doc: Mention the effects of AC_SYS_LARGEFILE.

[gnulib.git] / doc / posix-functions / fopen.texi

diff --git a/doc/posix-functions/fopen.texi b/doc/posix-functions/fopen.texi
index 3affa39..77f671d 100644 (file)
--- a/doc/posix-functions/fopen.texi
+++ b/doc/posix-functions/fopen.texi
@@ -28,6 +28,10 @@ On Windows, this function returns a file stream in ``text'' mode by default;
 this means that it translates @code{'\n'} to CR/LF by default.  Use the
 @code{"b"} flag if you need reliable binary I/O.
 @item
+On platforms where @code{off_t} is a 32-bit type, @code{fopen} may not work
+correctly with files larger than 2 GB.  The fix is to use the
+@code{AC_SYS_LARGEFILE} macro.
+@item
 On Windows platforms (excluding Cygwin), this function fails to open
 directories for reading.  Such streams have implementation-defined
 semantics on other platforms.  To avoid directory streams with a