--- /dev/null
+/* 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 <string.h>
+#include <unistd.h>
+#include <limits.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <dirent.h>
+#include <fnmatch.h>
+#include <sys/stat.h>
+#include <assert.h>
+
+#include "error.h"
+#include "fts_.h"
+#include "full-write.h"
+#include "xalloc.h"
+#include "xvasprintf.h"
+
+#include "helper.h"
+
+/* Buffer size used in copy operations throughout. Large for
+ * greatest efficiency.
+ */
+#define BUFFER_SIZE 65536
+
+static void iterate_inputs (char **inputs, int nr_inputs);
+static void iterate_input_directory (const char *dirname, int dirfd);
+static void write_kernel_modules (const char *whitelist, const char *modpath);
+static void write_hostfiles (const char *hostfiles_file);
+static void write_to_fd (const void *buffer, size_t len);
+static void write_file_to_fd (const char *filename);
+static void write_file_len_to_fd (const char *filename, size_t len);
+static void write_padding (size_t len);
+static void cpio_append_fts_entry (FTSENT *entry);
+static void cpio_append_stat (const char *filename, struct stat *);
+static void cpio_append (const char *filename);
+static void cpio_append_trailer (void);
+
+static int out_fd = -1;
+static off_t out_offset = 0;
+
+/* Create the appliance.
+ *
+ * The initrd consists of these components concatenated together:
+ *
+ * (1) The base skeleton appliance that we constructed at build time.
+ * format = plain cpio
+ * (2) The host files which match wildcards in *.supermin.hostfiles.
+ * input format = plain text, output format = plain cpio
+ * (3) The modules from modpath which are on the module whitelist.
+ * output format = plain cpio
+ *
+ * The original shell script used the external cpio program to create
+ * parts (2) and (3), but we have decided it's going to be faster if
+ * we just write out the data outselves. The reasons are that
+ * external cpio is slow (particularly when used with SELinux because
+ * it does 512 byte reads), and the format that we're writing is
+ * narrow and well understood, because we only care that the Linux
+ * kernel can read it.
+ *
+ * This version contains some improvements over the C version written
+ * for libguestfs, in that we can have multiple base images (or
+ * hostfiles) or use a directory to store these files.
+ */
+void
+create_appliance (char **inputs, int nr_inputs,
+ const char *whitelist,
+ const char *modpath,
+ const char *initrd)
+{
+ out_fd = open (initrd, O_WRONLY | O_CREAT | O_TRUNC | O_NOCTTY, 0644);
+ if (out_fd == -1)
+ error (EXIT_FAILURE, errno, "open: %s", initrd);
+ out_offset = 0;
+
+ iterate_inputs (inputs, nr_inputs);
+
+ /* Kernel modules (3). */
+ write_kernel_modules (whitelist, modpath);
+
+ cpio_append_trailer ();
+
+ /* Finish off and close output file. */
+ if (close (out_fd) == -1)
+ error (EXIT_FAILURE, errno, "close: %s", initrd);
+}
+
+/* Iterate over the inputs to find out what they are, visiting
+ * directories if specified.
+ */
+static void
+iterate_inputs (char **inputs, int nr_inputs)
+{
+ int i;
+ for (i = 0; i < nr_inputs; ++i) {
+ if (verbose)
+ print_timestamped_message ("visiting %s", inputs[i]);
+
+ int fd = open (inputs[i], O_RDONLY);
+ if (fd == -1)
+ error (EXIT_FAILURE, errno, "open: %s", inputs[i]);
+
+ struct stat statbuf;
+ if (fstat (fd, &statbuf) == -1)
+ error (EXIT_FAILURE, errno, "fstat: %s", inputs[i]);
+
+ /* Directory? */
+ if (S_ISDIR (statbuf.st_mode))
+ iterate_input_directory (inputs[i], fd);
+ else if (S_ISREG (statbuf.st_mode)) {
+ /* Is it a cpio file? */
+ char buf[6];
+ if (read (fd, buf, 6) == 6 && memcmp (buf, "070701", 6) == 0)
+ /* Yes, a cpio file. This is a skeleton appliance, case (1). */
+ write_file_to_fd (inputs[i]);
+ else
+ /* No, must be hostfiles, case (2). */
+ write_hostfiles (inputs[i]);
+ }
+ else
+ error (EXIT_FAILURE, 0, "%s: input is not a regular file or directory",
+ inputs[i]);
+
+ close (fd);
+ }
+}
+
+static void
+iterate_input_directory (const char *dirname, int dirfd)
+{
+ char path[PATH_MAX];
+ strcpy (path, dirname);
+ size_t len = strlen (dirname);
+ path[len++] = '/';
+
+ char *inputs[] = { path };
+
+ DIR *dir = fdopendir (dirfd);
+ if (dir == NULL)
+ error (EXIT_FAILURE, errno, "fdopendir: %s", dirname);
+
+ struct dirent *d;
+ while ((errno = 0, d = readdir (dir)) != NULL) {
+ if (d->d_name[0] == '.') /* ignore ., .. and any hidden files. */
+ continue;
+
+ strcpy (&path[len], d->d_name);
+ iterate_inputs (inputs, 1);
+ }
+
+ if (errno != 0)
+ error (EXIT_FAILURE, errno, "readdir: %s", dirname);
+
+ if (closedir (dir) == -1)
+ error (EXIT_FAILURE, errno, "closedir: %s", dirname);
+}
+
+/* Copy kernel modules.
+ *
+ * Find every file under modpath.
+ *
+ * Exclude all *.ko files, *except* ones which match names in
+ * the whitelist (which may contain wildcards). Include all
+ * other files.
+ *
+ * Add chosen files to the output.
+ *
+ * whitelist_file may be NULL, to include ALL kernel modules.
+ */
+static void
+write_kernel_modules (const char *whitelist_file, const char *modpath)
+{
+ char **whitelist = NULL;
+ if (whitelist_file != NULL)
+ whitelist = load_file (whitelist_file);
+
+ char *paths[2] = { (char *) modpath, NULL };
+ FTS *fts = fts_open (paths, FTS_COMFOLLOW|FTS_PHYSICAL, NULL);
+ if (fts == NULL)
+ error (EXIT_FAILURE, errno, "write_kernel_modules: fts_open: %s", modpath);
+
+ for (;;) {
+ errno = 0;
+ FTSENT *entry = fts_read (fts);
+ if (entry == NULL && errno != 0)
+ error (EXIT_FAILURE, errno, "write_kernel_modules: fts_read: %s", modpath);
+ if (entry == NULL)
+ break;
+
+ /* Ignore directories being visited in post-order. */
+ if (entry->fts_info & FTS_DP)
+ continue;
+
+ /* Is it a *.ko file? */
+ if (entry->fts_namelen >= 3 &&
+ entry->fts_name[entry->fts_namelen-3] == '.' &&
+ entry->fts_name[entry->fts_namelen-2] == 'k' &&
+ entry->fts_name[entry->fts_namelen-1] == 'o') {
+ if (whitelist) {
+ /* Is it a *.ko file which is on the whitelist? */
+ size_t j;
+ for (j = 0; whitelist[j] != NULL; ++j) {
+ int r;
+ r = fnmatch (whitelist[j], entry->fts_name, 0);
+ if (r == 0) {
+ /* It's on the whitelist, so include it. */
+ if (verbose >= 2)
+ fprintf (stderr, "including kernel module %s (matches whitelist entry %s)\n",
+ entry->fts_name, whitelist[j]);
+ cpio_append_fts_entry (entry);
+ break;
+ } else if (r != FNM_NOMATCH)
+ error (EXIT_FAILURE, 0, "internal error: fnmatch ('%s', '%s', %d) returned unexpected non-zero value %d\n",
+ whitelist[j], entry->fts_name, 0, r);
+ } /* for (j) */
+ } else { /* whitelist == NULL, always include */
+ if (verbose >= 2)
+ fprintf (stderr, "including kernel module %s\n", entry->fts_name);
+ cpio_append_fts_entry (entry);
+ }
+ } else
+ /* It's some other sort of file, or a directory, always include. */
+ cpio_append_fts_entry (entry);
+ }
+
+ if (fts_close (fts) == -1)
+ error (EXIT_FAILURE, errno, "write_kernel_modules: fts_close: %s", modpath);
+}
+
+/* Copy the host files.
+ *
+ * Read the list of entries in hostfiles (which may contain
+ * wildcards). Look them up in the filesystem, and add those files
+ * that exist. Ignore any files that don't exist or are not readable.
+ */
+static void
+write_hostfiles (const char *hostfiles_file)
+{
+ char **hostfiles = load_file (hostfiles_file);
+
+ /* Hostfiles list can contain "." before each path - ignore it.
+ * It also contains each directory name before we enter it. But
+ * we don't read that until we see a wildcard for that directory.
+ */
+ size_t i, j;
+ for (i = 0; hostfiles[i] != NULL; ++i) {
+ char *hostfile = hostfiles[i];
+ if (hostfile[0] == '.')
+ hostfile++;
+
+ struct stat statbuf;
+
+ /* Is it a wildcard? */
+ if (strchr (hostfile, '*') || strchr (hostfile, '?')) {
+ char *dirname = xstrdup (hostfile);
+ char *patt = strrchr (dirname, '/');
+ assert (patt);
+ *patt++ = '\0';
+
+ char **files = read_dir (dirname);
+ files = filter_fnmatch (files, patt, FNM_NOESCAPE);
+
+ /* Add matching files. */
+ for (j = 0; files[j] != NULL; ++j) {
+ char *tmp = xasprintf ("%s/%s", dirname, files[j]);
+
+ if (verbose >= 2)
+ fprintf (stderr, "including host file %s (matches %s)\n", tmp, patt);
+
+ cpio_append (tmp);
+
+ free (tmp);
+ }
+ }
+ /* Else does this file/directory/whatever exist? */
+ else if (lstat (hostfile, &statbuf) == 0) {
+ if (verbose >= 2)
+ fprintf (stderr, "including host file %s (directly referenced)\n",
+ hostfile);
+
+ cpio_append_stat (hostfile, &statbuf);
+ } /* Ignore files that don't exist. */
+ }
+}
+
+/* Copy contents of buffer to out_fd and keep out_offset correct. */
+static void
+write_to_fd (const void *buffer, size_t len)
+{
+ if (full_write (out_fd, buffer, len) != len)
+ error (EXIT_FAILURE, errno, "write");
+ out_offset += len;
+}
+
+/* Copy contents of file to out_fd. */
+static void
+write_file_to_fd (const char *filename)
+{
+ char buffer[BUFFER_SIZE];
+ int fd2;
+ ssize_t r;
+
+ if (verbose >= 2)
+ fprintf (stderr, "write_file_to_fd %s -> %d\n", filename, out_fd);
+
+ fd2 = open (filename, O_RDONLY);
+ if (fd2 == -1)
+ error (EXIT_FAILURE, errno, "open: %s", filename);
+ for (;;) {
+ r = read (fd2, buffer, sizeof buffer);
+ if (r == 0)
+ break;
+ if (r == -1) {
+ if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR)
+ continue;
+ error (EXIT_FAILURE, errno, "read: %s", filename);
+ }
+ write_to_fd (buffer, r);
+ }
+
+ if (close (fd2) == -1)
+ error (EXIT_FAILURE, errno, "close: %s", filename);
+}
+
+/* Copy file of given length to output, and fail if the file has
+ * changed size.
+ */
+static void
+write_file_len_to_fd (const char *filename, size_t len)
+{
+ char buffer[BUFFER_SIZE];
+ size_t count = 0;
+
+ if (verbose >= 2)
+ fprintf (stderr, "write_file_to_fd %s -> %d\n", filename, out_fd);
+
+ int fd2 = open (filename, O_RDONLY);
+ if (fd2 == -1)
+ error (EXIT_FAILURE, errno, "open: %s", filename);
+ for (;;) {
+ ssize_t r = read (fd2, buffer, sizeof buffer);
+ if (r == 0)
+ break;
+ if (r == -1) {
+ if (errno == EAGAIN || errno == EWOULDBLOCK || errno == EINTR)
+ continue;
+ error (EXIT_FAILURE, errno, "read: %s", filename);
+ }
+ write_to_fd (buffer, r);
+ count += r;
+ if (count > len)
+ error (EXIT_FAILURE, 0, "write_file_len_to_fd: %s: file has increased in size\n", filename);
+ }
+
+ if (close (fd2) == -1)
+ error (EXIT_FAILURE, errno, "close: %s", filename);
+
+ if (count != len)
+ error (EXIT_FAILURE, 0, "febootstrap-supermin-helper: write_file_len_to_fd: %s: file has changed size\n", filename);
+}
+
+/* Append the file pointed to by FTSENT to the cpio output. */
+static void
+cpio_append_fts_entry (FTSENT *entry)
+{
+ if (entry->fts_info & FTS_NS || entry->fts_info & FTS_NSOK)
+ cpio_append (entry->fts_path);
+ else
+ cpio_append_stat (entry->fts_path, entry->fts_statp);
+}
+
+/* Append the file named 'filename' to the cpio output. */
+static void
+cpio_append (const char *filename)
+{
+ struct stat statbuf;
+
+ if (lstat (filename, &statbuf) == -1)
+ error (EXIT_FAILURE, errno, "lstat: %s", filename);
+ cpio_append_stat (filename, &statbuf);
+}
+
+/* Append the file to the cpio output. */
+#define PADDING(len) ((((len) + 3) & ~3) - (len))
+
+#define CPIO_HEADER_LEN (6 + 13*8)
+
+static void
+cpio_append_stat (const char *filename, struct stat *statbuf)
+{
+ const char *orig_filename = filename;
+
+ if (*filename == '/')
+ filename++;
+ if (*filename == '\0')
+ filename = ".";
+
+ if (verbose >= 2)
+ fprintf (stderr, "cpio_append_stat %s 0%o -> %d\n",
+ orig_filename, statbuf->st_mode, out_fd);
+
+ /* Regular files and symlinks are the only ones that have a "body"
+ * in this cpio entry.
+ */
+ int has_body = S_ISREG (statbuf->st_mode) || S_ISLNK (statbuf->st_mode);
+
+ size_t len = strlen (filename) + 1;
+
+ char header[CPIO_HEADER_LEN + 1];
+ snprintf (header, sizeof header,
+ "070701" /* magic */
+ "%08X" /* inode */
+ "%08X" /* mode */
+ "%08X" "%08X" /* uid, gid */
+ "%08X" /* nlink */
+ "%08X" /* mtime */
+ "%08X" /* file length */
+ "%08X" "%08X" /* device holding file major, minor */
+ "%08X" "%08X" /* for specials, device major, minor */
+ "%08X" /* name length (including \0 byte) */
+ "%08X", /* checksum (not used by the kernel) */
+ (unsigned) statbuf->st_ino, statbuf->st_mode,
+ statbuf->st_uid, statbuf->st_gid,
+ (unsigned) statbuf->st_nlink, (unsigned) statbuf->st_mtime,
+ has_body ? (unsigned) statbuf->st_size : 0,
+ major (statbuf->st_dev), minor (statbuf->st_dev),
+ major (statbuf->st_rdev), minor (statbuf->st_rdev),
+ (unsigned) len, 0);
+
+ /* Write the header. */
+ write_to_fd (header, CPIO_HEADER_LEN);
+
+ /* Follow with the filename, and pad it. */
+ write_to_fd (filename, len);
+ size_t padding_len = PADDING (CPIO_HEADER_LEN + len);
+ write_padding (padding_len);
+
+ /* Follow with the file or symlink content, and pad it. */
+ if (has_body) {
+ if (S_ISREG (statbuf->st_mode))
+ write_file_len_to_fd (orig_filename, statbuf->st_size);
+ else if (S_ISLNK (statbuf->st_mode)) {
+ char tmp[PATH_MAX];
+ if (readlink (orig_filename, tmp, sizeof tmp) == -1)
+ error (EXIT_FAILURE, errno, "readlink: %s", orig_filename);
+ write_to_fd (tmp, statbuf->st_size);
+ }
+
+ padding_len = PADDING (statbuf->st_size);
+ write_padding (padding_len);
+ }
+}
+
+/* CPIO voodoo. */
+static void
+cpio_append_trailer (void)
+{
+ struct stat statbuf;
+ memset (&statbuf, 0, sizeof statbuf);
+ statbuf.st_nlink = 1;
+ cpio_append_stat ("TRAILER!!!", &statbuf);
+
+ /* CPIO seems to pad up to the next block boundary, ie. up to
+ * the next 512 bytes.
+ */
+ write_padding (((out_offset + 511) & ~511) - out_offset);
+ assert ((out_offset & 511) == 0);
+}
+
+/* Write 'len' bytes of zeroes out. */
+static void
+write_padding (size_t len)
+{
+ static const char buffer[512] = { 0 };
+
+ while (len > 0) {
+ size_t n = len < sizeof buffer ? len : sizeof buffer;
+ write_to_fd (buffer, n);
+ len -= n;
+ }
+}
git.annexia.org / febootstrap.git / blobdiff