xstr(1) 							   User Commands							   xstr(1)

NAME

       xstr - extract strings from C programs to implement shared strings

SYNOPSIS

       xstr -c filename [-v] [-l array]

       xstr [-l array]

       xstr filename [-v] [-l array]

DESCRIPTION

       xstr  maintains	a file called 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, which are most useful if they are also read-only.

       The command:

	      example% xstr -c filename

       extracts the strings from the C source in name, 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.

       After all components of a large program have been compiled, a file declaring the common xstr space called xs.c can be created by a  command
       of the form:

	      example% xstr

       This xs.c file should then be compiled and loaded with the rest of the program.	If possible, the array can be made read-only (shared) sav-
       ing space and swap overhead.

       xstr can also be used on a single file.	A command:

	      example% xstr filename

       creates files x.c and xs.c as before, without using or affecting any strings file in the same directory.

       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. xstr reads from the standard input when the argument `-' is given. An appropriate command
       sequence for running xstr after the C preprocessor is:

	      example% cc -E name.c | xstr -c -
	      example% cc -c x.c
	      example% mv x.o name.o

       xstr does not touch the file strings unless new items are added; thus make(1S) can avoid remaking xs.o unless truly necessary.

OPTIONS

       -c filename	       Take C source text from filename.

       -v		       Verbose: display a progress report indicating where new or duplicate strings were found.

       -l array 	       Specify the named  array in program references to abstracted strings.  The default array name is xstr.

FILES

       strings	       data base of strings

       x.c	       massaged C source

       xs.c	       C source for definition of array "xstr*(rq

       /tmp/xs*        temp file when xstr filename doesn't touch strings

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWcsu			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       make(1S), attributes(5)

BUGS

       If a string is a suffix of another string in the data base, but the shorter string is seen first by xstr both strings will be placed in the
       data base, when just placing the longer one there would do.

NOTES

       Be  aware  that	xstr indiscriminately replaces all strings with expressions of the form &xstr[number] regardless of the way the original C
       code might have used the string.  For example, you will encounter a problem with  code that uses sizeof() to determine the length of a lit-
       eral  string  because xstr will replace the literal string with a pointer that most likely will have a different size than the string's. To
       circumvent this problem:

	 o  use strlen() instead of  sizeof(); note that  sizeof() returns the size of the array (including the null byte  at  the  end),  whereas
	    strlen() doesn't count the null byte. The equivalent of sizeof("xxx") really is (strlen("xxx"))+1.

	 o  use  #define  for operands of sizeof() and use the define'd version. xstr ignores #define statements.  Make sure you run xstr on file-
	    name before you run it on the preprocessor.

       You will also encounter a problem when declaring an initialized character array of the form

	      char x[] = "xxx";

       xstr will replace  xxx with an expression of the form &xstr[number] which will not compile.  To circumvent this problem, use static char *x
       = "xxx" instead of static char x[] = "xxx".

SunOS 5.10							    14 Sep 1992 							   xstr(1)