#include <fnmatch.h>
#include <unistd.h>
#include <errno.h>
+#include <sys/utsname.h>
#include "error.h"
#include "xvasprintf.h"
#define KERNELDIR "/boot"
#define MODULESDIR "/lib/modules"
+static char* get_kernel_version (char* filename);
+static const char *create_kernel_from_env (const char *hostcpu, const char *kernel, const char *kernel_env, const char *modpath_env);
+
static char *
get_modpath (const char *kernel_name)
{
exit (EXIT_FAILURE);
}
+ if (! isdir (modpath)) {
+ char* path;
+ char* version;
+ path = xasprintf (KERNELDIR "/%s", kernel_name);
+ if (!path) {
+ perror ("xasprintf");
+ exit (EXIT_FAILURE);
+ }
+ version = get_kernel_version (path);
+ free (path);
+ if (version != NULL) {
+ free (modpath);
+ modpath = xasprintf (MODULESDIR "/%s", version);
+ free (version);
+ if (!path) {
+ perror ("xasprintf");
+ exit (EXIT_FAILURE);
+ }
+ }
+ }
+
return modpath;
}
}
}
-static const char *create_kernel_archlinux (const char *hostcpu, const char *kernel);
-
/* Create the kernel. This chooses an appropriate kernel and makes a
* symlink to it.
*
const char *
create_kernel (const char *hostcpu, const char *kernel)
{
- /* In ArchLinux, kernel is always named /boot/vmlinuz26. */
- if (access ("/boot/vmlinuz26", F_OK) == 0)
- return create_kernel_archlinux (hostcpu, kernel);
+ /* Override kernel selection using environment variables? */
+ char *kernel_env = getenv ("FEBOOTSTRAP_KERNEL");
+ if (kernel_env) {
+ char *modpath_env = getenv ("FEBOOTSTRAP_MODULES");
+ return create_kernel_from_env (hostcpu, kernel, kernel_env, modpath_env);
+ }
/* In original: ls -1dvr /boot/vmlinuz-*.$arch* 2>/dev/null | grep -v xen */
const char *patt;
exit (EXIT_FAILURE);
}
-/* In ArchLinux, kernel is always named /boot/vmlinuz26, and we have
- * to use the 'file' command to work out what version it is.
+/* Select the kernel from environment variables set by the user.
+ * modpath_env may be NULL, in which case we attempt to work it out
+ * from kernel_env.
*/
static const char *
-create_kernel_archlinux (const char *hostcpu, const char *kernel)
+create_kernel_from_env (const char *hostcpu, const char *kernel,
+ const char *kernel_env, const char *modpath_env)
{
- const char *file_cmd = "file /boot/vmlinuz26 | awk '{print $9}'";
- FILE *pp;
- char modversion[256];
- char *modpath;
- size_t len;
-
- pp = popen (file_cmd, "r");
- if (pp == NULL) {
- error:
- fprintf (stderr, "febootstrap-supermin-helper: %s: command failed\n",
- file_cmd);
- exit (EXIT_FAILURE);
+ if (verbose) {
+ fprintf (stderr,
+ "febootstrap-supermin-helper: using environment variable(s) FEBOOTSTRAP_* to\n"
+ "select kernel %s", kernel_env);
+ if (modpath_env)
+ fprintf (stderr, " and module path %s", modpath_env);
+ fprintf (stderr, "\n");
}
- if (fgets (modversion, sizeof modversion, pp) == NULL)
- goto error;
-
- if (pclose (pp) == -1)
- goto error;
-
- /* Chomp final \n */
- len = strlen (modversion);
- if (len > 0 && modversion[len-1] == '\n') {
- modversion[len-1] = '\0';
- len--;
+ if (!isfile (kernel_env)) {
+ fprintf (stderr,
+ "febootstrap-supermin-helper: %s: not a regular file\n"
+ "(what is $FEBOOTSTRAP_KERNEL set to?)\n", kernel_env);
+ exit (EXIT_FAILURE);
}
- /* Generate module path. */
- modpath = xasprintf (MODULESDIR "/%s", modversion);
+ if (!modpath_env) {
+ /* Try to guess modpath from kernel path. */
+ const char *p = strrchr (kernel_env, '/');
+ if (p) p++; else p = kernel_env;
+
+ /* NB: We need the extra test to ensure calling get_modpath is safe. */
+ if (strncmp (p, "vmlinuz-", 8) != 0) {
+ fprintf (stderr,
+ "febootstrap-supermin-helper: cannot guess module path.\n"
+ "Set $FEBOOTSTRAP_MODULES to the modules directory corresponding to\n"
+ "kernel %s, or unset $FEBOOTSTRAP_KERNEL to autoselect a kernel.\n",
+ kernel_env);
+ exit (EXIT_FAILURE);
+ }
+
+ modpath_env = get_modpath (p);
+ }
- /* Check module path is a directory. */
- if (!isdir (modpath)) {
- fprintf (stderr, "febootstrap-supermin-helper: /boot/vmlinuz26 kernel exists but %s is not a valid module path\n",
- modpath);
+ if (!isdir (modpath_env)) {
+ fprintf (stderr,
+ "febootstrap-supermin-helper: %s: not a directory\n"
+ "(what is $FEBOOTSTRAP_MODULES set to?)\n", modpath_env);
exit (EXIT_FAILURE);
}
+ /* Create the symlink. */
if (kernel) {
- /* Symlink from kernel to /boot/vmlinuz26. */
- if (symlink ("/boot/vmlinuz26", kernel) == -1)
+ if (verbose >= 2)
+ fprintf (stderr, "creating symlink %s -> %s\n", kernel_env, kernel);
+
+ if (symlink (kernel_env, kernel) == -1)
error (EXIT_FAILURE, errno, "symlink kernel");
}
- /* Return module path. */
- return modpath;
+ return modpath_env;
+}
+
+/* Read an unsigned little endian short at a specified offset in a file.
+ * Returns a non-negative int on success or -1 on failure.
+ */
+static int
+read_leshort (FILE* fp, int offset)
+{
+ char buf[2];
+ if (fseek (fp, offset, SEEK_SET) != 0 ||
+ fread (buf, sizeof(char), 2, fp) != 2)
+ {
+ return -1;
+ }
+ return ((buf[1] & 0xFF) << 8) | (buf[0] & 0xFF);
+}
+
+/* Extract the kernel version from a Linux kernel file.
+ * Returns a malloc'd string containing the version or NULL if the
+ * file can't be read, is not a Linux kernel, or the version can't
+ * be found.
+ *
+ * See ftp://ftp.astron.com/pub/file/file-<ver>.tar.gz
+ * (file-<ver>/magic/Magdir/linux) for the rules used to find the
+ * version number:
+ * 514 string HdrS Linux kernel
+ * >518 leshort >0x1ff
+ * >>(526.s+0x200) string >\0 version %s,
+ *
+ * Bugs: probably limited to x86 kernels.
+ */
+static char*
+get_kernel_version (char* filename)
+{
+ FILE* fp;
+ int size = 132;
+ char buf[size];
+ int offset;
+
+ fp = fopen (filename, "rb");
+
+ if (fseek (fp, 514, SEEK_SET) != 0 ||
+ fgets (buf, size, fp) == NULL ||
+ strncmp (buf, "HdrS", 4) != 0 ||
+ read_leshort (fp, 518) < 0x1FF)
+ {
+ /* not a Linux kernel */
+ fclose (fp);
+ return NULL;
+ }
+
+ offset = read_leshort (fp, 526);
+ if (offset == -1)
+ {
+ /* can't read version offset */
+ fclose (fp);
+ return NULL;
+ }
+
+ if (fseek (fp, offset + 0x200, SEEK_SET) != 0 ||
+ fgets (buf, size, fp) == NULL)
+ {
+ /* can't read version string */
+ fclose (fp);
+ return NULL;
+ }
+
+ fclose (fp);
+
+ buf[strcspn (buf, " \t\n")] = '\0';
+ return strdup (buf);
}
git.annexia.org / febootstrap.git / blobdiff