Windbg调试（1）- pdb
在windows下调试，首要的是获得Symbols。在开发环境下，开发者自己编译程序就可以得到pdb, 所生成的Binary会自动设置符号表的地址指向这个文件，调试器很容易就可以获得。但如果针对安装版本，对其调试就必须设置Symbol Path，告诉调试器哪里去寻找这些pdb。
做几个简单的实验查询pdb文件路径。实验前需要先从以下网址下载Debugging Tools for Windows，里面包含windbg, symchk等工具。
- https://msdn.microsoft.com/en-us/windows/hardware/hh852365
- http://msdn.microsoft.com/en-us/windows/hardware/dn913721.aspx
用SymChk查看nodepad的pdb文件路径
执行命令 C:\symchk c:\Windows\notepad.exe /v 得到下面的结果：
C:\>symchk c:\Windows\notepad.exe /v
[SYMCHK] Searching for symbols to c:\Windows\notepad.exe in path SRV*C:\WINDOWS\SYMBOLS*http://msdl.microsoft.com/download/symbols
DBGHELP: Symbol Search Path: SRV*C:\WINDOWS\SYMBOLS*http://msdl.microsoft.com/download/symbols
[SYMCHK] Using search path "SRV*C:\WINDOWS\SYMBOLS*http://msdl.microsoft.com/download/symbols"
DBGHELP: No header for c:\Windows\notepad.exe. Searching for image on disk
DBGHELP: c:\Windows\notepad.exe - OK
DBGHELP: notepad - public symbols
C:\WINDOWS\SYMBOLS\notepad.pdb\57060987A4344E1A9B9B77F57D14388A2\notepad.pdb
[SYMCHK] MODULE64 Info ----------------------
[SYMCHK] Struct size: 1680 bytes
[SYMCHK] Base: 0x0000000100000000
[SYMCHK] Image size: 217088 bytes
[SYMCHK] Date: 0x559ea8be
[SYMCHK] Checksum: 0x00036da2
[SYMCHK] NumSyms: 0
[SYMCHK] SymType: Sympdb
[SYMCHK] ModName: notepad
[SYMCHK] ImageName: c:\Windows\notepad.exe
[SYMCHK] LoadedImage: c:\Windows\notepad.exe
[SYMCHK] pdb: "C:\WINDOWS\SYMBOLS\notepad.pdb\57060987A4344E1A9B9B77F57D14388A2\notepad.pdb"
[SYMCHK] CV: RSDS
[SYMCHK] CV DWORD: 0x53445352
[SYMCHK] CV Data: notepad.pdb
[SYMCHK] pdb Sig: 0
[SYMCHK] pdb7 Sig: {57060987-A434-4E1A-9B9B-77F57D14388A}
[SYMCHK] Age: 2
[SYMCHK] pdb Matched: TRUE
[SYMCHK] DBG Matched: TRUE
[SYMCHK] Line nubmers: FALSE
[SYMCHK] Global syms: FALSE
[SYMCHK] Type Info: FALSE
[SYMCHK] ------------------------------------
SymbolCheckVersion 0x00000002
Result 0x00030001
DbgFilename
DbgTimeDateStamp 0x559ea8be
DbgSizeOfImage 0x00035000
DbgChecksum 0x00036da2
pdbFilename C:\WINDOWS\SYMBOLS\notepad.pdb\57060987A4344E1A9B9B77F57D14388A2\notepad.pdb
pdbSignature {57060987-A434-4E1A-9B9B-77F57D14388A}
pdbDbiAge 0x00000002
[SYMCHK] [ 0x00000000 - 0x00030001 ] Checked "c:\Windows\notepad.exe"
SYMCHK: FAILED files = 0
SYMCHK: PASSED + IGNORED files = 1
在C:\WINDOWS\SYMBOLS目录下你会发现下载的notepad.pdb文件。
用SymChk查看node的pdb文件路径
最近对node.js有些着迷，就以node为例来查找其pdb文件路径
C:\>where node
C:\Program Files\nodejs\node.exe
C:\>symchk "c:\Program Files\nodejs\node.exe" /v
[SYMCHK] Searching for symbols to c:\Program Files\nodejs\node.exe in path SRV*C:\WINDOWS\SYMBOLS*http://msdl.microsoft.com/download/symbols
DBGHELP: Symbol Search Path: SRV*C:\WINDOWS\SYMBOLS*http://msdl.microsoft.com/download/symbols
[SYMCHK] Using search path "SRV*C:\WINDOWS\SYMBOLS*http://msdl.microsoft.com/download/symbols"
DBGHELP: No header for c:\Program Files\nodejs\node.exe. Searching for image on disk
DBGHELP: c:\Program Files\nodejs\node.exe - OK
SYMSRV: C:\WINDOWS\SYMBOLS\node.pdb\5DAD44455A83417DBDB6BE0655EE650D1\node.pdb not found
SYMSRV: http://msdl.microsoft.com/download/symbols/node.pdb/5DAD44455A83417DBDB6BE0655EE650D1/node.pdb not found
DBGHELP: node - no symbols loaded
[SYMCHK] MODULE64 Info ----------------------
[SYMCHK] Struct size: 1680 bytes
[SYMCHK] Base: 0x0000000140000000
[SYMCHK] Image size: 11161600 bytes
[SYMCHK] Date: 0x551b2623
[SYMCHK] Checksum: 0x00aa62c8
[SYMCHK] NumSyms: 0
[SYMCHK] SymType: SymNone
[SYMCHK] ModName: node
[SYMCHK] ImageName: c:\Program Files\nodejs\node.exe
[SYMCHK] LoadedImage: c:\Program Files\nodejs\node.exe
[SYMCHK] pdb: ""
[SYMCHK] CV: RSDS
[SYMCHK] CV DWORD: 0x53445352
[SYMCHK] CV Data: d:\jenkins\workspace\nodejs-msi-julien\d8c2e2bb\Release\node.pdb
[SYMCHK] pdb Sig: 0
[SYMCHK] pdb7 Sig: {00000000-0000-0000-0000-000000000000}
[SYMCHK] Age: 0
[SYMCHK] pdb Matched: TRUE
[SYMCHK] DBG Matched: TRUE
[SYMCHK] Line nubmers: FALSE
[SYMCHK] Global syms: FALSE
[SYMCHK] Type Info: FALSE
[SYMCHK] ------------------------------------
SymbolCheckVersion 0x00000002
Result 0x00010001
DbgFilename node.dbg
DbgTimeDateStamp 0x00000000
DbgSizeOfImage 0x00000000
DbgChecksum 0x00000000
pdbFilename d:\jenkins\workspace\nodejs-msi-julien\d8c2e2bb\Release\node.pdb
pdbSignature {5DAD4445-5A83-417D-BDB6-BE0655EE650D}
pdbDbiAge 0x00000001
[SYMCHK] [ 0x00000000 - 0x00010001 ] Checked "c:\Program Files\nodejs\node.exe"
SYMCHK: node.exe FAILED - node.pdb mismatched or not found
SYMCHK: FAILED files = 1
SYMCHK: PASSED + IGNORED files = 0
很明显在这种情况下是无法查找到pdb文件的，但通过这个命令可以获得一些信息，比如这个node.exe所对应的pdb 文件最初的位置，pdbFilename在d:\jenkins\workspace\nodejs-msi-julien\d8c2e2bb\Release\node.pdb。
如果你通过某种渠道得到了这个node.pdb,你可以按照这个路径放置node.pdb, 然后就可以调试了：）
用Windbg查看pdb文件路径 - 方法(1)
这里以百度云管家为例，启动Windbg并Attach上百度云管家，执行命令!lmi
0:000> !lmi baiduyunguanjia
Loaded Module Info: [baiduyunguanjia]
Module: BaiduYunGuanjia
Base Address: 0000000000360000
Image Name: C:\Users\chenju\AppData\Roaming\Baidu\BaiduYunGuanjia\BaiduYunGuanjia.exe
Machine Type: 332 (I386)
Time Stamp: 55f9de3e Thu Sep 17 05:25:18 2015
Size: 59a000
CheckSum: 58a857
Characteristics: 102
Debug Data Dirs: Type Size VA Pointer
CODEVIEW 88, 4079d8, 406dd8 RSDS - GUID: {DB20D638-5930-4F7A-BA34-2D64C7A4491A}
Age: 1, pdb: D:\cygwin\home\scmpf\compiler_src\jinjiqiang_1581659_win64\0\mc\wangpan\windows\yunbrowser\output\pdb\YunUi.pdb
?? 14, 407a60, 406e60 [Data not mapped]
Image Type: FILE - Image read successfully from debugger.
C:\Users\chenju\AppData\Roaming\Baidu\BaiduYunGuanjia\BaiduYunGuanjia.exe
Symbol Type: NONE - pdb not found from image path.
Load Report: no symbols loaded
用Windbg查看pdb文件路径 - 方法(2)
结合使用!sym和reload
0:043> !sym noisy
noisy mode - symbol prompts on
0:043> .reload /f BaiduYunGuanjia.exe
SYMSRV: c:\symbols\YunUi.pdb\DB20D63859304F7ABA342D64C7A4491A1\YunUi.pdb not found
SYMSRV: http://msdl.microsoft.com/download/symbols/YunUi.pdb/DB20D63859304F7ABA342D64C7A4491A1/YunUi.pdb not found
DBGHELP: C:\Users\chenju\AppData\Roaming\Baidu\BaiduYunGuanjia\YunUi.pdb - file not found
DBGHELP: D:\cygwin\home\scmpf\compiler_src\jinjiqiang_1581659_win64\0\mc\wangpan\windows\yunbrowser\output\pdb\YunUi.pdb - file not found
*** ERROR: Module load completed but symbols could not be loaded for C:\Users\chenju\AppData\Roaming\Baidu\BaiduYunGuanjia\BaiduYunGuanjia.exe
DBGHELP: BaiduYunGuanjia - no symbols loaded
************* Symbol Loading Error Summary **************
Module name Error
BaiduYunGuanjia The system cannot find the file specified : srv*c:\symbols*http://msdl.microsoft.com/download/symbols
The SYMSRV client failed to find a file iån the UNC store, or there
is an invalid UNC store (an invalid path or the pingme.txt file is
not present in the root directory), or the file is present in the
symbol server exclusion list.
用Windbg查看pdb文件路径 - 方法(3)
使用命令!chksym或者是!itoldyouso，发现两者的结果一样
0:043> !chksym baiduyunguanjia
C:\Users\chenju\AppData\Roaming\Baidu\BaiduYunGuanjia\BaiduYunGuanjia.exe
Timestamp: 55F9DE3E
SizeOfImage: 59A000
pdb: D:\cygwin\home\scmpf\compiler_src\jinjiqiang_1581659_win64\0\mc\wangpan\windows\yunbrowser\output\pdb\YunUi.pdb
pdb sig: DB20D638-5930-4F7A-BA34-2D64C7A4491A
age: 1
用Dumpbin查看pdb文件路径
dumpbin /pdbpath baiduyunguanjia.exe
查看静态链接库的pdb文件
Static linking使用/Z7或者/Zi选项。使用/Z7选项的话，不会生成pdb文件，所有调试信息保存在.obj文件中。使用/Zi选项将生成一个pdb文件，但这个pdb文件的路径却只能用文字编辑器打开.lib文件来查看。
我们习惯于将第三方静态库预先编译好，传到source server上。然后在其他工程中来link这个库文件。潜在的一个风险如下所示，就是找不到pdb文件，因为lib文件所对应的pdb文件路径和实际的pdb文件路径可能不一致，结果linking的对象没有debug信息。
libldap_r.lib(controls.obj) : warning LNK4099: PDB 'libldap_r.pdb' was not found with 'libldap_r.lib(controls.obj)' or at 'C:\Projects\trunk\components\csf-person\out\windows-x86-MD-unicode-vs2015-rel\bin\libldap_r.pdb'; linking object as if no debug info
libldap_r.lib(tls2.obj) : warning LNK4099: PDB 'libldap_r.pdb' was not found with 'libldap_r.lib(tls2.obj)' or at 'C:\Projects\trunk\components\csf-person\out\windows-x86-MD-unicode-vs2015-rel\bin\libldap_r.pdb'; linking object as if no debug info
libldap_r.lib(messages.obj) : warning LNK4099: PDB 'libldap_r.pdb' was not found with 'libldap_r.lib(messages.obj)' or at 'C:\Projects\trunk\components\csf-person\out\windows-x86-MD-unicode-vs2015-rel\bin\libldap_r.pdb'; linking object as if no debug info
参考阅读以下链接：
