Squashed 'third_party/elfutils/' content from commit 555e15e
Change-Id: I61cde98949e47e5c8c09c33260de17f30921be79
git-subtree-dir: third_party/elfutils
git-subtree-split: 555e15ebe8bf1eb33d00747173cfc80cc65648a4
diff --git a/libdwfl/image-header.c b/libdwfl/image-header.c
new file mode 100644
index 0000000..25fbfd9
--- /dev/null
+++ b/libdwfl/image-header.c
@@ -0,0 +1,105 @@
+/* Linux kernel image support for libdwfl.
+ Copyright (C) 2009-2011 Red Hat, Inc.
+ This file is part of elfutils.
+
+ This file is free software; you can redistribute it and/or modify
+ it under the terms of either
+
+ * the GNU Lesser General Public License as published by the Free
+ Software Foundation; either version 3 of the License, or (at
+ your option) any later version
+
+ or
+
+ * 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
+
+ or both in parallel, as here.
+
+ elfutils 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 copies of the GNU General Public License and
+ the GNU Lesser General Public License along with this program. If
+ not, see <http://www.gnu.org/licenses/>. */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include "libdwflP.h"
+#include "system.h"
+
+#include <unistd.h>
+#include <endian.h>
+
+#if BYTE_ORDER == LITTLE_ENDIAN
+# define LE16(x) (x)
+#else
+# define LE16(x) bswap_16 (x)
+#endif
+
+/* See Documentation/x86/boot.txt in Linux kernel sources
+ for an explanation of these format details. */
+
+#define MAGIC1 0xaa55
+#define MAGIC2 0x53726448 /* "HdrS" little-endian */
+#define MIN_VERSION 0x0208
+
+#define H_START (H_SETUP_SECTS & -4)
+#define H_SETUP_SECTS 0x1f1
+#define H_MAGIC1 0x1fe
+#define H_MAGIC2 0x202
+#define H_VERSION 0x206
+#define H_PAYLOAD_OFFSET 0x248
+#define H_PAYLOAD_LENGTH 0x24c
+#define H_END 0x250
+#define H_READ_SIZE (H_END - H_START)
+
+Dwfl_Error
+internal_function
+__libdw_image_header (int fd, off_t *start_offset,
+ void *mapped, size_t mapped_size)
+{
+ if (likely (mapped_size > H_END))
+ {
+ const void *header = mapped;
+ char header_buffer[H_READ_SIZE];
+ if (header == NULL)
+ {
+ ssize_t n = pread_retry (fd, header_buffer, H_READ_SIZE,
+ *start_offset + H_START);
+ if (n < 0)
+ return DWFL_E_ERRNO;
+ if (n < H_READ_SIZE)
+ return DWFL_E_BADELF;
+
+ header = header_buffer - H_START;
+ }
+
+ if (*(uint16_t *) (header + H_MAGIC1) == LE16 (MAGIC1)
+ && *(uint32_t *) (header + H_MAGIC2) == LE32 (MAGIC2)
+ && LE16 (*(uint16_t *) (header + H_VERSION)) >= MIN_VERSION)
+ {
+ /* The magic numbers match and the version field is sufficient.
+ Extract the payload bounds. */
+
+ uint32_t offset = LE32 (*(uint32_t *) (header + H_PAYLOAD_OFFSET));
+ uint32_t length = LE32 (*(uint32_t *) (header + H_PAYLOAD_LENGTH));
+
+ offset += ((*(uint8_t *) (header + H_SETUP_SECTS) ?: 4) + 1) * 512;
+
+ if (offset > H_END && offset < mapped_size
+ && mapped_size - offset >= length)
+ {
+ /* It looks kosher. Use it! */
+ *start_offset += offset;
+ return DWFL_E_NOERROR;
+ }
+ }
+ }
+ return DWFL_E_BADELF;
+}