New subject: [Bug 25062] popen: the stderr from the child process is (wrongly) redirected to the parent's stdin

7 Nov 2010


      http://bugs.winehq.org/show_bug.cgi?id=25062
Summary: popen: the stderr from the child process is (wrongly)
                    redirected to the parent's stdin
           Product: Wine
           Version: 1.2
          Platform: x86
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: msvcrt
        AssignedTo: wine-bugs@winehq.org
        ReportedBy: borut.razem@gmail.com
When a child process is popened in read mode, the child's stdout and stderr are
both redirected do parent's stdin, which is wrong: only the child's stdout
shoud be redirected, child's stderr should be the same as (inherited from) the
parent's stderr.
In the following example the "This is stdout" text should be displayd in
upper-case: "THIS IS STDOUT", and the "This is stderr" should be displayed in
lower-case.
Both child.c and parent.c should be compiled, executables should be located in
the same directory and parent.exe should be executed.
I compiled the example in three different ways:
1) msvc 6.0 using static libraries on Windows
2) msvc 6.0 using msvcrt.dll compilation on Windows
3) mingw using msvcrt.dll cross-compilation on Linux
All three executables works correctly on Windows platforms (tested on Windows
XP), while ony the no. 1) woks correctly on Linux + Wine: it uses the
statically linked popen implementation from msvc library. No. 2) and no. 3)
display incorrect uppercase "THIS IS STDERR": they both use the Wine
msvcrt.dll.
I think that this proves that the bug is in the Wine msvcrt.dll popen
implementation.
Example:
child.c:
----8<----
#include <stdio.h>
int
main (void)
{
  fprintf (stdout, "This is stdout\n");
  fprintf (stderr, "This is stderr\n");
  return 0;
}
---->8----
parent.c:
----8<----
#include <stdio.h>
#include <ctype.h>
int
main (void)
{
  FILE *fp;
if (NULL != (fp = _popen(".\child", "rt")))
    {
      int c;
while (EOF != (c = getc (fp)))
        putc (toupper (c), stdout);
      _pclose (fp);
return 0;
    }
  else
    {
      perror ("parent");
      return 1;
    }
}
---->8----
I took a look to the popen implementation in wine-1.3.6/dlls/msvcrt/process.c,
function MSVCRT__wpopen(): all special handling of fdStdErr in case of readPipe
seems suspicious to me...
Borut
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[Bug 25062] New: popen: the stderr from the child process is (wrongly) redirected to the parent's stdin