text: /* crypto/bio/bss_mem.c */
  /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
   * All rights reserved.
   *
   * This package is an SSL implementation written
   * by Eric Young (eay@cryptsoft.com).
   * The implementation was written so as to conform with Netscapes SSL.
   *
   * This library is free for commercial and non-commercial use as long as
   * the following conditions are aheared to.  The following conditions
   * apply to all code found in this distribution, be it the RC4, RSA,
   * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
   * included with this distribution is covered by the same copyright terms
   * except that the holder is Tim Hudson (tjh@cryptsoft.com).
   *
   * Copyright remains Eric Young's, and as such any Copyright notices in
   * the code are not to be removed.
   * If this package is used in a product, Eric Young should be given attribution
   * as the author of the parts of the library used.
   * This can be in the form of a textual message at program startup or
   * in documentation (online or textual) provided with the package.
   *
   * 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 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.
   * 3. All advertising materials mentioning features or use of this software
   *    must display the following acknowledgement:
   *    "This product includes cryptographic software written by
   *     Eric Young (eay@cryptsoft.com)"
   *    The word 'cryptographic' can be left out if the rouines from the library
   *    being used are not cryptographic related :-).
   * 4. If you include any Windows specific code (or a derivative thereof) from
   *    the apps directory (application code) you must include an acknowledgement:
   *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
   *
   * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``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.
   *
   * The licence and distribution terms for any publically available version or
   * derivative of this code cannot be changed.  i.e. this code cannot simply be
   * copied and put under another distribution licence
   * [including the GNU Public Licence.]
   */
  
  #include <stdio.h>
  #include <errno.h>
  #include "cryptlib.h"
  #include <openssl/bio.h>
  
  static int mem_write(BIO *h, const char *buf, int num);
  static int mem_read(BIO *h, char *buf, int size);
  static int mem_puts(BIO *h, const char *str);
  static int mem_gets(BIO *h, char *str, int size);
  static long mem_ctrl(BIO *h, int cmd, long arg1, void *arg2);
  static int mem_new(BIO *h);
  static int mem_free(BIO *data);
  static BIO_METHOD mem_method = {
      BIO_TYPE_MEM,
      "memory buffer",
      mem_write,
      mem_read,
      mem_puts,
      mem_gets,
      mem_ctrl,
      mem_new,
      mem_free,
      NULL,
  };
  
  /*
   * bio->num is used to hold the value to return on 'empty', if it is 0,
   * should_retry is not set
   */
  
  BIO_METHOD *BIO_s_mem(void)
  {
      return (&mem_method);
  }
  
  BIO *BIO_new_mem_buf(void *buf, int len)
  {
      BIO *ret;
      BUF_MEM *b;
      size_t sz;
  
      if (!buf) {
          BIOerr(BIO_F_BIO_NEW_MEM_BUF, BIO_R_NULL_PARAMETER);
          return NULL;
      }
      sz = (len < 0) ? strlen(buf) : (size_t)len;
      if (!(ret = BIO_new(BIO_s_mem())))
          return NULL;
      b = (BUF_MEM *)ret->ptr;
      b->data = buf;
      b->length = sz;
      b->max = sz;
      ret->flags |= BIO_FLAGS_MEM_RDONLY;
      /* Since this is static data retrying wont help */
      ret->num = 0;
      return ret;
  }
  
  static int mem_new(BIO *bi)
  {
      BUF_MEM *b;
  
      if ((b = BUF_MEM_new()) == NULL)
          return (0);
      bi->shutdown = 1;
      bi->init = 1;
      bi->num = -1;
      bi->ptr = (char *)b;
      return (1);
  }
  
  static int mem_free(BIO *a)
  {
      if (a == NULL)
          return (0);
      if (a->shutdown) {
          if ((a->init) && (a->ptr != NULL)) {
              BUF_MEM *b;
              b = (BUF_MEM *)a->ptr;
              if (a->flags & BIO_FLAGS_MEM_RDONLY)
                  b->data = NULL;
              BUF_MEM_free(b);
              a->ptr = NULL;
          }
      }
      return (1);
  }
  
  static int mem_read(BIO *b, char *out, int outl)
  {
      int ret = -1;
      BUF_MEM *bm;
  
      bm = (BUF_MEM *)b->ptr;
      BIO_clear_retry_flags(b);
      ret = (outl >= 0 && (size_t)outl > bm->length) ? (int)bm->length : outl;
      if ((out != NULL) && (ret > 0)) {
          memcpy(out, bm->data, ret);
          bm->length -= ret;
          if (b->flags & BIO_FLAGS_MEM_RDONLY)
              bm->data += ret;
          else {
              memmove(&(bm->data[0]), &(bm->data[ret]), bm->length);
          }
      } else if (bm->length == 0) {
          ret = b->num;
          if (ret != 0)
              BIO_set_retry_read(b);
      }
      return (ret);
  }
  
  static int mem_write(BIO *b, const char *in, int inl)
  {
      int ret = -1;
      int blen;
      BUF_MEM *bm;
  
      bm = (BUF_MEM *)b->ptr;
      if (in == NULL) {
          BIOerr(BIO_F_MEM_WRITE, BIO_R_NULL_PARAMETER);
          goto end;
      }
  
      if (b->flags & BIO_FLAGS_MEM_RDONLY) {
          BIOerr(BIO_F_MEM_WRITE, BIO_R_WRITE_TO_READ_ONLY_BIO);
          goto end;
      }
  
      BIO_clear_retry_flags(b);
      blen = bm->length;
      if (BUF_MEM_grow_clean(bm, blen + inl) != (blen + inl))
          goto end;
      memcpy(&(bm->data[blen]), in, inl);
      ret = inl;
   end:
      return (ret);
  }
  
  static long mem_ctrl(BIO *b, int cmd, long num, void *ptr)
  {
      long ret = 1;
      char **pptr;
  
      BUF_MEM *bm = (BUF_MEM *)b->ptr;
  
      switch (cmd) {
      case BIO_CTRL_RESET:
          if (bm->data != NULL) {
              /* For read only case reset to the start again */
              if (b->flags & BIO_FLAGS_MEM_RDONLY) {
                  bm->data -= bm->max - bm->length;
                  bm->length = bm->max;
              } else {
                  memset(bm->data, 0, bm->max);
                  bm->length = 0;
              }
          }
          break;
      case BIO_CTRL_EOF:
          ret = (long)(bm->length == 0);
          break;
      case BIO_C_SET_BUF_MEM_EOF_RETURN:
          b->num = (int)num;
          break;
      case BIO_CTRL_INFO:
          ret = (long)bm->length;
          if (ptr != NULL) {
              pptr = (char **)ptr;
              *pptr = (char *)&(bm->data[0]);
          }
          break;
      case BIO_C_SET_BUF_MEM:
          mem_free(b);
          b->shutdown = (int)num;
          b->ptr = ptr;
          break;
      case BIO_C_GET_BUF_MEM_PTR:
          if (ptr != NULL) {
              pptr = (char **)ptr;
              *pptr = (char *)bm;
          }
          break;
      case BIO_CTRL_GET_CLOSE:
          ret = (long)b->shutdown;
          break;
      case BIO_CTRL_SET_CLOSE:
          b->shutdown = (int)num;
          break;
  
      case BIO_CTRL_WPENDING:
          ret = 0L;
          break;
      case BIO_CTRL_PENDING:
          ret = (long)bm->length;
          break;
      case BIO_CTRL_DUP:
      case BIO_CTRL_FLUSH:
          ret = 1;
          break;
      case BIO_CTRL_PUSH:
      case BIO_CTRL_POP:
      default:
          ret = 0;
          break;
      }
      return (ret);
  }
  
  static int mem_gets(BIO *bp, char *buf, int size)
  {
      int i, j;
      int ret = -1;
      char *p;
      BUF_MEM *bm = (BUF_MEM *)bp->ptr;
  
      BIO_clear_retry_flags(bp);
      j = bm->length;
      if ((size - 1) < j)
          j = size - 1;
      if (j <= 0) {
          *buf = '\0';
          return 0;
      }
      p = bm->data;
      for (i = 0; i < j; i++) {
          if (p[i] == '\n') {
              i++;
              break;
          }
      }
  
      /*
       * i is now the max num of bytes to copy, either j or up to
       * and including the first newline
       */
  
      i = mem_read(bp, buf, i);
      if (i > 0)
          buf[i] = '\0';
      ret = i;
      return (ret);
  }
  
  static int mem_puts(BIO *bp, const char *str)
  {
      int n, ret;
  
      n = strlen(str);
      ret = mem_write(bp, str, n);
      /* memory semantics is that it will always work */
      return (ret);
  }
  