blob: ce4a7bbd280df22aad6893d7f26597e8b0527949
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 | //config:config ADD_SHELL |
11 | //config: bool "add-shell" |
12 | //config: default y if DESKTOP |
13 | //config: help |
14 | //config: Add shells to /etc/shells. |
15 | //config: |
16 | //config:config REMOVE_SHELL |
17 | //config: bool "remove-shell" |
18 | //config: default y if DESKTOP |
19 | //config: help |
20 | //config: Remove shells from /etc/shells. |
21 | |
22 | //applet:IF_ADD_SHELL( APPLET_ODDNAME(add-shell , add_remove_shell, BB_DIR_USR_SBIN, BB_SUID_DROP, add_shell )) |
23 | //applet:IF_REMOVE_SHELL(APPLET_ODDNAME(remove-shell, add_remove_shell, BB_DIR_USR_SBIN, BB_SUID_DROP, remove_shell)) |
24 | |
25 | //kbuild:lib-$(CONFIG_ADD_SHELL) += add-remove-shell.o |
26 | //kbuild:lib-$(CONFIG_REMOVE_SHELL) += add-remove-shell.o |
27 | |
28 | //usage:#define add_shell_trivial_usage |
29 | //usage: "SHELL..." |
30 | //usage:#define add_shell_full_usage "\n\n" |
31 | //usage: "Add SHELLs to /etc/shells" |
32 | |
33 | //usage:#define remove_shell_trivial_usage |
34 | //usage: "SHELL..." |
35 | //usage:#define remove_shell_full_usage "\n\n" |
36 | //usage: "Remove SHELLs from /etc/shells" |
37 | |
38 | #include "libbb.h" |
39 | |
40 | #define SHELLS_FILE "/etc/shells" |
41 | |
42 | #define REMOVE_SHELL (ENABLE_REMOVE_SHELL && (!ENABLE_ADD_SHELL || applet_name[0] == 'r')) |
43 | #define ADD_SHELL (ENABLE_ADD_SHELL && (!ENABLE_REMOVE_SHELL || applet_name[0] == 'a')) |
44 | |
45 | /* NB: we use the _address_, not the value, of this string |
46 | * as a "special value of pointer" in the code. |
47 | */ |
48 | static const char dont_add[] ALIGN1 = "\n"; |
49 | |
50 | int add_remove_shell_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
51 | int add_remove_shell_main(int argc UNUSED_PARAM, char **argv) |
52 | { |
53 | FILE *orig_fp; |
54 | char *orig_fn; |
55 | char *new_fn; |
56 | |
57 | argv++; |
58 | |
59 | orig_fn = xmalloc_follow_symlinks(SHELLS_FILE); |
60 | if (!orig_fn) |
61 | return EXIT_FAILURE; |
62 | orig_fp = fopen_for_read(orig_fn); |
63 | |
64 | new_fn = xasprintf("%s.tmp", orig_fn); |
65 | /* |
66 | * O_TRUNC or O_EXCL? At the first glance, O_EXCL looks better, |
67 | * since it prevents races. But: (1) it requires a retry loop, |
68 | * (2) if /etc/shells.tmp is *stale*, then retry loop |
69 | * with O_EXCL will never succeed - it should have a timeout, |
70 | * after which it should revert to O_TRUNC. |
71 | * For now, I settle for O_TRUNC instead. |
72 | */ |
73 | xmove_fd(xopen(new_fn, O_WRONLY | O_CREAT | O_TRUNC), STDOUT_FILENO); |
74 | |
75 | /* TODO: |
76 | struct stat sb; |
77 | xfstat(fileno(orig_fp), &sb); |
78 | xfchown(STDOUT_FILENO, sb.st_uid, sb.st_gid); |
79 | xfchmod(STDOUT_FILENO, sb.st_mode); |
80 | */ |
81 | |
82 | if (orig_fp) { |
83 | /* Copy old file, possibly skipping removed shell names */ |
84 | char *line; |
85 | while ((line = xmalloc_fgetline(orig_fp)) != NULL) { |
86 | char **cpp = argv; |
87 | while (*cpp) { |
88 | if (strcmp(*cpp, line) == 0) { |
89 | /* Old file has this shell name */ |
90 | if (REMOVE_SHELL) { |
91 | /* we are remove-shell */ |
92 | /* delete this name by not copying it */ |
93 | goto next_line; |
94 | } |
95 | /* we are add-shell */ |
96 | /* mark this name as "do not add" */ |
97 | *cpp = (char*)dont_add; |
98 | } |
99 | cpp++; |
100 | } |
101 | /* copy shell name from old to new file */ |
102 | puts(line); |
103 | next_line: |
104 | free(line); |
105 | } |
106 | if (ENABLE_FEATURE_CLEAN_UP) |
107 | fclose(orig_fp); |
108 | } |
109 | |
110 | if (ADD_SHELL) { |
111 | char **cpp = argv; |
112 | while (*cpp) { |
113 | if (*cpp != dont_add) |
114 | puts(*cpp); |
115 | cpp++; |
116 | } |
117 | } |
118 | |
119 | /* Ensure we wrote out everything */ |
120 | if (fclose(stdout) != 0) { |
121 | xunlink(new_fn); |
122 | bb_perror_msg_and_die("%s: write error", new_fn); |
123 | } |
124 | |
125 | /* Small hole: if rename fails, /etc/shells.tmp is not removed */ |
126 | xrename(new_fn, orig_fn); |
127 | |
128 | if (ENABLE_FEATURE_CLEAN_UP) { |
129 | free(orig_fn); |
130 | free(new_fn); |
131 | } |
132 | |
133 | return EXIT_SUCCESS; |
134 | } |
135 |