#3231: Permission denied error with runProcess/openFile
-----------------------------+----------------------------------------------
Reporter: NeilMitchell | Owner: simonmar
Type: bug | Status: new
Priority: normal | Milestone: 7.6.1
Component: libraries/base | Version: 6.10.4
Resolution: | Keywords:
Os: Windows | Architecture: Unknown/Multiple
Failure: None/Unknown | Difficulty: Unknown
Testcase: | Blockedby:
Blocking: | Related:
-----------------------------+----------------------------------------------
Changes (by simonmar):
* priority: high => normal
* component: Runtime System => libraries/base
* milestone: 7.4.1 => 7.6.1
Comment:
'''Current status of this ticket'''
* We have implemented automatic delay+retry for many of the filesystem
operations in the `win32` package
(085b11285b6adbc6484d9c21f5e0b8105556869c), and this behaviour is
inherited by `System.Directory`. This means that accidental sharing
violations for things like `removeFile` do not happen any more.
* However, we have not implemented delay+retry for `System.IO.openFile`.
It is not clear how to do that easily, because `openFile` calls into
`msvcrt` rather than `Win32` directly. Ideally we should rewrite the IO
library to call `Win32` rather than `msvcrt` or `mingw` APIs.
I'll reproduce the test case from above. First, compile this C file with
`gcc tmp.c`:
{{{
#include <windows.h>
#include <stdlib.h>
#include <stdio.h>
#include <assert.h>
#define PIPE_NAME "\\\\.\\pipe\\MySmallPipe"
#define PIPE_BUF_SIZE 10
#define TIMEOUT 1000
#define NCLIENTS 30
int main(int argc, char *argv[]) {
if( 1 == argc ) {
//Caller
struct {
HANDLE hProcess;
HANDLE hPipe;
OVERLAPPED ov;
} data[NCLIENTS];
//Start clients
int i;
for(i = 0; i < NCLIENTS; ++i) {
fprintf(stderr, "Starting %d\n", i);
data[i].hPipe = CreateNamedPipe(
PIPE_NAME,
PIPE_ACCESS_DUPLEX | FILE_FLAG_OVERLAPPED,
PIPE_TYPE_BYTE | PIPE_READMODE_BYTE |
PIPE_WAIT,
100,
PIPE_BUF_SIZE,
PIPE_BUF_SIZE,
TIMEOUT,
0
);
assert(INVALID_HANDLE_VALUE != data[i].hPipe);
STARTUPINFO si;
memset(&si, 0, sizeof (STARTUPINFO));
si.cb = sizeof(STARTUPINFO);
PROCESS_INFORMATION pi;
BOOL res = CreateProcess(0, strdup("a.exe 1"), 0,
0, TRUE, 0, 0, 0, &si, &pi);
assert(res);
data[i].hProcess = pi.hProcess;
ConnectNamedPipe(data[i].hPipe, &data[i].ov);
} //i
fprintf(stderr, "Delay\n");
Sleep(TIMEOUT);
//Kill clients
for(i = 0; i < NCLIENTS; ++i) {
fprintf(stderr, "Terminating %d\n", i);
BOOL res = TerminateProcess(data[i].hProcess, 0);
DisconnectNamedPipe(data[i].hPipe);
CloseHandle(data[i].hPipe);
} //i
} else {
//Callee
fprintf(stderr, "Started\n");
BOOL res = WaitNamedPipe(PIPE_NAME, TIMEOUT);
assert(res);
HANDLE hPipe = CreateFile(
PIPE_NAME,
GENERIC_READ | GENERIC_WRITE,
0,
0,
OPEN_EXISTING,
0,
0
);
//Sleep forever
char buf[PIPE_BUF_SIZE];
DWORD n;
res = ReadFile(
hPipe,
buf,
PIPE_BUF_SIZE,
&n,
0
);
}
return 0;
}
}}}
Now, compile this Haskell file with `ghc bug.hs`:
{{{
module Main where
-- import System
import System.IO
import System.Process (runProcess, waitForProcess)
import System.Directory (removeFile)
import Control.Monad (replicateM_)
import qualified Data.ByteString as B
run :: FilePath -> IO ()
run exe = do
let tempFile = "mytempfile.txt"
h <- openFile tempFile WriteMode
exitCode <- waitForProcess =<< runProcess exe [] Nothing Nothing Nothing
(Just h) (Just h)
hClose h >> {- (if exitCode /= ExitSuccess then return () else
B.readFile tempFile >>= B.putStr) >> -} removeFile tempFile
main = replicateM_ 100 (putStrLn "Next:" >> run "a.exe")
}}}
And run with `./bug.exe`.
* As is, the program will succeed with GHC 7.4.1 (but not earlier),
because we fixed `removeFile`.
* If the `(if exitCode ...)` is uncommented, then the program will fail,
because we have not fixed `openFile` yet.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3231#comment:44>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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