mirror of
https://github.com/libguestfs/libguestfs.git
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147 lines
3.4 KiB
C
147 lines
3.4 KiB
C
/* guestfish - guest filesystem shell
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* Copyright (C) 2009-2020 Red Hat Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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/**
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* This file implements tilde (C<~>) expansion of home directories
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* in L<guestfish(1)>.
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*/
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#include <config.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <assert.h>
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#include <pwd.h>
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#include <sys/types.h>
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#include <errno.h>
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#include <error.h>
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#include "fish.h"
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static char *expand_home (char *orig, const char *append);
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static const char *find_home_for_username (const char *, size_t);
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static const char *find_home_for_current_user (void);
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/**
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* This is called from the script loop if we find a candidate for
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* C<~username> (tilde-expansion).
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*/
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char *
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try_tilde_expansion (char *str)
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{
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assert (str[0] == '~');
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/* Expand "~" to current user's home directory. */
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if (str[1] == '\0') /* ~ */
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return expand_home (str, NULL);
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else if (str[1] == '/') /* ~/... */
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return expand_home (str, &str[1]);
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/* Try expanding the part up to the following '\0' or '/' as a
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* username from the password file.
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*/
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else {
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const char *home, *rest;
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size_t len = strcspn (&str[1], "/");
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rest = &str[1+len];
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home = find_home_for_username (&str[1], len);
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if (home) {
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len = strlen (home) + strlen (rest) + 1;
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str = malloc (len);
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if (str == NULL)
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error (EXIT_FAILURE, errno, "malloc");
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strcpy (str, home);
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strcat (str, rest);
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return str;
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}
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}
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/* No match, return the original string. */
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return str;
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}
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/**
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* Return C<$HOME> + append string.
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*/
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static char *
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expand_home (char *orig, const char *append)
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{
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const char *home;
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size_t len;
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char *str;
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home = getenv ("HOME");
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if (!home) {
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/* $HOME not set, bash can look up the current user in the
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* password file and find their home that way. (RHBZ#617440).
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*/
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home = find_home_for_current_user ();
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if (!home)
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return orig;
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}
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len = strlen (home) + (append ? strlen (append) : 0) + 1;
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str = malloc (len);
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if (str == NULL)
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error (EXIT_FAILURE, errno, "malloc");
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strcpy (str, home);
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if (append)
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strcat (str, append);
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return str;
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}
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/**
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* Lookup C<username> (of length C<ulen>), return home directory if
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* found, or C<NULL> if not found.
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*/
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static const char *
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find_home_for_username (const char *username, size_t ulen)
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{
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struct passwd *pw;
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setpwent ();
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while ((pw = getpwent ()) != NULL) {
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if (strlen (pw->pw_name) == ulen &&
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STREQLEN (username, pw->pw_name, ulen))
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return pw->pw_dir;
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}
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return NULL;
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}
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static const char *
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find_home_for_current_user (void)
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{
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struct passwd *pw;
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uid_t euid = geteuid ();
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setpwent ();
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while ((pw = getpwent ()) != NULL) {
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if (pw->pw_uid == euid)
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return pw->pw_dir;
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}
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return NULL;
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}
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