xstr

 

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 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) saving space and swap overhead.
 
      xstr can also be used on a single file.  A command:
 
           example% xstr filename
 
 
 
 
 
 
 SunOS 5.8           Last change: 14 Sep 1992                    1
 
 
 
 
 
 
 User Commands                                             xstr(1)
 
 
 
      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  attri-
      butes:
 
      ____________________________________________________________
     |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
     |_____________________________|_____________________________|
     | Availability                | SUNWcsu                     |
     |_____________________________|_____________________________|
 
 
 
 
 SunOS 5.8           Last change: 14 Sep 1992                    2
 
 
 
 
 
 
 User Commands                                             xstr(1)
 
 
 


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 literal 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:
 
         +  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.
 
         +  use #define for  operands  of  sizeof()  and  use  the
            define'd  version.  xstr  ignores  #define statements.
            Make sure you run xstr on filename before you  run  it
            on the preprocessor.
 
      You will also encounter a problem when declaring an initial-
      ized 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 5.8           Last change: 14 Sep 1992                    3
 
 
 

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