/* Copyright (C) 2001-2023 Artifex Software, Inc.
   All Rights Reserved.

   This software is provided AS-IS with no warranty, either express or
   implied.

   This software is distributed under license and may not be copied,
   modified or distributed except as expressly authorized under the terms
   of the license contained in the file LICENSE in this distribution.

   Refer to licensing information at http://www.artifex.com or contact
   Artifex Software, Inc.,  39 Mesa Street, Suite 108A, San Francisco,
   CA 94129, USA, for further information.
*/


/* Filters included in Level 1 systems: NullEncode/Decode, PFBDecode, */
/*   SubFileDecode. */
#include "stdio_.h"		/* includes std.h */
#include "memory_.h"
#include "strimpl.h"
#include "sfilter.h"

/* ------ PFBDecode ------ */

private_st_PFBD_state();

/* Initialize the state */
static int
s_PFBD_init(stream_state * st)
{
    stream_PFBD_state *const ss = (stream_PFBD_state *) st;

    ss->record_type = -1;
    return 0;
}

/* Process a buffer */
static int
s_PFBD_process(stream_state * st, stream_cursor_read * pr,
               stream_cursor_write * pw, bool last)
{
    stream_PFBD_state *const ss = (stream_PFBD_state *) st;
    register const byte *p = pr->ptr;
    register byte *q = pw->ptr;
    int rcount, wcount;
    int c;
    int status = 0;

top:
    rcount = pr->limit - p;
    wcount = pw->limit - q;
    switch (ss->record_type) {
        case -1:		/* new record */
            if (rcount < 2)
                goto out;
            if (p[1] != 0x80)
                goto err;
            c = p[2];
            switch (c) {
                case 1:
                case 2:
                    break;
                case 3:
                    status = EOFC;
                    p += 2;
                    goto out;
                default:
                    p += 2;
                    goto err;
            }
            if (rcount < 6)
                goto out;
            ss->record_type = c;
            ss->record_left = p[3] + ((uint) p[4] << 8) +
                ((ulong) p[5] << 16) +
                ((ulong) p[6] << 24);

            /* Check for an invalid counter found in an Adobe font, bug 689617 */
            if (ss->record_left == 0 && ss->record_type == 1) {
               if (p + 7 < pr->limit) {
                   if (p[6] ==  128)
                     ; /* normal empty block */
                   else {
                     ss->record_type = 4; /* ASCII stuff between blocks */
                     ss->record_left = ~0;
                   }
               } else {
                   if (!last)
                      goto out;
               }
            }
            p += 6;
            goto top;
        case 1:		/* text data */
            /* Translate \r to \n. */
            {
                int count = (wcount < rcount ? (status = 1, wcount) : rcount);

                if (count > ss->record_left)
                    count = ss->record_left,
                        status = 0;
                ss->record_left -= count;
                for (; count != 0; count--) {
                    c = *++p;
                    *++q = (c == '\r' ? '\n' : c);
                }
            }
            break;
        case 2:		/* binary data */
            if (ss->binary_to_hex) {
                /* Translate binary to hex. */
                int count;
                const char *const hex_digits = "0123456789abcdef";

                wcount >>= 1;	/* 2 chars per input byte */
                count = (wcount < rcount ? (status = 1, wcount) : rcount);
                if (count > ss->record_left)
                    count = ss->record_left,
                        status = 0;
                ss->record_left -= count;
                for (; count != 0; count--) {
                    c = *++p;
                    q[1] = hex_digits[c >> 4];
                    q[2] = hex_digits[c & 0xf];
                    q += 2;
                }
            } else {		/* Just read binary data. */
                int count = (wcount < rcount ? (status = 1, wcount) : rcount);

                if (count > ss->record_left)
                    count = ss->record_left,
                        status = 0;
                ss->record_left -= count;
                memcpy(q + 1, p + 1, count);
                p += count;
                q += count;
            }
            break;
        case 4:
            /* Treat the text after empty ASCII block as ACSII stream */
            /* Translate \r to \n. */
            {
                int count = (wcount < rcount ? (status = 1, wcount) : rcount);
                for (; count != 0; count--) {
                    c = *++p;
                    if (c == 128)
                      { --p;
                        ss->record_left = 0;
                        break;
                      }
                    *++q = (c == '\r' ? '\n' : c);
                }
            }
            break;
    }
    if (ss->record_left == 0) {
        ss->record_type = -1;
        goto top;
    }
out:
    pr->ptr = p;
    pw->ptr = q;
    return status;
err:
    pr->ptr = p;
    pw->ptr = q;
    return ERRC;
}

/* Stream template */
const stream_template s_PFBD_template = {
    &st_PFBD_state, s_PFBD_init, s_PFBD_process, 6, 2
};

/* ------ SubFileDecode ------ */

private_st_SFD_state();

/* Set default parameter values. */
static void
s_SFD_set_defaults(stream_state * st)
{
    stream_SFD_state *const ss = (stream_SFD_state *) st;

    ss->count = 0;
    ss->eod.data = 0;
    ss->eod.size = 0;
    ss->skip_count = 0;
}

/* Initialize the stream */
static int
s_SFD_init(stream_state * st)
{
    stream_SFD_state *const ss = (stream_SFD_state *) st;

    ss->match = 0;
    ss->copy_count = 0;
    ss->min_left = (ss->eod.size != 0);

    return 0;
}

/* Refill the buffer */
static int
s_SFD_process(stream_state * st, stream_cursor_read * pr,
              stream_cursor_write * pw, bool last)
{
    stream_SFD_state *const ss = (stream_SFD_state *) st;
    register const byte *p = pr->ptr;
    register byte *q = pw->ptr;
    const byte *rlimit = pr->limit;
    byte *wlimit = pw->limit;
    int status = 0;

    if (ss->eod.size == 0) {	/* Just read, with no EOD pattern. */
        int rcount = rlimit - p;
        int wcount = wlimit - q;
        int count;

        if (rcount <= ss->skip_count) { /* skipping */
            ss->skip_count -= rcount;
            pr->ptr = rlimit;
            return 0;
        } else if (ss->skip_count > 0) {
            rcount -= ss->skip_count;
            pr->ptr = p += ss->skip_count;
            ss->skip_count = 0;
        }
        count = min(rcount, wcount);
        if (ss->count == 0)	/* no EOD limit */
            return stream_move(pr, pw);
        else if (ss->count > count) {	/* not EOD yet */
            ss->count -= count;
            return stream_move(pr, pw);
        } else {		/* We're going to reach EOD. */
            count = ss->count;
            if (count > 0) {
                memcpy(q + 1, p + 1, count);
                pr->ptr = p + count;
                pw->ptr = q + count;
            }
            ss->count = -1;
            return EOFC;
        }
    } else {			/* Read looking for an EOD pattern. */
        const byte *pattern = ss->eod.data;
        uint match = ss->match;

cp:
        /* Check whether we're still copying a partial match. */
        if (ss->copy_count) {
            int count = min(wlimit - q, ss->copy_count);

            memcpy(q + 1, ss->eod.data + ss->copy_ptr, count);
            ss->copy_count -= count;
            ss->copy_ptr += count;
            q += count;
            if (ss->copy_count != 0) {	/* hit wlimit */
                status = 1;
                goto xit;
            } else if (ss->count < 0) {
                status = EOFC;
                goto xit;
            }
        }
        while (p < rlimit) {
            int c = *++p;

            if (c == pattern[match]) {
                if (++match == ss->eod.size) {
                    if (ss->skip_count > 0) {
                        q = pw->ptr; /* undo any writes */
                        ss->skip_count--;
                        match = 0;
                        continue;
                    }
                    /*
                     * We use if/else rather than switch because the value
                     * is long, which is not supported as a switch value in
                     * pre-ANSI C.
                     */
                    if (ss->count <= 0) {
                        status = EOFC;
                        goto xit;
                    } else if (ss->count == 1) {
                        ss->count = -1;
                    } else
                        ss->count--;
                    ss->copy_ptr = 0;
                    ss->copy_count = match;
                    match = 0;
                    goto cp;
                }
                continue;
            }
            /*
             * No match here, back up to find the longest one.
             * This may be quadratic in string_size, but
             * we don't expect this to be a real problem.
             */
            if (match > 0) {
                int end = match;

                while (match > 0) {
                    match--;
                    if (!memcmp(pattern, pattern + end - match, match))
                        break;
                }
                /*
                 * Copy the unmatched initial portion of
                 * the EOD string to the output.
                 */
                p--;
                ss->copy_ptr = 0;
                ss->copy_count = end - match;
                goto cp;
            }
            if (q == wlimit) {
                p--;
                status = 1;
                break;
            }
            *++q = c;
        }
xit:	pr->ptr = p;
        if (ss->skip_count <= 0)
            pw->ptr = q;
        ss->match = match;
    }
    return status;
}

/* Stream template */
const stream_template s_SFD_template = {
    &st_SFD_state, s_SFD_init, s_SFD_process, 1, 1, 0, s_SFD_set_defaults
};
