// -----------------------------
// ---- PAL layer ends here ----
// -----------------------------
internal static Interop.libc.OpenFlags TranslateFlags(PipeDirection direction, PipeOptions options, HandleInheritability inheritability)
{
// Translate direction
Interop.libc.OpenFlags flags =
direction == PipeDirection.InOut ? Interop.libc.OpenFlags.O_RDWR :
direction == PipeDirection.Out ? Interop.libc.OpenFlags.O_WRONLY :
Interop.libc.OpenFlags.O_RDONLY;
// Translate options
if ((options & PipeOptions.WriteThrough) != 0)
{
flags |= Interop.libc.OpenFlags.O_SYNC;
}
// Translate inheritability.
if ((inheritability & HandleInheritability.Inheritable) == 0)
{
flags |= Interop.libc.OpenFlags.O_CLOEXEC;
}
// PipeOptions.Asynchronous is ignored, at least for now. Asynchronous processing
// is handling just by queueing a work item to do the work synchronously on a pool thread.
return(flags);
}
private static FileStream CreateSharedBackingObject(
Interop.libc.MemoryMappedProtections protections, long capacity)
{
// The POSIX shared memory object name must begin with '/'. After that we just want something short and unique.
string mapName = "/corefx_map_" + Guid.NewGuid().ToString("N");
// Determine the flags to use when creating the shared memory object
Interop.libc.OpenFlags flags = (protections & Interop.libc.MemoryMappedProtections.PROT_WRITE) != 0 ?
Interop.libc.OpenFlags.O_RDWR :
Interop.libc.OpenFlags.O_RDONLY;
flags |= Interop.libc.OpenFlags.O_CREAT | Interop.libc.OpenFlags.O_EXCL; // CreateNew
// Determine the permissions with which to create the file
Interop.libc.Permissions perms = default(Interop.libc.Permissions);
if ((protections & Interop.libc.MemoryMappedProtections.PROT_READ) != 0)
{
perms |= Interop.libc.Permissions.S_IRUSR;
}
if ((protections & Interop.libc.MemoryMappedProtections.PROT_WRITE) != 0)
{
perms |= Interop.libc.Permissions.S_IWUSR;
}
if ((protections & Interop.libc.MemoryMappedProtections.PROT_EXEC) != 0)
{
perms |= Interop.libc.Permissions.S_IXUSR;
}
// Create the shared memory object.
int fd;
Interop.CheckIo(fd = Interop.libc.shm_open(mapName, flags, (int)perms), mapName);
SafeFileHandle fileHandle = new SafeFileHandle((IntPtr)fd, ownsHandle: true);
try
{
// Unlink the shared memory object immediatley so that it'll go away once all handles
// to it are closed (as with opened then unlinked files, it'll remain usable via
// the open handles even though it's unlinked and can't be opened anew via its name).
Interop.CheckIo(Interop.libc.shm_unlink(mapName));
// Give it the right capacity. We do this directly with ftruncate rather
// than via FileStream.SetLength after the FileStream is created because, on some systems,
// lseek fails on shared memory objects, causing the FileStream to think it's unseekable,
// causing it to preemptively throw from SetLength.
Interop.CheckIo(Interop.libc.ftruncate(fd, capacity));
// Wrap the file descriptor in a stream and return it.
return(new FileStream(fileHandle, TranslateProtectionsToFileAccess(protections)));
}
catch
{
fileHandle.Dispose();
throw;
}
}
/// <summary>Initializes a stream for reading or writing a Unix file.</summary>
/// <param name="path">The path to the file.</param>
/// <param name="mode">How the file should be opened.</param>
/// <param name="access">Whether the file will be read, written, or both.</param>
/// <param name="share">What other access to the file should be allowed. This is currently ignored.</param>
/// <param name="bufferSize">The size of the buffer to use when buffering.</param>
/// <param name="options">Additional options for working with the file.</param>
internal UnixFileStream(String path, FileMode mode, FileAccess access, FileShare share, int bufferSize, FileOptions options, FileStream parent)
: base(parent)
{
// FileStream performs most of the general argument validation. We can assume here that the arguments
// are all checked and consistent (e.g. non-null-or-empty path; valid enums in mode, access, share, and options; etc.)
// Store the arguments
_path = path;
_access = access;
_mode = mode;
_options = options;
_bufferLength = bufferSize;
_useAsyncIO = (options & FileOptions.Asynchronous) != 0;
// Translate the arguments into arguments for an open call
Interop.libc.OpenFlags openFlags = PreOpenConfigurationFromOptions(mode, access, options); // FileShare currently ignored
Interop.libc.Permissions openPermissions = Interop.libc.Permissions.S_IRWXU; // creator has read/write/execute permissions; no permissions for anyone else
// Open the file and store the safe handle. Subsequent code in this method expects the safe handle to be initialized.
_fileHandle = SafeFileHandle.Open(path, openFlags, (int)openPermissions);
_fileHandle.IsAsync = _useAsyncIO;
// Lock the file if requested via FileShare. This is only advisory locking. FileShare.None implies an exclusive
// lock on the file and all other modes use a shared lock. While this is not as granular as Windows, not mandatory,
// and not atomic with file opening, it's better than nothing.
try
{
Interop.libc.LockOperations lockOperation = (share == FileShare.None) ? Interop.libc.LockOperations.LOCK_EX : Interop.libc.LockOperations.LOCK_SH;
SysCall <Interop.libc.LockOperations, int>((fd, op, _) => Interop.libc.flock(fd, op), lockOperation | Interop.libc.LockOperations.LOCK_NB);
}
catch
{
_fileHandle.Dispose();
throw;
}
// Support additional options after the file has been opened.
// These provide hints around how the file will be accessed.
Interop.libc.Advice fadv =
_options == FileOptions.RandomAccess ? Interop.libc.Advice.POSIX_FADV_RANDOM :
_options == FileOptions.SequentialScan ? Interop.libc.Advice.POSIX_FADV_SEQUENTIAL :
0;
if (fadv != 0)
{
SysCall <Interop.libc.Advice, int>((fd, advice, _) => Interop.libc.posix_fadvise(fd, 0, 0, advice), fadv);
}
// Jump to the end of the file if opened as Append.
if (_mode == FileMode.Append)
{
_appendStart = SeekCore(0, SeekOrigin.End);
}
}
/// <summary>Opens the specified file with the requested flags and mode.</summary>
/// <param name="path">The path to the file.</param>
/// <param name="flags">The flags with which to open the file.</param>
/// <param name="mode">The mode for opening the file.</param>
/// <returns>A SafeFileHandle for the opened file.</returns>
internal static SafeFileHandle Open(string path, Interop.libc.OpenFlags flags, int mode)
{
Debug.Assert(path != null);
// SafeFileHandle wraps a file descriptor rather than a pointer, and a file descriptor is always 4 bytes
// rather than being pointer sized, which means we can't utilize the runtime's ability to marshal safe handles.
// Ideally this would be a constrained execution region, but we don't have access to PrepareConstrainedRegions.
// We still use a finally block to house the code that opens the file and stores the handle in hopes
// of making it as non-interruptable as possible. The SafeFileHandle is also allocated first to avoid
// the allocation after getting the file descriptor but before storing it.
SafeFileHandle handle = new SafeFileHandle(ownsHandle: true);
try { } finally
{
// If we fail to open the file due to a path not existing, we need to know whether to blame
// the file itself or its directory. If we're creating the file, then we blame the directory,
// otherwise we blame the file.
bool enoentDueToDirectory = (flags & Interop.libc.OpenFlags.O_CREAT) != 0;
// Open the file.
int fd;
while (Interop.CheckIo(fd = Interop.libc.open(path, flags, mode), path, isDirectory: enoentDueToDirectory,
errorRewriter: errno => (errno == Interop.Errors.EISDIR) ? Interop.Errors.EACCES : errno))
{
;
}
Debug.Assert(fd >= 0);
handle.SetHandle((IntPtr)fd);
Debug.Assert(!handle.IsInvalid);
// Make sure it's not a directory; we do this after opening it once we have a file descriptor
// to avoid race conditions.
Interop.libcoreclrpal.fileinfo buf;
if (Interop.libcoreclrpal.GetFileInformationFromFd(fd, out buf) != 0)
{
handle.Dispose();
throw Interop.GetExceptionForIoErrno(Marshal.GetLastWin32Error(), path);
}
if ((buf.mode & Interop.libcoreclrpal.FileTypes.S_IFMT) == Interop.libcoreclrpal.FileTypes.S_IFDIR)
{
handle.Dispose();
throw Interop.GetExceptionForIoErrno(Interop.Errors.EACCES, path, isDirectory: true);
}
}
return(handle);
}
private static FileStream CreateSharedBackingObject(
Interop.libc.MemoryMappedProtections protections, long capacity,
out string mapName, out SafeMemoryMappedFileHandle.FileStreamSource fileStreamSource)
{
// The POSIX shared memory object name must begin with '/'. After that we just want something short and unique.
mapName = "/" + MemoryMapObjectFilePrefix + Guid.NewGuid().ToString("N");
fileStreamSource = SafeMemoryMappedFileHandle.FileStreamSource.ManufacturedSharedMemory;
// Determine the flags to use when creating the shared memory object
Interop.libc.OpenFlags flags = (protections & Interop.libc.MemoryMappedProtections.PROT_WRITE) != 0 ?
Interop.libc.OpenFlags.O_RDWR :
Interop.libc.OpenFlags.O_RDONLY;
flags |= Interop.libc.OpenFlags.O_CREAT | Interop.libc.OpenFlags.O_EXCL; // CreateNew
// Determine the permissions with which to create the file
Interop.libc.Permissions perms = default(Interop.libc.Permissions);
if ((protections & Interop.libc.MemoryMappedProtections.PROT_READ) != 0)
{
perms |= Interop.libc.Permissions.S_IRUSR;
}
if ((protections & Interop.libc.MemoryMappedProtections.PROT_WRITE) != 0)
{
perms |= Interop.libc.Permissions.S_IWUSR;
}
if ((protections & Interop.libc.MemoryMappedProtections.PROT_EXEC) != 0)
{
perms |= Interop.libc.Permissions.S_IXUSR;
}
// Create the shared memory object. Then enlarge it to the requested capacity.
int fd;
Interop.CheckIo(fd = Interop.libc.shm_open(mapName, flags, (int)perms), mapName);
SafeFileHandle fileHandle = new SafeFileHandle((IntPtr)fd, ownsHandle: true);
// Wrap the handle in a stream and return it.
var fs = new FileStream(fileHandle, TranslateProtectionsToFileAccess(protections));
fs.SetLength(capacity);
return(fs);
}
/// <summary>Opens the specified file with the requested flags and mode.</summary>
/// <param name="path">The path to the file.</param>
/// <param name="flags">The flags with which to open the file.</param>
/// <param name="mode">The mode for opening the file.</param>
/// <returns>A SafeFileHandle for the opened file.</returns>
internal static SafeFileHandle Open(string path, Interop.libc.OpenFlags flags, int mode)
{
// SafeFileHandle wraps a file descriptor rather than a pointer, and a file descriptor is always 4 bytes
// rather than being pointer sized, which means we can't utilize the runtime's ability to marshal safe handles.
// Ideally this would be a constrained execution region, but we don't have access to PrepareConstrainedRegions.
// We still use a finally block to house the code that opens the file and stores the handle in hopes
// of making it as non-interruptable as possible. The SafeFileHandle is also allocated first to avoid
// the allocation after getting the file descriptor but before storing it.
SafeFileHandle handle = new SafeFileHandle(ownsHandle: true);
try { } finally
{
int fd;
while (Interop.CheckIo(fd = Interop.libc.open64(path, flags, mode)))
{
;
}
Contract.Assert(fd >= 0);
handle.SetHandle((IntPtr)fd);
}
return(handle);
}
private static SafeFileHandle CreateNewSharedMemoryObject(
string mapName, Interop.libc.MemoryMappedProtections protections, long capacity)
{
// Determine the flags to use when creating the shared memory object
Interop.libc.OpenFlags flags = (protections & Interop.libc.MemoryMappedProtections.PROT_WRITE) != 0 ?
Interop.libc.OpenFlags.O_RDWR :
Interop.libc.OpenFlags.O_RDONLY;
flags |= Interop.libc.OpenFlags.O_CREAT | Interop.libc.OpenFlags.O_EXCL; // CreateNew
// Create the shared memory object
int fd;
Interop.CheckIo(fd = Interop.libc.shm_open(mapName, flags, (int)Interop.libc.Permissions.S_IRWXU), mapName);
SafeFileHandle fileHandle = new SafeFileHandle((IntPtr)fd, ownsHandle: true);
// Then enlarge it to the requested capacity
bool gotFd = false;
fileHandle.DangerousAddRef(ref gotFd);
try
{
while (Interop.CheckIo(Interop.libc.ftruncate((int)fileHandle.DangerousGetHandle(), capacity), mapName))
{
;
}
}
finally
{
if (gotFd)
{
fileHandle.DangerousRelease();
}
}
// Return the fd for the object
return(fileHandle);
}
/// <summary>Translates the FileMode, FileAccess, and FileOptions values into flags to be passed when opening the file.</summary>
/// <param name="mode">The FileMode provided to the stream's constructor.</param>
/// <param name="access">The FileAccess provided to the stream's constructor</param>
/// <param name="options">The FileOptions provided to the stream's constructor</param>
/// <returns>The flags value to be passed to the open system call.</returns>
private static Interop.libc.OpenFlags PreOpenConfigurationFromOptions(FileMode mode, FileAccess access, FileOptions options)
{
// Translate FileMode. Most of the values map cleanly to one or more options for open.
Interop.libc.OpenFlags flags = Interop.libc.OpenFlags.O_LARGEFILE;
switch (mode)
{
default:
case FileMode.Open: // Open maps to the default behavior for open(...). No flags needed.
break;
case FileMode.Append: // Append is the same as OpenOrCreate, except that we'll also separately jump to the end later
case FileMode.OpenOrCreate:
flags |= Interop.libc.OpenFlags.O_CREAT;
break;
case FileMode.Create:
flags |= (Interop.libc.OpenFlags.O_CREAT | Interop.libc.OpenFlags.O_TRUNC);
break;
case FileMode.CreateNew:
flags |= (Interop.libc.OpenFlags.O_CREAT | Interop.libc.OpenFlags.O_EXCL);
break;
case FileMode.Truncate:
flags |= Interop.libc.OpenFlags.O_TRUNC;
break;
}
// Translate FileAccess. All possible values map cleanly to corresponding values for open.
switch (access)
{
case FileAccess.Read:
flags |= Interop.libc.OpenFlags.O_RDONLY;
break;
case FileAccess.ReadWrite:
flags |= Interop.libc.OpenFlags.O_RDWR;
break;
case FileAccess.Write:
flags |= Interop.libc.OpenFlags.O_WRONLY;
break;
}
// Translate some FileOptions; some just aren't supported, and others will be handled after calling open.
switch (options)
{
case FileOptions.Asynchronous: // Handled in ctor, setting _useAsync and SafeFileHandle.IsAsync to true
case FileOptions.DeleteOnClose: // DeleteOnClose doesn't have a Unix equivalent, but we approximate it in Dispose
case FileOptions.Encrypted: // Encrypted does not have an equivalent on Unix and is ignored.
case FileOptions.RandomAccess: // Implemented after open via posix_fadvise
case FileOptions.SequentialScan: // Implemented after open via posix_fadvise
break;
case FileOptions.WriteThrough:
flags |= Interop.libc.OpenFlags.O_SYNC;
break;
}
return(flags);
}