1 /* febootstrap-supermin-helper reimplementation in C.
2 * Copyright (C) 2009-2010 Red Hat Inc.
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
29 #include "xvasprintf.h"
33 /* Directory containing candidate kernels. We could make this
34 * configurable at some point.
36 #define KERNELDIR "/boot"
37 #define MODULESDIR "/lib/modules"
40 get_modpath (const char *kernel_name)
42 /* Ignore "vmlinuz-" at the beginning of the kernel name. */
43 const char *version = &kernel_name[8];
45 /* /lib/modules/<version> */
46 char *modpath = xasprintf (MODULESDIR "/%s", version);
55 /* kernel_name is "vmlinuz-*". Check if there is a corresponding
56 * module path in /lib/modules.
59 has_modpath (const char *kernel_name)
61 char *modpath = get_modpath (kernel_name);
64 fprintf (stderr, "checking modpath %s is a directory\n", modpath);
66 int r = isdir (modpath);
70 fprintf (stderr, "picked %s because modpath %s exists\n",
71 kernel_name, modpath);
81 static const char *create_kernel_archlinux (const char *hostcpu, const char *kernel);
82 static const char *create_kernel_from_env (const char *hostcpu, const char *kernel, const char *kernel_env, const char *modpath_env);
84 /* Create the kernel. This chooses an appropriate kernel and makes a
87 * Look for the most recent kernel named vmlinuz-*.<arch>* which has a
88 * corresponding directory in /lib/modules/. If the architecture is
89 * x86, look for any x86 kernel.
91 * RHEL 5 didn't append the arch to the kernel name, so look for
92 * kernels without arch second.
94 * If no suitable kernel can be found, exit with an error.
96 * This function returns the module path (ie. /lib/modules/<version>).
99 create_kernel (const char *hostcpu, const char *kernel)
101 /* Override kernel selection using environment variables? */
102 char *kernel_env = getenv ("FEBOOTSTRAP_KERNEL");
104 char *modpath_env = getenv ("FEBOOTSTRAP_MODULES");
105 return create_kernel_from_env (hostcpu, kernel, kernel_env, modpath_env);
108 /* In ArchLinux, kernel is always named /boot/vmlinuz26. */
109 if (access ("/boot/vmlinuz26", F_OK) == 0)
110 return create_kernel_archlinux (hostcpu, kernel);
112 /* In original: ls -1dvr /boot/vmlinuz-*.$arch* 2>/dev/null | grep -v xen */
114 if (hostcpu[0] == 'i' && hostcpu[2] == '8' && hostcpu[3] == '6' &&
116 patt = "vmlinuz-*.i?86*";
118 patt = xasprintf ("vmlinuz-*.%s*", hostcpu);
120 char **all_files = read_dir (KERNELDIR);
122 candidates = filter_fnmatch (all_files, patt, FNM_NOESCAPE);
123 candidates = filter_notmatching_substring (candidates, "xen");
124 candidates = filter (candidates, has_modpath);
126 if (candidates[0] == NULL) {
127 /* In original: ls -1dvr /boot/vmlinuz-* 2>/dev/null | grep -v xen */
129 candidates = filter_fnmatch (all_files, patt, FNM_NOESCAPE);
130 candidates = filter_notmatching_substring (candidates, "xen");
131 candidates = filter (candidates, has_modpath);
133 if (candidates[0] == NULL)
137 sort (candidates, reverse_filevercmp);
140 /* Choose the first candidate. */
141 char *tmp = xasprintf (KERNELDIR "/%s", candidates[0]);
144 fprintf (stderr, "creating symlink %s -> %s\n", kernel, tmp);
146 if (symlink (tmp, kernel) == -1)
147 error (EXIT_FAILURE, errno, "symlink kernel");
152 return get_modpath (candidates[0]);
154 /* Print more diagnostics here than the old script did. */
157 "febootstrap-supermin-helper: failed to find a suitable kernel.\n"
158 "I looked for kernels in " KERNELDIR " and modules in " MODULESDIR
160 "If this is a Xen guest, and you only have Xen domU kernels\n"
161 "installed, try installing a fullvirt kernel (only for\n"
162 "febootstrap use, you shouldn't boot the Xen guest with it).\n");
166 /* In ArchLinux, kernel is always named /boot/vmlinuz26, and we have
167 * to use the 'file' command to work out what version it is.
170 create_kernel_archlinux (const char *hostcpu, const char *kernel)
172 const char *file_cmd = "file /boot/vmlinuz26 | awk '{print $9}'";
174 char modversion[256];
178 pp = popen (file_cmd, "r");
181 fprintf (stderr, "febootstrap-supermin-helper: %s: command failed\n",
186 if (fgets (modversion, sizeof modversion, pp) == NULL)
189 if (pclose (pp) == -1)
193 len = strlen (modversion);
194 if (len > 0 && modversion[len-1] == '\n') {
195 modversion[len-1] = '\0';
199 /* Generate module path. */
200 modpath = xasprintf (MODULESDIR "/%s", modversion);
202 /* Check module path is a directory. */
203 if (!isdir (modpath)) {
204 fprintf (stderr, "febootstrap-supermin-helper: /boot/vmlinuz26 kernel exists but %s is not a valid module path\n",
210 /* Symlink from kernel to /boot/vmlinuz26. */
211 if (symlink ("/boot/vmlinuz26", kernel) == -1)
212 error (EXIT_FAILURE, errno, "symlink kernel");
215 /* Return module path. */
219 /* Select the kernel from environment variables set by the user.
220 * modpath_env may be NULL, in which case we attempt to work it out
224 create_kernel_from_env (const char *hostcpu, const char *kernel,
225 const char *kernel_env, const char *modpath_env)
229 "febootstrap-supermin-helper: using environment variable(s) FEBOOTSTRAP_* to\n"
230 "select kernel %s", kernel_env);
232 fprintf (stderr, " and module path %s", modpath_env);
233 fprintf (stderr, "\n");
236 if (!isfile (kernel_env)) {
238 "febootstrap-supermin-helper: %s: not a regular file\n"
239 "(what is $FEBOOTSTRAP_KERNEL set to?)\n", kernel_env);
244 /* Try to guess modpath from kernel path. */
245 const char *p = strrchr (kernel_env, '/');
246 if (p) p++; else p = kernel_env;
248 /* NB: We need the extra test to ensure calling get_modpath is safe. */
249 if (strncmp (p, "vmlinuz-", 8) != 0) {
251 "febootstrap-supermin-helper: cannot guess module path.\n"
252 "Set $FEBOOTSTRAP_MODULES to the modules directory corresponding to\n"
253 "kernel %s, or unset $FEBOOTSTRAP_KERNEL to autoselect a kernel.\n",
258 modpath_env = get_modpath (p);
261 if (!isdir (modpath_env)) {
263 "febootstrap-supermin-helper: %s: not a directory\n"
264 "(what is $FEBOOTSTRAP_MODULES set to?)\n", modpath_env);
268 /* Create the symlink. */
271 fprintf (stderr, "creating symlink %s -> %s\n", kernel_env, kernel);
273 if (symlink (kernel_env, kernel) == -1)
274 error (EXIT_FAILURE, errno, "symlink kernel");