1/*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 */
4
5#include <sys/param.h>
6#include <sys/systm.h>
7#include <sys/kernel.h>
8#include <sys/malloc.h>
9
10#include <geom/geom.h>
11#include <geom/geom_dbg.h>
12#include <geom/label/g_label.h>
13
14/*
15 * Taken from
16 * https://github.com/util-linux/util-linux/blob/master/include/swapheader.h
17 */
18
19#define SWAP_VERSION 1
20#define SWAP_UUID_LENGTH 16
21#define SWAP_LABEL_LENGTH 16
22#define SWAP_SIGNATURE "SWAPSPACE2"
23#define SWAP_SIGNATURE_SZ (sizeof(SWAP_SIGNATURE) - 1)
24
25struct swap_header_v1_2 {
26	char	      bootbits[1024];    /* Space for disklabel etc. */
27	uint32_t      version;
28	uint32_t      last_page;
29	uint32_t      nr_badpages;
30	unsigned char uuid[SWAP_UUID_LENGTH];
31	char	      volume_name[SWAP_LABEL_LENGTH];
32	uint32_t      padding[117];
33	uint32_t      badpages[1];
34};
35
36typedef union {
37	struct swap_header_v1_2	header;
38	struct {
39		uint8_t reserved[PAGE_SIZE - SWAP_SIGNATURE_SZ];
40		char	signature[SWAP_SIGNATURE_SZ];
41	} tail;
42} swhdr_t;
43
44#define sw_version	header.version
45#define sw_volume_name	header.volume_name
46#define sw_signature	tail.signature
47
48static void
49g_label_swaplinux_taste(struct g_consumer *cp, char *label, size_t size)
50{
51	struct g_provider *pp;
52	swhdr_t *hdr;
53
54	g_topology_assert_not();
55	pp = cp->provider;
56	label[0] = '\0';
57
58	KASSERT(pp->sectorsize != 0, ("Tasting a disk with 0 sectorsize"));
59	if ((PAGE_SIZE % pp->sectorsize) != 0)
60		return;
61
62	hdr = (swhdr_t *)g_read_data(cp, 0, PAGE_SIZE, NULL);
63	if (hdr == NULL)
64		return;
65
66	/* Check version and magic string */
67	if (hdr->sw_version == SWAP_VERSION &&
68	    !memcmp(hdr->sw_signature, SWAP_SIGNATURE, SWAP_SIGNATURE_SZ))
69		G_LABEL_DEBUG(1, "linux swap detected on %s.", pp->name);
70	else
71		goto exit_free;
72
73	/* Check for volume label */
74	if (hdr->sw_volume_name[0] == '\0')
75		goto exit_free;
76
77	/* Terminate label */
78	hdr->sw_volume_name[sizeof(hdr->sw_volume_name) - 1] = '\0';
79	strlcpy(label, hdr->sw_volume_name, size);
80
81exit_free:
82	g_free(hdr);
83}
84
85struct g_label_desc g_label_swaplinux = {
86	.ld_taste = g_label_swaplinux_taste,
87	.ld_dirprefix = "swaplinux/",
88	.ld_enabled = 1
89};
90
91G_LABEL_INIT(swaplinux, g_label_swaplinux, "Create device nodes for Linux swap");
92