file.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.] */

#if defined(__linux) || defined(__sun) || defined(__hpux)
// Following definition aliases fopen to fopen64 on above mentioned
// platforms. This makes it possible to open and sequentially access
// files larger than 2GB from 32-bit application. It does not allow to
// traverse them beyond 2GB with fseek/ftell, but on the other hand *no*
// 32-bit platform permits that, not with fseek/ftell. Not to mention
// that breaking 2GB limit for seeking would require surgery to *our*
// API. But sequential access suffices for practical cases when you
// can run into large files, such as fingerprinting, so we can let API
// alone. For reference, the list of 32-bit platforms which allow for
// sequential access of large files without extra "magic" comprise *BSD,
// Darwin, IRIX...
#ifndef _FILE_OFFSET_BITS
#define _FILE_OFFSET_BITS 64
#endif
#endif

#include <openssl/bio.h>

#include <errno.h>
#include <stdio.h>
#include <string.h>

#if defined(OPENSSL_WINDOWS)
#include <fcntl.h>
#include <io.h>
#endif  // OPENSSL_WINDOWS

#include <openssl/err.h>
#include <openssl/mem.h>

#include "../internal.h"


#define BIO_FP_READ 0x02
#define BIO_FP_WRITE 0x04
#define BIO_FP_APPEND 0x08

#if !defined(OPENSSL_NO_FILESYSTEM)
#define fopen_if_available fopen
#else
static FILE *fopen_if_available(const char *path, const char *mode) {
  errno = ENOENT;
  return NULL;
}
#endif

BIO *BIO_new_file(const char *filename, const char *mode) {
  BIO *ret;
  FILE *file;

  file = fopen_if_available(filename, mode);
  if (file == NULL) {
    OPENSSL_PUT_SYSTEM_ERROR();

    ERR_add_error_data(5, "fopen('", filename, "','", mode, "')");
    if (errno == ENOENT) {
      OPENSSL_PUT_ERROR(BIO, BIO_R_NO_SUCH_FILE);
    } else {
      OPENSSL_PUT_ERROR(BIO, BIO_R_SYS_LIB);
    }
    return NULL;
  }

  ret = BIO_new_fp(file, BIO_CLOSE);
  if (ret == NULL) {
    fclose(file);
    return NULL;
  }

  return ret;
}

BIO *BIO_new_fp(FILE *stream, int close_flag) {
  BIO *ret = BIO_new(BIO_s_file());

  if (ret == NULL) {
    return NULL;
  }

  BIO_set_fp(ret, stream, close_flag);
  return ret;
}

static int file_free(BIO *bio) {
  if (!bio->shutdown) {
    return 1;
  }

  if (bio->init && bio->ptr != NULL) {
    fclose(bio->ptr);
    bio->ptr = NULL;
  }
  bio->init = 0;

  return 1;
}

static int file_read(BIO *b, char *out, int outl) {
  if (!b->init) {
    return 0;
  }

  size_t ret = fread(out, 1, outl, (FILE *)b->ptr);
  if (ret == 0 && ferror((FILE *)b->ptr)) {
    OPENSSL_PUT_SYSTEM_ERROR();
    OPENSSL_PUT_ERROR(BIO, ERR_R_SYS_LIB);
    return -1;
  }

  // fread reads at most |outl| bytes, so |ret| fits in an int.
  return (int)ret;
}

static int file_write(BIO *b, const char *in, int inl) {
  if (!b->init) {
    return 0;
  }

  int ret = (int)fwrite(in, inl, 1, (FILE *)b->ptr);
  if (ret > 0) {
    ret = inl;
  }
  return ret;
}

static long file_ctrl(BIO *b, int cmd, long num, void *ptr) {
  long ret = 1;
  FILE *fp = (FILE *)b->ptr;
  FILE **fpp;

  switch (cmd) {
    case BIO_CTRL_RESET:
      num = 0;
      OPENSSL_FALLTHROUGH;
    case BIO_C_FILE_SEEK:
      ret = (long)fseek(fp, num, 0);
      break;
    case BIO_CTRL_EOF:
      ret = (long)feof(fp);
      break;
    case BIO_C_FILE_TELL:
    case BIO_CTRL_INFO:
      ret = ftell(fp);
      break;
    case BIO_C_SET_FILE_PTR:
      file_free(b);
      b->shutdown = (int)num & BIO_CLOSE;
      b->ptr = ptr;
      b->init = 1;
#if defined(OPENSSL_WINDOWS)
      // Windows differentiates between "text" and "binary" file modes, so set
      // the file to text mode if caller specifies BIO_FP_TEXT flag.
      //
      // https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/setmode?view=msvc-170#remarks
      _setmode(_fileno(b->ptr), num & BIO_FP_TEXT ? _O_TEXT : _O_BINARY);
#endif
      break;
    case BIO_C_SET_FILENAME:
      file_free(b);
      b->shutdown = (int)num & BIO_CLOSE;
      const char *mode;
      if (num & BIO_FP_APPEND) {
        if (num & BIO_FP_READ) {
          mode = "a+";
        } else {
          mode = "a";
        }
      } else if ((num & BIO_FP_READ) && (num & BIO_FP_WRITE)) {
        mode = "r+";
      } else if (num & BIO_FP_WRITE) {
        mode = "w";
      } else if (num & BIO_FP_READ) {
        mode = "r";
      } else {
        OPENSSL_PUT_ERROR(BIO, BIO_R_BAD_FOPEN_MODE);
        ret = 0;
        break;
      }
      fp = fopen_if_available(ptr, mode);
      if (fp == NULL) {
        OPENSSL_PUT_SYSTEM_ERROR();
        ERR_add_error_data(5, "fopen('", ptr, "','", mode, "')");
        OPENSSL_PUT_ERROR(BIO, ERR_R_SYS_LIB);
        ret = 0;
        break;
      }
      b->ptr = fp;
      b->init = 1;
      break;
    case BIO_C_GET_FILE_PTR:
      // the ptr parameter is actually a FILE ** in this case.
      if (ptr != NULL) {
        fpp = (FILE **)ptr;
        *fpp = (FILE *)b->ptr;
      }
      break;
    case BIO_CTRL_GET_CLOSE:
      ret = (long)b->shutdown;
      break;
    case BIO_CTRL_SET_CLOSE:
      b->shutdown = (int)num;
      break;
    case BIO_CTRL_FLUSH:
      ret = 0 == fflush((FILE *)b->ptr);
      break;
    case BIO_CTRL_WPENDING:
    case BIO_CTRL_PENDING:
    default:
      ret = 0;
      break;
  }
  return ret;
}

static int file_gets(BIO *bp, char *buf, int size) {
  if (size == 0) {
    return 0;
  }

  if (!fgets(buf, size, (FILE *)bp->ptr)) {
    buf[0] = 0;
    // TODO(davidben): This doesn't distinguish error and EOF. This should check
    // |ferror| as in |file_read|.
    return 0;
  }

  return (int)strlen(buf);
}

static const BIO_METHOD methods_filep = {
    BIO_TYPE_FILE,   "FILE pointer",
    file_write,      file_read,
    NULL /* puts */, file_gets,
    file_ctrl,       NULL /* create */,
    file_free,       NULL /* callback_ctrl */,
};

const BIO_METHOD *BIO_s_file(void) { return &methods_filep; }


int BIO_get_fp(BIO *bio, FILE **out_file) {
  return (int)BIO_ctrl(bio, BIO_C_GET_FILE_PTR, 0, (char *)out_file);
}

int BIO_set_fp(BIO *bio, FILE *file, int close_flag) {
  return (int)BIO_ctrl(bio, BIO_C_SET_FILE_PTR, close_flag, (char *)file);
}

int BIO_read_filename(BIO *bio, const char *filename) {
  return (int)BIO_ctrl(bio, BIO_C_SET_FILENAME, BIO_CLOSE | BIO_FP_READ,
                       (char *)filename);
}

int BIO_write_filename(BIO *bio, const char *filename) {
  return (int)BIO_ctrl(bio, BIO_C_SET_FILENAME, BIO_CLOSE | BIO_FP_WRITE,
                       (char *)filename);
}

int BIO_append_filename(BIO *bio, const char *filename) {
  return (int)BIO_ctrl(bio, BIO_C_SET_FILENAME, BIO_CLOSE | BIO_FP_APPEND,
                       (char *)filename);
}

int BIO_rw_filename(BIO *bio, const char *filename) {
  return (int)BIO_ctrl(bio, BIO_C_SET_FILENAME,
                       BIO_CLOSE | BIO_FP_READ | BIO_FP_WRITE,
                       (char *)filename);
}

long BIO_tell(BIO *bio) { return BIO_ctrl(bio, BIO_C_FILE_TELL, 0, NULL); }

long BIO_seek(BIO *bio, long offset) {
  return BIO_ctrl(bio, BIO_C_FILE_SEEK, offset, NULL);
}