WinDBG加载符号表的一点心得体会

新建一个环境变量_NT_SYMBOL_PATH 值为: SRV*c:\mysymbol* http://msdl.microsoft.com/download/symbols

WinDBG无法加载符号表是很痛苦的事情，明明符号表的路径已经加载进去了，可是还是无法加断点，下面直接进入主题：

符号表无法加载，无法触发断点。

1、检查sympath是否正确

kd> .sympath
Symbol search path is: srv*http://msdl.microsoft.com/download/symbols;C:\Windows\symbols;D:\VSSDataBase\TrueCrypt\Driver\obj_driver_debug\i386
Expanded Symbol search path is: srv*http://msdl.microsoft.com/download/symbols;c:\windows\symbols;d:\vssdatabase\truecrypt\driver\obj_driver_debug\i386

之前的尝试，以为符号表的路径在前面和在后面关系很大，毕竟是依次查找路径的嘛，只要查找正确了，路径前后和符号表在什么位置又有什么关系呢。

src*与;之前的区别：src*是符号表服务器上找，而;是去本地路径上去找，对于一台机子来说就一样的。

sys文件会记录PDB文件的位置，从而找到符号表，所以设置目录必须是编译时候的目录，即使把编译目录下的文件拷贝出来放到其他地方 然后在把windbg符号目录设置成那个目录 windbg也是不认识的 因为windbg对SYS的符号文件的寻找只会去SYS指定的那个目录寻找 这点很奇特 以前配置windbg的时候百思不得其解

2、!lmi truecrypt查找相应的模块信息

kd> !lmi truecrypt
Loaded Module Info: [truecrypt]
         Module: truecrypt
   Base Address: ee21b000
     Image Name: truecrypt.sys
   Machine Type: 332 (I386)
     Time Stamp: 4d889673 Tue Mar 22 20:30:43 2011
           Size: 4ef80
       CheckSum: 55776
Characteristics: 102 
Debug Data Dirs: Type  Size     VA  Pointer
             CODEVIEW    5c, 43fc8,   43fc8 RSDS - GUID: {1B9489BA-E47D-4E48-89EB-D0CB60055F22}
               Age: 1, Pdb: d:\vssdatabase\truecrypt\driver\obj_driver_debug\i386\truecrypt.pdb
     Image Type: MEMORY   - Image read successfully from loaded memory.
    Symbol Type: EXPORT   - PDB not found
    Load Report: export symbols



Symbol Type: EXPORT   - PDB not found 符号表没有找到
Export
没有发现符号文件，使用映像文件的输出信息（如DLL的Export）作为符号
3、检查符号表加载详细情况
!sym noisy
当Windbg加载Symbol文件的时候，显示Symbol的路径，默认情况下是不显示的。
YMSRV:  无法与服务器建立连接
SYMSRV:  c:\windows\symbols\truecrypt.pdb\1B9489BAE47D4E4889EBD0CB60055F221\truecrypt.pdb not found
!sym quiet 不显示路径
SYMSRV: truecrypt.pdb not found

kd> !sym noisy
noisy mode - symbol prompts on

kd> .reload /f truecrypt.sys
SYMSRV: 无法与服务器建立连接
SYMSRV: c:\windows\symbols\truecrypt.pdb\1B9489BAE47D4E4889EBD0CB60055F221\truecrypt.pdb not found
SYMSRV: http://msdl.microsoft.com/download/symbols/truecrypt.pdb/1B9489BAE47D4E4889EBD0CB60055F221/truecrypt.pdb not found
DBGHELP: d:\vssdatabase\truecrypt\driver\obj_driver_debug\i386\truecrypt.pdb - mismatched pdb
DBGHELP: d:\vssdatabase\truecrypt\driver\obj_driver_debug\i386\sys\truecrypt.pdb - file not found
DBGHELP: d:\vssdatabase\truecrypt\driver\obj_driver_debug\i386\symbols\sys\truecrypt.pdb - file not found
SYMSRV: 无法与服务器建立连接
SYMSRV: d:\vssdatabase\truecrypt\driver\obj_driver_debug\i386\truecrypt.pdb\1B9489BAE47D4E4889EBD0CB60055F221\truecrypt.pdb not found
SYMSRV: c:\windows\symbols\truecrypt.pdb\1B9489BAE47D4E4889EBD0CB60055F221\truecrypt.pdb not found
SYMSRV: http://msdl.microsoft.com/download/symbols/truecrypt.pdb/1B9489BAE47D4E4889EBD0CB60055F221/truecrypt.pdb not found
DBGHELP: d:\vssdatabase\truecrypt\driver\obj_driver_debug\i386\truecrypt.pdb - mismatched pdb
DBGHELP: Couldn't load mismatched pdb for truecrypt.sys
*** ERROR: Symbol file could not be found. Defaulted to export symbols for truecrypt.sys -
DBGHELP: truecrypt - export symbols


注意上面那一行，符号表的位置是正确的，也找对了，但是结果却是mismatched pdb，于是我就将debug目录下内容，删除后重新生成，并拷贝到虚拟机里，结果仍然是一样的，
仍然是mismatched pdb。
4、模块详情对照
!IToldYouSo tests the validity of a module against a symbol file.The module can be specified by either its name or base address.If a symbol file is not specified, then the loaded symbol is tested.
Otherwise, if a pdb or dbg symbol file path is specified, it is tested against the loaded module.

kd> !itoldyouso truecrypt d:\vssdatabase\truecrypt\driver\obj_driver_debug\i386\truecrypt.pdb

truecrypt.sys
    Timestamp: 4D889673
  SizeOfImage: 4EF80
          pdb: d:\vssdatabase\truecrypt\driver\obj_driver_debug\i386\truecrypt.pdb
      pdb sig: 1B9489BA-E47D-4E48-89EB-D0CB60055F22
          age: 1

truecrypt.pdb
      pdb sig: 329A35FA-70B8-4A97-BB0E-99BA6342AB6A
          age: 1

sig MISMATCH: truecrypt.pdb and truecrypt.sys



签名不一样，结果说明我虚拟机里装载的驱动和我重新生成的符号表不一致。经过检查发现，truecrypt.exe启动时候装载的truecrypt.sys并不是在C:\Windows\System32\Drivers下面，
而是在truecrypt.exe本身的安装目录下，替换之后，已经能够成功装载符号表了。
如下：

kd> !lmi truecrypt
Loaded Module Info: [truecrypt]
         Module: truecrypt
   Base Address: ee1ef000
     Image Name: truecrypt.sys
   Machine Type: 332 (I386)
     Time Stamp: 4d8c8e61 Fri Mar 25 20:45:21 2011
           Size: 4f180
       CheckSum: 5b7fa
Characteristics: 102 
Debug Data Dirs: Type  Size     VA  Pointer
             CODEVIEW    5c, 44148,   44148 RSDS - GUID: {160409E4-8EFC-4412-B760-4E9BF8F1A05A}
               Age: 1, Pdb: d:\vssdatabase\truecrypt\driver\obj_driver_debug\i386\truecrypt.pdb
     Image Type: MEMORY   - Image read successfully from loaded memory.
    Symbol Type: PDB      - Symbols loaded successfully from symbol search path.
                 d:\vssdatabase\truecrypt\driver\obj_driver_debug\i386\truecrypt.pdb
       Compiler: Resource - front end [0.0 bld 0] - back end [9.0 bld 30729]
    Load Report: private symbols & lines, not source indexed
                 d:\vssdatabase\truecrypt\driver\obj_driver_debug\i386\truecrypt.pdb