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Computing (FOLDOC) dictionary (also found in English - Vietnamese, English - English (Wordnet), )
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software 1. 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. To insert a patch into a piece of code.
3. [in the Unix world] A diff.
4. A set of modifications to binaries to be applied by a
patching program. IBM 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 code. 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.
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.
5. Larry Wall's "patch" utility, which automatically applies
a patch to a set of source code or other text files. It
accepts input in any of the four forms output by the Unix
diff utility and uses many helpful heuristics to determine
how to apply them.