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Fclose works differently on Android and Linux

The following program:

#include <stdlib.h>
#include <stdio.h>
#include <sys/stat.h>
#include <sys/types.h>

int main() {
  fclose( stderr );
  printf( "%d\n", fileno( stderr ) );
  return 0;
}

shows -1on ubuntu 11.04 and 2on the ICS 4.0.3 emulator. There is no way to find information about this problem - can I make this code look like on both platforms? freopenon stderrhas the same problem.

Update:

The previous small program demonstrates the cause of the actual problem that I encountered: if I try to execute freopen stderrfor a file in the inexistent directory, then it stderrcloses on linux , but on android it remains open! And even more - if I write smth in this open file stderrand then do it fopenin another file, the text printed on stderrwill be written to this open file.

So this program:

#include <stdlib.h>
#include <stdio.h>
#include <sys/stat.h>
#include <sys/types.h>

# define LOGD( ... ) printf( __VA_ARGS__ ); printf( "\n" )

# ifdef ANDROID
#   define HOMEDIR "/data/data/com.myapp/" // for android
# else
#   define HOMEDIR "/home/darkmist/" // for linux
# endif

# define _T( x ) x

void TestFreopen_mkdir() {
  int mkdirres = mkdir( HOMEDIR "1.d", 0777 );
  LOGD(_T("TestFreopen mkdirres=0x%08x"),mkdirres);
}

void TestFreopen() {
  LOGD(_T("TestFreopen begin"));

  LOGD(_T("TestFreopen stderr=0x%08x"),fileno(stderr));
  fprintf(stderr,"fprintf_1 to stderr\n");

  // TestFreopen_mkdir(); // case 1

  if ( NULL == freopen( HOMEDIR "1.d/1", "w", stderr ) ) {
    LOGD( "freopen failed" );
    if ( -1 != fileno( stderr ) ) {
      fclose( stderr );
      LOGD( "freopen closed" );
    }
  }

  LOGD(_T("TestFreopen stderr=0x%08x"),fileno(stderr));
  fprintf(stderr,"fprintf_2 to stderr\n");

  TestFreopen_mkdir(); // case 2

  FILE* fopen_file = fopen( HOMEDIR "1.d/2", _T( "wb" ) );

  LOGD(_T("TestFreopen fopen_file=0x%08x"),fileno(fopen_file)); // same as for reopened stderr!!

  fprintf(stderr,"fprintf_3 to stderr\n");
  fprintf(fopen_file,"fprintf_1 to fopen_file\n");
  fflush(fopen_file);

  LOGD(_T("TestFreopen end"));
}

int main() {
  TestFreopen();
  return 0;
}

shows this on linux:

$ ./a.out
TestFreopen begin
TestFreopen stderr=0x00000002
fprintf_1 to stderr
freopen failed
TestFreopen stderr=0xffffffff
TestFreopen mkdirres=0x00000000
TestFreopen fopen_file=0x00000002
TestFreopen end

$ cat ~/1.d/2 
fprintf_1 to fopen_file

and this is on android:

$ adb push ./a.out /data/data/com.myapp
573 KB/s (34635 bytes in 0.058s)

$ adb shell run-as com.myapp /data/data/com.myapp/a.out
TestFreopen begin
TestFreopen stderr=0x00000002
fprintf_1 to stderr
freopen failed
freopen closed
TestFreopen stderr=0x00000002
TestFreopen mkdirres=0x00000000
TestFreopen fopen_file=0x00000002
TestFreopen end

$ adb shell run-as com.myapp cat /data/data/com.myapp/1.d/2
fprintf_3 to stderr
fprintf_1 to fopen_file
+5
3

stderr .

+4

, , undefined , C.

freopen() , , .

, , , - , , , .

, , .

+10

fclose() - , libc, libc , fclose()

Ubuntu eglibc, android bionic libc.

eglibc

eglibc 2.15 fclose(), :

iofclose.c:

...
_IO_acquire_lock (fp);
if (fp->_IO_file_flags & _IO_IS_FILEBUF)
    status = INTUSE(_IO_file_close_it) (fp);
else
    status = fp->_flags & _IO_ERR_SEEN ? -1 : 0;
...

strerr, . , :

from fileops.c:

fp->_flags = _IO_MAGIC|CLOSED_FILEBUF_FLAGS;
fp->_fileno = -1;
fp->_offset = _IO_pos_BAD;

return close_status ? close_status : write_status;

, eglibc fileno -1.

bionic

Bionic -, fileno(), fp → _:

stdio.h

#define __sfileno(p)    ((p)->_file)

from fileno.c

int
fileno(FILE *fp)
{
        int ret;

    FLOCKFILE(fp);
        ret = __sfileno(fp);
        FUNLOCKFILE(fp);
        return (ret);
}

fclose(), :

fclose.c

int
fclose(FILE *fp)
{
        int r;

        if (fp->_flags == 0) {  /* not open! */
                errno = EBADF;
                return (EOF);
        }
        FLOCKFILE(fp);
        WCIO_FREE(fp);
        r = fp->_flags & __SWR ? __sflush(fp) : 0;
        if (fp->_close != NULL && (*fp->_close)(fp->_cookie) < 0)
                r = EOF;
        if (fp->_flags & __SMBF)
                free((char *)fp->_bf._base);
        if (HASUB(fp))
                FREEUB(fp);
        if (HASLB(fp))
                FREELB(fp);
        fp->_r = fp->_w = 0;    /* Mess up if reaccessed. */
        fp->_flags = 0;         /* Release this FILE for reuse. */
        FUNLOCKFILE(fp);
        return (r);
}

wcio.h

#define WCIO_FREE(fp) ((void)(0))

local.h

#define HASUB(fp) (_UB(fp)._base != NULL)
#define FREEUB(fp) { \
        if (_UB(fp)._base != (fp)->_ubuf) \
                free(_UB(fp)._base); \
        _UB(fp)._base = NULL; \
}

, fp → _ fclose(). , fclose() , Ubuntu Android.

, stderr - /dev/null .

+3
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