/*      $NetBSD: file.c,v 1.5 2011/02/16 18:35:39 joerg Exp $   */
/*      $OpenBSD: file.c,v 1.11 2010/07/02 20:48:48 nicm Exp $  */

/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 1999 James Howard and Dag-Erling 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.
 */

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

static char *buffer;
static char *bufpos;
static size_t bufrem;
static size_t fsiz;

static char *lnbuf;
static size_t lnbuflen;

static inline int
grep_refill(struct file *f)
{
        ssize_t nr;

        if (filebehave == FILE_MMAP)
                return (0);

        bufpos = buffer;
        bufrem = 0;

        nr = read(f->fd, buffer, MAXBUFSIZ);
        if (nr < 0 && errno == EISDIR)
                nr = 0;
        if (nr < 0)
                return (-1);

        bufrem = nr;
        return (0);
}

static inline int
grep_lnbufgrow(size_t newlen)
{

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

        return (0);
}

char *
grep_fgetln(struct file *f, struct parsec *pc)
{
        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 */
                pc->ln.len= 0;
                return (bufpos);
        }

        /* Look for a newline in the remaining part of the buffer */
        if ((p = memchr(bufpos, fileeol, bufrem)) != NULL) {
                ++p; /* advance over newline */
                len = p - bufpos;
                if (grep_lnbufgrow(len + 1))
                        goto error;
                memcpy(lnbuf, bufpos, len);
                bufrem -= len;
                bufpos = p;
                pc->ln.len = len;
                lnbuf[len] = '\0';
                return (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 */
                if (grep_lnbufgrow(len + LNBUFBUMP))
                        goto error;
                memcpy(lnbuf + off, bufpos, len - off);
                /* With FILE_MMAP, this is EOF; there's no more to refill */
                if (filebehave == FILE_MMAP) {
                        bufrem -= len;
                        break;
                }
                off = len;
                /* Fetch more to try and find EOL/EOF */
                if (grep_refill(f) != 0)
                        goto error;
                if (bufrem == 0)
                        /* EOF: return partial line */
                        break;
                if ((p = memchr(bufpos, fileeol, bufrem)) == NULL)
                        continue;
                /* got it: finish up the line (like code above) */
                ++p;
                diff = p - bufpos;
                len += diff;
                if (grep_lnbufgrow(len + 1))
                    goto error;
                memcpy(lnbuf + off, bufpos, diff);
                bufrem -= diff;
                bufpos = p;
                break;
        }
        pc->ln.len = len;
        lnbuf[len] = '\0';
        return (lnbuf);

error:
        pc->ln.len = 0;
        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)
                goto error1;

        if (filebehave == FILE_MMAP) {
                struct stat st;

                if (fstat(f->fd, &st) == -1 || !S_ISREG(st.st_mode))
                        filebehave = FILE_STDIO;
                else {
                        int flags = MAP_PRIVATE | MAP_NOCORE | MAP_NOSYNC;
#ifdef MAP_PREFAULT_READ
                        flags |= MAP_PREFAULT_READ;
#endif
                        fsiz = st.st_size;
                        buffer = mmap(NULL, fsiz, PROT_READ, flags,
                             f->fd, (off_t)0);
                        if (buffer == MAP_FAILED)
                                filebehave = FILE_STDIO;
                        else {
                                bufrem = st.st_size;
                                bufpos = buffer;
                                madvise(buffer, st.st_size, MADV_SEQUENTIAL);
                        }
                }
        }

        if ((buffer == NULL) || (buffer == MAP_FAILED))
                buffer = grep_malloc(MAXBUFSIZ);

        /* Fill read buffer, also catches errors early */
        if (bufrem == 0 && grep_refill(f) != 0)
                goto error2;

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

        return (f);

error2:
        close(f->fd);
error1:
        free(f);
        return (NULL);
}

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

        close(f->fd);

        /* Reset read buffer and line buffer */
        if (filebehave == FILE_MMAP) {
                munmap(buffer, fsiz);
                buffer = NULL;
        }
        bufpos = buffer;
        bufrem = 0;

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