/// <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 SafePipeHandle Open(string path, Interop.libc.OpenFlags flags, int mode)
{
// SafePipeHandle 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 SafePipeHandle is also allocated first to avoid
// the allocation after getting the file descriptor but before storing it.
SafePipeHandle handle = new SafePipeHandle();
try { }
finally
{
int fd;
while (Interop.CheckIo(fd = Interop.libc.open(path, flags, mode))) ;
Debug.Assert(fd >= 0);
handle.SetHandle((IntPtr)fd);
}
return handle;
}
/// <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 SafePipeHandle Open(string path, Interop.libc.OpenFlags flags, int mode)
{
// SafePipeHandle 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 SafePipeHandle is also allocated first to avoid
// the allocation after getting the file descriptor but before storing it.
SafePipeHandle handle = new SafePipeHandle();
try { }
finally
{
int fd;
while (Interop.CheckIo(fd = Interop.libc.open(path, flags, mode)))
{
;
}
Debug.Assert(fd >= 0);
handle.SetHandle((IntPtr)fd);
}
return(handle);
}
/// <summary>Creates an anonymous pipe.</summary>
/// <param name="inheritability">The inheritability to try to use. This may not always be honored, depending on platform.</param>
/// <param name="reader">The resulting reader end of the pipe.</param>
/// <param name="writer">The resulting writer end of the pipe.</param>
internal static unsafe void CreateAnonymousPipe(
HandleInheritability inheritability, out SafePipeHandle reader, out SafePipeHandle writer)
{
// Allocate the safe handle objects prior to calling pipe/pipe2, in order to help slightly in low-mem situations
reader = new SafePipeHandle();
writer = new SafePipeHandle();
// Create the OS pipe
int* fds = stackalloc int[2];
CreateAnonymousPipe(inheritability, fds);
// Store the file descriptors into our safe handles
reader.SetHandle(fds[Interop.Sys.ReadEndOfPipe]);
writer.SetHandle(fds[Interop.Sys.WriteEndOfPipe]);
}
