path: root/util-linux/blockdev.c (plain)
blob: bf4d49792eaa3184ebce3e4a268b98b5ef9efa33

1	/*
2	* blockdev implementation for busybox
3	*
4	* Copyright (C) 2010 Sergey Naumov <sknaumov@gmail.com>
5	*
6	* Licensed under GPLv2, see file LICENSE in this source tree.
7	*/
8	//config:config BLOCKDEV
9	//config: bool "blockdev"
10	//config: default y
11	//config: help
12	//config: Performs some ioctls with block devices.
13
14	//applet:IF_BLOCKDEV(APPLET(blockdev, BB_DIR_SBIN, BB_SUID_DROP))
15
16	//kbuild:lib-$(CONFIG_BLOCKDEV) += blockdev.o
17
18	//usage:#define blockdev_trivial_usage
19	//usage: "OPTION BLOCKDEV"
20	//usage:#define blockdev_full_usage "\n\n"
21	//usage: " --setro Set ro"
22	//usage: "\n --setrw Set rw"
23	//usage: "\n --getro Get ro"
24	//usage: "\n --getss Get sector size"
25	//usage: "\n --getbsz Get block size"
26	//usage: "\n --setbsz BYTES Set block size"
27	//usage: "\n --getsz Get device size in 512-byte sectors"
28	/*//usage: "\n --getsize Get device size in sectors (deprecated)"*/
29	//usage: "\n --getsize64 Get device size in bytes"
30	//usage: "\n --flushbufs Flush buffers"
31	//usage: "\n --rereadpt Reread partition table"
32
33
34	#include "libbb.h"
35	#include <linux/fs.h>
36
37	enum {
38	ARG_NONE = 0,
39	ARG_INT = 1,
40	ARG_ULONG = 2,
41	/* Yes, BLKGETSIZE64 takes pointer to uint64_t, not ullong! */
42	ARG_U64 = 3,
43	ARG_MASK = 3,
44
45	FL_USRARG = 4, /* argument is provided by user */
46	FL_NORESULT = 8,
47	FL_SCALE512 = 16,
48	};
49
50	struct bdc {
51	uint32_t ioc; /* ioctl code */
52	const char name[sizeof("flushbufs")]; /* "--setfoo" wothout "--" */
53	uint8_t flags;
54	int8_t argval; /* default argument value */
55	};
56
57	static const struct bdc bdcommands[] = {
58	{
59	.ioc = BLKROSET,
60	.name = "setro",
61	.flags = ARG_INT + FL_NORESULT,
62	.argval = 1,
63	},{
64	.ioc = BLKROSET,
65	.name = "setrw",
66	.flags = ARG_INT + FL_NORESULT,
67	.argval = 0,
68	},{
69	.ioc = BLKROGET,
70	.name = "getro",
71	.flags = ARG_INT,
72	.argval = -1,
73	},{
74	.ioc = BLKSSZGET,
75	.name = "getss",
76	.flags = ARG_INT,
77	.argval = -1,
78	},{
79	.ioc = BLKBSZGET,
80	.name = "getbsz",
81	.flags = ARG_INT,
82	.argval = -1,
83	},{
84	.ioc = BLKBSZSET,
85	.name = "setbsz",
86	.flags = ARG_INT + FL_NORESULT + FL_USRARG,
87	.argval = 0,
88	},{
89	.ioc = BLKGETSIZE64,
90	.name = "getsz",
91	.flags = ARG_U64 + FL_SCALE512,
92	.argval = -1,
93	},{
94	.ioc = BLKGETSIZE,
95	.name = "getsize",
96	.flags = ARG_ULONG,
97	.argval = -1,
98	},{
99	.ioc = BLKGETSIZE64,
100	.name = "getsize64",
101	.flags = ARG_U64,
102	.argval = -1,
103	},{
104	.ioc = BLKFLSBUF,
105	.name = "flushbufs",
106	.flags = ARG_NONE + FL_NORESULT,
107	.argval = 0,
108	},{
109	.ioc = BLKRRPART,
110	.name = "rereadpt",
111	.flags = ARG_NONE + FL_NORESULT,
112	.argval = 0,
113	}
114	};
115
116	static const struct bdc *find_cmd(const char *s)
117	{
118	const struct bdc *bdcmd = bdcommands;
119	if (s[0] == '-' && s[1] == '-') {
120	s += 2;
121	do {
122	if (strcmp(s, bdcmd->name) == 0)
123	return bdcmd;
124	bdcmd++;
125	} while (bdcmd != bdcommands + ARRAY_SIZE(bdcommands));
126	}
127	bb_show_usage();
128	}
129
130	int blockdev_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
131	int blockdev_main(int argc UNUSED_PARAM, char **argv)
132	{
133	const struct bdc *bdcmd;
134	int fd;
135	uint64_t u64;
136	union {
137	int i;
138	unsigned long lu;
139	uint64_t u64;
140	} ioctl_val_on_stack;
141
142	argv++;
143	if (!argv[0] || !argv[1]) /* must have at least 2 args */
144	bb_show_usage();
145
146	bdcmd = find_cmd(*argv);
147
148	u64 = (int)bdcmd->argval;
149	if (bdcmd->flags & FL_USRARG)
150	u64 = xatoi_positive(*++argv);
151
152	argv++;
153	if (!argv[0] || argv[1])
154	bb_show_usage();
155	fd = xopen(argv[0], O_RDONLY);
156
157	ioctl_val_on_stack.u64 = u64;
158	#if BB_BIG_ENDIAN
159	/* Store data properly wrt data size.
160	* (1) It's no-op for little-endian.
161	* (2) it's no-op for 0 and -1. Only --setro uses arg != 0 and != -1,
162	* and it is ARG_INT. --setbsz USER_VAL is also ARG_INT.
163	* Thus, we don't need to handle ARG_ULONG.
164	*/
165	switch (bdcmd->flags & ARG_MASK) {
166	case ARG_INT:
167	ioctl_val_on_stack.i = (int)u64;
168	break;
169	# if 0 /* unused */
170	case ARG_ULONG:
171	ioctl_val_on_stack.lu = (unsigned long)u64;
172	break;
173	# endif
174	}
175	#endif
176
177	if (ioctl(fd, bdcmd->ioc, &ioctl_val_on_stack.u64) == -1)
178	bb_simple_perror_msg_and_die(*argv);
179
180	/* Fetch it into register(s) */
181	u64 = ioctl_val_on_stack.u64;
182
183	if (bdcmd->flags & FL_SCALE512)
184	u64 >>= 9;
185
186	/* Zero- or one-extend the value if needed, then print */
187	switch (bdcmd->flags & (ARG_MASK+FL_NORESULT)) {
188	case ARG_INT:
189	/* Smaller code when we use long long
190	* (gcc tail-merges printf call)
191	*/
192	printf("%lld\n", (long long)(int)u64);
193	break;
194	case ARG_ULONG:
195	u64 = (unsigned long)u64;
196	/* FALLTHROUGH */
197	case ARG_U64:
198	printf("%llu\n", (unsigned long long)u64);
199	break;
200	}
201
202	if (ENABLE_FEATURE_CLEAN_UP)
203	close(fd);
204	return EXIT_SUCCESS;
205	}
206