public static void ThrowExceptionForErrorIf(int retval, Errno errno)
{
if (retval == -1)
{
UnixMarshal.ThrowExceptionForError(errno);
}
}
// Read the specified symbolic link. If the file isn't a symbolic link,
// return null; otherwise, return the contents of the symbolic link.
//
// readlink(2) is horribly evil, as there is no way to query how big the
// symlink contents are. Consequently, it's trial and error...
internal static string ReadSymbolicLink(string path)
{
StringBuilder buf = new StringBuilder(256);
do
{
int r = Native.Syscall.readlink(path, buf);
if (r < 0)
{
Native.Errno e;
switch (e = Native.Stdlib.GetLastError())
{
case Native.Errno.EINVAL:
// path isn't a symbolic link
return(null);
default:
UnixMarshal.ThrowExceptionForError(e);
break;
}
}
else if (r == buf.Capacity)
{
buf.Capacity *= 2;
}
else
{
return(buf.ToString(0, r));
}
} while (true);
}
internal static string ReadSymbolicLink(string path)
{
int num;
StringBuilder stringBuilder = new StringBuilder(256);
while (true)
{
num = Syscall.readlink(path, stringBuilder);
if (num >= 0)
{
if (num != stringBuilder.Capacity)
{
break;
}
StringBuilder capacity = stringBuilder;
capacity.Capacity = capacity.Capacity * 2;
}
else
{
Errno lastError = Stdlib.GetLastError();
Errno errno = lastError;
if (lastError == Errno.EINVAL)
{
return(null);
}
UnixMarshal.ThrowExceptionForError(errno);
}
}
return(stringBuilder.ToString(0, num));
}
public static string ReadLink(string path)
{
Native.Errno errno;
path = ReadSymbolicLink(path, out errno);
if (errno != 0)
{
UnixMarshal.ThrowExceptionForError(errno);
}
return(path);
}
// Read the specified symbolic link. If the file isn't a symbolic link,
// return null; otherwise, return the contents of the symbolic link.
internal static string ReadSymbolicLink(string path)
{
string target = TryReadLink(path);
if (target == null)
{
Native.Errno errno = Native.Stdlib.GetLastError();
if (errno != Native.Errno.EINVAL)
{
UnixMarshal.ThrowExceptionForError(errno);
}
}
return(target);
}