source: branches/3.0/mindi-busybox/loginutils/add-remove-shell.c @ 2899

Last change on this file since 2899 was 2725, checked in by bruno, 8 years ago
  • Update mindi-busybox to 1.18.3 to avoid problems with the tar command which is now failing on recent versions with busybox 1.7.3
  • Property svn:eol-style set to native
File size: 3.7 KB
Line 
1/*
2 * add-shell and remove-shell implementation for busybox
3 *
4 * Copyright (C) 2010 Nokia Corporation. All rights reserved.
5 * Written by Alexander Shishkin <virtuoso@slind.org>
6 *
7 * Licensed under GPLv2 or later, see the LICENSE file in this source tree
8 * for details.
9 */
10
11//applet:IF_ADD_SHELL(   APPLET_ODDNAME(add-shell   , add_remove_shell, _BB_DIR_USR_BIN, _BB_SUID_DROP, add_shell   ))
12//applet:IF_REMOVE_SHELL(APPLET_ODDNAME(remove-shell, add_remove_shell, _BB_DIR_USR_BIN, _BB_SUID_DROP, remove_shell))
13
14//kbuild:lib-$(CONFIG_ADD_SHELL)    += add-remove-shell.o
15//kbuild:lib-$(CONFIG_REMOVE_SHELL) += add-remove-shell.o
16
17//config:config ADD_SHELL
18//config:       bool "add-shell"
19//config:       default y if DESKTOP
20//config:       help
21//config:         Add shells to /etc/shells.
22//config:
23//config:config REMOVE_SHELL
24//config:       bool "remove-shell"
25//config:       default y if DESKTOP
26//config:       help
27//config:         Remove shells from /etc/shells.
28
29//usage:#define add_shell_trivial_usage
30//usage:       "SHELL..."
31//usage:#define add_shell_full_usage "\n\n"
32//usage:       "Add SHELLs to /etc/shells"
33
34//usage:#define remove_shell_trivial_usage
35//usage:       "SHELL..."
36//usage:#define remove_shell_full_usage "\n\n"
37//usage:       "Remove SHELLs from /etc/shells"
38
39#include "libbb.h"
40
41#define SHELLS_FILE "/etc/shells"
42
43#define REMOVE_SHELL (ENABLE_REMOVE_SHELL && (!ENABLE_ADD_SHELL || applet_name[0] == 'r'))
44#define ADD_SHELL    (ENABLE_ADD_SHELL && (!ENABLE_REMOVE_SHELL || applet_name[0] == 'a'))
45
46/* NB: we use the _address_, not the value, of this string
47 * as a "special value of pointer" in the code.
48 */
49static const char dont_add[] ALIGN1 = "\n";
50
51int add_remove_shell_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
52int add_remove_shell_main(int argc UNUSED_PARAM, char **argv)
53{
54    FILE *orig_fp;
55    char *orig_fn;
56    char *new_fn;
57
58    argv++;
59
60    orig_fn = xmalloc_follow_symlinks(SHELLS_FILE);
61    if (!orig_fn)
62        return EXIT_FAILURE;
63    orig_fp = fopen_for_read(orig_fn);
64
65    new_fn = xasprintf("%s.tmp", orig_fn);
66    /*
67     * O_TRUNC or O_EXCL? At the first glance, O_EXCL looks better,
68     * since it prevents races. But: (1) it requires a retry loop,
69     * (2) if /etc/shells.tmp is *stale*, then retry loop
70     * with O_EXCL will never succeed - it should have a timeout,
71     * after which it should revert to O_TRUNC.
72     * For now, I settle for O_TRUNC instead.
73     */
74    xmove_fd(xopen(new_fn, O_WRONLY | O_CREAT | O_TRUNC), STDOUT_FILENO);
75
76    /* TODO:
77    struct stat sb;
78    xfstat(fileno(orig_fp), &sb);
79    xfchown(STDOUT_FILENO, sb.st_uid, sb.st_gid);
80    xfchmod(STDOUT_FILENO, sb.st_mode);
81    */
82
83    if (orig_fp) {
84        /* Copy old file, possibly skipping removed shell names */
85        char *line;
86        while ((line = xmalloc_fgetline(orig_fp)) != NULL) {
87            char **cpp = argv;
88            while (*cpp) {
89                if (strcmp(*cpp, line) == 0) {
90                    /* Old file has this shell name */
91                    if (REMOVE_SHELL) {
92                        /* we are remove-shell */
93                        /* delete this name by not copying it */
94                        goto next_line;
95                    }
96                    /* we are add-shell */
97                    /* mark this name as "do not add" */
98                    *cpp = (char*)dont_add;
99                }
100                cpp++;
101            }
102            /* copy shell name from old to new file */
103            printf("%s\n", line);
104 next_line:
105            free(line);
106        }
107        if (ENABLE_FEATURE_CLEAN_UP)
108            fclose(orig_fp);
109    }
110
111    if (ADD_SHELL) {
112        char **cpp = argv;
113        while (*cpp) {
114            if (*cpp != dont_add)
115                printf("%s\n", *cpp);
116            cpp++;
117        }
118    }
119
120    /* Ensure we wrote out everything */
121    if (fclose(stdout) != 0) {
122        xunlink(new_fn);
123        bb_perror_msg_and_die("%s: write error", new_fn);
124    }
125
126    /* Small hole: if rename fails, /etc/shells.tmp is not removed */
127    xrename(new_fn, orig_fn);
128
129    if (ENABLE_FEATURE_CLEAN_UP) {
130        free(orig_fn);
131        free(new_fn);
132    }
133
134    return EXIT_SUCCESS;
135}
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