Library functions for manipulating initramfs

Library support for constructing initramfs.  This version is *not*
complete, as it doesn't take into account alignment requirements
properly.

1 files changed, 154 insertions, 0 deletions

diff --git a/com32/lib/syslinux/initramfs_file.c b/com32/lib/syslinux/initramfs_file.c
new file mode 100644
index 00000000..75b3f29f
--- /dev/null
+++ b/com32/lib/syslinux/initramfs_file.c
@@ -0,0 +1,154 @@
+/* ----------------------------------------------------------------------- *
+ *
+ *   Copyright 2007 H. Peter Anvin - All Rights Reserved
+ *
+ *   Permission is hereby granted, free of charge, to any person
+ *   obtaining a copy of this software and associated documentation
+ *   files (the "Software"), to deal in the Software without
+ *   restriction, including without limitation the rights to use,
+ *   copy, modify, merge, publish, distribute, sublicense, and/or
+ *   sell copies of the Software, and to permit persons to whom
+ *   the Software is furnished to do so, subject to the following
+ *   conditions:
+ *
+ *   The above copyright notice and this permission notice shall
+ *   be included in all copies or substantial portions of the Software.
+ *
+ *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ *   OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * ----------------------------------------------------------------------- */
+
+/*
+ * initramfs_file.c
+ *
+ * Utility functions to add arbitrary files including cpio header
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <syslinux/linux.h>
+
+#define CPIO_MAGIC "070701"
+struct cpio_header {
+  char c_magic[6];		/* 070701 */
+  char c_ino[8];		/* Inode number */
+  char c_mode[8];		/* File mode and permissions */
+  char c_uid[8];		/* uid */
+  char c_gid[8];		/* gid */
+  char c_nlink[8];		/* Number of links */
+  char c_mtime[8];		/* Modification time */
+  char c_filesize[8];		/* Size of data field */
+  char c_maj[8];		/* File device major number */
+  char c_min[8];		/* File device minor number */
+  char c_rmaj[8];		/* Device node reference major number */
+  char c_rmin[8];		/* Device node reference minor number */
+  char c_namesize[8];		/* Length of filename including final \0 */
+  char c_chksum[8];		/* Checksum if c_magic ends in 2 */
+};
+
+static uint32_t next_ino = 1;
+
+/* Create cpio headers for the directory entries leading up to a file.
+   Returns the number of bytes; doesn't touch the buffer if too small. */
+static size_t initramfs_mkdirs(const char *filename, void *buffer,
+			       size_t buflen)
+{
+  const char *p = filename;
+  char *bp = buffer;
+  int len;
+  size_t bytes = 0;
+  int pad;
+
+  while ((p = strchr(p, '/'))) {
+    if (p != filename && p[-1] != '/') {
+      len = p-filename;
+      bytes += ((sizeof(struct cpio_header)+len+1)+3) & ~3;
+    }
+    p++;
+  }
+
+  if (buflen >= bytes) {
+    p = filename;
+    while ((p = strchr(p, '/'))) {
+      if (p != filename && p[-1] != '/') {
+	len = p-filename;
+	bp += sprintf(bp, "070701%08x%08x%08x%08x%08x%08x%08x%08x%08x"
+		      "%08x%08x%08x%08x", next_ino++, S_IFDIR|0755,
+		      0, 0, 1, 0, 0, 0, 1, 0, 1, len+1, 0);
+	memcpy(bp, filename, len);
+	bp += len;
+	pad = (-(sizeof(struct cpio_header)+len) & 3) + 1;
+	memset(bp, 0, pad);
+	bp += pad;
+      }
+    }
+  }
+
+  return bytes;
+}
+
+int initramfs_mknod(struct initramfs *ihead, const char *filename,
+		    int do_mkdir,
+		    uint16_t mode, size_t len,
+		    uint32_t major, uint32_t minor)
+{
+  size_t bytes;
+  int namelen = strlen(filename);
+  int pad;
+  char *buffer, *bp;
+
+  if (do_mkdir)
+    bytes = initramfs_mkdirs(filename, NULL, 0);
+  else
+    bytes = 0;
+
+  bytes += ((sizeof(struct cpio_header)+namelen+1)+3) & ~3;
+
+  bp = buffer = malloc(bytes);
+  if (!buffer)
+    return -1;
+
+  if (do_mkdir)
+    bp += initramfs_mkdirs(filename, bp, bytes);
+
+  bp += sprintf(bp, "070701%08x%08x%08x%08x%08x%08x%08x%08x%08x"
+		"%08x%08x%08x%08x", next_ino++, mode,
+		0, 0, 1, 0, len, 0, 1, major, minor, len+1, 0);
+  memcpy(bp, filename, namelen);
+  bp += len;
+  pad = (-(sizeof(struct cpio_header)+namelen) & 3) + 1;
+  memset(bp, 0, pad);
+
+  if (initramfs_add_data(ihead, buffer, bytes, bytes)) {
+    free(buffer);
+    return -1;
+  }
+
+  return 0;
+}
+
+int initramfs_add_file(struct initramfs *ihead, const void *data,
+		       size_t data_len, size_t len,
+		       const char *filename, int do_mkdir, uint32_t mode)
+{
+  if (initramfs_mknod(ihead, filename, do_mkdir,
+		      (mode & S_IFMT) ? mode : mode|S_IFREG,
+		      len, 0, 1))
+    return -1;
+
+  return initramfs_add_data(ihead, data, data_len, len);
+}
+
+int initramfs_add_trailer(struct initramfs *ihead)
+{
+  return initramfs_mknod(ihead, "TRAILER!!!", 0, 0, 0, 0, 0);
+}