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Table of Contents
- Operation
- Interactive patching
- ; (semicolon)
- BACKOUT
- Error Messages
- DISPLAY
- Error Messages
- EXIT
- FIND
- HELP
- LIST
- LOG
- Error Messages
- MODIFY
- Error Messages
- OFFSET
- OPEN
- PATCHFILE
- QUIT
- SAVE
- SHOW
- Error Messages
- SOM
- SYMBOL
- Error Message
- USE
- VERSION
Use the SOMPATCH utility for binary modification of a native mode
spectrum object module (SOM) program or library file. Binary modification
is referred to informally as patching.
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WARNING! Do not use this utility without service center support.
Unauthorized use will void your warranty and may cause data loss.
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This utility is capable of tracking all of the modifications that it makes to a
SOM file. This history is kept in the SOM file in an unloadable buffer space,
which affects neither performance nor memory usage of the program. This buffer
space is provided by linking in a ypatch file when the executable SOM file is
created.
The ypatch file to be linked into SOM 0 of NL.PUB.SYS creates loadable
code because the storage area needs to be in the boot images, and the
SAINT utility does not store unloadable spaces in the boot images.
This special ypatch file is ypatsom0 and would normally be used only
in the NL.
The SOMPATCH utility will accept as input a file not linked with a
ypatch file. However, you should use it to build files with
the ypatch file, so that at any time you can view and query the file and patch
history. If the ypatch file is not linked in, no logging is available. All
native-mode system products are required to link with the ypatch file if the
product is to be supported in the field to any extent with binary patching.
MPE/iX contains a symbolic debugger that can be used for memory patching or to
generate patches that you will permanently apply with the SOMPATCH
utility.
To patch compatibility mode files, use the slpatch and patch
files.
Input Files
The SOMPATCH utility has one required file and that is the input file
to be queried or patched. This file can be a relocatable or executable library
SOM or a program SOM. The SOMPATCH utility treats this file as a
read-only file. No backup copy is made; however, a QUIT command can be
used at any time, with this file remaining unchanged.
The user can also optionally specify a second input file, a script file of
modification instructions and logging information, referred to hereafter as a
patch file. A patch file is an ASCII file, created by an editor
or other text utility, that specifies one or more commands to the
SOMPATCH utility. The patch file is given on the command line, or by
the USE command, to apply one or more patches. Patches can also be
applied interactively. Refer to the paragraph "Interactive Patching" under
"Operation."
Error Handling
The input file is maintained in its original state until the user types
EXIT or SAVE. If there is a system malfunction between the
EXIT command and the colon prompt, purge the possibly modified file
and start over with a backup. If no backup is available, redo all patches on
the possibly modified input file. (This may cause the oval/verify option on the
modify command to generate false error messages). As long as the ypatch file
was used, all old patches can be backed out.
Output File
The user can optionally specify an output list file containing all patch
instructions issued, any error messages, and any displays. This is saved as a
permanent disk file, unless overridden by a user-specified file equation.
The SOMPATCH utility writes to the primary file all patches that did
not contain errors. If a patch has several modify instructions, or the count is
greater than one for one modify, and one or more generated errors, none of the
modifies for that patch are applied. Patches are broken up by LOG
commands.
JCW Handling
The SOMPATCH utility sets two JCWs: the system JCW and a private JCW,
PATCHJCW. PATCHJCW is set as follows:
No error -- value of 0
Nonfatal error -- value of 1
Fatal error -- value of 2
Really fatal -- value of 3 (Program will gracefully abort.)
Under these error conditions, the SOMPATCH utility also sets the
system JCW to the standard MPE values, OKAY, WARN, and
FATAL.
Preparation for Use
Patching modifies object code when a problem cannot be easily or conveniently
fixed in source code. The SOMPATCH utility is used to fix a software
problem without recompiling or relinking. A patch is usually developed using
the symbolic debugger, with the patch applier using the SOMPATCH
utility to permanently install a modification in the defective software.
You should link in one of two available ypatch files when you build the product
that you are patching. Which one you link depends on how much the product is
patched.
When linking a single-SOM library, or a program file, specify the ypatch file
you want to use at the end of the source object files for the user's executable
SOM. For example:
link>LINK from=mysomfile,ypatch4.lib.sys; to=myprogfile
When linking a multi-SOM library, specify the desired ypatch file at the end of
the source object files for each SOM. For example:
link>LINK from=mymod1,mymod2,mymod3,ypatch4.lib.sys; to=myint1
link>LINK from=mymod4,mymod5,mymod6,ypatch4.lib.sys; to=myint2
link>BUILDXL mynl
link>LINK from=myint1,myint2; to=mynl
HP product files should contain a minimum of 300 bytes of storage for each
anticipated patch. Refer to "Error Handling" in this chapter for information
of how to handle errors when this storage area overflows.
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