Add description of crypt_r().

man3/crypt.3

@@ -32,16 +32,21 @@
 .\" added _XOPEN_SOURCE, aeb, 970705
 .\" added GNU MD5 stuff, aeb, 011223
 .\"
-.TH CRYPT 3 2008-07-28 "" "Linux Programmer's Manual"
+.TH CRYPT 3 2008-08-25 "" "Linux Programmer's Manual"
 .SH NAME
-crypt \- password and data encryption
+crypt, crypt_r \- password and data encryption
 .SH SYNOPSIS
+.nf
 .B #define _XOPEN_SOURCE
 .br
 .B #include <unistd.h>
 .sp
 .BI "char *crypt(const char *" key ", const char *" salt );
 .sp
+.BI "char *crypt_r(const char *" key ", const char *" salt , 
+.BI "              struct crypt_data *" data );
+.fi
+.sp
 Link with \fI\-lcrypt\fP.
 .SH DESCRIPTION
 .BR crypt ()
@@ -95,8 +100,20 @@ If you are planning on using the
 .BR crypt ()
 interface for a cryptography project, don't do it: get a good book on
 encryption and one of the widely available DES libraries.
+
+.BR crypt_r ()
+is a reentrant version of
+.BR crypt ().
+The structure pointed to by
+.I data
+is used to store result data and bookkeeping information.
+Other than allocating it,
+the only thing that the caller should do with this structure is to set
+.I data->initialized
+to zero before the first call to
+.BR crypt_r ().
 .SH "RETURN VALUE"
-A pointer to the encrypted password is returned.
+On success, a pointer to the encrypted password is returned.
 On error, NULL is returned.
 .SH ERRORS
 .TP
@@ -139,7 +156,9 @@ function was not implemented, probably because of U.S.A. export restrictions.
 .\" Making encrypted data computed using crypt() publicly available has
 .\" to be considered insecure for the given reasons.
 .SH "CONFORMING TO"
+.BR crypt ():
 SVr4, 4.3BSD, POSIX.1-2001.
+.BR crypt_r () is a GNU extension.
 .SH NOTES
 .SS Glibc Notes
 The glibc2 version of this function supports additional