc->res = EXTRACTOR_plugin_add (dlc->res,
                                      sym,
                                      NULL,
                                      dlc->flags);
     free (sym);
   }
   closedir (dir);
 }
 
 
 /**
  * Load the default set of plugins. The default can be changed
  * by setting the LIBEXTRACTOR_LIBRARIES environment variable.
  * If it is set to "env", then this function will return
  * #EXTRACTOR_plugin_add_config(NULL, env, flags).  Otherwise,
  * it will load all of the installed plugins and return them.
  *
  * @param flags options for all of the plugins loaded
  * @return the default set of plugins, NULL if no plugins were found
  */
 struct EXTRACTOR_PluginList *
 EXTRACTOR_plugin_add_defaults (enum EXTRACTOR_Options flags)
 {
   struct DefaultLoaderContext dlc;
   char *env;
 
   env = getenv ("LIBEXTRACTOR_LIBRARIES");
   if (NULL != env)
     return EXTRACTOR_plugin_add_config (NULL, env, flags);
   dlc.res = NULL;
   dlc.flags = flags;
   get_installation_paths (&load_plugins_from_dir,
                           &dlc);
   return dlc.res;
 }
 
 
 /* end of extractor_plugpath.c */