From: Roland McGrath <roland@redhat.com>
Date: Wed, 26 Aug 2009 07:23:01 +0000 (-0700)
Subject: libdwfl: Support Linux bzip2 kernel images for automatic decompression.
X-Git-Tag: elfutils-0.143~26
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=d6ccdc1a05f27bf0bb5d802ec14f879aa9fe3e98;p=thirdparty%2Felfutils.git

libdwfl: Support Linux bzip2 kernel images for automatic decompression.
---

diff --git a/NEWS b/NEWS
index 4d08e2b34..e0ff9dcc8 100644
--- a/NEWS
+++ b/NEWS
@@ -3,6 +3,8 @@ Version 0.143:
 libdw: Various convenience functions for individual attributes now use
        dwarf_attr_integrate to look up indirect inherited attributes.
 
+libdwfl: Support Linux bzip2 kernel images for automatic decompression.
+
 Version 0.142:
 
 libelf: Add elf_getshdrnum alias for elf_getshnum and elf_getshdrstrndx alias
diff --git a/libdwfl/ChangeLog b/libdwfl/ChangeLog
index 129d520f0..c5b8edf32 100644
--- a/libdwfl/ChangeLog
+++ b/libdwfl/ChangeLog
@@ -1,3 +1,8 @@
+2009-08-26  Roland McGrath  <roland@redhat.com>
+
+	* gzip.c (mapped_zImage): Limit scan to 32kb.
+	Make this unconditional, support bzip2 kernel images too.
+
 2009-08-09  Roland McGrath  <roland@redhat.com>
 
 	* dwfl_module_build_id.c: Use new macros for versioned definitions.
diff --git a/libdwfl/gzip.c b/libdwfl/gzip.c
index 664452541..42352db7c 100644
--- a/libdwfl/gzip.c
+++ b/libdwfl/gzip.c
@@ -53,7 +53,6 @@
 
 #ifdef BZLIB
 # define inflate_groks_header	true
-# define mapped_zImage(...)	false
 # include <bzlib.h>
 # define unzip		__libdw_bunzip2
 # define DWFL_E_ZLIB	DWFL_E_BZLIB
@@ -74,13 +73,15 @@
 # define unzip		__libdw_gunzip
 # define MAGIC		"\037\213"
 # define Z(what)	Z_##what
+#endif
 
 /* We can also handle Linux kernel zImage format in a very hackish way.
-   If it looks like one, we actually just scan the image for the gzip
-   magic bytes to figure out where the gzip image starts.  */
+   If it looks like one, we actually just scan the image for the right
+   magic bytes to figure out where the compressed image starts.  */
 
-# define LINUX_MAGIC_OFFSET	514
-# define LINUX_MAGIC		"HdrS"
+#define LINUX_MAGIC_OFFSET	514
+#define LINUX_MAGIC		"HdrS"
+#define LINUX_MAX_SCAN		32768
 
 static bool
 mapped_zImage (off64_t *start_offset, void **mapped, size_t *mapped_size)
@@ -90,8 +91,10 @@ mapped_zImage (off64_t *start_offset, void **mapped, size_t *mapped_size)
       && !memcmp (*mapped + LINUX_MAGIC_OFFSET,
 		  LINUX_MAGIC, sizeof LINUX_MAGIC - 1))
     {
-      void *p = memmem (*mapped + pos, *mapped_size - pos,
-			MAGIC, sizeof MAGIC - 1);
+      size_t scan = *mapped_size - pos;
+      if (scan > LINUX_MAX_SCAN)
+	scan = LINUX_MAX_SCAN;
+      void *p = memmem (*mapped + pos, scan, MAGIC, sizeof MAGIC - 1);
       if (p != NULL)
 	{
 	  *start_offset += p - *mapped;
@@ -102,7 +105,6 @@ mapped_zImage (off64_t *start_offset, void **mapped, size_t *mapped_size)
     }
   return false;
 }
-#endif
 
 /* If this is not a compressed image, return DWFL_E_BADELF.
    If we uncompressed it into *WHOLE, *WHOLE_SIZE, return DWFL_E_NOERROR.