/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2009 David Schultz <das@FreeBSD.org>
 * Copyright (c) 2021 Dell EMC
 * 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 "namespace.h"
#include <sys/param.h>
#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "un-namespace.h"

#include "libc_private.h"
#include "local.h"

static inline size_t
p2roundup(size_t n)
{

        if (!powerof2(n)) {
                n--;
                n |= n >> 1;
                n |= n >> 2;
                n |= n >> 4;
                n |= n >> 8;
                n |= n >> 16;
#if SIZE_T_MAX > 0xffffffffU
                n |= n >> 32;
#endif
                n++;
        }
        return (n);
}

/*
 * Expand *linep to hold len bytes (up to SSIZE_MAX + 1).
 */
static inline int
expandtofit(char ** __restrict linep, size_t len, size_t * __restrict capp)
{
        char *newline;
        size_t newcap;

        if (len > (size_t)SSIZE_MAX + 1) {
                errno = EOVERFLOW;
                return (-1);
        }
        if (len > *capp) {
                if (len == (size_t)SSIZE_MAX + 1)       /* avoid overflow */
                        newcap = (size_t)SSIZE_MAX + 1;
                else
                        newcap = p2roundup(len);
                newline = realloc(*linep, newcap);
                if (newline == NULL)
                        return (-1);
                *capp = newcap;
                *linep = newline;
        }
        return (0);
}

/*
 * Append the src buffer to the *dstp buffer. The buffers are of
 * length srclen and *dstlenp, respectively, and dst has space for
 * *dstlenp bytes. After the call, *dstlenp and *dstcapp are updated
 * appropriately, and *dstp is reallocated if needed. Returns 0 on
 * success, -1 on allocation failure.
 */
static int
sappend(char ** __restrict dstp, size_t * __restrict dstlenp,
        size_t * __restrict dstcapp, char * __restrict src, size_t srclen)
{

        /* ensure room for srclen + dstlen + terminating NUL */
        if (expandtofit(dstp, srclen + *dstlenp + 1, dstcapp))
                return (-1);
        memcpy(*dstp + *dstlenp, src, srclen);
        *dstlenp += srclen;
        return (0);
}

ssize_t
getdelim(char ** __restrict linep, size_t * __restrict linecapp, int delim,
         FILE * __restrict fp)
{
        u_char *endp;
        size_t linelen;

        FLOCKFILE_CANCELSAFE(fp);
        ORIENT(fp, -1);

        if (linep == NULL || linecapp == NULL) {
                errno = EINVAL;
                goto error;
        }

        if (*linep == NULL)
                *linecapp = 0;

        if (fp->_r <= 0 && __srefill(fp)) {
                /* If fp is at EOF already, we just need space for the NUL. */
                if (!__sfeof(fp) || expandtofit(linep, 1, linecapp))
                        goto error;
                (*linep)[0] = '\0';
                linelen = -1;
                goto end;
        }

        linelen = 0;
        while ((endp = memchr(fp->_p, delim, fp->_r)) == NULL) {
                if (sappend(linep, &linelen, linecapp, fp->_p, fp->_r))
                        goto error;
                errno = 0;
                if (__srefill(fp)) {
                        if (__sfeof(fp))
                                goto done;
                        if (errno == EAGAIN) {
                                /*
                                 * We need to undo a partial read that has
                                 * been placed into linep or we would otherwise
                                 * lose it on the next read.
                                 */
                                while (linelen > 0) {
                                        if (__ungetc((*linep)[--linelen],
                                            fp) == EOF)
                                                goto error;
                                }
                                /*
                                 * This is not strictly needed but it is
                                 * possible a consumer has worked around an
                                 * older EAGAIN bug by buffering a partial
                                 * return.
                                 */
                                (*linep)[0] = '\0';
                        }
                        goto error;
                }
        }
        endp++; /* snarf the delimiter, too */
        if (sappend(linep, &linelen, linecapp, fp->_p, endp - fp->_p))
                goto error;
        fp->_r -= endp - fp->_p;
        fp->_p = endp;
done:
        /* Invariant: *linep has space for at least linelen+1 bytes. */
        (*linep)[linelen] = '\0';
end:
        FUNLOCKFILE_CANCELSAFE();
        return (linelen);

error:
        fp->_flags |= __SERR;
        linelen = -1;
        goto end;
}