ext/misc/sqlite3_stdio.c

/*
** 2024-09-24
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** Implementation of standard I/O interfaces for UTF-8 that are missing
** on Windows.
*/
#ifdef _WIN32  /* This file is a no-op on all platforms except Windows */
#ifndef _SQLITE3_STDIO_H_
#include "sqlite3_stdio.h"
#endif
#undef WIN32_LEAN_AND_MEAN
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <assert.h>
#include "sqlite3.h"
#include <ctype.h>
#include <stdarg.h>
#include <io.h>
#include <fcntl.h>

/*
** If the SQLITE_U8TEXT_ONLY option is defined, then use O_U8TEXT
** when appropriate on all output.  (Sometimes use O_BINARY when
** rendering ASCII text in cases where NL-to-CRLF expansion would
** not be correct.)
**
** If the SQLITE_U8TEXT_STDIO option is defined, then use O_U8TEXT
** when appropriate when writing to stdout or stderr.  Use O_BINARY
** or O_TEXT (depending on things like the .mode and the .crlf setting
** in the CLI, or other context clues in other applications) for all
** other output channels.
**
** The default behavior, if neither of the above is defined is to
** use O_U8TEXT when writing to the Windows console (or anything
** else for which _isatty() returns true) and to use O_BINARY or O_TEXT
** for all other output channels.
**
** The SQLITE_USE_W32_FOR_CONSOLE_IO macro is also available.  If
** defined, it forces the use of Win32 APIs for all console I/O, both
** input and output.  This is necessary for some non-Microsoft run-times
** that implement stdio differently from Microsoft/Visual-Studio.
*/
#if defined(SQLITE_U8TEXT_ONLY)
# define UseWtextForOutput(fd) 1
# define UseWtextForInput(fd)  1
# define IsConsole(fd)         _isatty(_fileno(fd))
#elif defined(SQLITE_U8TEXT_STDIO)
# define UseWtextForOutput(fd) ((fd)==stdout || (fd)==stderr)
# define UseWtextForInput(fd)  ((fd)==stdin)
# define IsConsole(fd)         _isatty(_fileno(fd))
#else
# define UseWtextForOutput(fd) _isatty(_fileno(fd))
# define UseWtextForInput(fd)  _isatty(_fileno(fd))
# define IsConsole(fd)         1
#endif

/*
** Global variables determine if simulated O_BINARY mode is to be
** used for stdout or other, respectively.  Simulated O_BINARY mode
** means the mode is usually O_BINARY, but switches to O_U8TEXT for
** unicode characters U+0080 or greater (any character that has a
** multi-byte representation in UTF-8).  This is the only way we
** have found to render Unicode characters on a Windows console while
** at the same time avoiding undesirable \n to \r\n translation.
*/
static int simBinaryStdout = 0;
static int simBinaryOther = 0;


/*
** Determine if simulated binary mode should be used for output to fd
*/
static int UseBinaryWText(FILE *fd){
  if( fd==stdout || fd==stderr ){
    return simBinaryStdout;
  }else{
    return simBinaryOther;
  }
}


/*
** Work-alike for the fopen() routine from the standard C library.
*/
FILE *sqlite3_fopen(const char *zFilename, const char *zMode){
  FILE *fp = 0;
  wchar_t *b1, *b2;
  int sz1, sz2;

  sz1 = (int)strlen(zFilename);
  sz2 = (int)strlen(zMode);
  b1 = sqlite3_malloc( (sz1+1)*sizeof(b1[0]) );
  b2 = sqlite3_malloc( (sz2+1)*sizeof(b1[0]) );
  if( b1 && b2 ){
    sz1 = MultiByteToWideChar(CP_UTF8, 0, zFilename, sz1, b1, sz1);
    b1[sz1] = 0;
    sz2 = MultiByteToWideChar(CP_UTF8, 0, zMode, sz2, b2, sz2);
    b2[sz2] = 0;
    fp = _wfopen(b1, b2);
  }
  sqlite3_free(b1);
  sqlite3_free(b2);
  simBinaryOther = 0;
  return fp;
}


/*
** Work-alike for the popen() routine from the standard C library.
*/
FILE *sqlite3_popen(const char *zCommand, const char *zMode){
  FILE *fp = 0;
  wchar_t *b1, *b2;
  int sz1, sz2;

  sz1 = (int)strlen(zCommand);
  sz2 = (int)strlen(zMode);
  b1 = sqlite3_malloc( (sz1+1)*sizeof(b1[0]) );
  b2 = sqlite3_malloc( (sz2+1)*sizeof(b1[0]) );
  if( b1 && b2 ){
    sz1 = MultiByteToWideChar(CP_UTF8, 0, zCommand, sz1, b1, sz1);
    b1[sz1] = 0;
    sz2 = MultiByteToWideChar(CP_UTF8, 0, zMode, sz2, b2, sz2);
    b2[sz2] = 0;
    fp = _wpopen(b1, b2);
  }
  sqlite3_free(b1);
  sqlite3_free(b2);
  return fp;
}

/*
** Work-alike for fgets() from the standard C library.
*/
char *sqlite3_fgets(char *buf, int sz, FILE *in){
  if( UseWtextForInput(in) ){
    /* When reading from the command-prompt in Windows, it is necessary
    ** to use _O_WTEXT input mode to read UTF-16 characters, then translate
    ** that into UTF-8.  Otherwise, non-ASCII characters all get translated
    ** into '?'.
    */
    wchar_t *b1 = sqlite3_malloc( sz*sizeof(wchar_t) );
    if( b1==0 ) return 0;
#ifdef SQLITE_USE_W32_FOR_CONSOLE_IO
    DWORD nRead = 0;
    if( IsConsole(in)
     && ReadConsoleW(GetStdHandle(STD_INPUT_HANDLE), b1, sz-1, &nRead, 0)
    ){
      b1[nRead] = 0;
    }else
#endif
    {
      _setmode(_fileno(in), IsConsole(in) ? _O_WTEXT : _O_U8TEXT);
      if( fgetws(b1, sz/4, in)==0 ){
        sqlite3_free(b1);
        return 0;
      }
    }
    WideCharToMultiByte(CP_UTF8, 0, b1, -1, buf, sz, 0, 0);
    sqlite3_free(b1);
    return buf;
  }else{
    /* Reading from a file or other input source, just read bytes without
    ** any translation. */
    return fgets(buf, sz, in);
  }
}

/*
** Send ASCII text as O_BINARY.  But for Unicode characters U+0080 and
** greater, switch to O_U8TEXT.
*/
static void piecemealOutput(wchar_t *b1, int sz, FILE *out){
  int i;
  wchar_t c;
  while( sz>0 ){
    for(i=0; i<sz && b1[i]>=0x80; i++){}
    if( i>0 ){
      c = b1[i];
      b1[i] = 0;
      fflush(out);
      _setmode(_fileno(out), _O_U8TEXT);
      fputws(b1, out);
      fflush(out);
      b1 += i;
      b1[0] = c;
      sz -= i;
    }else{
      fflush(out);
      _setmode(_fileno(out), _O_TEXT);
      _setmode(_fileno(out), _O_BINARY);
      fwrite(&b1[0], 1, 1, out);
      for(i=1; i<sz && b1[i]<0x80; i++){
        fwrite(&b1[i], 1, 1, out);
      }
      fflush(out);
      _setmode(_fileno(out), _O_U8TEXT);
      b1 += i;
      sz -= i;
    }
  }
}

/*
** Work-alike for fputs() from the standard C library.
*/
int sqlite3_fputs(const char *z, FILE *out){
  if( !UseWtextForOutput(out) ){
    /* Writing to a file or other destination, just write bytes without
    ** any translation. */
    return fputs(z, out);
  }else{
    /* One must use UTF16 in order to get unicode support when writing
    ** to the console on Windows. 
    */
    int sz = (int)strlen(z);
    wchar_t *b1 = sqlite3_malloc( (sz+1)*sizeof(wchar_t) );
    if( b1==0 ) return 0;
    sz = MultiByteToWideChar(CP_UTF8, 0, z, sz, b1, sz);
    b1[sz] = 0;

#ifdef SQLITE_USE_W32_FOR_CONSOLE_IO
    DWORD nWr = 0;
    if( IsConsole(out)
      && WriteConsoleW(GetStdHandle(STD_OUTPUT_HANDLE),b1,sz,&nWr,0)
    ){
      /* If writing to the console, then the WriteConsoleW() is all we
      ** need to do. */
    }else
#endif
    {
      /* As long as SQLITE_USE_W32_FOR_CONSOLE_IO is not defined, or for
      ** non-console I/O even if that macro is defined, write using the
      ** standard library. */
      _setmode(_fileno(out), _O_U8TEXT);
      if( UseBinaryWText(out) ){
        piecemealOutput(b1, sz, out);
      }else{
        fputws(b1, out);
      }
    }
    sqlite3_free(b1);
    return 0;
  }
}


/*
** Work-alike for fprintf() from the standard C library.
*/
int sqlite3_fprintf(FILE *out, const char *zFormat, ...){
  int rc;
  if( UseWtextForOutput(out) ){
    /* When writing to the command-prompt in Windows, it is necessary
    ** to use _O_WTEXT input mode and write UTF-16 characters.
    */
    char *z;
    va_list ap;

    va_start(ap, zFormat);
    z = sqlite3_vmprintf(zFormat, ap);
    va_end(ap);
    sqlite3_fputs(z, out);
    rc = (int)strlen(z);
    sqlite3_free(z);
  }else{
    /* Writing to a file or other destination, just write bytes without
    ** any translation. */
    va_list ap;
    va_start(ap, zFormat);
    rc = vfprintf(out, zFormat, ap);
    va_end(ap);
  }
  return rc;
}

/*
** Set the mode for an output stream.  mode argument is typically _O_BINARY or
** _O_TEXT.
*/
void sqlite3_fsetmode(FILE *fp, int mode){
  if( !UseWtextForOutput(fp) ){
    fflush(fp);
    _setmode(_fileno(fp), mode);
  }else if( fp==stdout || fp==stderr ){
    simBinaryStdout = (mode==_O_BINARY);
  }else{
    simBinaryOther = (mode==_O_BINARY);
  }
}

#endif /* defined(_WIN32) */