xstr - extract strings from C programs to implement shared
xstr [-cv] [-l array] [-] [file ...]
xstr maintains a file strings into which strings in component parts of a
large program are hashed. These strings are replaced with
this common area. This serves to implement shared constant
useful if they are also read-only.
The options are as follows:
- Cause xstr to read from the standard input.
-c xstr will extract the strings from the C source
file or the
standard input (-), replacing string references
of the form (&xstr[number]) for some number. An appropriate
declaration of xstr is prepended to the
file. The resulting
C text is placed in the file x.c, to
then be compiled.
The strings from this file are placed in
database if they are not there already. Repeated strings and
strings which are suffixes of existing strings
do not cause
changes to the database.
-l array Specify the named array in program references to
strings. The default array name is ``xstr''.
-v Be verbose.
After all components of a large program have been compiled,
a file xs.c
declaring the common xstr space can be created by a command
of the form:
The file xs.c should then be compiled and loaded with the
rest of the
program. If possible, the array can be made read-only
space and swap overhead.
xstr can also be used on a single file. The following command creates
files x.c and xs.c as before, without using or affecting any
in the same directory:
$ xstr name
It may be useful to run xstr after the C preprocessor if any
yield strings or if there is conditional code which
strings which may not, in fact, be needed. An appropriate
for running xstr after the C preprocessor is:
$ cc -E name.c | xstr -c -
$ cc -c x.c
$ mv x.o name.o
xstr does not touch the file strings unless new items are
added, so that
make(1) can avoid remaking xs.o unless truly necessary.
strings database of strings
x.c massaged C source
xs.c C source for definition of array ``xstr''
/tmp/xs* temporary file when ``xstr name'' doesn't touch
The xstr command appeared in 3.0BSD.
If a string is a suffix of another string in the database,
but the shorter
string is seen first by xstr both strings will be placed
database, when just placing the longer one there will do.
OpenBSD 3.6 December 30, 1993
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