findcmd.c

android-w.song.android.widget

/* findcmd.c -- Functions to search for commands by name. */

/* Copyright (C) 1997-2009 Free Software Foundation, Inc.

   This file is part of GNU Bash, the Bourne Again SHell.

   Bash 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 of the License, or
   (at your option) any later version.

   Bash 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 Bash.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "config.h"

#include <stdio.h>
#include "chartypes.h"
#include "bashtypes.h"
#if !defined (_MINIX) && defined (HAVE_SYS_FILE_H)
#  include <sys/file.h>
#endif
#include "filecntl.h"
#include "posixstat.h"

#if defined (HAVE_UNISTD_H)
#  include <unistd.h>
#endif
#include <errno.h>

#include "bashansi.h"

#include "memalloc.h"
#include "shell.h"
#include "flags.h"
#include "hashlib.h"
#include "pathexp.h"
#include "hashcmd.h"
#include "findcmd.h"	/* matching prototypes and declarations */

#if !defined (errno)
extern int errno;
#endif

extern int posixly_correct;

/* Static functions defined and used in this file. */
static char *_find_user_command_internal __P((const char *, int));
static char *find_user_command_internal __P((const char *, int));
static char *find_user_command_in_path __P((const char *, char *, int));
static char *find_in_path_element __P((const char *, char *, int, int, struct stat *));
static char *find_absolute_program __P((const char *, int));

static char *get_next_path_element __P((char *, int *));

/* The file name which we would try to execute, except that it isn't
   possible to execute it.  This is the first file that matches the
   name that we are looking for while we are searching $PATH for a
   suitable one to execute.  If we cannot find a suitable executable
   file, then we use this one. */
static char *file_to_lose_on;

/* Non-zero if we should stat every command found in the hash table to
   make sure it still exists. */
int check_hashed_filenames;

/* DOT_FOUND_IN_SEARCH becomes non-zero when find_user_command ()
   encounters a `.' as the directory pathname while scanning the
   list of possible pathnames; i.e., if `.' comes before the directory
   containing the file of interest. */
int dot_found_in_search = 0;

/* Return some flags based on information about this file.
   The EXISTS bit is non-zero if the file is found.
   The EXECABLE bit is non-zero the file is executble.
   Zero is returned if the file is not found. */
int
file_status (name)
     const char *name;
{
  struct stat finfo;
  int r;

  /* Determine whether this file exists or not. */
  if (stat (name, &finfo) < 0)
    return (0);

  /* If the file is a directory, then it is not "executable" in the
     sense of the shell. */
  if (S_ISDIR (finfo.st_mode))
    return (FS_EXISTS|FS_DIRECTORY);

  r = FS_EXISTS;

#if defined (HAVE_EACCESS)
  /* Use eaccess(2) if we have it to take things like ACLs and other
     file access mechanisms into account.  eaccess uses the effective
     user and group IDs, not the real ones.  We could use sh_eaccess,
     but we don't want any special treatment for /dev/fd. */
  if (eaccess (name, X_OK) == 0)
    r |= FS_EXECABLE;
  if (eaccess (name, R_OK) == 0)
    r |= FS_READABLE;

  return r;
#elif defined (AFS)
  /* We have to use access(2) to determine access because AFS does not
     support Unix file system semantics.  This may produce wrong
     answers for non-AFS files when ruid != euid.  I hate AFS. */
  if (access (name, X_OK) == 0)
    r |= FS_EXECABLE;
  if (access (name, R_OK) == 0)
    r |= FS_READABLE;

  return r;
#else /* !HAVE_EACCESS && !AFS */

  /* Find out if the file is actually executable.  By definition, the
     only other criteria is that the file has an execute bit set that
     we can use.  The same with whether or not a file is readable. */

  /* Root only requires execute permission for any of owner, group or
     others to be able to exec a file, and can read any file. */
  if (current_user.euid == (uid_t)0)
    {
      r |= FS_READABLE;
      if (finfo.st_mode & S_IXUGO)
	r |= FS_EXECABLE;
      return r;
    }

  /* If we are the owner of the file, the owner bits apply. */
  if (current_user.euid == finfo.st_uid)
    {
      if (finfo.st_mode & S_IXUSR)
	r |= FS_EXECABLE;
      if (finfo.st_mode & S_IRUSR)
	r |= FS_READABLE;
    }

  /* If we are in the owning group, the group permissions apply. */
  else if (group_member (finfo.st_gid))
    {
      if (finfo.st_mode & S_IXGRP)
	r |= FS_EXECABLE;
      if (finfo.st_mode & S_IRGRP)
	r |= FS_READABLE;
    }

  /* Else we check whether `others' have permission to execute the file */
  else
    {
      if (finfo.st_mode & S_IXOTH)
	r |= FS_EXECABLE;
      if (finfo.st_mode & S_IROTH)
	r |= FS_READABLE;
    }

  return r;
#endif /* !AFS */
}

/* Return non-zero if FILE exists and is executable.
   Note that this function is the definition of what an
   executable file is; do not change this unless YOU know
   what an executable file is. */
int
executable_file (file)
     const char *file;
{
  int s;

  s = file_status (file);
#if defined EISDIR
  if (s & FS_DIRECTORY)
    errno = EISDIR;	/* let's see if we can improve error messages */
#endif
  return ((s & FS_EXECABLE) && ((s & FS_DIRECTORY) == 0));
}

int
is_directory (file)
     const char *file;
{
  return (file_status (file) & FS_DIRECTORY);
}

int
executable_or_directory (file)
     const char *file;
{
  int s;

  s = file_status (file);
  return ((s & FS_EXECABLE) || (s & FS_DIRECTORY));
}

/* Locate the executable file referenced by NAME, searching along
   the contents of the shell PATH variable.  Return a new string
   which is the full pathname to the file, or NULL if the file
   couldn't be found.  If a file is found that isn't executable,
   and that is the only match, then return that. */
char *
find_user_command (name)
     const char *name;
{
  return (find_user_command_internal (name, FS_EXEC_PREFERRED|FS_NODIRS));
}

/* Locate the file referenced by NAME, searching along the contents
   of the shell PATH variable.  Return a new string which is the full
   pathname to the file, or NULL if the file couldn't be found.  This
   returns the first readable file found; designed to be used to look
   for shell scripts or files to source. */
char *
find_path_file (name)
     const char *name;
{
  return (find_user_command_internal (name, FS_READABLE));
}

static char *
_find_user_command_internal (name, flags)
     const char *name;
     int flags;
{
  char *path_list, *cmd;
  SHELL_VAR *var;

  /* Search for the value of PATH in both the temporary environments and
     in the regular list of variables. */
  if (var = find_variable_internal ("PATH", 1))	/* XXX could be array? */
    path_list = value_cell (var);
  else
    path_list = (char *)NULL;

  if (path_list == 0 || *path_list == '\0')
    return (savestring (name));

  cmd = find_user_command_in_path (name, path_list, flags);

  return (cmd);
}

static char *
find_user_command_internal (name, flags)
     const char *name;
     int flags;
{
#ifdef __WIN32__
  char *res, *dotexe;

  dotexe = (char *)xmalloc (strlen (name) + 5);
  strcpy (dotexe, name);
  strcat (dotexe, ".exe");
  res = _find_user_command_internal (dotexe, flags);
  free (dotexe);
  if (res == 0)
    res = _find_user_command_internal (name, flags);
  return res;
#else
  return (_find_user_command_internal (name, flags));
#endif
}

/* Return the next element from PATH_LIST, a colon separated list of
   paths.  PATH_INDEX_POINTER is the address of an index into PATH_LIST;
   the index is modified by this function.
   Return the next element of PATH_LIST or NULL if there are no more. */
static char *
get_next_path_element (path_list, path_index_pointer)
     char *path_list;
     int *path_index_pointer;
{
  char *path;

  path = extract_colon_unit (path_list, path_index_pointer);

  if (path == 0)
    return (path);

  if (*path == '\0')
    {
      free (path);
      path = savestring (".");
    }

  return (path);
}

/* Look for PATHNAME in $PATH.  Returns either the hashed command
   corresponding to PATHNAME or the first instance of PATHNAME found
   in $PATH.  Returns a newly-allocated string. */
char *
search_for_command (pathname)
     const char *pathname;
{
  char *hashed_file, *command;
  int temp_path, st;
  SHELL_VAR *path;

  hashed_file = command = (char *)NULL;