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<title>Berkeley DB Reference Guide: Name spaces</title>
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<td><dl><dt>Berkeley DB Reference Guide:<dd>Programmer Notes</dl></td>
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Name spaces
C Language Name Space
The Berkeley DB library is careful to avoid C language programmer name spaces,
but there are a few potential areas for concern, mostly in the Berkeley DB
include file db.h. The db.h include file defines a number of types and
strings. Where possible, all of these types and strings are prefixed with
"DB_" or "db_". There are a few notable exceptions.
The Berkeley DB library uses a macro named "__P" to configure for systems that
do not provide ANSI C function prototypes. This could potentially collide
with other systems using a "__P" macro for similar or different purposes.
The Berkeley DB library needs information about specifically sized types for
each architecture. If they are not provided by the system, they are
typedef'd in the db.h include file. The types that may be typedef'd
by db.h include the following: u_int8_t, int16_t, u_int16_t, int32_t,
u_int32_t, u_char, u_short, u_int, and u_long.
The Berkeley DB library declares a few external routines. All these routines
are prefixed with the strings "db_". All internal Berkeley DB routines are
prefixed with the strings "__XXX_", where "XXX" is the subsystem prefix
(for example, "__db_XXX_" and "__txn_XXX_").
Filesystem Name Space
Berkeley DB environments create or use some number of files in environment
home directories. These files are named <a href="../../ref/env/db_config.html#DB_CONFIG">DB_CONFIG</a>, "log.NNNNN"
(for example, log.0000000003, where the number of digits following the
dot is unspecified), or with the string prefix "__db" (for example,
__db.001). Applications should never create files or databases in
database environment home directories with names beginning with the
characters "log" or "__db".
In some cases, applications may choose to remove Berkeley DB files as part of
their cleanup procedures, using system utilities instead of Berkeley DB
interfaces (for example, using the UNIX rm utility instead of the
<a href="../../api_c/env_remove.html">DB_ENV-&gt;remove</a> method). This is not a problem, as long as applications
limit themselves to removing only files named "__db.###", where "###"
are the digits 0 through 9. Applications should never remove any files
named with the prefix "__db" or "log", other than "__db.###" files.
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