1 files changed, 358 insertions, 0 deletions
diff --git a/helper/ext2cpio.c b/helper/ext2cpio.c
new file mode 100644
index 0000000..7690553
--- /dev/null
+++ b/helper/ext2cpio.c
@@ -0,0 +1,358 @@
+/* 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 <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+#include <limits.h>
+#include <sys/stat.h>
+#include <assert.h>
+
+#include "error.h"
+
+#include "helper.h"
+#include "ext2internal.h"
+
+/* This function must unpack the cpio file and add the files it
+ * contains to the ext2 filesystem.  Essentially this is doing the
+ * same thing as the kernel init/initramfs.c code.  Note that we
+ * assume that the cpio is uncompressed newc format and can't/won't
+ * deal with anything else.  All this cpio parsing code is copied to
+ * some extent from init/initramfs.c in the kernel.
+ */
+#define N_ALIGN(len) ((((len) + 1) & ~3) + 2)
+
+static unsigned long cpio_ino, nlink;
+static mode_t mode;
+static unsigned long body_len, name_len;
+static uid_t uid;
+static gid_t gid;
+static time_t mtime;
+static int dev_major, dev_minor, rdev_major, rdev_minor;
+static loff_t curr, next_header;
+static FILE *fp;
+
+static void parse_header (char *s);
+static int parse_next_entry (void);
+static void skip_to_next_header (void);
+static void read_file (void);
+static char *read_whole_body (void);
+static ext2_ino_t maybe_link (void);
+static void add_link (ext2_ino_t real_ino);
+static void clear_links (void);
+
+void
+ext2_cpio_file (const char *cpio_file)
+{
+  fp = fopen (cpio_file, "r");
+  if (fp == NULL)
+    error (EXIT_FAILURE, errno, "open: %s", cpio_file);
+
+  curr = 0;
+  while (parse_next_entry ())
+    ;
+
+  fclose (fp);
+}
+
+static int
+parse_next_entry (void)
+{
+  clearerr (fp);
+
+  char header[110];
+
+  /* Skip padding and synchronize with the next header. */
+ again:
+  if (fread (&header[0], 4, 1, fp) != 1) {
+    if (feof (fp))
+      return 0;
+    error (EXIT_FAILURE, errno, "read failure reading cpio file");
+  }
+  curr += 4;
+  if (memcmp (header, "\0\0\0\0", 4) == 0)
+    goto again;
+
+  /* Read the rest of the header field. */
+  if (fread (&header[4], sizeof header - 4, 1, fp) != 1)
+    error (EXIT_FAILURE, errno, "read failure reading cpio file");
+  curr += sizeof header - 4;
+
+  if (verbose >= 2)
+    fprintf (stderr, "cpio header %s\n", header);
+
+  if (memcmp (header, "070707", 6) == 0)
+    error (EXIT_FAILURE, 0, "incorrect cpio method: use -H newc option");
+  if (memcmp (header, "070701", 6) != 0)
+    error (EXIT_FAILURE, 0, "input is not a cpio file");
+
+  parse_header (header);
+
+  next_header = curr + N_ALIGN(name_len) + body_len;
+  next_header = (next_header + 3) & ~3;
+  if (name_len <= 0 || name_len > PATH_MAX)
+    skip_to_next_header ();
+  else if (S_ISLNK (mode)) {
+    if (body_len <= 0 || body_len > PATH_MAX)
+      skip_to_next_header ();
+    else
+      read_file ();
+  }
+  else if (!S_ISREG (mode) && body_len > 0)
+    skip_to_next_header (); /* only regular files have bodies */
+  else
+    read_file (); /* could be file, directory, block special, ... */
+
+  return 1;
+}
+
+static void
+parse_header (char *s)
+{
+  unsigned long parsed[12];
+  char buf[9];
+  int i;
+
+  buf[8] = '\0';
+  for (i = 0, s += 6; i < 12; i++, s += 8) {
+    memcpy (buf, s, 8);
+    parsed[i] = strtoul (buf, NULL, 16);
+  }
+  cpio_ino = parsed[0]; /* fake inode number from cpio file */
+  mode = parsed[1];
+  uid = parsed[2];
+  gid = parsed[3];
+  nlink = parsed[4];
+  mtime = parsed[5];
+  body_len = parsed[6];
+  dev_major = parsed[7];
+  dev_minor = parsed[8];
+  rdev_major = parsed[9];
+  rdev_minor = parsed[10];
+  name_len = parsed[11];
+}
+
+static void
+skip_to_next_header (void)
+{
+  char buf[65536];
+
+  while (curr < next_header) {
+    size_t bytes = (size_t) (next_header - curr);
+    if (bytes > sizeof buf)
+      bytes = sizeof buf;
+    size_t r = fread (buf, 1, bytes, fp);
+    if (r == 0)
+      error (EXIT_FAILURE, errno, "error or unexpected end of cpio file");
+    curr += r;
+  }
+}
+
+/* Read any sort of file.  The body will only be present for
+ * regular files and symlinks.
+ */
+static void
+read_file (void)
+{
+  errcode_t err;
+  int dir_ft;
+  char name[N_ALIGN(name_len)+1]; /* asserted above this is <= PATH_MAX */
+
+  if (fread (name, N_ALIGN(name_len), 1, fp) != 1)
+    error (EXIT_FAILURE, errno, "read failure reading name field in cpio file");
+  curr += N_ALIGN(name_len);
+
+  name[name_len] = '\0';
+
+  if (verbose >= 2)
+    fprintf (stderr, "ext2 read_file %s %o\n", name, mode);
+
+  if (strcmp (name, "TRAILER!!!") == 0) {
+    clear_links ();
+    goto skip;
+  }
+
+  /* The name will be something like "bin/ls" or "./bin/ls".  It won't
+   * (ever?) be an absolute path.  Skip leading parts, and if it refers
+   * to the root directory just skip it entirely.
+   */
+  char *dirname = name, *basename;
+  if (*dirname == '.')
+    dirname++;
+  if (*dirname == '/')
+    dirname++;
+  if (*dirname == '\0')
+    goto skip;
+
+  ext2_ino_t dir_ino;
+  basename = strrchr (dirname, '/');
+  if (basename == NULL) {
+    basename = dirname;
+    dir_ino = EXT2_ROOT_INO;
+  } else {
+    *basename++ = '\0';
+
+    /* Look up the parent directory. */
+    err = ext2fs_namei (fs, EXT2_ROOT_INO, EXT2_ROOT_INO, dirname, &dir_ino);
+    if (err != 0)
+      error (EXIT_FAILURE, 0, "ext2: parent directory not found: %s: %s",
+             dirname, error_message (err));
+  }
+
+  if (verbose >= 2)
+    fprintf (stderr, "ext2 read_file dirname %s basename %s\n",
+             dirname, basename);
+
+  ext2_clean_path (dir_ino, dirname, basename, S_ISDIR (mode));
+
+  /* Create a regular file. */
+  if (S_ISREG (mode)) {
+    ext2_ino_t ml = maybe_link ();
+    ext2_ino_t ino;
+    if (ml <= 1) {
+      ext2_empty_inode (dir_ino, dirname, basename,
+                        mode, uid, gid, mtime, mtime, mtime,
+                        0, 0, EXT2_FT_REG_FILE, &ino);
+      if (ml == 1)
+        add_link (ino);
+    }
+    else /* ml >= 2 */ {
+      /* It's a hard link back to a previous file. */
+      ino = ml;
+      ext2_link (dir_ino, basename, ino, EXT2_FT_REG_FILE);
+    }
+
+    if (body_len) {
+      char *buf = read_whole_body ();
+      ext2_write_file (ino, buf, body_len);
+      free (buf);
+    }
+  }
+  /* Create a symlink. */
+  else if (S_ISLNK (mode)) {
+    ext2_ino_t ino;
+    ext2_empty_inode (dir_ino, dirname, basename,
+                      mode, uid, gid, mtime, mtime, mtime,
+                      0, 0, EXT2_FT_SYMLINK, &ino);
+
+    char *buf = read_whole_body ();
+    ext2_write_file (ino, buf, body_len);
+    free (buf);
+  }
+  /* Create a directory. */
+  else if (S_ISDIR (mode)) {
+    ext2_mkdir (dir_ino, dirname, basename,
+                mode, uid, gid, mtime, mtime, mtime);
+  }
+  /* Create a special file. */
+  else if (S_ISBLK (mode)) {
+    dir_ft = EXT2_FT_BLKDEV;
+    goto make_special;
+  }
+  else if (S_ISCHR (mode)) {
+    dir_ft = EXT2_FT_CHRDEV;
+    goto make_special;
+  } else if (S_ISFIFO (mode)) {
+    dir_ft = EXT2_FT_FIFO;
+    goto make_special;
+  } else if (S_ISSOCK (mode)) {
+    dir_ft = EXT2_FT_SOCK;
+  make_special:
+    /* Just like the kernel, we ignore special files with nlink > 1. */
+    if (maybe_link () == 0)
+      ext2_empty_inode (dir_ino, dirname, basename,
+                        mode, uid, gid, mtime, mtime, mtime,
+                        rdev_major, rdev_minor, dir_ft, NULL);
+  }
+
+ skip:
+  skip_to_next_header ();
+}
+
+static char *
+read_whole_body (void)
+{
+  char *buf = malloc (body_len);
+  if (buf == NULL)
+    error (EXIT_FAILURE, errno, "malloc");
+
+  size_t r = fread (buf, body_len, 1, fp);
+  if (r != 1)
+    error (EXIT_FAILURE, errno, "read failure reading body in cpio file");
+  curr += body_len;
+
+  return buf;
+}
+
+struct links {
+  struct links *next;
+  unsigned long cpio_ino;       /* fake ino from cpio file */
+  int minor;
+  int major;
+  ext2_ino_t real_ino;          /* real inode number on ext2 filesystem */
+};
+static struct links *links_head = NULL;
+
+/* If it's a hard link, return the linked inode number in the real
+ * ext2 filesystem.
+ *
+ * Returns: 0 = not a hard link
+ *          1 = possible unresolved hard link
+ *          inode number = resolved hard link to this inode
+ */
+static ext2_ino_t
+maybe_link (void)
+{
+  if (nlink >= 2) {
+    struct links *p;
+    for (p = links_head; p; p = p->next) {
+      if (p->cpio_ino != cpio_ino)
+        continue;
+      if (p->minor != dev_minor)
+        continue;
+      if (p->major != dev_major)
+        continue;
+      return p->real_ino;
+    }
+    return 1;
+  }
+
+  return 0;
+}
+
+static void
+add_link (ext2_ino_t real_ino)
+{
+  struct links *p = malloc (sizeof (*p));
+  p->cpio_ino = cpio_ino;
+  p->minor = dev_minor;
+  p->major = dev_major;
+  p->real_ino = real_ino;
+}
+
+static void
+clear_links (void)
+{
+  /* Don't bother to free the linked list in this short-lived program. */
+  links_head = NULL;
+}