/// <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;
}
