Annotation of /trunk/mkinitrd-magellan/klibc/usr/kinit/run-init/runinitlib.c
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Revision 1297 -
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Fri May 27 15:12:11 2011 UTC (12 years, 11 months ago) by niro
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File size: 5310 byte(s)
Fri May 27 15:12:11 2011 UTC (12 years, 11 months ago) by niro
File MIME type: text/plain
File size: 5310 byte(s)
-updated to klibc-1.5.22 with mntproc definitions patch included
1 | niro | 532 | /* ----------------------------------------------------------------------- * |
2 | * | ||
3 | * Copyright 2004-2006 H. Peter Anvin - All Rights Reserved | ||
4 | * | ||
5 | * Permission is hereby granted, free of charge, to any person | ||
6 | * obtaining a copy of this software and associated documentation | ||
7 | * files (the "Software"), to deal in the Software without | ||
8 | * restriction, including without limitation the rights to use, | ||
9 | * copy, modify, merge, publish, distribute, sublicense, and/or | ||
10 | * sell copies of the Software, and to permit persons to whom | ||
11 | * the Software is furnished to do so, subject to the following | ||
12 | * conditions: | ||
13 | * | ||
14 | * The above copyright notice and this permission notice shall | ||
15 | * be included in all copies or substantial portions of the Software. | ||
16 | * | ||
17 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, | ||
18 | * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES | ||
19 | * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND | ||
20 | * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT | ||
21 | * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, | ||
22 | * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING | ||
23 | * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR | ||
24 | * OTHER DEALINGS IN THE SOFTWARE. | ||
25 | * | ||
26 | * ----------------------------------------------------------------------- */ | ||
27 | |||
28 | /* | ||
29 | * run_init(consoledev, realroot, init, initargs) | ||
30 | * | ||
31 | * This function should be called as the last thing in kinit, | ||
32 | * from initramfs, it does the following: | ||
33 | * | ||
34 | * - Delete all files in the initramfs; | ||
35 | * - Remounts /real-root onto the root filesystem; | ||
36 | * - Chroots; | ||
37 | * - Opens /dev/console; | ||
38 | * - Spawns the specified init program (with arguments.) | ||
39 | * | ||
40 | * On failure, returns a human-readable error message. | ||
41 | */ | ||
42 | |||
43 | #include <assert.h> | ||
44 | #include <dirent.h> | ||
45 | #include <errno.h> | ||
46 | #include <fcntl.h> | ||
47 | #include <string.h> | ||
48 | #include <stdlib.h> | ||
49 | #include <stdio.h> | ||
50 | #include <unistd.h> | ||
51 | #include <sys/mount.h> | ||
52 | #include <sys/stat.h> | ||
53 | #include <sys/types.h> | ||
54 | #include <sys/vfs.h> | ||
55 | #include "run-init.h" | ||
56 | |||
57 | /* Make it possible to compile on glibc by including constants that the | ||
58 | always-behind shipped glibc headers may not include. Classic example | ||
59 | on why the lack of ABI headers screw us up. */ | ||
60 | #ifndef TMPFS_MAGIC | ||
61 | # define TMPFS_MAGIC 0x01021994 | ||
62 | #endif | ||
63 | #ifndef RAMFS_MAGIC | ||
64 | # define RAMFS_MAGIC 0x858458f6 | ||
65 | #endif | ||
66 | #ifndef MS_MOVE | ||
67 | # define MS_MOVE 8192 | ||
68 | #endif | ||
69 | |||
70 | static int nuke(const char *what); | ||
71 | |||
72 | static int nuke_dirent(int len, const char *dir, const char *name, dev_t me) | ||
73 | { | ||
74 | int bytes = len + strlen(name) + 2; | ||
75 | char path[bytes]; | ||
76 | int xlen; | ||
77 | struct stat st; | ||
78 | |||
79 | xlen = snprintf(path, bytes, "%s/%s", dir, name); | ||
80 | assert(xlen < bytes); | ||
81 | |||
82 | if (lstat(path, &st)) | ||
83 | return ENOENT; /* Return 0 since already gone? */ | ||
84 | |||
85 | if (st.st_dev != me) | ||
86 | return 0; /* DO NOT recurse down mount points!!!!! */ | ||
87 | |||
88 | return nuke(path); | ||
89 | } | ||
90 | |||
91 | /* Wipe the contents of a directory, but not the directory itself */ | ||
92 | static int nuke_dir(const char *what) | ||
93 | { | ||
94 | int len = strlen(what); | ||
95 | DIR *dir; | ||
96 | struct dirent *d; | ||
97 | int err = 0; | ||
98 | struct stat st; | ||
99 | |||
100 | if (lstat(what, &st)) | ||
101 | return errno; | ||
102 | |||
103 | if (!S_ISDIR(st.st_mode)) | ||
104 | return ENOTDIR; | ||
105 | |||
106 | if (!(dir = opendir(what))) { | ||
107 | /* EACCES means we can't read it. Might be empty and removable; | ||
108 | if not, the rmdir() in nuke() will trigger an error. */ | ||
109 | return (errno == EACCES) ? 0 : errno; | ||
110 | } | ||
111 | |||
112 | while ((d = readdir(dir))) { | ||
113 | /* Skip . and .. */ | ||
114 | if (d->d_name[0] == '.' && | ||
115 | (d->d_name[1] == '\0' || | ||
116 | (d->d_name[1] == '.' && d->d_name[2] == '\0'))) | ||
117 | continue; | ||
118 | |||
119 | err = nuke_dirent(len, what, d->d_name, st.st_dev); | ||
120 | if (err) { | ||
121 | closedir(dir); | ||
122 | return err; | ||
123 | } | ||
124 | } | ||
125 | |||
126 | closedir(dir); | ||
127 | |||
128 | return 0; | ||
129 | } | ||
130 | |||
131 | static int nuke(const char *what) | ||
132 | { | ||
133 | int rv; | ||
134 | int err = 0; | ||
135 | |||
136 | rv = unlink(what); | ||
137 | if (rv < 0) { | ||
138 | if (errno == EISDIR) { | ||
139 | /* It's a directory. */ | ||
140 | err = nuke_dir(what); | ||
141 | if (!err) | ||
142 | err = rmdir(what) ? errno : err; | ||
143 | } else { | ||
144 | err = errno; | ||
145 | } | ||
146 | } | ||
147 | |||
148 | if (err) { | ||
149 | errno = err; | ||
150 | return err; | ||
151 | } else { | ||
152 | return 0; | ||
153 | } | ||
154 | } | ||
155 | |||
156 | const char *run_init(const char *realroot, const char *console, | ||
157 | const char *init, char **initargs) | ||
158 | { | ||
159 | niro | 1297 | struct stat rst, cst; |
160 | niro | 532 | struct statfs sfs; |
161 | int confd; | ||
162 | |||
163 | /* First, change to the new root directory */ | ||
164 | if (chdir(realroot)) | ||
165 | return "chdir to new root"; | ||
166 | |||
167 | /* This is a potentially highly destructive program. Take some | ||
168 | extra precautions. */ | ||
169 | |||
170 | /* Make sure the current directory is not on the same filesystem | ||
171 | as the root directory */ | ||
172 | if (stat("/", &rst) || stat(".", &cst)) | ||
173 | return "stat"; | ||
174 | |||
175 | if (rst.st_dev == cst.st_dev) | ||
176 | return "current directory on the same filesystem as the root"; | ||
177 | |||
178 | /* Make sure we're on a ramfs */ | ||
179 | if (statfs("/", &sfs)) | ||
180 | return "statfs /"; | ||
181 | if (sfs.f_type != RAMFS_MAGIC && sfs.f_type != TMPFS_MAGIC) | ||
182 | return "rootfs not a ramfs or tmpfs"; | ||
183 | |||
184 | /* Okay, I think we should be safe... */ | ||
185 | |||
186 | /* Delete rootfs contents */ | ||
187 | if (nuke_dir("/")) | ||
188 | return "nuking initramfs contents"; | ||
189 | |||
190 | /* Overmount the root */ | ||
191 | if (mount(".", "/", NULL, MS_MOVE, NULL)) | ||
192 | return "overmounting root"; | ||
193 | |||
194 | /* chroot, chdir */ | ||
195 | if (chroot(".") || chdir("/")) | ||
196 | return "chroot"; | ||
197 | |||
198 | /* Open /dev/console */ | ||
199 | if ((confd = open(console, O_RDWR)) < 0) | ||
200 | return "opening console"; | ||
201 | dup2(confd, 0); | ||
202 | dup2(confd, 1); | ||
203 | dup2(confd, 2); | ||
204 | close(confd); | ||
205 | |||
206 | /* Spawn init */ | ||
207 | execv(init, initargs); | ||
208 | return init; /* Failed to spawn init */ | ||
209 | } |