cmd/mailwrapper/fparseln.c

/*  $NetBSD: fparseln.c,v 1.9 1999/09/20 04:48:06 lukem Exp $   */

/*
 * Copyright (c) 1997 Christos Zoulas.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *  This product includes software developed by Christos Zoulas.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <compat.h>

static int isescaped(const char *, const char *, int);

/*
 * isescaped():
 *  Return true if the character in *p that belongs to a string
 *  that starts in *sp, is escaped by the escape character esc.
 */
static int
isescaped(const char *sp, const char *p, int esc)
{
    const char  *cp;
    size_t      ne;

    /* No escape character */
    if (esc == '\0')
        return (1);

    /* Count the number of escape characters that precede ours */
    for (ne = 0, cp = p; --cp >= sp && *cp == esc; ne++)
        continue;

    /* Return true if odd number of escape characters */
    return ((ne & 1) != 0);
}


/*
 * fparseln():
 *  Read a line from a file parsing continuations ending in \
 *  and eliminating trailing newlines, or comments starting with
 *  the comment char.
 */
char *
fparseln(FILE *fp, size_t *size, size_t *lineno, const char str[3], int flags)
{
    static const char dstr[3] = { '\\', '\\', '#' };

    size_t  s, len;
    char   *buf;
    char   *ptr, *cp;
    int cnt;
    char    esc, con, nl, com;

    len = 0;
    buf = NULL;
    cnt = 1;

    if (str == NULL)
        str = dstr;

    esc = str[0];
    con = str[1];
    com = str[2];
    /*
     * XXX: it would be cool to be able to specify the newline character,
     * but unfortunately, fgetln does not let us
     */
    nl  = '\n';

    while (cnt) {
        cnt = 0;

        if (lineno)
            (*lineno)++;

        if ((ptr = fgetln(fp, &s)) == NULL)
            break;

        if (s && com) {     /* Check and eliminate comments */
            for (cp = ptr; cp < ptr + s; cp++)
                if (*cp == com && !isescaped(ptr, cp, esc)) {
                    s = cp - ptr;
                    cnt = s == 0 && buf == NULL;
                    break;
                }
        }

        if (s && nl) {      /* Check and eliminate newlines */
            cp = &ptr[s - 1];

            if (*cp == nl)
                s--;    /* forget newline */
        }

        if (s && con) {     /* Check and eliminate continuations */
            cp = &ptr[s - 1];

            if (*cp == con && !isescaped(ptr, cp, esc)) {
                s--;    /* forget escape */
                cnt = 1;
            }
        }

        if (s == 0 && buf != NULL)
            continue;

        if ((cp = realloc(buf, len + s + 1)) == NULL) {
            free(buf);
            return (NULL);
        }
        buf = cp;

        (void) memcpy(buf + len, ptr, s);
        len += s;
        buf[len] = '\0';
    }

    if ((flags & FPARSELN_UNESCALL) != 0 && esc && buf != NULL &&
        strchr(buf, esc) != NULL) {
        ptr = cp = buf;
        while (cp[0] != '\0') {
            int skipesc;

            while (cp[0] != '\0' && cp[0] != esc)
                *ptr++ = *cp++;
            if (cp[0] == '\0' || cp[1] == '\0')
                break;

            skipesc = 0;
            if (cp[1] == com)
                skipesc += (flags & FPARSELN_UNESCCOMM);
            if (cp[1] == con)
                skipesc += (flags & FPARSELN_UNESCCONT);
            if (cp[1] == esc)
                skipesc += (flags & FPARSELN_UNESCESC);
            if (cp[1] != com && cp[1] != con && cp[1] != esc)
                skipesc = (flags & FPARSELN_UNESCREST);

            if (skipesc)
                cp++;
            else
                *ptr++ = *cp++;
            *ptr++ = *cp++;
        }
        *ptr = '\0';
        len = strlen(buf);
    }

    if (size) {
        *size = len;
    }
    return (buf);
}

#ifdef TEST

int
main(int argc, char *argv[])
{
    char   *ptr;
    size_t  size, line;

    line = 0;
    while ((ptr = fparseln(stdin, &size, &line, NULL,
        FPARSELN_UNESCALL)) != NULL) {
        printf("line %d (%d) |%s|\n", line, size, ptr);
    }
    return (0);
}

/*
 * # This is a test
 * line 1
 * line 2 \
 * line 3 # Comment
 * line 4 \# Not comment \\\\
 *
 * # And a comment \
 * line 5 \\\
 * line 6
 *
 */

#endif /* TEST */