/*
 * Copyright 1995-2026 The OpenSSL Project Authors. All Rights Reserved.
 *
 * Licensed under the Apache License 2.0 (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#include <stdio.h>
#include <errno.h>
#include "bio_local.h"
#include "internal/cryptlib.h"
#include <openssl/evp.h>

static int linebuffer_write(BIO *h, const char *buf, int num);
static int linebuffer_read(BIO *h, char *buf, int size);
static int linebuffer_puts(BIO *h, const char *str);
static int linebuffer_gets(BIO *h, char *str, int size);
static long linebuffer_ctrl(BIO *h, int cmd, long arg1, void *arg2);
static int linebuffer_new(BIO *h);
static int linebuffer_free(BIO *data);
static long linebuffer_callback_ctrl(BIO *h, int cmd, BIO_info_cb *fp);

/* A 10k maximum should be enough for most purposes */
#define DEFAULT_LINEBUFFER_SIZE 1024 * 10

/* #define DEBUG */

static const BIO_METHOD methods_linebuffer = {
    BIO_TYPE_LINEBUFFER,
    "linebuffer",
    bwrite_conv,
    linebuffer_write,
    bread_conv,
    linebuffer_read,
    linebuffer_puts,
    linebuffer_gets,
    linebuffer_ctrl,
    linebuffer_new,
    linebuffer_free,
    linebuffer_callback_ctrl,
};

const BIO_METHOD *BIO_f_linebuffer(void)
{
    return &methods_linebuffer;
}

typedef struct bio_linebuffer_ctx_struct {
    char *obuf; /* the output char array */
    int obuf_size; /* how big is the output buffer */
    int obuf_len; /* how many bytes are in it */
} BIO_LINEBUFFER_CTX;

static int linebuffer_new(BIO *bi)
{
    BIO_LINEBUFFER_CTX *ctx;

    if ((ctx = OPENSSL_malloc(sizeof(*ctx))) == NULL)
        return 0;
    ctx->obuf = OPENSSL_malloc(DEFAULT_LINEBUFFER_SIZE);
    if (ctx->obuf == NULL) {
        OPENSSL_free(ctx);
        return 0;
    }
    ctx->obuf_size = DEFAULT_LINEBUFFER_SIZE;
    ctx->obuf_len = 0;

    bi->init = 1;
    bi->ptr = (char *)ctx;
    bi->flags = 0;
    return 1;
}

static int linebuffer_free(BIO *a)
{
    BIO_LINEBUFFER_CTX *b;

    if (a == NULL)
        return 0;
    b = (BIO_LINEBUFFER_CTX *)a->ptr;
    OPENSSL_free(b->obuf);
    OPENSSL_free(a->ptr);
    a->ptr = NULL;
    a->init = 0;
    a->flags = 0;
    return 1;
}

static int linebuffer_read(BIO *b, char *out, int outl)
{
    int ret = 0;

    if (out == NULL)
        return 0;
    if (b->next_bio == NULL)
        return 0;
    ret = BIO_read(b->next_bio, out, outl);
    BIO_clear_retry_flags(b);
    BIO_copy_next_retry(b);
    return ret;
}

static int linebuffer_write(BIO *b, const char *in, int inl)
{
    int i, num = 0, foundnl;
    BIO_LINEBUFFER_CTX *ctx;

    if ((in == NULL) || (inl <= 0))
        return 0;
    ctx = (BIO_LINEBUFFER_CTX *)b->ptr;
    if ((ctx == NULL) || (b->next_bio == NULL))
        return 0;

    BIO_clear_retry_flags(b);

    do {
        const char *p;
        char c;

        for (p = in, c = '\0'; p < in + inl && (c = *p) != '\n'; p++)
            ;
        if (c == '\n') {
            p++;
            foundnl = 1;
        } else
            foundnl = 0;

        /*
         * If a NL was found and we already have text in the save buffer,
         * concatenate them and write
         */
        while ((foundnl || p - in > ctx->obuf_size - ctx->obuf_len)
            && ctx->obuf_len > 0) {
            int orig_olen = ctx->obuf_len;
            int llen = (int)(p - in);

            i = ctx->obuf_size - ctx->obuf_len;
            if (llen > 0) {
                if (i >= llen) {
                    memcpy(&(ctx->obuf[ctx->obuf_len]), in, llen);
                    ctx->obuf_len += llen;
                    inl -= llen;
                    num += llen;
                    in = p;
                } else {
                    memcpy(&(ctx->obuf[ctx->obuf_len]), in, i);
                    ctx->obuf_len += i;
                    inl -= i;
                    in += i;
                    num += i;
                }
            }
            i = BIO_write(b->next_bio, ctx->obuf, ctx->obuf_len);
            if (i <= 0) {
                ctx->obuf_len = orig_olen;
                BIO_copy_next_retry(b);

                if (i < 0)
                    return ((num > 0) ? num : i);
                if (i == 0)
                    return num;
            }
            if (i < ctx->obuf_len)
                memmove(ctx->obuf, ctx->obuf + i, ctx->obuf_len - i);
            ctx->obuf_len -= i;
        }

        /*
         * Now that the save buffer is emptied, let's write the input buffer
         * if a NL was found and there is anything to write.
         */
        if ((foundnl || p - in > ctx->obuf_size) && p - in > 0) {
            i = BIO_write(b->next_bio, in, (int)(p - in));
            if (i <= 0) {
                BIO_copy_next_retry(b);
                if (i < 0)
                    return ((num > 0) ? num : i);
                if (i == 0)
                    return num;
            }
            num += i;
            in += i;
            inl -= i;
        }
    } while (foundnl && inl > 0);
    /*
     * We've written as much as we can.  The rest of the input buffer, if
     * any, is text that doesn't end with a NL and therefore we need to try
     * free up some space in our obuf so we can make forward progress.
     */
    while (inl > 0) {
        size_t avail = (size_t)ctx->obuf_size - (size_t)ctx->obuf_len;
        size_t to_copy;

        if (avail == 0) {
            /* Flush buffered data to make room */
            i = BIO_write(b->next_bio, ctx->obuf, ctx->obuf_len);
            if (i <= 0) {
                BIO_copy_next_retry(b);
                return num > 0 ? num : i;
            }
            if (i < ctx->obuf_len)
                memmove(ctx->obuf, ctx->obuf + i, ctx->obuf_len - i);
            ctx->obuf_len -= i;
            continue;
        }

        to_copy = inl > (int)avail ? avail : (size_t)inl;
        memcpy(&(ctx->obuf[ctx->obuf_len]), in, to_copy);
        ctx->obuf_len += (int)to_copy;
        in += to_copy;
        inl -= (int)to_copy;
        num += (int)to_copy;
    }

    return num;
}

static long linebuffer_ctrl(BIO *b, int cmd, long num, void *ptr)
{
    BIO *dbio;
    BIO_LINEBUFFER_CTX *ctx;
    long ret = 1;
    char *p;
    int r;
    int obs;

    ctx = (BIO_LINEBUFFER_CTX *)b->ptr;

    switch (cmd) {
    case BIO_CTRL_RESET:
        ctx->obuf_len = 0;
        if (b->next_bio == NULL)
            return 0;
        ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
        break;
    case BIO_CTRL_INFO:
        ret = (long)ctx->obuf_len;
        break;
    case BIO_CTRL_WPENDING:
        ret = (long)ctx->obuf_len;
        if (ret == 0) {
            if (b->next_bio == NULL)
                return 0;
            ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
        }
        break;
    case BIO_C_SET_BUFF_SIZE:
        if (num > INT_MAX)
            return 0;
        obs = (int)num;
        p = ctx->obuf;
        if ((obs > DEFAULT_LINEBUFFER_SIZE) && (obs != ctx->obuf_size)) {
            p = OPENSSL_malloc((size_t)obs);
            if (p == NULL)
                return 0;
        }
        if (ctx->obuf != p) {
            if (ctx->obuf_len > obs) {
                ctx->obuf_len = obs;
            }
            memcpy(p, ctx->obuf, ctx->obuf_len);
            OPENSSL_free(ctx->obuf);
            ctx->obuf = p;
            ctx->obuf_size = obs;
        }
        break;
    case BIO_C_DO_STATE_MACHINE:
        if (b->next_bio == NULL)
            return 0;
        BIO_clear_retry_flags(b);
        ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
        BIO_copy_next_retry(b);
        break;

    case BIO_CTRL_FLUSH:
        if (b->next_bio == NULL)
            return 0;
        if (ctx->obuf_len <= 0) {
            ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
            BIO_copy_next_retry(b);
            break;
        }

        for (;;) {
            BIO_clear_retry_flags(b);
            if (ctx->obuf_len > 0) {
                r = BIO_write(b->next_bio, ctx->obuf, ctx->obuf_len);
                BIO_copy_next_retry(b);
                if (r <= 0)
                    return (long)r;
                if (r < ctx->obuf_len)
                    memmove(ctx->obuf, ctx->obuf + r, ctx->obuf_len - r);
                ctx->obuf_len -= r;
            } else {
                ctx->obuf_len = 0;
                break;
            }
        }
        ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
        BIO_copy_next_retry(b);
        break;
    case BIO_CTRL_DUP:
        dbio = (BIO *)ptr;
        if (BIO_set_write_buffer_size(dbio, ctx->obuf_size) <= 0)
            ret = 0;
        break;
    case BIO_CTRL_EOF:
        /*
         * If there is no next BIO, BIO_read() returns 0, which means EOF.
         * BIO_eof() should return 1 in this case.
         */
        if (b->next_bio == NULL)
            return 1;
        ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
        break;
    default:
        if (b->next_bio == NULL)
            return 0;
        ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
        break;
    }
    return ret;
}

static long linebuffer_callback_ctrl(BIO *b, int cmd, BIO_info_cb *fp)
{
    if (b->next_bio == NULL)
        return 0;
    return BIO_callback_ctrl(b->next_bio, cmd, fp);
}

static int linebuffer_gets(BIO *b, char *buf, int size)
{
    int ret = 0;

    if (b->next_bio == NULL)
        return 0;
    ret = BIO_gets(b->next_bio, buf, size);
    BIO_clear_retry_flags(b);
    BIO_copy_next_retry(b);
    return ret;
}

static int linebuffer_puts(BIO *b, const char *str)
{
    size_t len = strlen(str);

    if (len > INT_MAX)
        return -1;
    return linebuffer_write(b, str, (int)len);
}
