Mail Archives: cygwin/2002/11/25/08:07:41
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Hi,
I have come across a problem with cygwin which relates to the Windows
CreateProcess() function.
Tested on
Cygwin DLLs: 1003.15.0.0 & 1003.16.0.0
Windows 2000 sp3
I have a Visual C++ program which uses CreateProcess to launch an executable
much like the example provided in the attachment. The example has been hard
coded to execute a cygwin compiled binary (ls) as this is what I was
attempting to do in the real thing.
When the program is run from a dos command prompt, it all works perfectly.
However when the program is run from cygwin bash, the launched program (ls)
fails with a read exception somewhere in the cygwin dll.
If the program is changed to execute a non cygwin-built binary, it all seems
to work fine.
I also bring your attention to the following lines from the example...
/* Something to do with bInheritHandles being FALSE, as when it is TRUE,
it works. */
CreateProcess(0, cmd, 0, 0, FALSE,
DETACHED_PROCESS | NORMAL_PRIORITY_CLASS,
0,
cwd,
&StartupInfo,
&ProcessInformation);
When the CreateProcess call is changed so handles are inherited, it all
works perfectly.
If this is the wrong place to report an issue like this, then please let me
know where I should email instead. I couldn't spot any other likely
candidates.
Regards,
Steve Fairbairn.
<<test.c>>
PS. Full VC++ Workspace and binaries are available, I just didn't want to
attach it on a mail to the whole list.
PPS. Apologies for the disclaimer, nothing I can do to stop it :(.
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Content-Type: application/octet-stream;
name="test.c"
Content-Disposition: attachment;
filename="test.c"
#include <stdio.h>
#include <stdlib.h>
#include <windows.h>
long win32_execute_binary(char *cwd, char *cmd, char *envp[])
{
HANDLE hndl, opfp=0;
int i,r,append2file=0;
STARTUPINFO StartupInfo={0};
PROCESS_INFORMATION ProcessInformation={0};
GetStartupInfo(&StartupInfo);
StartupInfo.dwFlags = STARTF_USESHOWWINDOW;
StartupInfo.wShowWindow = SW_HIDE;
StartupInfo.cb = sizeof(STARTUPINFO);
/* add new ENV variables - not thread safe tho.
*/
for (i=0;envp && envp[i];i++)
{
_putenv(envp[i]);
}
/* Something to do with bInheritHandles being FALSE, as when it is TRUE, it works. */
CreateProcess(0, cmd, 0, 0, FALSE,
DETACHED_PROCESS | NORMAL_PRIORITY_CLASS,
0,
cwd,
&StartupInfo,
&ProcessInformation);
hndl = ProcessInformation.hProcess;
if (!hndl)
r = GetLastError();
/* wait for it to finish */
{
DWORD w;
w= WaitForSingleObject(hndl, INFINITE);
if (w == WAIT_FAILED)
r = GetLastError();
}
// handles must be closed as not used
if (ProcessInformation.hProcess)
CloseHandle(ProcessInformation.hProcess);
if (ProcessInformation.hThread)
CloseHandle(ProcessInformation.hThread);
return (long)hndl;
}
int main(int arc, char *argv[], char *envp[])
{
long ret = 0;
ret = win32_execute_binary("/home/Administrator", "ls", envp);
printf("Return val = %ld\n", ret);
exit(0);
}
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