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/*
* add-shell and remove-shell implementation for busybox
*
* Copyright (C) 2010 Nokia Corporation. All rights reserved.
* Written by Alexander Shishkin <virtuoso@slind.org>
*
* Licensed under GPLv2 or later, see the LICENSE file in this source tree
* for details.
*/
//config:config ADD_SHELL
//config: bool "add-shell"
//config: default y if DESKTOP
//config: help
//config: Add shells to /etc/shells.
//config:
//config:config REMOVE_SHELL
//config: bool "remove-shell"
//config: default y if DESKTOP
//config: help
//config: Remove shells from /etc/shells.
// APPLET_ODDNAME:name main location suid_type help
//applet:IF_ADD_SHELL( APPLET_ODDNAME(add-shell , add_remove_shell, BB_DIR_USR_SBIN, BB_SUID_DROP, add_shell ))
//applet:IF_REMOVE_SHELL(APPLET_ODDNAME(remove-shell, add_remove_shell, BB_DIR_USR_SBIN, BB_SUID_DROP, remove_shell))
//kbuild:lib-$(CONFIG_ADD_SHELL) += add-remove-shell.o
//kbuild:lib-$(CONFIG_REMOVE_SHELL) += add-remove-shell.o
//usage:#define add_shell_trivial_usage
//usage: "SHELL..."
//usage:#define add_shell_full_usage "\n\n"
//usage: "Add SHELLs to /etc/shells"
//usage:#define remove_shell_trivial_usage
//usage: "SHELL..."
//usage:#define remove_shell_full_usage "\n\n"
//usage: "Remove SHELLs from /etc/shells"
#include "libbb.h"
#define SHELLS_FILE "/etc/shells"
#define REMOVE_SHELL (ENABLE_REMOVE_SHELL && (!ENABLE_ADD_SHELL || applet_name[0] == 'r'))
#define ADD_SHELL (ENABLE_ADD_SHELL && (!ENABLE_REMOVE_SHELL || applet_name[0] == 'a'))
/* NB: we use the _address_, not the value, of this string
* as a "special value of pointer" in the code.
*/
static const char dont_add[] ALIGN1 = "\n";
int add_remove_shell_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int add_remove_shell_main(int argc UNUSED_PARAM, char **argv)
{
FILE *orig_fp;
char *orig_fn;
char *new_fn;
argv++;
orig_fn = xmalloc_follow_symlinks(SHELLS_FILE);
if (!orig_fn)
return EXIT_FAILURE;
orig_fp = fopen_for_read(orig_fn);
new_fn = xasprintf("%s.tmp", orig_fn);
/*
* O_TRUNC or O_EXCL? At the first glance, O_EXCL looks better,
* since it prevents races. But: (1) it requires a retry loop,
* (2) if /etc/shells.tmp is *stale*, then retry loop
* with O_EXCL will never succeed - it should have a timeout,
* after which it should revert to O_TRUNC.
* For now, I settle for O_TRUNC instead.
*/
xmove_fd(xopen(new_fn, O_WRONLY | O_CREAT | O_TRUNC), STDOUT_FILENO);
/* TODO:
struct stat sb;
xfstat(fileno(orig_fp), &sb);
xfchown(STDOUT_FILENO, sb.st_uid, sb.st_gid);
xfchmod(STDOUT_FILENO, sb.st_mode);
*/
if (orig_fp) {
/* Copy old file, possibly skipping removed shell names */
char *line;
while ((line = xmalloc_fgetline(orig_fp)) != NULL) {
char **cpp = argv;
while (*cpp) {
if (strcmp(*cpp, line) == 0) {
/* Old file has this shell name */
if (REMOVE_SHELL) {
/* we are remove-shell */
/* delete this name by not copying it */
goto next_line;
}
/* we are add-shell */
/* mark this name as "do not add" */
*cpp = (char*)dont_add;
}
cpp++;
}
/* copy shell name from old to new file */
puts(line);
next_line:
free(line);
}
if (ENABLE_FEATURE_CLEAN_UP)
fclose(orig_fp);
}
if (ADD_SHELL) {
char **cpp = argv;
while (*cpp) {
if (*cpp != dont_add)
puts(*cpp);
cpp++;
}
}
/* Ensure we wrote out everything */
if (fclose(stdout) != 0) {
xunlink(new_fn);
bb_perror_msg_and_die("%s: write error", new_fn);
}
/* Small hole: if rename fails, /etc/shells.tmp is not removed */
xrename(new_fn, orig_fn);
if (ENABLE_FEATURE_CLEAN_UP) {
free(orig_fn);
free(new_fn);
}
return EXIT_SUCCESS;
}
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