#4363: openFile sharing permissions are inconsistent across platforms
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Reporter: jystic | Owner:
Type: bug | Status: new
Priority: high | Milestone: 7.6.1
Component: libraries/base | Version: 6.12.3
Keywords: | Os: Windows
Architecture: Unknown/Multiple | Failure: Incorrect result at runtime
Difficulty: | Testcase:
Blockedby: | Blocking:
Related: |
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Comment(by jystic):
On the topic of sharing permissions being inconsistent across platforms,
there is another scenario which I have noticed that probably needs
attention as well. Perhaps it needs its own ticket, but it could be part
of this clean up.
When we open a file on POSIX systems, it is legal to delete or rename the
file even though it is open. On Windows however, we are locking the file
so that it may not be deleted or renamed.
This is purely because we are using the POSIX style APIs (i.e. _wsopen)
for opening files. These APIs do not have flags for specifying all the
possible sharing permissions and unfortunately Windows defaults to
preventing open files from being deleted or renamed.
This program on POSIX will allow the test file to be deleted while the
program is running (standard behaviour):
{{{
#include <stdio.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
int main()
{
const char *file = "./test.txt";
int fd;
int i = 0;
char buf[16];
fd = open(file, O_WRONLY | O_CREAT, 0644);
while (1)
{
sprintf(buf, "%d\n", i++);
write(fd, buf, strlen(buf));
sleep(1);
}
return 0;
}
}}}
The following program achieves the same behaviour on Windows by using the
FILE_SHARE_DELETE flag:
{{{
#include <stdio.h>
#include <fcntl.h>
#include <windows.h>
int main()
{
const wchar_t *file = L"test.txt";
int fd;
HANDLE h;
int i = 0;
char buf[16];
h = CreateFileW(file,
GENERIC_WRITE,
FILE_SHARE_READ | FILE_SHARE_DELETE,
NULL,
CREATE_NEW,
FILE_ATTRIBUTE_NORMAL,
NULL);
fd = _open_osfhandle((intptr_t)h, 0);
while (1)
{
sprintf(buf, "%d\n", i++);
write(fd, buf, strlen(buf));
Sleep(1000);
}
return 0;
}
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/4363#comment:12>
GHC <http://www.haskell.org/ghc/>
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