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