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/* guestfish - guest filesystem shell
* Copyright (C) 2009-2016 Red Hat Inc.
*
* This program 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 2 of the License, or
* (at your option) any later version.
*
* This program 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 this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/**
* This file implements tilde (C<~>) expansion of home directories
* in L<guestfish(1)>.
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <assert.h>
#include <pwd.h>
#include <sys/types.h>
#include <errno.h>
#include <error.h>
#include "fish.h"
static char *expand_home (char *orig, const char *append);
static const char *find_home_for_username (const char *, size_t);
static const char *find_home_for_current_user (void);
/**
* This is called from the script loop if we find a candidate for
* C<~username> (tilde-expansion).
*/
char *
try_tilde_expansion (char *str)
{
assert (str[0] == '~');
/* Expand "~" to current user's home directory. */
if (str[1] == '\0') /* ~ */
return expand_home (str, NULL);
else if (str[1] == '/') /* ~/... */
return expand_home (str, &str[1]);
/* Try expanding the part up to the following '\0' or '/' as a
* username from the password file.
*/
else {
const char *home, *rest;
size_t len = strcspn (&str[1], "/");
rest = &str[1+len];
home = find_home_for_username (&str[1], len);
if (home) {
len = strlen (home) + strlen (rest) + 1;
str = malloc (len);
if (str == NULL)
error (EXIT_FAILURE, errno, "malloc");
strcpy (str, home);
strcat (str, rest);
return str;
}
}
/* No match, return the orignal string. */
return str;
}
/**
* Return C<$HOME> + append string.
*/
static char *
expand_home (char *orig, const char *append)
{
const char *home;
size_t len;
char *str;
home = getenv ("HOME");
if (!home) {
/* $HOME not set, bash can look up the current user in the
* password file and find their home that way. (RHBZ#617440).
*/
home = find_home_for_current_user ();
if (!home)
return orig;
}
len = strlen (home) + (append ? strlen (append) : 0) + 1;
str = malloc (len);
if (str == NULL)
error (EXIT_FAILURE, errno, "malloc");
strcpy (str, home);
if (append)
strcat (str, append);
return str;
}
/**
* Lookup C<username> (of length C<ulen>), return home directory if
* found, or C<NULL> if not found.
*/
static const char *
find_home_for_username (const char *username, size_t ulen)
{
struct passwd *pw;
setpwent ();
while ((pw = getpwent ()) != NULL) {
if (strlen (pw->pw_name) == ulen &&
STREQLEN (username, pw->pw_name, ulen))
return pw->pw_dir;
}
return NULL;
}
static const char *
find_home_for_current_user (void)
{
struct passwd *pw;
uid_t euid = geteuid ();
setpwent ();
while ((pw = getpwent ()) != NULL) {
if (pw->pw_uid == euid)
return pw->pw_dir;
}
return NULL;
}
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