libgrub_bargs.c revision 9160:1517e6edbc6f 
1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21/*
22 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
23 * Use is subject to license terms.
24 */
25
26/*
27 * This file contains functions for constructing boot arguments
28 * from GRUB menu for Fast Reboot.
29 */
30#include <stdio.h>
31#include <stdlib.h>
32#include <errno.h>
33#include <strings.h>
34#include <unistd.h>
35#include <fcntl.h>
36#include <assert.h>
37#include <sys/types.h>
38#include <sys/elf.h>
39
40#include "libgrub_impl.h"
41
42#if defined(__sparc)
43#define	CUR_ELFDATA	ELFDATA2MSB
44#elif defined(__i386)
45#define	CUR_ELFDATA	ELFDATA2LSB
46#endif /* __i386 */
47
48/*
49 * Open the kernel file.
50 * Return zero on sucess or error code otherwise.
51 * On success the kernel file descriptor is returned in fdp.
52 */
53static int
54get_kernel_fd(const char *path, int *fdp)
55{
56	const char	*bname;
57	int		fd = -1, class, format;
58	char		ident[EI_NIDENT];
59
60	/* kernel basename must be unix */
61	if ((bname = strrchr(path, '/')) == NULL)
62		bname = path;
63	else
64		bname++;
65
66	if (strcmp(bname, "unix") != 0) {
67		if (strcmp(bname, "xen.gz") == 0)
68			return (EG_XVMNOTSUP);
69		return (EG_NOTUNIX);
70	}
71
72	if ((fd = open64(path, O_RDONLY)) >= 0 &&
73	    (pread64(fd, ident, sizeof (ident), 0) == sizeof (ident))) {
74
75		class = ident[EI_CLASS];
76		format = ident[EI_DATA];
77
78		if ((class == ELFCLASS32 || class == ELFCLASS64) &&
79		    (memcmp(&ident[EI_MAG0], ELFMAG, 4) == 0) &&
80		    format == CUR_ELFDATA) {
81			*fdp = fd;
82			return (0);
83		}
84	}
85
86	if (fd >= 0)
87		(void) close(fd);
88	return (EG_OPENKERNFILE);
89}
90
91/*
92 * Construct boot arguments for Fast Reboot from the ge_barg field of
93 * a GRUB menu entry.
94 * Return 0 on success, errno on failure.
95 */
96static int
97barg2bootargs(const grub_barg_t *barg, grub_boot_args_t *fbarg)
98{
99	int	rc = 0;
100	char	path[BOOTARGS_MAX];
101	char	rpath[BOOTARGS_MAX];
102	const grub_fsdesc_t	*fsd;
103
104	assert(fbarg);
105	bzero(fbarg, sizeof (*fbarg));
106	fbarg->gba_kernel_fd = -1;
107
108	if (!IS_BARG_VALID(barg))
109		return (EINVAL);
110	if ((fsd = grub_get_rootfsd(&barg->gb_root)) == NULL)
111		return (EG_UNKNOWNFS);
112
113	bcopy(fsd, &fbarg->gba_fsd, sizeof (fbarg->gba_fsd));
114	bcopy(barg->gb_kernel, fbarg->gba_kernel, sizeof (fbarg->gba_kernel));
115	bcopy(barg->gb_module, fbarg->gba_module, sizeof (fbarg->gba_module));
116
117	if (fbarg->gba_fsd.gfs_mountp[0] == 0 &&
118	    (rc = grub_fsd_mount_tmp(&fbarg->gba_fsd,
119	    barg->gb_root.gr_fstyp)) != 0)
120		return (rc);
121
122	if (snprintf(path, sizeof (path), "%s%s", fbarg->gba_fsd.gfs_mountp,
123	    fbarg->gba_kernel) >= sizeof (path)) {
124		rc = E2BIG;
125		goto err_out;
126	}
127	(void) strtok(path, " \t");
128	(void) clean_path(path);
129
130	/*
131	 * GRUB requires absolute path, no symlinks, so do we
132	 */
133	if ((rc = resolvepath(path, rpath, sizeof (rpath))) == -1)
134		rc = errno;
135	else {
136		rpath[rc] = 0;
137		if (strcmp(rpath, path) != 0)
138			rc = EG_NOTABSPATH;
139		else
140			rc = get_kernel_fd(rpath, &fbarg->gba_kernel_fd);
141	}
142
143	/* construct bootargs command-line */
144	if (rc == 0 && snprintf(fbarg->gba_bootargs,
145	    sizeof (fbarg->gba_bootargs), "%s %s", fbarg->gba_fsd.gfs_mountp,
146	    fbarg->gba_kernel) >= sizeof (fbarg->gba_bootargs))
147		rc = E2BIG;
148
149err_out:
150	if (rc != 0)
151		grub_cleanup_boot_args(fbarg);
152
153	return (rc);
154}
155
156/*
157 * Construct boot arguments for Fast Reboot from grub_menu_t.
158 * Return 0 on success, errno on failure.
159 */
160static int
161grub_entry_get_boot_args(grub_entry_t *ent, grub_boot_args_t *fbarg)
162{
163	int rc = EG_INVALIDENT;
164
165	if (IS_ENTRY_VALID(ent) && (rc = grub_entry_construct_barg(ent)) == 0)
166		return (barg2bootargs(&ent->ge_barg, fbarg));
167	else
168		return (rc);
169}
170
171/*
172 * Construct boot arguments for Fast Reboot from grub_menu_t and the
173 * entry number.
174 * Return 0 on success, errno on failure.
175 */
176static int
177grub_menu_get_boot_args(const grub_menu_t *mp, int num,
178    grub_boot_args_t *fbarg)
179{
180	grub_entry_t *ent;
181
182	assert(mp);
183	assert(fbarg);
184
185	if ((ent = grub_menu_get_entry(mp, num)) == NULL)
186		return (EG_NOENTRY);
187
188	return (grub_entry_get_boot_args(ent, fbarg));
189}
190
191/*
192 * Construct boot arguments from the specified GRUB menu entry.
193 * Caller must allocate space for fbarg, and call grub_cleanup_boot_args()
194 * when it's done with fbarg to clean up.
195 *
196 * Return 0 on success, errno on failure.
197 */
198int
199grub_get_boot_args(grub_boot_args_t *fbarg, const char *menupath, int num)
200{
201	int rc;
202	grub_menu_t *mp;
203
204	assert(fbarg);
205	if ((rc = grub_menu_init(menupath, &mp)) == 0) {
206		rc = grub_menu_get_boot_args(mp, num, fbarg);
207		grub_menu_fini(mp);
208	}
209	return (rc);
210}
211
212/*
213 * Clean up when done with fbarg: close file handle, unmount file
214 * systems.  Must be safe to call even if not all the fields are
215 * set up.
216 */
217void
218grub_cleanup_boot_args(grub_boot_args_t *fbarg)
219{
220	if (fbarg == NULL)
221		return;
222
223	(void) close(fbarg->gba_kernel_fd);
224	grub_fsd_umount_tmp(&fbarg->gba_fsd);
225}
226