patch
1. n. A temporary addition to a piece of code, usually as a
quick-and-dirty remedy to an existing bug or misfeature. A
patch may or may not work, and may or may not eventually be
incorporated permanently into the program. Distinguished from a
diff or mod by the fact that a patch is generated by more
primitive means than the rest of the program; the classical
examples are instructions modified by using the front panel
switches, and changes made directly to the binary executable of a
program originally written in an HLL. Compare one-line fix.
2. vt. To insert a patch into a piece of code. 3. [in the
UNIX world] n. A diff (sense 2). 4. A set of modifications to
binaries to be applied by a patching program. IBM operating
systems often receive updates to the operating system in the form
of absolute hexadecimal patches. If you have modified your OS, you
have to disassemble these back to the source. The patches might
later be corrected by other patches on top of them (patches were
said to "grow scar tissue"). The result was often a convoluted
patch space and headaches galore. 5. [UNIX] the
`patch(1)' program, written by Larry Wall, which automatically
applies a patch (sense 3) to a set of source code.
There is a classic story of a tiger team penetrating a secure
military computer that illustrates the danger inherent in binary
patches (or, indeed, any patches that you can't --- or don't ---
inspect and examine before installing). They couldn't find any
trap doors or any way to penetrate security of IBM's OS, so
they made a site visit to an IBM office (remember, these were
official military types who were purportedly on official business),
swiped some IBM stationery, and created a fake patch. The patch
was actually the trapdoor they needed. The patch was distributed
at about the right time for an IBM patch, had official stationery
and all accompanying documentation, and was dutifully installed.
The installation manager very shortly thereafter learned something
about proper procedures.
