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'\" te
.\" Copyright (c) 1992, Sun Microsystems, Inc.
.\" The contents of this file are subject to the terms of the Common Development and Distribution License (the "License").  You may not use this file except in compliance with the License.
.\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing.  See the License for the specific language governing permissions and limitations under the License.
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.TH XSTR 1 "Sep 14, 1992"
.SH NAME
xstr \- extract strings from C programs to implement shared strings
.SH SYNOPSIS
.LP
.nf
\fBxstr\fR \fB-c\fR \fIfilename\fR [\fB-v\fR] [\fB-l\fR \fIarray\fR]
.fi

.LP
.nf
\fBxstr\fR [\fB-l\fR \fIarray\fR]
.fi

.LP
.nf
\fBxstr\fR \fIfilename\fR [\fB-v\fR] [\fB-l\fR \fIarray\fR]
.fi

.SH DESCRIPTION
.sp
.LP
\fBxstr\fR maintains a file called \fBstrings\fR 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.
.sp
.LP
The command:
.sp
.in +2
.nf
\fBexample% xstr \(mic \fR\fIfilename\fR
.fi
.in -2
.sp

.sp
.LP
extracts the strings from the C source in name, replacing string references by
expressions of the form \fB&xstr[\fR\fInumber\fR\fB]\fR for some number. An
appropriate declaration of \fBxstr\fR is prepended to the file.  The resulting
C text is placed in the file \fBx.c\fR, to then be compiled.  The strings from
this file are placed in the \fBstrings\fR 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.
.sp
.LP
After all components of a large program have been compiled, a file declaring
the common \fBxstr\fR space called \fBxs.c\fR can be created by a command of
the form:
.sp
.in +2
.nf
\fBexample%\fR \fBxstr\fR
.fi
.in -2
.sp

.sp
.LP
This \fBxs.c\fR 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.
.sp
.LP
\fBxstr\fR can also be used on a single file.  A command:
.sp
.LP
\fBexample% xstr \fR\fIfilename\fR
.sp
.LP
creates files \fBx.c\fR and \fBxs.c\fR as before, without using or affecting
any \fBstrings\fR file in the same directory.
.sp
.LP
It may be useful to run \fBxstr\fR 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. \fBxstr\fR reads from the standard
input when the argument `\fB\(mi\fR\&' is given. An appropriate command
sequence for running \fBxstr\fR after the C preprocessor is:
.sp
.in +2
.nf
\fBexample% cc \(miE name.c | xstr \(mic \(mi
example% cc \(mic x.c
example% mv x.o name.o\fR
.fi
.in -2
.sp

.sp
.LP
\fBxstr\fR does not touch the file \fBstrings\fR unless new items are added;
thus \fBmake\fR(1S) can avoid remaking \fBxs.o\fR unless truly necessary.
.SH OPTIONS
.sp
.ne 2
.na
\fB\fB\(mic \fR\fIfilename\fR\fR
.ad
.RS 18n
Take C source text from \fIfilename\fR.
.RE

.sp
.ne 2
.na
\fB\fB-v\fR\fR
.ad
.RS 18n
Verbose: display a progress report indicating where new or duplicate strings
were found.
.RE

.sp
.ne 2
.na
\fB\fB\(mil \fR\fIarray\fR\fR
.ad
.RS 18n
Specify the named  \fIarray\fR in program references to abstracted strings.
The default array name is \fBxstr\fR.
.RE

.SH FILES
.sp
.ne 2
.na
\fB\fBstrings\fR\fR
.ad
.RS 12n
data base of strings
.RE

.sp
.ne 2
.na
\fB\fBx.c\fR\fR
.ad
.RS 12n
massaged C source
.RE

.sp
.ne 2
.na
\fB\fBxs.c\fR\fR
.ad
.RS 12n
C source for definition of array "xstr*(rq
.RE

.sp
.ne 2
.na
\fB\fB/tmp/xs*\fR\fR
.ad
.RS 12n
temp file when \fBxstr \fR\fIfilename\fR doesn't touch \fBstrings\fR
.RE

.SH SEE ALSO
.sp
.LP
\fBmake\fR(1S), \fBattributes\fR(5)
.SH BUGS
.sp
.LP
If a string is a suffix of another string in the data base, but the shorter
string is seen first by \fBxstr\fR both strings will be placed in the data
base, when just placing the longer one there would do.
.SH NOTES
.sp
.LP
Be aware that \fBxstr\fR indiscriminately replaces all strings with expressions
of the form \fB&xstr[\fR\fInumber\fR\fB]\fR regardless of the way the original
C code might have used the string.  For example, you will encounter a problem
with  code that uses \fBsizeof()\fR to determine the length of a literal string
because \fBxstr\fR will replace the literal string with a pointer that most
likely will have a different size than the string's. To circumvent this
problem:
.RS +4
.TP
.ie t \(bu
.el o
use \fBstrlen()\fR instead of  \fBsizeof()\fR; note that  \fBsizeof()\fR
returns the size of the array (including the null byte at the end), whereas
\fBstrlen()\fR doesn't count the null byte. The equivalent of
\fBsizeof("\fR\fIxxx\fR\fB")\fR really is \fB(strlen("\fR\fIxxx\fR\fB"))+1\fR.
.RE
.RS +4
.TP
.ie t \(bu
.el o
use \fB#define\fR for operands of \fBsizeof()\fR and use the \fBdefine\fR'd
version. \fBxstr\fR ignores \fB#define\fR statements.  Make sure you run
\fBxstr\fR on \fIfilename\fR before you run it on the preprocessor.
.RE
.sp
.LP
You will also encounter a problem when declaring an initialized character array
of the form
.sp
.in +2
.nf
\fBchar x[] = "\fR\fIxxx\fR\fB";\fR
.fi
.in -2
.sp

.sp
.LP
\fBxstr\fR will replace  \fIxxx\fR with an expression of the form
\fB&xstr[\fR\fInumber\fR\fB]\fR which will not compile.  To circumvent this
problem, use \fBstatic char *x = "xxx"\fR instead of \fBstatic char x[] =
"xxx"\fR.