summaryrefslogtreecommitdiffstats
path: root/helper/kernel.c
blob: 33018263de5bbf0ab3a252d31143d5dc54ad7450 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
/* febootstrap-supermin-helper reimplementation in C.
 * Copyright (C) 2009-2010 Red Hat Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <config.h>

#include <stdio.h>
#include <stdlib.h>
#include <fnmatch.h>
#include <unistd.h>
#include <errno.h>

#include "error.h"
#include "xvasprintf.h"

#include "helper.h"

/* Directory containing candidate kernels.  We could make this
 * configurable at some point.
 */
#define KERNELDIR "/boot"
#define MODULESDIR "/lib/modules"

static char *
get_modpath (const char *kernel_name)
{
  /* Ignore "vmlinuz-" at the beginning of the kernel name. */
  const char *version = &kernel_name[8];

  /* /lib/modules/<version> */
  char *modpath = xasprintf (MODULESDIR "/%s", version);
  if (!modpath) {
    perror ("xasprintf");
    exit (EXIT_FAILURE);
  }

  return modpath;
}

/* kernel_name is "vmlinuz-*".  Check if there is a corresponding
 * module path in /lib/modules.
 */
static int
has_modpath (const char *kernel_name)
{
  char *modpath = get_modpath (kernel_name);

  if (verbose)
    fprintf (stderr, "checking modpath %s is a directory\n", modpath);

  int r = isdir (modpath);

  if (r) {
    if (verbose)
      fprintf (stderr, "picked %s because modpath %s exists\n",
               kernel_name, modpath);
    free (modpath);
    return 1;
  }
  else {
    free (modpath);
    return 0;
  }
}

/* Create the kernel.  This chooses an appropriate kernel and makes a
 * symlink to it.
 *
 * Look for the most recent kernel named vmlinuz-*.<arch>* which has a
 * corresponding directory in /lib/modules/. If the architecture is
 * x86, look for any x86 kernel.
 *
 * RHEL 5 didn't append the arch to the kernel name, so look for
 * kernels without arch second.
 *
 * If no suitable kernel can be found, exit with an error.
 *
 * This function returns the module path (ie. /lib/modules/<version>).
 */
const char *
create_kernel (const char *hostcpu, const char *kernel)
{
  char **all_files = read_dir (KERNELDIR);

  /* In original: ls -1dvr /boot/vmlinuz-*.$arch* 2>/dev/null | grep -v xen */
  const char *patt;
  if (hostcpu[0] == 'i' && hostcpu[2] == '8' && hostcpu[3] == '6' &&
      hostcpu[4] == '\0')
    patt = "vmlinuz-*.i?86*";
  else
    patt = xasprintf ("vmlinuz-*.%s*", hostcpu);

  char **candidates;
  candidates = filter_fnmatch (all_files, patt, FNM_NOESCAPE);
  candidates = filter_notmatching_substring (candidates, "xen");
  candidates = filter (candidates, has_modpath);

  if (candidates[0] == NULL) {
    /* In original: ls -1dvr /boot/vmlinuz-* 2>/dev/null | grep -v xen */
    patt = "vmlinuz-*";
    candidates = filter_fnmatch (all_files, patt, FNM_NOESCAPE);
    candidates = filter_notmatching_substring (candidates, "xen");
    candidates = filter (candidates, has_modpath);

    if (candidates[0] == NULL)
      goto no_kernels;
  }

  sort (candidates, reverse_filevercmp);

  /* Choose the first candidate. */
  char *tmp = xasprintf (KERNELDIR "/%s", candidates[0]);

  if (verbose)
    fprintf (stderr, "creating symlink %s -> %s\n", kernel, tmp);

  if (symlink (tmp, kernel) == -1)
    error (EXIT_FAILURE, errno, "symlink kernel");

  free (tmp);

  return get_modpath (candidates[0]);

  /* Print more diagnostics here than the old script did. */
 no_kernels:
  fprintf (stderr,
           "febootstrap-supermin-helper: failed to find a suitable kernel.\n"
           "I looked for kernels in " KERNELDIR " and modules in " MODULESDIR
           ".\n"
           "If this is a Xen guest, and you only have Xen domU kernels\n"
           "installed, try installing a fullvirt kernel (only for\n"
           "febootstrap use, you shouldn't boot the Xen guest with it).\n");
  exit (EXIT_FAILURE);
}