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PATCH22 version 1.2 (8 August 1991) Jurgen A. Doornik 1. Introduction. ___________________________________________________________________ PATCH22 can be used to make patches to any file. The main advantage is that it gives a format to distribute patches. You can avoid detailed description of DEBUG commands. Instead you just supply PATCH22 with the patch in a *.P22 file. PATCH22 can also accept patches on the command line. Patches have a C-like character constant format, making it easy to enter hexadecimal values. PATCH22 will show the context of the patch, but can work silently as well. PATCH22 is written in C (source code provided), and faster than many other public domain patch programs. PATCH22 is written by Jurgen Doornik. The disk (or archive) should contain the following files: PATCH22.C - source code (MSC 6.0) PATCH22.DOC - this documentation PATCH22.EXE - executable file. *.P22 - patch files (if any). If you have any suggestions for improvement, or find any bugs, please report them to me, via email: BITNET/EARN: ECONZ@UK.AC.OX.VAX or by mail: Jurgen Doornik Institute of Economics and Statistics St Cross Building, Manor Road Oxford OX1 3UL United Kingdom Special thanks are due to Arjen Merckens, who spotted many bugs and gave useful suggestions. Needless to say that all remaining errors are mine. Arjen is author of BOOTCOMP.zip: a package which uses the original BIOS interrupts to detect ANY changes to the bootsector [possibly] made by a virus. He also wrote ACD (ChDir FAST; more features than LCD/NCD and free). 2. How to execute PATCH22. ___________________________________________________________________ PATCH22 can accept patches on the command line or from a file. 2.1 Command line patch. _______________________ form: PATCH22 fname patch fname - file to be patched patch - patch command: +##*##si?search_text?new_text? If the patch line on the command line contains spaces, it must be enclosed in double quotes. examples: PATCH22 test.exe ?abc?cde? replace (with confirmation) every occurrence of abc with cde. PATCH22 test.exe "?a c?c e?" replace (with confirmation) every occurrence of a c with c e. If in the last example the double quotes are omitted, PATCH22 will think that the patch is ?a, and tell you that it expects a ?. 2.2 Command file patch. _______________________ form: PATCH22 @fname @fname - file with (multiple) PATCH22 commands, with format: fname +##*##si?Search_text?New_text? If the patch command is in a file, line breaks in the Search_text and New_text are ignored. example: PATCH22 @test.p22 where test.p22 looks like: ; comment lines start with a semi colon. test.exe ?a c?c e? ; line breaks in the Search_text and New_text are ignored: test.exe ?a cdd?c edd? ; equals test.exe ?a cd d?c ed d? ; note that no double quotes are used here. 3. The patch command. ___________________________________________________________________ form: +##*##si?Search_text?New_text?" syntax: patch = Conditions "?" Search_text "?" New_text "?". The syntax reads as follows: "a" indicates a literal text a. [b] indicates an optional item b. {c} indicates one or more occurences of c. d|e indicates either d or e. 3.1 The Conditions. syntax: Conditions = [Offset][Max_#_patches][Silent_mode]. Offset = ["+"] long | "-" long. Max_#_patches= "*" int. long = ["0"] ["x" | "X"] digit {digit}. int = ["0"] ["x" | "X"] digit {digit}. Silent_mode = "s". Ignore_case = "i". The Offset is a signed long integer, while the maximum number of patches is a * followed by an unsigned integer. These integers can be decimal, hexadecimal (leading 0x or 0X) or octal (leading 0). An s indicates silent mode. Each number is read up to the first character which is not part of it. An i indicates case insensitive searching. The search string is converted to uppercase, so comparosion is mad in uppercase. The default is case sensitivity. The Conditions field can be empty, in which case the Offset is zero, every patch has to be confirmed, and there is no maximum number of patches. examples: 0x131d Offset is 131d (hexadecimal), no maximum number of patches. +0177*12 Offset is 177 (octal), not more than 12 patches. +177*12 Offset is 177 (decimal), not more than 12 patches. *1s Zero Offset, one patch, silent mode (no prompt for confirmation of patch). *09?n?n? The 0 in the Max_#_patches field indicates an octal number, but 9 is not octal, so scanning stops and a 0 is read. The 9 then is interpreted as the Offset. However a request of 0 patches generates an error message. 3.2 The Search_text and New_text. _________________________________ syntax: Search_text = [ {chars | escape_code} ]. escape_code = "\a" | "\b" | "\f" | "\n" | "\r" | "\t" | "\v" | "\\" | "\?" | "\'" | "\"" | "\" octal [octal [octal]] | "\x" hex [hex] | "\w" hex [hex [hex [hex]]] | "\h" hex hex {hex hex}. New_text = Search_text. The text is a C-type character constant. It may contain the C escape codes \a (07h), \b (08h), \f (0Ch), \n (0Ah), \r (0Dh), \t (09h), \v (0Bh); or \### (octal byte, not more than 3 digits); \x## (hexadecimal byte, not more than 2 digits). \w#### (hexadecimal word, not more than 4 digits). The characters \ ? ' " must be written as: \" \\ \? \' \". An additional escape code is \h, which indicates that the rest of the text (up to the question mark which indicates the end) consists of two-digit hexadecimal numbers. examples: \h0d0a00 three hexadecimal numbers: carriage return, line feed, null character. \r\n\0 the same three characters, in escape codes, (note that \0 is an octal number). «gr_» literal text. \x1\xa\wb000 two bytes and one word: 01h 0Ah B000h (since on IBM PC's low order byte comes before hi order byte this is written as 01h 0Ah 00h B0h) 3.3 How the patch is executed. ______________________________ Assume non-silent mode (default). First PATCH22 locates the search string. If the search string is empty, the first byte in the file matches. Then PATCH22 displays the search string. Next it moves the file pointer Offset bytes from the start of the found search string. (If the Offset is negative, PATCH22 will move backwards.) Then it will display the context with the bytes selected for modi- fication highlighted. PATCH22 will also display the new text, and prompt for confirmation of the patch. The file will be unchanged in size, unless the patch extends beyond the current end of the file. The time and date stamp of the file are updated. Example 1: replace a text with a new text *1?\he8d30e?\h909090? Only one patch is requested. Example 2: modify text at a certain offset from an identification text 168*1?<gr_>?\h010a00b0? Modify the 4 bytes at offset 168 (decimal) from the start of <gr_>. Don't make more than one patch. Example 3: search for a certain text. ?\h303132?? PATCH22 will look for 012 (which has hexadecimal ASCII code 30,31,32). PATCH22 will display the context without any highlights, since the replace string is empty. If if the patch is confirmed, none will be made (although PATCH22 will report it as a patch). Example 4: modify a text at a certain location in the file. 0x131d??\h707070? There is no search string, so the first byte will match. Then at offset 131d from the start the text ppp will be written. Note that this will overwrite whatever is at offset 131d..131f. With an empty search string, there will be only one search, and hence not more than one possible patch. Example 5: case insensitive patching. i?\x73ymbol?symbol? The search string is converted to upper- case before the escape sequences are converted. So here the search string becomes sYMBOL. The first letter must match exactly, the rest is case insensitive. Examples of matching words are sYmBol and sYMBol, a non matching word is Symbol. 4. Some notes. ___________________________________________________________________ I have used PATCH22 to write a configuration program for PC-GIVE (an econometric program). In the help code, for example, the configurable data is preceded by a signature. Using PATCH22, the data after the signature can be modified in the executable file. Of course the signature has to be unique if you want to do a silent patch. NOTE that LINK has the capability to remove sequences of repeated bytes (/Exepack). So make sure that you initialize the configurable data to have different bytes. PATCH22 has a very simple password protection scheme, which I shall use as an illustration. By default there is no password, but when a password has been installed, it has to be the first argument on the command line, for PATCH22 to execute. The declaration in PATCH22.c looks like: char sP22[] = { '«','p','2','2','_','»' }; /* signature */ char sPassword[] = "\0 gf ggv aewf bvsbago";/* password: 21 chars+\0 */ /* leading \0 indicates no password; rest avoids .exe compression */ Of course, you must be certain that the two strings are stored consecutively in the executable (otherwise make it into one string). Do not write char sPassword[22] = ""; This, in combination with /E, cannot be patched. In this example «p22_» is the signature, written like this to avoid the ending '\0'. To set the password to "user": PATCH22 patch22.exe 6?«p22_»?user\0? The 6 is the offset from the start of «p22_». Then, to change the password: PATCH22 user patch22.exe 6?«p22_»?anonymous\0? If you have any useful (and legal!) patches of interest, I look forward to receiving them. They can then be included with PATCH22. 5. License, warranty and disclaimer. ___________________________________________________________________ PATCH22 is written by Jurgen A. Doornik for the IBM PC using DOS 2.0 or later. You may distribute PATCH22 given these restrictions: o the program shall be supplied in its original, unmodified form, which includes this documentation; o no fee is charged; o the program may be included, or bundled, with any other programs/products (including for-profit products) on the condition that I shall receive one copy of the program/ product (as given/sold), and an update each time PATCH22 is bundled with the update. o You may use and modify the source code for personal pur- poses only, and on the condition that I shall receive a copy of the modified version. For any other use contact me. Jurgen Doornik BITNET: ECONZ@UK.AC.OX.VAX Nuffield College Oxford OX1 1NF United Kingdom DISCLAIMER: I shall not be responsible for any damages or inconveniences incurred due to the usage of PATCH22, nor to the usage of files patched with PATCH22. I shall not be liable if PATCH22 is used to patch files illegally. More formally: IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW WILL JURGEN DOORNIK BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY LOST PROFITS, LOST MONIES, OR OTHER SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY THIRD PARTIES) THESE PROGRAMS, EVEN IF YOU HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES, OR FOR ANY CLAIM BY ANY OTHER PARTY. 6. Revision history. ___________________________________________________________________ 8-08-91: released version 1.2 22-07-91: - The date/time stamp of a file is reset if any patches are made. - Added (simple) password protection option, see ch 4. Maximum password length is 21 characters (excl. trailing \0). 7-07-91: - If user chooces Quit, now breaks out of while loop, instead of spooling to end of file. - Corrected bug pointed out by Ernst Raedecker of Amsterdam: find function did not allow for search string matching within itself. EG. file PIET containing "wwwp bevalt", then patch22 PIET ?wwp?ord? failed. This is fixed by doing a fseek backwards after a partially successful match. As Ernst pointed out, the search can be done more efficiently. Thanks a lot for your comments, Ernst! - Now the next search continues one byte after the start of the previous match. 12-05-91: released version 1.1