printable.c

[詳解]

/*++
/* NAME
/*  printable 3
/* SUMMARY
/*  mask non-printable characters
/* SYNOPSIS
/*  #include <stringops.h>
/*
/*  int util_utf8_enable;
/*
/*  char    *printable(buffer, replacement)
/*  char    *buffer;
/*  int replacement;
/* DESCRIPTION
/*  printable() replaces non-printable characters
/*  in its input with the given replacement.
/*
/*  util_utf8_enable controls whether UTF8 is considered printable.
/*  With util_utf8_enable equal to zero, non-ASCII text is replaced.
/*
/*  Arguments:
/* .IP buffer
/*  The null-terminated input string.
/* .IP replacement
/*  Replacement value for characters in \fIbuffer\fR that do not
/*  pass the ASCII isprint(3) test or that are not valid UTF8.
/* LICENSE
/* .ad
/* .fi
/*  The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/*  Wietse Venema
/*  IBM T.J. Watson Research
/*  P.O. Box 704
/*  Yorktown Heights, NY 10598, USA
/*--*/

/* System library. */

#include "sys_defs.h"
#include <ctype.h>

/* Utility library. */

#include "stringops.h"

int util_utf8_enable = 0;

char   *printable(char *string, int replacement)
{
    unsigned char *cp;
    int     ch;

    /*
     * XXX Replace invalid UTF8 sequences (too short, over-long encodings,
     * out-of-range code points, etc). See valid_utf8_string.c.
     */
    cp = (unsigned char *) string;
    while ((ch = *cp) != 0) {
    if (ISASCII(ch) && ISPRINT(ch)) {
        /* ok */
    } else if (util_utf8_enable && ch >= 194 && ch <= 254
           && cp[1] >= 128 && cp[1] < 192) {
        /* UTF8; skip the rest of the bytes in the character. */
        while (cp[1] >= 128 && cp[1] < 192)
        cp++;
    } else {
        /* Not ASCII and not UTF8. */
        *cp = replacement;
    }
    cp++;
    }
    return (string);
}