blob: cb8fa2442b89a68c3b331f85610a0e08be8f94c6 [file] [log] [blame]
Eric Andersenaad1a882001-03-16 22:47:14 +00001/* vi: set sw=4 ts=4: */
2/*
3 * Utility routines.
4 *
Bernhard Reutner-Fischer7547a6e2005-10-15 20:56:31 +00005 * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
Rob Landley53437472006-07-16 08:14:35 +00006 * Copyright (C) 2005 by Rob Landley <rob@landley.net>
Eric Andersenaad1a882001-03-16 22:47:14 +00007 *
Denys Vlasenko0ef64bd2010-08-16 20:14:46 +02008 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
Eric Andersenaad1a882001-03-16 22:47:14 +00009 */
Eric Andersenaad1a882001-03-16 22:47:14 +000010#include "libbb.h"
Denys Vlasenko9b1b62a2009-07-05 03:34:12 +020011#include <linux/version.h>
12
13#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0)
Eric Andersenef8cd3b2004-02-06 07:16:36 +000014
Rob Landley6a6798b2005-08-10 20:35:54 +000015/* For 2.6, use the cleaned up header to get the 64 bit API. */
Denys Vlasenko98f1dc12010-03-18 14:38:21 +010016// Commented out per Rob's request
17//# include "fix_u32.h" /* some old toolchains need __u64 for linux/loop.h */
Denys Vlasenko9b1b62a2009-07-05 03:34:12 +020018# include <linux/loop.h>
Rob Landley6a6798b2005-08-10 20:35:54 +000019typedef struct loop_info64 bb_loop_info;
Denys Vlasenko9b1b62a2009-07-05 03:34:12 +020020# define BB_LOOP_SET_STATUS LOOP_SET_STATUS64
21# define BB_LOOP_GET_STATUS LOOP_GET_STATUS64
22
23#else
Eric Andersenef8cd3b2004-02-06 07:16:36 +000024
Rob Landley6a6798b2005-08-10 20:35:54 +000025/* For 2.4 and earlier, use the 32 bit API (and don't trust the headers) */
Denys Vlasenko9b1b62a2009-07-05 03:34:12 +020026/* Stuff stolen from linux/loop.h for 2.4 and earlier kernels */
27# include <linux/posix_types.h>
28# define LO_NAME_SIZE 64
29# define LO_KEY_SIZE 32
30# define LOOP_SET_FD 0x4C00
31# define LOOP_CLR_FD 0x4C01
32# define BB_LOOP_SET_STATUS 0x4C02
33# define BB_LOOP_GET_STATUS 0x4C03
Rob Landley6a6798b2005-08-10 20:35:54 +000034typedef struct {
Eric Andersenef8cd3b2004-02-06 07:16:36 +000035 int lo_number;
Rob Landley6a6798b2005-08-10 20:35:54 +000036 __kernel_dev_t lo_device;
Eric Andersenef8cd3b2004-02-06 07:16:36 +000037 unsigned long lo_inode;
Rob Landley6a6798b2005-08-10 20:35:54 +000038 __kernel_dev_t lo_rdevice;
Eric Andersenef8cd3b2004-02-06 07:16:36 +000039 int lo_offset;
40 int lo_encrypt_type;
41 int lo_encrypt_key_size;
42 int lo_flags;
Rob Landley6a6798b2005-08-10 20:35:54 +000043 char lo_file_name[LO_NAME_SIZE];
Eric Andersenef8cd3b2004-02-06 07:16:36 +000044 unsigned char lo_encrypt_key[LO_KEY_SIZE];
45 unsigned long lo_init[2];
46 char reserved[4];
Rob Landley6a6798b2005-08-10 20:35:54 +000047} bb_loop_info;
48#endif
Eric Andersenaad1a882001-03-16 22:47:14 +000049
Denis Vlasenkodefc1ea2008-06-27 02:52:20 +000050char* FAST_FUNC query_loop(const char *device)
Eric Andersenaad1a882001-03-16 22:47:14 +000051{
Rob Landley1d589b22005-11-29 23:47:10 +000052 int fd;
53 bb_loop_info loopinfo;
Denys Vlasenko44fbfa72010-03-05 13:20:28 +010054 char *dev = NULL;
Tim Rikerc1ef7bd2006-01-25 00:08:53 +000055
Denis Vlasenko13858992006-10-08 12:49:22 +000056 fd = open(device, O_RDONLY);
Denys Vlasenko44fbfa72010-03-05 13:20:28 +010057 if (fd >= 0) {
58 if (ioctl(fd, BB_LOOP_GET_STATUS, &loopinfo) == 0) {
Denys Vlasenko92510142010-05-19 00:39:17 +020059 dev = xasprintf("%"OFF_FMT"u %s", (off_t) loopinfo.lo_offset,
Denys Vlasenko44fbfa72010-03-05 13:20:28 +010060 (char *)loopinfo.lo_file_name);
61 }
62 close(fd);
63 }
Eric Andersenaad1a882001-03-16 22:47:14 +000064
Rob Landley1d589b22005-11-29 23:47:10 +000065 return dev;
Tim Rikerc1ef7bd2006-01-25 00:08:53 +000066}
Rob Landley1d589b22005-11-29 23:47:10 +000067
Denis Vlasenkodefc1ea2008-06-27 02:52:20 +000068int FAST_FUNC del_loop(const char *device)
Rob Landley1d589b22005-11-29 23:47:10 +000069{
70 int fd, rc;
71
Denis Vlasenko13858992006-10-08 12:49:22 +000072 fd = open(device, O_RDONLY);
Denys Vlasenko44fbfa72010-03-05 13:20:28 +010073 if (fd < 0)
74 return 1;
Denis Vlasenko13858992006-10-08 12:49:22 +000075 rc = ioctl(fd, LOOP_CLR_FD, 0);
Rob Landley1d589b22005-11-29 23:47:10 +000076 close(fd);
Tim Rikerc1ef7bd2006-01-25 00:08:53 +000077
Rob Landley6a6798b2005-08-10 20:35:54 +000078 return rc;
Eric Andersenaad1a882001-03-16 22:47:14 +000079}
80
Denys Vlasenko3b69ba72019-06-09 23:20:49 +020081/* Obtain an unused loop device number */
82int FAST_FUNC get_free_loop(void)
83{
84 int fd;
85 int loopdevno;
86
87 fd = open("/dev/loop-control", O_RDWR | O_CLOEXEC);
88 if (fd == -1)
89 return fd - 1; /* -2: "no /dev/loop-control" */
90
91#ifndef LOOP_CTL_GET_FREE
92# define LOOP_CTL_GET_FREE 0x4C82
93#endif
94 loopdevno = ioctl(fd, LOOP_CTL_GET_FREE);
95 close(fd);
96 return loopdevno; /* can be -1 if error */
97}
98
Denys Vlasenkoab518ee2017-03-16 16:49:37 +010099/* Returns opened fd to the loop device, <0 on error.
100 * *device is loop device to use, or if *device==NULL finds a loop device to
Denys Vlasenko4bc59a42020-12-17 15:05:14 +0100101 * mount it on and sets *device to a strdup of that loop device name.
Bernhard Reutner-Fischer94c33312005-10-15 14:13:09 +0000102 */
Steffen Trumtrar6561e072020-07-29 10:43:53 +0200103int FAST_FUNC set_loop(char **device, const char *file, unsigned long long offset,
104 unsigned long long sizelimit, unsigned flags)
Eric Andersenaad1a882001-03-16 22:47:14 +0000105{
Denis Vlasenko0e2c9fb2007-08-03 14:16:24 +0000106 char dev[LOOP_NAMESIZE];
107 char *try;
Rob Landley6a6798b2005-08-10 20:35:54 +0000108 bb_loop_info loopinfo;
Eric Andersenaad1a882001-03-16 22:47:14 +0000109 struct stat statbuf;
Denys Vlasenko4bc59a42020-12-17 15:05:14 +0100110 int i, lfd, ffd, mode, rc;
Denis Vlasenko9213a9e2006-09-17 16:28:10 +0000111
Bernhard Reutner-Fischer94c33312005-10-15 14:13:09 +0000112 /* Open the file. Barf if this doesn't work. */
Denys Vlasenkoab518ee2017-03-16 16:49:37 +0100113 mode = (flags & BB_LO_FLAGS_READ_ONLY) ? O_RDONLY : O_RDWR;
Denys Vlasenkofa6ab562014-01-21 13:44:21 +0100114 open_ffd:
Denis Vlasenko13858992006-10-08 12:49:22 +0000115 ffd = open(file, mode);
116 if (ffd < 0) {
Denys Vlasenko13e709c2011-09-12 02:13:47 +0200117 if (mode != O_RDONLY) {
118 mode = O_RDONLY;
Denys Vlasenkofa6ab562014-01-21 13:44:21 +0100119 goto open_ffd;
Denys Vlasenko13e709c2011-09-12 02:13:47 +0200120 }
Denys Vlasenkofa6ab562014-01-21 13:44:21 +0100121 return -errno;
Denis Vlasenko13858992006-10-08 12:49:22 +0000122 }
Bernhard Reutner-Fischer94c33312005-10-15 14:13:09 +0000123
Denys Vlasenko3b69ba72019-06-09 23:20:49 +0200124 try = *device;
125 if (!try) {
Denys Vlasenko4bc59a42020-12-17 15:05:14 +0100126 get_free_loopN:
Denys Vlasenko3b69ba72019-06-09 23:20:49 +0200127 i = get_free_loop();
Denys Vlasenko3b69ba72019-06-09 23:20:49 +0200128 if (i == -1) {
129 close(ffd);
130 return -1; /* no free loop devices */
131 }
Denys Vlasenko4bc59a42020-12-17 15:05:14 +0100132 if (i >= 0) {
133 try = xasprintf(LOOP_FORMAT, i);
134 goto open_lfd;
135 }
136 /* i == -2: no /dev/loop-control. Do an old-style search for a free device */
137 try = dev;
Denys Vlasenko3b69ba72019-06-09 23:20:49 +0200138 }
139
Denys Vlasenko4bc59a42020-12-17 15:05:14 +0100140 /* Find a loop device */
141 /* 0xfffff is a max possible minor number in Linux circa 2010 */
142 for (i = 0; i <= 0xfffff; i++) {
Rob Landleyb70ccd92006-01-22 23:17:18 +0000143 sprintf(dev, LOOP_FORMAT, i);
Rob Landleyaae8b342006-03-18 02:38:10 +0000144
Lauri Kasanen375a8ef2010-04-14 12:31:26 -0700145 IF_FEATURE_MOUNT_LOOP_CREATE(errno = 0;)
Denys Vlasenko44fbfa72010-03-05 13:20:28 +0100146 if (stat(try, &statbuf) != 0 || !S_ISBLK(statbuf.st_mode)) {
Lauri Kasanen375a8ef2010-04-14 12:31:26 -0700147 if (ENABLE_FEATURE_MOUNT_LOOP_CREATE
148 && errno == ENOENT
149 && try == dev
150 ) {
Denys Vlasenko4bc59a42020-12-17 15:05:14 +0100151 /* Node doesn't exist, try to create it */
Lauri Kasanen375a8ef2010-04-14 12:31:26 -0700152 if (mknod(dev, S_IFBLK|0644, makedev(7, i)) == 0)
Denys Vlasenko4bc59a42020-12-17 15:05:14 +0100153 goto open_lfd;
Lauri Kasanen375a8ef2010-04-14 12:31:26 -0700154 }
Denys Vlasenko4bc59a42020-12-17 15:05:14 +0100155 /* Ran out of block devices, return failure */
Denys Vlasenkofa6ab562014-01-21 13:44:21 +0100156 rc = -1;
Rob Landley6a6798b2005-08-10 20:35:54 +0000157 break;
Eric Andersenaad1a882001-03-16 22:47:14 +0000158 }
Denys Vlasenko4bc59a42020-12-17 15:05:14 +0100159 open_lfd:
160 /* Open the sucker and check its loopiness */
161 lfd = rc = open(try, mode);
162 if (lfd < 0 && errno == EROFS) {
Denis Vlasenko13858992006-10-08 12:49:22 +0000163 mode = O_RDONLY;
Denys Vlasenko4bc59a42020-12-17 15:05:14 +0100164 lfd = rc = open(try, mode);
Denis Vlasenko13858992006-10-08 12:49:22 +0000165 }
Denys Vlasenko4bc59a42020-12-17 15:05:14 +0100166 if (lfd < 0) {
Denys Vlasenkofa6ab562014-01-21 13:44:21 +0100167 if (errno == ENXIO) {
168 /* Happens if loop module is not loaded */
Denys Vlasenko4bc59a42020-12-17 15:05:14 +0100169 /* rc is -1; */
Denys Vlasenkofa6ab562014-01-21 13:44:21 +0100170 break;
171 }
Denys Vlasenko4bc59a42020-12-17 15:05:14 +0100172 goto try_next_loopN;
Denys Vlasenkofa6ab562014-01-21 13:44:21 +0100173 }
Eric Andersenaad1a882001-03-16 22:47:14 +0000174
Denys Vlasenko4bc59a42020-12-17 15:05:14 +0100175 rc = ioctl(lfd, BB_LOOP_GET_STATUS, &loopinfo);
Rob Landley1d589b22005-11-29 23:47:10 +0000176
Denys Vlasenko4bc59a42020-12-17 15:05:14 +0100177 /* If device is free, try to claim it */
Denis Vlasenko13858992006-10-08 12:49:22 +0000178 if (rc && errno == ENXIO) {
Denys Vlasenko4bc59a42020-12-17 15:05:14 +0100179 /* Associate free loop device with file */
180 if (ioctl(lfd, LOOP_SET_FD, ffd)) {
181 /* Ouch. Are we racing with other mount? */
182 if (!*device /* yes */
183 && try != dev /* tried a _kernel-offered_ loopN? */
184 ) {
185 free(try);
186 close(lfd);
187//TODO: add "if (--failcount != 0) ..."?
188 goto get_free_loopN;
Denys Vlasenkoab518ee2017-03-16 16:49:37 +0100189 }
Denys Vlasenko15733cb2020-12-17 23:38:06 +0100190 goto close_and_try_next_loopN;
Rob Landley934da822006-06-25 15:29:12 +0000191 }
Denys Vlasenko4bc59a42020-12-17 15:05:14 +0100192 memset(&loopinfo, 0, sizeof(loopinfo));
193 safe_strncpy((char *)loopinfo.lo_file_name, file, LO_NAME_SIZE);
194 loopinfo.lo_offset = offset;
195 loopinfo.lo_sizelimit = sizelimit;
196 /*
197 * Used by mount to set LO_FLAGS_AUTOCLEAR.
198 * LO_FLAGS_READ_ONLY is not set because RO is controlled by open type of the file.
199 * Note that closing LO_FLAGS_AUTOCLEARed lfd before mount
200 * is wrong (would free the loop device!)
201 */
202 loopinfo.lo_flags = (flags & ~BB_LO_FLAGS_READ_ONLY);
203 rc = ioctl(lfd, BB_LOOP_SET_STATUS, &loopinfo);
204 if (rc != 0 && (loopinfo.lo_flags & BB_LO_FLAGS_AUTOCLEAR)) {
205 /* Old kernel, does not support LO_FLAGS_AUTOCLEAR? */
206 /* (this code path is not tested) */
207 loopinfo.lo_flags -= BB_LO_FLAGS_AUTOCLEAR;
208 rc = ioctl(lfd, BB_LOOP_SET_STATUS, &loopinfo);
209 }
210 if (rc == 0) {
211 /* SUCCESS! */
212 if (try != dev) /* tried a kernel-offered free loopN? */
213 *device = try; /* malloced */
214 if (!*device) /* was looping in search of free "/dev/loopN"? */
215 *device = xstrdup(dev);
216 rc = lfd; /* return this */
217 break;
218 }
219 /* failure, undo LOOP_SET_FD */
220 ioctl(lfd, LOOP_CLR_FD, 0); // actually, 0 param is unnecessary
Denis Vlasenko7039a662006-10-08 17:54:47 +0000221 }
Denys Vlasenko4bc59a42020-12-17 15:05:14 +0100222 /* else: device is not free (rc == 0) or error other than ENXIO */
Denys Vlasenko15733cb2020-12-17 23:38:06 +0100223 close_and_try_next_loopN:
Denys Vlasenko4bc59a42020-12-17 15:05:14 +0100224 close(lfd);
225 try_next_loopN:
226 rc = -1;
227 if (*device) /* was looking for a particular "/dev/loopN"? */
228 break; /* yes, do not try other names */
229 } /* for() */
230
Rob Landley6a6798b2005-08-10 20:35:54 +0000231 close(ffd);
Denis Vlasenko13858992006-10-08 12:49:22 +0000232 return rc;
Rob Landley6a6798b2005-08-10 20:35:54 +0000233}