Symbol Storage Format

SymStore uses the file system itself as a database. It creates a large tree of directories, with directory names based on such things as the symbol file time stamps, signatures, age, and other data.

For example, after several different acpi.dbgs have been added to the server, the directories could look like this:


Directory of \\mybuilds\symsrv\acpi.dbg
10/06/1999  05:46p      <DIR>          .
10/06/1999  05:46p      <DIR>          ..
10/04/1999  01:54p      <DIR>          37cdb03962040
10/04/1999  01:49p      <DIR>          37cdb04027740
10/04/1999  12:56p      <DIR>          37e3eb1c62060
10/04/1999  12:51p      <DIR>          37e3ebcc27760
10/04/1999  12:45p      <DIR>          37ed151662060
10/04/1999  12:39p      <DIR>          37ed15dd27760
10/04/1999  11:33a      <DIR>          37f03ce962020
10/04/1999  11:21a      <DIR>          37f03cf7277c0
10/06/1999  05:38p      <DIR>          37fa7f00277e0
10/06/1999  05:46p      <DIR>          37fa7f01620a0

In this example, the lookup path for the acpi.dbg symbol file might look like this: \\mybuilds\symsrv\acpi.dbg\37cdb03962040.

Three files may exist inside the lookup directory:

  1. acpi.dbg, if the file was stored

  2. file.ptr with a path to the actual symbol file, if a pointer was stored

  3. refs.ptr, which contains a list of all the current locations for acpi.dbg with this timestamp and image size that are currently added to the symbol store

Displaying the directory listing of \\mybuilds\symsrv\acpi.dbg\37cdb03962040 gives the following:


10/04/1999  01:54p                  52 file.ptr
10/04/1999  01:54p                  67 refs.ptr

The file file.ptr contains the text string "\\mybuilds\symbols\x86\2128.chk\symbols\sys\acpi.dbg". Since there is no file called acpi.dbg in this directory, the debugger will try to find the file at \\mybuilds\symbols\x86\2128.chk\symbols\sys\acpi.dbg.

The contents of refs.ptr are used only by SymStore, not the debugger. This file contains a record of all transactions that have taken place in this directory. A sample line from refs.ptr might be:


0000000026,ptr,\\mybuilds\symbols\x86\2128.chk\symbols\sys\acpi.dbg

This shows that a pointer to \\mybuilds\symbols\x86\2128.chk\symbols\sys\acpi.dbg was added with transaction "0000000026".

Some symbol files stay constant through various products or builds or a particular product. One example of this is the Windows 2000 file msvcrt.pdb. A directory listing of \\mybuilds\symsrv\msvcrt.pdb shows that only two versions of msvcrt.pdb have been added to the symbols server:


Directory of \\mybuilds\symsrv\msvcrt.pdb
10/06/1999  05:37p      <DIR>          .
10/06/1999  05:37p      <DIR>          ..
10/04/1999  11:19a      <DIR>          37a8f40e2
10/06/1999  05:37p      <DIR>          37f2c2272

However, a directory listing of \\mybuilds\symsrv\msvcrt.pdb\37a8f40e2 shows that refs.ptr has several pointers in it.


Directory of \\mybuilds\symsrv\msvcrt.pdb\37a8f40e2
10/05/1999  02:50p              54     file.ptr
10/05/1999  02:50p           2,039     refs.ptr

The contents of \\mybuilds\symsrv\msvcrt.pdb\37a8f40e2\refs.ptr are the following:


0000000001,ptr,\\mybuilds\symbols\x86\2137\symbols\dll\msvcrt.pdb
0000000002,ptr,\\mybuilds\symbols\x86\2137.chk\symbols\dll\msvcrt.pdb
0000000003,ptr,\\mybuilds\symbols\x86\2138\symbols\dll\msvcrt.pdb
0000000004,ptr,\\mybuilds\symbols\x86\2138.chk\symbols\dll\msvcrt.pdb
0000000005,ptr,\\mybuilds\symbols\x86\2139\symbols\dll\msvcrt.pdb
0000000006,ptr,\\mybuilds\symbols\x86\2139.chk\symbols\dll\msvcrt.pdb
0000000007,ptr,\\mybuilds\symbols\x86\2140\symbols\dll\msvcrt.pdb
0000000008,ptr,\\mybuilds\symbols\x86\2140.chk\symbols\dll\msvcrt.pdb
0000000009,ptr,\\mybuilds\symbols\x86\2136\symbols\dll\msvcrt.pdb
0000000010,ptr,\\mybuilds\symbols\x86\2136.chk\symbols\dll\msvcrt.pdb
0000000011,ptr,\\mybuilds\symbols\x86\2135\symbols\dll\msvcrt.pdb
0000000012,ptr,\\mybuilds\symbols\x86\2135.chk\symbols\dll\msvcrt.pdb
0000000013,ptr,\\mybuilds\symbols\x86\2134\symbols\dll\msvcrt.pdb
0000000014,ptr,\\mybuilds\symbols\x86\2134.chk\symbols\dll\msvcrt.pdb
0000000015,ptr,\\mybuilds\symbols\x86\2133\symbols\dll\msvcrt.pdb
0000000016,ptr,\\mybuilds\symbols\x86\2133.chk\symbols\dll\msvcrt.pdb
0000000017,ptr,\\mybuilds\symbols\x86\2132\symbols\dll\msvcrt.pdb
0000000018,ptr,\\mybuilds\symbols\x86\2132.chk\symbols\dll\msvcrt.pdb
0000000019,ptr,\\mybuilds\symbols\x86\2131\symbols\dll\msvcrt.pdb
0000000020,ptr,\\mybuilds\symbols\x86\2131.chk\symbols\dll\msvcrt.pdb
0000000021,ptr,\\mybuilds\symbols\x86\2130\symbols\dll\msvcrt.pdb
0000000022,ptr,\\mybuilds\symbols\x86\2130.chk\symbols\dll\msvcrt.pdb
0000000023,ptr,\\mybuilds\symbols\x86\2129\symbols\dll\msvcrt.pdb
0000000024,ptr,\\mybuilds\symbols\x86\2129.chk\symbols\dll\msvcrt.pdb
0000000025,ptr,\\mybuilds\symbols\x86\2128\symbols\dll\msvcrt.pdb
0000000026,ptr,\\mybuilds\symbols\x86\2128.chk\symbols\dll\msvcrt.pdb
0000000027,ptr,\\mybuilds\symbols\x86\2141\symbols\dll\msvcrt.pdb
0000000028,ptr,\\mybuilds\symbols\x86\2141.chk\symbols\dll\msvcrt.pdb
0000000029,ptr,\\mybuilds\symbols\x86\2142\symbols\dll\msvcrt.pdb
0000000030,ptr,\\mybuilds\symbols\x86\2142.chk\symbols\dll\msvcrt.pdb

This shows that the same msvcrt.pdb was used for multiple builds of symbols for Windows 2000 stored on \\mybuilds\symsrv.

Here is an example of a directory that contains a mixture of file and pointer additions:


Directory of E:\symsrv\dbghelp.dbg\38039ff439000
10/12/1999  01:54p         141,232     dbghelp.dbg
10/13/1999  04:57p              49     file.ptr
10/13/1999  04:57p             306     refs.ptr

In this case, refs.ptr has the following contents:


0000000043,file,e:\binaries\symbols\retail\dll\dbghelp.dbg
0000000044,file,f:\binaries\symbols\retail\dll\dbghelp.dbg
0000000045,file,g:\binaries\symbols\retail\dll\dbghelp.dbg
0000000046,ptr,\\MyDir\bin\symbols\retail\dll\dbghelp.dbg
0000000047,ptr,\\foo2\bin\symbols\retail\dll\dbghelp.dbg

Thus, transactions 43, 44, and 45 added the same file to the server, and transactions 46 and 47 added pointers. If transactions 43, 44, and 45 are deleted, then the file dbghelp.dbg will be deleted from the directory. The directory will then have the following contents:


Directory of e:\symsrv\dbghelp.dbg\38039ff439000
10/13/1999  05:01p                   49 file.ptr
10/13/1999  05:01p                 130 refs.ptr

Now file.ptr contains "\\foo2\bin\symbols\retail\dll\dbghelp.dbg", and refs.ptr contains


0000000046,ptr,\\MyDir\bin\symbols\retail\dll\dbghelp.dbg
0000000047,ptr,\\foo2\bin\symbols\retail\dll\dbghelp.dbg

Whenever the final entry in refs.ptr is a pointer, the file file.ptr will exist and contain the path to the associated file. Whenever the final entry in refs.ptr is a file, no file.ptr will exist in this directory. Therefore, any delete operation that removes the final entry in refs.ptr may result in file.ptr being created, deleted, or changed.

 

 

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