xstr maintains a file
strings into which strings in component parts of a large program are hashed. These strings are replaced with references to this common area. This serves to implement shared constant strings, most useful if they are also read-only.
Available options:
-
xstr reads from the standard input.
-c
xstr will extract the strings from the C source file or the standard input (-), replacing string references by expressions 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 the strings data base if they are not there already. Repeated strings and strings which are suffixes of existing strings do not cause changes to the data base.
-l array
Specify the named array in program references to abstracted strings. The default array name is xstr.
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:
$ xstr
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 (shared) saving 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
strings file in the same directory:
$ xstr name
It may be useful to run
xstr after the C preprocessor if any macro definitions yield strings or if there is conditional code which contains strings which may not, in fact, be needed. An appropriate command sequence 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, thus
make(1) can avoid remaking
xs.o unless truly necessary.