SourceForge patch #103140, checked in at fdrake's invitation. Minor fixes and

additions to library docs.#

Doc/lib/libstat.tex

@@ -97,7 +97,8 @@ Group id of the owner.
 \end{datadesc}
 
 \begin{datadesc}{ST_SIZE}
-File size in bytes.
+Size in bytes of a plain file; amount of data waiting on some special
+files.
 \end{datadesc}
 
 \begin{datadesc}{ST_ATIME}
@@ -112,6 +113,16 @@ Time of last modification.
 Time of last status change (see manual pages for details).
 \end{datadesc}
 
+The interpretation of ``file size'' changes according to the file
+type.  For plain files this is the size of the file in bytes.  For
+FIFOs and sockets under most Unixes (including Linux in particular),
+the ``size'' is the number of bytes waiting to be read at the time of
+the stat(2)/fstat(2)/lstat(2) call; this can sometimes be useful,
+especially for polling one of these special files after a non-blocking
+open.  The meaning of the size field for other character and block
+devices varies more, depending on the local implementation of the
+underlying system call.
+
 Example:
 
 \begin{verbatim}