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Patches describing the statvfs() and fstatvfs() functions. Additional
text about large file support. All new text by Steve Clift <[email protected]>, with only minor revision / addition of markup.
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‎Doc/lib/libposix.tex‎

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@@ -2,8 +2,8 @@ \section{\module{posix} ---
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The most common \POSIX{} system calls.}
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\declaremodule{builtin}{posix}
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\modulesynopsis{The most common \POSIX{} system calls (normally used via module
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\module{os}).}
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\modulesynopsis{The most common \POSIX{} system calls (normally used
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via module \module{os}).}
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This module provides access to operating system functionality that is
@@ -17,10 +17,9 @@ \section{\module{posix} ---
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\module{posix} module is not available, but a subset is always
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available through the \module{os} interface. Once \module{os} is
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imported, there is \emph{no} performance penalty in using it instead
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of \module{posix}. In addition, \module{os} provides some additional
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functionality, such as automatically calling \function{putenv()}
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when an entry in \code{os.environ} is changed.
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\refstmodindex{os}
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of \module{posix}. In addition, \module{os}\refstmodindex{os}
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provides some additional functionality, such as automatically calling
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\function{putenv()} when an entry in \code{os.environ} is changed.
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The descriptions below are very terse; refer to the corresponding
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\UNIX{} manual (or \POSIX{} documentation) entry for more information.
@@ -29,19 +28,45 @@ \section{\module{posix} ---
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Errors are reported as exceptions; the usual exceptions are given for
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type errors, while errors reported by the system calls raise
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\exception{error} (a synonym for the standard exception
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\exception{OSError}), described
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below.
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\exception{OSError}), described below.
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\subsection{Large File Support \label{posix-large-files}}
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\index{large files}
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\index{file!large files}
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\sectionauthor{Steve Clift}{[email protected]}
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Several operating systems (including AIX, HPUX, Irix and Solaris)
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provide support for files that are larger than 2 Gb from a \C{}
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programming model where \ctype{int} and \ctype{long} are 32-bit
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values. This is typically accomplished by defining the relevant size
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and offset types as 64-bit values. Such files are sometimes referred
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to as \dfn{large files}.
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Large file support is enabled in Python when the size of an
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\ctype{off_t} is larger than a \ctype{long} and the \ctype{long long}
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type is available and is at least as large as an \ctype{off_t}. Python
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longs are then used to represent file sizes, offsets and other values
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that can exceed the range of a Python int. It may be necessary to
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configure and compile Python with certain compiler flags to enable
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this mode. For example, it is enabled by default with recent versions
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of Irix, but with Solaris 2.6 and 2.7 you need to do something like:
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\begin{verbatim}
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CFLAGS="-D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64" OPT="-g -O2 $CFLAGS" \
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configure
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\end{verbatim} % $ <-- bow to font-lock
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\subsection{\module{posix} Module Contents \label{posix-contents}}
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Module \module{posix} defines the following data items:
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\begin{datadesc}{environ}
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A dictionary or dictionary look-alike representing the string
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environment at the time the interpreter was started.
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For example,
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\code{posix.environ['HOME']}
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is the pathname of your home directory, equivalent to
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\code{getenv("HOME")}
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in \C{}.
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environment at the time the interpreter was started. For example,
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\code{posix.environ['HOME']} is the pathname of your home directory,
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equivalent to \code{getenv("HOME")} in \C{}.
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Modifying this dictionary does not affect the string environment
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passed on by \function{execv()}, \function{popen()} or
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\code{'OSError'}.
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\end{excdesc}
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It defines the following functions and constants:
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It defines the following functions and constants when the operating
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system provides them directly or provides the means to emulate them:
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\begin{funcdesc}{access}{path, mode}
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Check read/write/execute permissions for this process or extance of file
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Return status for file descriptor \var{fd}, like \function{stat()}.
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\end{funcdesc}
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\begin{funcdesc}{fstatvfs}{fd}
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Return information about the filesystem containing the file associated
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with file descriptor \var{fd}, like \function{statvfs()}.
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\end{funcdesc}
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\begin{funcdesc}{ftruncate}{fd, length}
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Truncate the file corresponding to file descriptor \var{fd},
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so that it is at most \var{length} bytes in size.
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Note: The standard module \module{stat}\refstmodindex{stat} defines
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functions and constants that are useful for extracting information
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from a stat structure.
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from a \ctype{stat} structure.
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\end{funcdesc}
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\begin{funcdesc}{statvfs}{path}
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Perform a \cfunction{statvfs()} system call on the given path. The
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return value is a tuple of 11 integers giving the most common
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members of the \ctype{statvfs} structure, in the order
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\code{f_bsize},
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\code{f_frsize},
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\code{f_blocks},
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\code{f_bfree},
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\code{f_bavail},
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\code{f_files},
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\code{f_ffree},
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\code{f_favail},
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\code{f_fsid},
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\code{f_flag},
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\code{f_namemax}.
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Note: The standard module \module{statvfs}\refstmodindex{statvfs}
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defines constants that are useful for extracting information
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from a \ctype{statvfs} structure.
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\end{funcdesc}
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\begin{funcdesc}{symlink}{src, dst}

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