/*      $NetBSD: file.c,v 1.13 2024/08/14 05:02:19 rin Exp $    */
/*      $FreeBSD: head/usr.bin/grep/file.c 211496 2010-08-19 09:28:59Z des $    */
/*      $OpenBSD: file.c,v 1.11 2010/07/02 20:48:48 nicm Exp $  */

/*-
 * Copyright (c) 1999 James Howard and Dag-Erling Coïdan Smørgrav
 * Copyright (C) 2008-2010 Gabor Kovesdan <gabor@FreeBSD.org>
 * Copyright (C) 2010 Dimitry Andric <dimitry@andric.com>
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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.
 */

#if HAVE_NBTOOL_CONFIG_H
#include "nbtool_config.h"
#endif

#include <sys/cdefs.h>
__RCSID("$NetBSD: file.c,v 1.13 2024/08/14 05:02:19 rin Exp $");

#include <sys/param.h>
#include <sys/types.h>
#include <sys/stat.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <wchar.h>
#include <wctype.h>

#include "grep.h"

#define MAXBUFSIZ       (32 * 1024)
#define LNBUFBUMP       80

#ifndef WITHOUT_GZIP
static gzFile gzbufdesc;
#endif
#ifndef WITHOUT_BZ2
static BZFILE* bzbufdesc;
#endif

static unsigned char buffer[MAXBUFSIZ + 1];
static unsigned char *bufpos;
static size_t bufrem;

static unsigned char *lnbuf;
static size_t lnbuflen;

static inline int
grep_refill(struct file *f)
{
        ssize_t nr = -1;
#ifndef WITHOUT_BZ2
        int bzerr;
#endif

        bufpos = buffer;
        bufrem = 0;

#ifndef WITHOUT_GZIP
        if (filebehave == FILE_GZIP) {
                nr = gzread(gzbufdesc, buffer, MAXBUFSIZ);
                if (nr == -1)
                        return -1;
        }
#endif
#ifndef WITHOUT_BZ2
        if (filebehave == FILE_BZIP && bzbufdesc != NULL) {
                nr = BZ2_bzRead(&bzerr, bzbufdesc, buffer, MAXBUFSIZ);
                switch (bzerr) {
                case BZ_OK:
                case BZ_STREAM_END:
                        /* No problem, nr will be okay */
                        break;
                case BZ_DATA_ERROR_MAGIC:
                        /*
                         * As opposed to gzread(), which simply returns the
                         * plain file data, if it is not in the correct
                         * compressed format, BZ2_bzRead() instead aborts.
                         *
                         * So, just restart at the beginning of the file again,
                         * and use plain reads from now on.
                         */
                        BZ2_bzReadClose(&bzerr, bzbufdesc);
                        bzbufdesc = NULL;
                        if (lseek(f->fd, 0, SEEK_SET) == -1)
                                return (-1);
                        nr = read(f->fd, buffer, MAXBUFSIZ);
                        break;
                default:
                        /* Make sure we exit with an error */
                        nr = -1;
                }
                if (nr == -1)
                        return -1;
        }
#endif
        if (nr == -1) {
                nr = read(f->fd, buffer, MAXBUFSIZ);
        }

        if (nr < 0)
                return (-1);

        bufrem = nr;
        return (0);
}

static inline void
grep_lnbufgrow(size_t newlen)
{

        if (lnbuflen < newlen) {
                lnbuf = grep_realloc(lnbuf, newlen);
                lnbuflen = newlen;
        }
}

static void
grep_copyline(size_t off, size_t len)
{
        memcpy(lnbuf + off, bufpos, len);
        lnbuf[off + len] = '\0';
}

char *
grep_fgetln(struct file *f, size_t *lenp)
{
        unsigned char *p;
        size_t len;
        size_t off;
        ptrdiff_t diff;

        /* Fill the buffer, if necessary */
        if (bufrem == 0 && grep_refill(f) != 0)
                goto error;

        if (bufrem == 0) {
                /* Return zero length to indicate EOF */
                *lenp = 0;
                return ((char *)bufpos);
        }

        /* Look for a newline in the remaining part of the buffer */
        if ((p = memchr(bufpos, line_sep, bufrem)) != NULL) {
                ++p; /* advance over newline */
                len = p - bufpos;
                grep_lnbufgrow(len + 1);
                grep_copyline(0, len);
                *lenp = len;
                bufrem -= len;
                bufpos = p;
                return (char *)lnbuf;
        }

        /* We have to copy the current buffered data to the line buffer */
        for (len = bufrem, off = 0; ; len += bufrem) {
                /* Make sure there is room for more data */
                grep_lnbufgrow(len + LNBUFBUMP);
                grep_copyline(off, len - off);
                off = len;
                if (grep_refill(f) != 0)
                        goto error;
                if (bufrem == 0)
                        /* EOF: return partial line */
                        break;
                if ((p = memchr(bufpos, line_sep, bufrem)) == NULL)
                        continue;
                /* got it: finish up the line (like code above) */
                ++p;
                diff = p - bufpos;
                len += diff;
                grep_lnbufgrow(len + 1);
                grep_copyline(off, diff);
                bufrem -= diff;
                bufpos = p;
                break;
        }
        *lenp = len;
        return ((char *)lnbuf);

error:
        *lenp = 0;
        return (NULL);
}

static inline struct file *
grep_file_init(struct file *f)
{

#ifndef WITHOUT_GZIP
        if (filebehave == FILE_GZIP &&
            (gzbufdesc = gzdopen(f->fd, "r")) == NULL)
                goto error;
#endif

#ifndef WITHOUT_BZ2
        if (filebehave == FILE_BZIP &&
            (bzbufdesc = BZ2_bzdopen(f->fd, "r")) == NULL)
                goto error;
#endif

        /* Fill read buffer, also catches errors early */
        if (grep_refill(f) != 0)
                goto error;

        /* Check for binary stuff, if necessary */
        if (!nulldataflag && binbehave != BINFILE_TEXT &&
            memchr(bufpos, '\0', bufrem) != NULL)
                f->binary = true;

        return (f);
error:
        close(f->fd);
        free(f);
        return (NULL);
}

/*
 * Opens a file for processing.
 */
struct file *
grep_open(const char *path)
{
        struct file *f;

        f = grep_malloc(sizeof *f);
        memset(f, 0, sizeof *f);
        if (path == NULL) {
                /* Processing stdin implies --line-buffered. */
                lbflag = true;
                f->fd = STDIN_FILENO;
        } else if ((f->fd = open(path, O_RDONLY)) == -1) {
                free(f);
                return (NULL);
        }

        return (grep_file_init(f));
}

/*
 * Closes a file.
 */
void
grep_close(struct file *f)
{

        close(f->fd);

        /* Reset read buffer and line buffer */
        bufpos = buffer;
        bufrem = 0;

        free(lnbuf);
        lnbuf = NULL;
        lnbuflen = 0;
}