curl/src/tool_cb_wrt.c

/***************************************************************************
 *                                  _   _ ____  _
 *  Project                     ___| | | |  _ \| |
 *                             / __| | | | |_) | |
 *                            | (__| |_| |  _ <| |___
 *                             \___|\___/|_| \_\_____|
 *
 * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
 *
 * This software is licensed as described in the file COPYING, which
 * you should have received as part of this distribution. The terms
 * are also available at https://curl.se/docs/copyright.html.
 *
 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
 * copies of the Software, and permit persons to whom the Software is
 * furnished to do so, under the terms of the COPYING file.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 * SPDX-License-Identifier: curl
 *
 ***************************************************************************/
#include "tool_setup.h"

#include "tool_cfgable.h"
#include "tool_msgs.h"
#include "tool_cb_wrt.h"
#include "tool_operate.h"

#include "memdebug.h" /* keep this as LAST include */

#ifdef _WIN32
#define OPENMODE S_IREAD | S_IWRITE
#else
#define OPENMODE S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH
#endif

/* create/open a local file for writing, return TRUE on success */
bool tool_create_output_file(struct OutStruct *outs,
                             struct OperationConfig *config)
{
  FILE *file = NULL;
  const char *fname = outs->filename;
  DEBUGASSERT(outs);
  DEBUGASSERT(config);
  DEBUGASSERT(fname && *fname);

  if(config->file_clobber_mode == CLOBBER_ALWAYS ||
     (config->file_clobber_mode == CLOBBER_DEFAULT &&
      !outs->is_cd_filename)) {
    /* open file for writing */
    file = curlx_fopen(fname, "wb");
  }
  else {
    int fd;
    do {
      fd = curlx_open(fname, O_CREAT | O_WRONLY | O_EXCL | CURL_O_BINARY,
                      OPENMODE);
      /* Keep retrying in the hope that it is not interrupted sometime */
      /* !checksrc! disable ERRNOVAR 1 */
    } while(fd == -1 && errno == EINTR);
    if(config->file_clobber_mode == CLOBBER_NEVER && fd == -1) {
      int next_num = 1;
      struct dynbuf fbuffer;
      curlx_dyn_init(&fbuffer, 1025);
      /* !checksrc! disable ERRNOVAR 1 */
      while(fd == -1 && /* have not successfully opened a file */
            (errno == EEXIST || errno == EISDIR) &&
            /* because we keep having files that already exist */
            next_num < 100 /* and we have not reached the retry limit */ ) {
        curlx_dyn_reset(&fbuffer);
        if(curlx_dyn_addf(&fbuffer, "%s.%d", fname, next_num))
          return FALSE;
        next_num++;
        do {
          fd = curlx_open(curlx_dyn_ptr(&fbuffer),
                          O_CREAT | O_WRONLY | O_EXCL | CURL_O_BINARY,
                          OPENMODE);
          /* Keep retrying in the hope that it is not interrupted sometime */
        } while(fd == -1 && errno == EINTR);
      }
      outs->filename = curlx_dyn_ptr(&fbuffer); /* remember the new one */
      outs->alloc_filename = TRUE;
    }
    /* An else statement to not overwrite existing files and not retry with
       new numbered names (which would cover
       config->file_clobber_mode == CLOBBER_DEFAULT && outs->is_cd_filename)
       is not needed because we would have failed earlier, in the while loop
       and `fd` would now be -1 */
    if(fd != -1) {
      file = curlx_fdopen(fd, "wb");
      if(!file)
        close(fd);
    }
  }

  if(!file) {
    char errbuf[STRERROR_LEN];
    warnf("Failed to open the file %s: %s", fname,
          curlx_strerror(errno, errbuf, sizeof(errbuf)));
    return FALSE;
  }
  outs->s_isreg = TRUE;
  outs->fopened = TRUE;
  outs->stream = file;
  outs->bytes = 0;
  outs->init = 0;
  return TRUE;
}

#if defined(_WIN32) && !defined(UNDER_CE)
static size_t win_console(intptr_t fhnd, struct OutStruct *outs,
                          char *buffer, size_t bytes,
                          size_t *retp)
{
  DWORD chars_written;
  unsigned char *rbuf = (unsigned char *)buffer;
  DWORD rlen = (DWORD)bytes;

#define IS_TRAILING_BYTE(x) (0x80 <= (x) && (x) < 0xC0)

  /* attempt to complete an incomplete UTF-8 sequence from previous call. the
     sequence does not have to be well-formed. */
  if(outs->utf8seq[0] && rlen) {
    bool complete = false;
    /* two byte sequence (lead byte 110yyyyy) */
    if(0xC0 <= outs->utf8seq[0] && outs->utf8seq[0] < 0xE0) {
      outs->utf8seq[1] = *rbuf++;
      --rlen;
      complete = true;
    }
    /* three byte sequence (lead byte 1110zzzz) */
    else if(0xE0 <= outs->utf8seq[0] && outs->utf8seq[0] < 0xF0) {
      if(!outs->utf8seq[1]) {
        outs->utf8seq[1] = *rbuf++;
        --rlen;
      }
      if(rlen && !outs->utf8seq[2]) {
        outs->utf8seq[2] = *rbuf++;
        --rlen;
        complete = true;
      }
    }
    /* four byte sequence (lead byte 11110uuu) */
    else if(0xF0 <= outs->utf8seq[0] && outs->utf8seq[0] < 0xF8) {
      if(!outs->utf8seq[1]) {
        outs->utf8seq[1] = *rbuf++;
        --rlen;
      }
      if(rlen && !outs->utf8seq[2]) {
        outs->utf8seq[2] = *rbuf++;
        --rlen;
      }
      if(rlen && !outs->utf8seq[3]) {
        outs->utf8seq[3] = *rbuf++;
        --rlen;
        complete = true;
      }
    }

    if(complete) {
      WCHAR prefix[3] = {0};  /* UTF-16 (1-2 WCHARs) + NUL */

      if(MultiByteToWideChar(CP_UTF8, 0, (LPCSTR)outs->utf8seq, -1,
                             prefix, CURL_ARRAYSIZE(prefix))) {
        DEBUGASSERT(prefix[2] == L'\0');
        if(!WriteConsoleW((HANDLE) fhnd, prefix, prefix[1] ? 2 : 1,
                          &chars_written, NULL)) {
          return CURL_WRITEFUNC_ERROR;
        }
      }
      /* else: UTF-8 input was not well formed and OS is pre-Vista which drops
         invalid characters instead of writing U+FFFD to output. */
      memset(outs->utf8seq, 0, sizeof(outs->utf8seq));
    }
  }

  /* suppress an incomplete utf-8 sequence at end of rbuf */
  if(!outs->utf8seq[0] && rlen && (rbuf[rlen - 1] & 0x80)) {
    /* check for lead byte from a two, three or four byte sequence */
    if(0xC0 <= rbuf[rlen - 1] && rbuf[rlen - 1] < 0xF8) {
      outs->utf8seq[0] = rbuf[rlen - 1];
      rlen -= 1;
    }
    else if(rlen >= 2 && IS_TRAILING_BYTE(rbuf[rlen - 1])) {
      /* check for lead byte from a three or four byte sequence */
      if(0xE0 <= rbuf[rlen - 2] && rbuf[rlen - 2] < 0xF8) {
        outs->utf8seq[0] = rbuf[rlen - 2];
        outs->utf8seq[1] = rbuf[rlen - 1];
        rlen -= 2;
      }
      else if(rlen >= 3 && IS_TRAILING_BYTE(rbuf[rlen - 2])) {
        /* check for lead byte from a four byte sequence */
        if(0xF0 <= rbuf[rlen - 3] && rbuf[rlen - 3] < 0xF8) {
          outs->utf8seq[0] = rbuf[rlen - 3];
          outs->utf8seq[1] = rbuf[rlen - 2];
          outs->utf8seq[2] = rbuf[rlen - 1];
          rlen -= 3;
        }
      }
    }
  }

  if(rlen) {
    /* calculate buffer size for wide characters */
    DWORD len = (DWORD)MultiByteToWideChar(CP_UTF8, 0, (LPCSTR)rbuf,
                                           (int)rlen, NULL, 0);
    if(!len)
      return CURL_WRITEFUNC_ERROR;

    /* grow the buffer if needed */
    if(len > global->term.len) {
      wchar_t *buf = (wchar_t *) realloc(global->term.buf,
                                         len * sizeof(wchar_t));
      if(!buf)
        return CURL_WRITEFUNC_ERROR;
      global->term.len = len;
      global->term.buf = buf;
    }

    len = (DWORD)MultiByteToWideChar(CP_UTF8, 0, (LPCSTR)rbuf, (int)rlen,
                                     global->term.buf,
                                     (int)len);
    if(!len)
      return CURL_WRITEFUNC_ERROR;

    if(!WriteConsoleW((HANDLE) fhnd, global->term.buf,
                      len, &chars_written, NULL))
      return CURL_WRITEFUNC_ERROR;
  }

  *retp = bytes;
  return 0;
}
#endif

/*
** callback for CURLOPT_WRITEFUNCTION
*/

size_t tool_write_cb(char *buffer, size_t sz, size_t nmemb, void *userdata)
{
  size_t rc;
  struct per_transfer *per = userdata;
  struct OutStruct *outs = &per->outs;
  struct OperationConfig *config = per->config;
  size_t bytes = sz * nmemb;
  bool is_tty = global->isatty;
#if defined(_WIN32) && !defined(UNDER_CE)
  CONSOLE_SCREEN_BUFFER_INFO console_info;
  intptr_t fhnd;
#endif

  if(outs->out_null)
    return bytes;

#ifdef DEBUGBUILD
  {
    char *tty = curl_getenv("CURL_ISATTY");
    if(tty) {
      is_tty = TRUE;
      curl_free(tty);
    }
  }

  if(config->show_headers) {
    if(bytes > (size_t)CURL_MAX_HTTP_HEADER) {
      warnf("Header data size exceeds write limit");
      return CURL_WRITEFUNC_ERROR;
    }
  }
  else {
    if(bytes > (size_t)CURL_MAX_WRITE_SIZE) {
      warnf("Data size exceeds write limit");
      return CURL_WRITEFUNC_ERROR;
    }
  }

  {
    /* Some internal congruency checks on received OutStruct */
    bool check_fails = FALSE;
    if(outs->filename) {
      /* regular file */
      if(!*outs->filename)
        check_fails = TRUE;
      if(!outs->s_isreg)
        check_fails = TRUE;
      if(outs->fopened && !outs->stream)
        check_fails = TRUE;
      if(!outs->fopened && outs->stream)
        check_fails = TRUE;
      if(!outs->fopened && outs->bytes)
        check_fails = TRUE;
    }
    else {
      /* standard stream */
      if(!outs->stream || outs->s_isreg || outs->fopened)
        check_fails = TRUE;
      if(outs->alloc_filename || outs->is_cd_filename || outs->init)
        check_fails = TRUE;
    }
    if(check_fails) {
      warnf("Invalid output struct data for write callback");
      return CURL_WRITEFUNC_ERROR;
    }
  }
#endif

  if(!outs->stream && !tool_create_output_file(outs, per->config))
    return CURL_WRITEFUNC_ERROR;

  if(is_tty && (outs->bytes < 2000) && !config->terminal_binary_ok) {
    /* binary output to terminal? */
    if(memchr(buffer, 0, bytes)) {
      warnf("Binary output can mess up your terminal. "
            "Use \"--output -\" to tell curl to output it to your terminal "
            "anyway, or consider \"--output <FILE>\" to save to a file.");
      config->synthetic_error = TRUE;
      return CURL_WRITEFUNC_ERROR;
    }
  }

#if defined(_WIN32) && !defined(UNDER_CE)
  fhnd = _get_osfhandle(fileno(outs->stream));
  /* if Windows console then UTF-8 must be converted to UTF-16 */
  if(isatty(fileno(outs->stream)) &&
     GetConsoleScreenBufferInfo((HANDLE)fhnd, &console_info)) {
    size_t retval = win_console(fhnd, outs, buffer, bytes, &rc);
    if(retval)
      return retval;
  }
  else
#endif
  {
    if(per->hdrcbdata.headlist) {
      if(tool_write_headers(&per->hdrcbdata, outs->stream))
        return CURL_WRITEFUNC_ERROR;
    }
    rc = fwrite(buffer, sz, nmemb, outs->stream);
  }

  if(bytes == rc)
    /* we added this amount of data to the output */
    outs->bytes += bytes;

  if(config->readbusy) {
    config->readbusy = FALSE;
    curl_easy_pause(per->curl, CURLPAUSE_CONT);
  }

  if(config->nobuffer) {
    /* output buffering disabled */
    int res;
    do {
      res = fflush(outs->stream);
      /* Keep retrying in the hope that it is not interrupted sometime */
      /* !checksrc! disable ERRNOVAR 1 */
    } while(res && errno == EINTR);
    if(res)
      return CURL_WRITEFUNC_ERROR;
  }

  return rc;
}