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SF 964876 mapping a 0 length file

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Document that it can't be done on Windows.
This commit is contained in:
Tim Peters 2004-06-06 16:51:46 +00:00
parent de48307f76
commit 0b4d1ee29d
1 changed files with 10 additions and 8 deletions
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18
Doc/lib/libmmap.tex
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@ -42,10 +42,12 @@ the underlying file.
\begin{funcdesc}{mmap}{fileno, length\optional{, tagname\optional{, access}}}
\strong{(Windows version)} Maps \var{length} bytes from the file
specified by the file handle \var{fileno}, and returns a mmap
object. If \var{length} is \code{0}, the maximum length of the map
will be the current size of the file when \function{mmap()} is
called.
object. If \var{length} is larger than the current size of the file,
the file is extended to contain \var{length} bytes. If \var{length}
is \code{0}, the maximum length of the map is the current size
of the file, except that if the file is empty Windows raises an
exception (you cannot create an empty mapping on Windows).
\var{tagname}, if specified and not \code{None}, is a string giving
a tag name for the mapping. Windows allows you to have many
different mappings against the same file. If you specify the name
@ -61,19 +63,19 @@ the underlying file.
\strong{(\UNIX{} version)} Maps \var{length} bytes from the file
specified by the file descriptor \var{fileno}, and returns a mmap
object.
\var{flags} specifies the nature of the mapping.
\constant{MAP_PRIVATE} creates a private copy-on-write mapping, so
changes to the contents of the mmap object will be private to this
process, and \constant{MAP_SHARED} creates a mapping that's shared
with all other processes mapping the same areas of the file. The
default value is \constant{MAP_SHARED}.
\var{prot}, if specified, gives the desired memory protection; the
two most useful values are \constant{PROT_READ} and
\constant{PROT_WRITE}, to specify that the pages may be read or
written. \var{prot} defaults to \constant{PROT_READ | PROT_WRITE}.
\var{access} may be specified in lieu of \var{flags} and \var{prot}
as an optional keyword parameter. It is an error to specify both
\var{flags}, \var{prot} and \var{access}. See the description of
@ -123,7 +125,7 @@ Memory-mapped file objects support the following methods:
\end{methoddesc}
\begin{methoddesc}{readline}{}
Returns a single line, starting at the current file position and up to
Returns a single line, starting at the current file position and up to
the next newline.
\end{methoddesc}