[20210304]bbed的assign命令.txt

[20210304]bbed的assign命令.txt --//曾经写过一篇bbed的assign命令，实际上使用它使得使用bbed变得更加简单快捷，不用考虑大小头问题，比modify修改更加方便快捷。 --//昨天偶然发现assign还可以不写offset完成同样的功能以及assign存在的一些弊端。我通过一个删除记录并恢复部分记录来说明问题： 1.环境： SCOTT@book> @ ver1 PORT_STRING                    VERSION        BANNER ------------------------------ -------------- -------------------------------------------------------------------------------- x86_64/Linux 2.4.xx            11.2.0.4.0     Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production SCOTT@book> create table deptx as select * from dept; Table created. SCOTT@book> select rowid,deptx.* from deptx; ROWID                  DEPTNO DNAME          LOC ------------------ ---------- -------------- ------------- AAAWHpAAEAAAAKrAAA         10 ACCOUNTING     NEW YORK AAAWHpAAEAAAAKrAAB         20 RESEARCH       DALLAS AAAWHpAAEAAAAKrAAC         30 SALES          CHICAGO AAAWHpAAEAAAAKrAAD         40 OPERATIONS     BOSTON SCOTT@book> @ rowid AAAWHpAAEAAAAKrAAA     OBJECT       FILE      BLOCK        ROW ROWID_DBA            DBA                  TEXT ---------- ---------- ---------- ---------- -------------------- -------------------- ----------------------------------------      90601          4        683          0  0x10002AB           4,683                alter system dump datafile 4 block 683 ; SCOTT@book> delete deptx where deptno in (20,40); 2 rows deleted. SCOTT@book> commit ; Commit complete. SCOTT@book> alter system checkpoint ; System altered. 2.尝试恢复: --//删除后表示从0x2c->0x3c，注意不包括出现行迁移的情况。 $ echo -e "set dba 4,683\nset offset 0\n$(seq 4 | xargs -IQ echo -e 'find /x 3c curr \nset offset +2')" | rlbbed BBED: Release 2.0.0.0.0 - Limited Production on Thu Mar 4 09:29:29 2021 Copyright (c) 1982, 2011, Oracle and/or its affiliates.  All rights reserved. ************* !!! For Oracle Internal Use only !!! *************** BBED> set count 64         COUNT           64 BBED> set width 160         WIDTH           160 BBED>   DBA             0x010002ab (16777899 4,683) BBED>   OFFSET          0 BBED>  File: /mnt/ramdisk/book/users01.dbf (4)  Block: 683                                                  Offsets:  146 to  209                                               Dba:0x010002ab ------------------------------------------------------------------------------------------------------------------------------------------------  3c1f241f 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000  <64 bytes per line> BBED>   OFFSET          148 BBED>  File: /mnt/ramdisk/book/users01.dbf (4)  Block: 683                                                  Offsets: 8096 to 8159                                               Dba:0x010002ab ------------------------------------------------------------------------------------------------------------------------------------------------  3c020302 c1290a4f 50455241 54494f4e 5306424f 53544f4e 2c000302 c11f0553 414c4553 07434849 4341474f 3c020302 c1150852 45534541 52434806 44414c4c  <64 bytes per line> BBED>   OFFSET          8098 BBED>  File: /mnt/ramdisk/book/users01.dbf (4)  Block: 683                                                  Offsets: 8140 to 8191                                               Dba:0x010002ab ------------------------------------------------------------------------------------------------------------------------------------------------  3c020302 c1150852 45534541 52434806 44414c4c 41532c00 0302c10b 0a414343 4f554e54 494e4708 4e455720 594f524b 03068098  <64 bytes per line> BBED>   OFFSET          8142 BBED> BBED-00212: search string not found BBED>   OFFSET          8144 --//可以发现删除表示偏移在8096，8140。 --//正常执行如下： assign dba  4,683 offset 8096＝0x2c assign dba  4,683 offset 8140＝0x2c --//可以去掉offset，执行如下，这是我不小心写错才发现可以这样操作： assign dba  4,683 8096=0x2c assign dba  4,683 8140=0x2c BBED> assign dba 4,683  8096=0x2c Warning: contents of previous BIFILE will be lost. Proceed? (Y/N) y ub1 rowdata[0]                              @8096     0x2c --//你可以发现修改的位置还是offset 8096的位置。 BBED> x  /rncc dba 4,683 offset 8096 rowdata[0]                                  @8096 ---------- flag@8096: 0x2c (KDRHFL, KDRHFF, KDRHFH) lock@8097: 0x02 cols@8098:    3 col    0[2] @8099: 40 col   1[10] @8102: OPERATIONS col    2[6] @8113: BOSTON BBED> sum apply  dba 4,683 Check value for File 4, Block 683: current = 0xe1d0, required = 0xe1d0 BBED> verify dba 4,683 DBVERIFY - Verification starting FILE = /mnt/ramdisk/book/users01.dbf BLOCK = 683 Block Checking: DBA = 16777899, Block Type = KTB-managed data block data header at 0xf54e7c kdbchk: the amount of space used is not equal to block size         used=98 fsc=42 avsp=7946 dtl=8064 Block 683 failed with check code 6110 --//我仅仅恢复1条，理论将修改fsc，这样比较麻烦。 --//dtl - used -fsc = avsp. --//8064-98-42 = 7924 BBED> set dba 4,683         DBA             0x010002ab (16777899 4,683) BBED> p kdbh.kdbhavsp sb2 kdbhavsp                                @134      7946 --//偏移在134. 占2个字节。 BBED> assign 134=7924; sb2 kdbhavsp                                @134      7924 --//我还可以写成： BBED> assign 135=7925; sb2 kdbhavsp                                @134      7925 --//bbed的assign会通过偏移计算正确的位置，对齐赋值。当然我并不建议这样操作，最佳的方式应该执行如下： BBED> assign kdbh.kdbhavsp=7924; sb2 kdbhavsp                                @134      7924 BBED> sum apply  dba 4,683 Check value for File 4, Block 683: current = 0xe02e, required = 0xe02e BBED> verify dba 4,683 DBVERIFY - Verification starting FILE = /mnt/ramdisk/book/users01.dbf BLOCK = 683 Block Checking: DBA = 16777899, Block Type = KTB-managed data block data header at 0xf76e7c kdbchk: space available on commit is incorrect         tosp=7992 fsc=42 stb=2 avsp=7924 Block 683 failed with check code 6111 --//avsp+stb+fsc=tosp. --//7924+2+42 = 7968 BBED> p kdbh.kdbhtosp sb2 kdbhtosp                                @136      7992 BBED> assign 136=7968 sb2 kdbhtosp                                @136      7968 BBED> sum apply  dba 4,683 Check value for File 4, Block 683: current = 0xe036, required = 0xe036 BBED> verify dba 4,683 DBVERIFY - Verification starting FILE = /mnt/ramdisk/book/users01.dbf BLOCK = 683 3.验证看看。 SCOTT@book> alter system flush buffer_cache ; System altered. SCOTT@book> select rowid,deptx.* from deptx; ROWID                  DEPTNO DNAME          LOC ------------------ ---------- -------------- ------------- AAAWHpAAEAAAAKrAAA         10 ACCOUNTING     NEW YORK AAAWHpAAEAAAAKrAAC         30 SALES          CHICAGO AAAWHpAAEAAAAKrAAD         40 OPERATIONS     BOSTON --//恢复正确。 4.继续尝试： --//不过我发现assign也存在1个缺点 BBED> p dba 4,683 kcbh struct kcbh, 20 bytes                       @0    ub1 type_kcbh                            @0        0x06    ub1 frmt_kcbh                            @1        0xa2    ub1 spare1_kcbh                          @2        0x00    ub1 spare2_kcbh                          @3        0x00    ub4 rdba_kcbh                            @4        0x010002ab    ub4 bas_kcbh                             @8        0x17689880    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~    ub2 wrp_kcbh                             @12       0x0003    ub1 seq_kcbh                             @14       0x03    ub1 flg_kcbh                             @15       0x06 (KCBHFDLC, KCBHFCKV)    ub2 chkval_kcbh                          @16       0xe036    ub2 spare3_kcbh                          @18       0x0000 --//尝试修改kcbh.bas_kcbh. BBED> assign 8=0x77689880 ub4 bas_kcbh                                @8        0x77689880 --//0x77689880 = 2003343488 BBED> assign 8=2003343488 ub4 bas_kcbh                                @8        0x77689880 --//10,16 进制一样没有问题。 --//但是这样修改存在缺点： BBED> assign 8=0x87689880 BBED-00206: out of range offset (87689880) --//第1位不能大于0x8. --//0x87689880 = 2271778944 BBED> assign 8=2271778944 BBED-00207: invalid offset specifier (2271778944) BBED> assign 8=0xa7689880 BBED-00207: invalid offset specifier (a7689880) --//0xa7689880 = 2808649856 BBED> assign 8=2808649856 BBED-00207: invalid offset specifier (2808649856) --//注意两个提示无一样。 --//也就是assign无法修改4字节内容时，第1位不能是大于0x8. BBED> assign kcbh.bas_kcbh=0x87689880 BBED-00206: out of range offset (87689880) BBED> assign kcbh.bas_kcbh=0xa7689880 BBED-00207: invalid offset specifier (a7689880) --//如果你的修改遇到这样的情况就比较麻烦了，感觉这个是bbed的bug。 BBED> assign kcbh.bas_kcbh=0x17689880 ub4 bas_kcbh                                @8        0x17689880 BBED> assign offset 8 = 0xa7 ub4 bas_kcbh                                @8        0x000000a7 --//你可以发现这个时候assign将偏移转换为一个整体，只能使用modify修改，实际上modify一样有这个问题存在。 --//注意modify修改要考虑大小头问题。 --//我以前的测试： BBED> modify /x 8affffff dba 101,1 offset 40 BBED-00209: invalid number (8affffff) ------------ --//还原： BBED> assign kcbh.bas_kcbh=0x17689880 ub4 bas_kcbh                                @8        0x17689880 5.总结： --//总之知道bbed assign与modify这些缺点，才能更好的利用这个工具。