os-k/kaleid/libbuf/bscan.c

//----------------------------------------------------------------------------//
//                           GNU GPL OS/K                                     //
//                                                                            //
//  Desc:       Buffer library                                                //
//                                                                            //
//                                                                            //
//  Copyright © 2018-2019 The OS/K Team                                       //
//                                                                            //
//  This file is part of OS/K.                                                //
//                                                                            //
//  OS/K is free software: you can redistribute it and/or modify              //
//  it under the terms of the GNU General Public License as published by      //
//  the Free Software Foundation, either version 3 of the License, or         //
//  any later version.                                                        //
//                                                                            //
//  OS/K is distributed in the hope that it will be useful,                   //
//  but WITHOUT ANY WARRANTY//without even the implied warranty of            //
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the             //
//  GNU General Public License for more details.                              //
//                                                                            //
//  You should have received a copy of the GNU General Public License         //
//  along with OS/K.  If not, see <https://www.gnu.org/licenses/>.            //
//----------------------------------------------------------------------------//

#include <lib/buf.h>

//
// Builds string reading from buf according to fmt
//
size_t BScanFromBuf(Buffer_t *buf, const char *fmt, ...)
{
    size_t sz;
    va_list ap;

    va_start(ap, fmt);
    ExAcquireLock(&buf->lock);
    sz = vbscanf(buf, fmt, ap);
    ExReleaseLock(&buf->lock);
    va_end(ap);

    return sz;
}

size_t BScanFromBufV(Buffer_t *buf, const char *fmt, va_list ap)
{
    size_t sz;
    
    ExAcquireLock(&buf->lock);
    sz = vbscanf(buf, fmt, ap);
    ExReleaseLock(&buf->lock);
    
    return sz;
}

size_t bscanf(Buffer_t *buf, const char *fmt, ...)
{
    size_t sz;
    va_list ap;

    va_start(ap, fmt);
    sz = vbscanf(buf, fmt, ap);
    va_end(ap);

    return sz;
}

size_t vbscanf(Buffer_t *buf, const char *fmt, va_list ap)
{
    error_t rc = EOK;

    size_t readcnt = 0;
    uchar ch = 0;
    char *chptr;

    bool l, h;

    size_t width;
    bool ignore;    // '*' modifier, don't write to va_list for current mod

    if (!buf || !fmt) { seterrno(EINVAL); return 0; }
    if (buf->flags & (BF_EOF|BF_ERR)) { seterrno(EENDF); return 0; }
    if (buf->state != BS_RDWR && buf->state != BS_WRONLY) {
        seterrno(EBADF);
        return 0;
    }

    // Progress in format string
    while (*fmt && !rc) {
        
        // Skip all kinds of whitespaces
        if (isspace(*fmt)) {

        another_space:
            rc = bgetc(buf, &ch);

            if (!rc) break;

            // Put back non-whitespaces and progress
            if (!isspace(ch)) {
                buf->rp--;
                do { fmt++; } while (isspace(*fmt));
                continue;
            }

            else goto another_space;
        }
    
        // Deal with all non-'%' non-whitespace characters
        if (*fmt != '%') {
            rc = bgetc(buf, &ch);

            // Is it what we expected?
            if (!rc && ch != *fmt) {
                // No, so put it back
                buf->rp--;
                break;
            }

            // We don't do anything with these characters
            continue;
        }

        //
        // %[*][width][modifier]type
        //

        // Skip the %
        fmt++;

        // '%%' type
        if (*fmt == '%') {
            rc = bgetc(buf, &ch);

            if (!rc && ch != '%') {
                buf->rp--;
                break;
            }
            
            continue;
        }

        l = h = 0;
        width = 0;
        ignore = 0;

        // Don't write to variable
        if (*fmt == '*') {
            ignore = 1;
            fmt++;
        }

        // Extract width field
        while (isdigit(*fmt)) {
            width = 10 * width + (*fmt - '0');
            fmt++;
        }

        //
        // Extract length field
        //

        if (*fmt == 'l') {
            l = 1;
            fmt++;
        }

        else if (*fmt == 'h') {
            h = 1;
            fmt++;
        }

        //
        // Types
        //

        // Read character(s)
        if (*fmt == 'c') {
            if (width == 0) width = 1;

            // For >1 width, read that many characters
            // then store them in successive argument pointers 
            for (; width; width--) {
                rc = bgetc(buf, &ch);
                if (!rc) break;
                if (ignore) continue;

                chptr = va_arg(ap, char *);
                *chptr = (char)ch;
                readcnt++;
            }
        }

        // Decimal integer
        else if (*fmt == 'd') {
            ;
        }
    }

    // For debugging purposes
    assert(!rc && "vbscanf() error");
    seterrno(rc);

    return readcnt;
}