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<html>
<head>
<meta http-equiv="Content-Language" content="en-us">
<meta name="GENERATOR" content="Microsoft FrontPage 5.0">
<meta name="ProgId" content="FrontPage.Editor.Document">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>
Draft Filesystem Technical Specification
</title>
<style type="text/css">
body { max-width : 7.5in; }
pre { background-color:#D7EEFF }
a { text-decoration: none}
a:link {COLOR: #2020FF;}
a:visited {COLOR: #2020FF;}
a:hover {COLOR: #FF2020;}
a:active {COLOR: #009933;}
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del { background-color:#FFD7D7 }
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</head>
<body>
<p>
<table border="0">
<tr>
<td>Document number: </td>
<td>N3790</td>
</tr>
<tr>
<td>Date:</td>
<td>
<!--webbot bot="Timestamp" S-Type="EDITED" S-Format="%Y-%m-%d" startspan -->2013-09-27<!--webbot bot="Timestamp" endspan i-checksum="12574" --></td>
</tr>
<tr>
<td>Revises:</td>
<td>
N3693</td>
</tr>
<tr>
<td>Project:</td>
<td>Programming Language C++</td>
</tr>
<tr>
<td valign="top">Project number:</td>
<td>TS 18822</td>
</tr>
<tr>
<td valign="top">Reply-to:</td>
<td>Beman Dawes <bdawes at acm dot org></td>
</tr>
</table>
<!-- generate-section-numbers=false -->
<h1 align="center">Working Draft,<br>
Technical Specification <font face="Times New Roman">—</font> File System</h1>
<p>© ISO/IEC</p>
<p><i><b><span style="background-color: #E0E0E0">Note: this is an early draft. It’s known to be incomplet and incorrekt,
and it has lots of <sub>bad formatting</sub>.</span></b></i></p>
<p><i><span style="background-color: #E0E0E0">Gray-shaded italic text is
editorial commentary on the draft. It will be removed from the actual Technical
Specification document.</span></i></p>
<h2> <a name="TOC">Contents</a></h2>
<blockquote>
<p> <a href="#TOC"> Contents</a><br>
<a href="#Foreword">Foreword</a><br>
<a href="#Introduction">Introduction</a><br>
<a href="#Scope">1 Scope </a><br>
<a href="#Conformance">2 Conformance </a><br>
<a href="#fs.conform.9945">2.1 POSIX conformance </a><br>
<a href="#fs.conform.os">2.2 Operating system dependent behavior conformance </a><br>
<a href="#Normative-references">3 Normative references </a><br>
<a href="#Definitions">4 Terms and definitions </a><br>
<a href="#Absolute-path">4.1 absolute path </a><br>
<a href="#canonical-path">4.2 canonical path </a><br>
<a href="#directory">4.3 directory </a><br>
<a href="#file">4.4 file </a><br>
<a href="#file-system">4.5 file system </a><br>
<a href="#file-system-race">4.6 file system race </a><br>
<a href="#filename">4.7 filename </a><br>
<a href="#hard-link">4.8 hard link </a><br>
<a href="#link">4.9 link </a><br>
<a href="#fs.def.native.encode">4.10 native encoding </a><br>
<a href="#fs.def.native">4.11 native pathname format </a><br>
<a href="#NTCTS">4.12 NTCTS </a><br>
<a href="#operating system dependent">4.13 operating system dependent behavior
</a><br>
<a href="#fs.def.parent">4.14 parent directory </a><br>
<a href="#path">4.15 path </a><br>
<a href="#fs.def.pathname">4.16 pathname </a><br>
<a href="#fs.def.pathres">4.17 pathname resolution </a><br>
<a href="#Relative-path">4.18 relative path </a><br>
<a href="#symbolic-link">4.19 symbolic link </a><br>
<a href="#fs.req">5 Requirements </a><br>
<a href="#Header-filesystem-synopsis">6 Header <code><filesystem></code> synopsis
</a><br>
<a href="#Error-reporting">7 Error reporting </a><br>
<a href="#class-path">8 Class <code>path</code> </a><br>
<a href="#path.generic">8.1 <code>path</code> generic pathname format grammar </a><br>
<a href="#path-Conversions">8.2 <code>path</code> conversions </a><br>
<a href="#path-Conversions-to-native-format">8.2.1 <code>path</code> argument format
conversions </a><br>
<a href="#path.arg.convert">8.2.2 <code>path</code> type and encoding conversions </a><br>
<a href="#path-Requirements">8.3 <code>path</code> requirements </a><br>
<a href="#path.member">8.4 <code>path</code> members </a><br>
<a href="#path-constructors">8.4.1 <code>path</code> constructors </a><br>
<a href="#path-assignments">8.4.2 <code>path</code> assignments </a><br>
<a href="#path-appends">8.4.3 <code>path</code> appends
</a><br>
<a href="#path-concatenation">8.4.4 <code>path</code> concatenation </a><br>
<a href="#path-modifiers">8.4.5 <code>path</code> modifiers </a><br>
<a href="#path-native-format-observers">8.4.6 <code>path</code> native format observers
</a><br>
<a href="#path-generic-format-observers">8.4.7 <code>path</code> generic format observers
</a><br>
<a href="#path-compare">8.4.8 <code>path</code> compare </a><br>
<a href="#path-decomposition">8.4.9 <code>path</code> decomposition
</a><br>
<a href="#path-query">8.4.10 <code>path</code> query </a><br>
<a href="#path-iterators">8.5 <code>path</code> iterators </a><br>
<a href="#path-non-member-functions">8.6 <code>path</code> non-member functions
</a><br>
<a href="#path-inserter-extractor">8.6.1 <code>path</code> inserter and extractor </a><br>
<a href="#path.factory">8.6.2 <code>path</code> factory functions </a><br>
<a href="#Class-filesystem_error">9 Class <code>filesystem_error</code>
</a><br>
<a href="#filesystem_error-members">9.1 <code>filesystem_error</code> members
</a><br>
<a href="#fs.enum">10 Enumerations </a><br>
<a href="#Enum-file_type">10.1 Enum class <code>file_type</code> </a><br>
<a href="#enum.copy_options">10.2 Enum class <code>copy_options</code> </a><br>
<a href="#enum.perms">10.3 Enum class <code>perms</code> </a><br>
<a href="#file_status">11 Class <code>file_status</code> </a><br>
<a href="#file_status-constructors">11.1 <code>file_status</code> constructors
</a><br>
<a href="#file_status-observers">11.2 <code>file_status</code> observers </a><br>
<a href="#file_status-modifiers">11.3 <code>file_status</code> modifiers </a><br>
<a href="#Class-directory_entry">12 Class <code>directory_entry</code> </a><br>
<a href="#directory_entry-constructors">12.1 <code>directory_entry</code> constructors
</a><br>
<a href="#directory_entry-modifiers">12.2 <code>directory_entry</code> modifiers
</a><br>
<a href="#directory_entry-observers">12.3 <code>directory_entry</code> observers
</a><br>
<a href="#Class-directory_iterator">13 Class <code>directory_iterator</code>
</a><br>
<a href="#directory_iterator-members">13.1 <code>directory_iterator</code> members
</a><br>
<a href="#directory_iterator-non-member-functions">13.2 <code>directory_iterator</code> non-member functions
</a><br>
<a href="#Class-recursive_directory_iterator">14 Class <code>recursive_directory_iterator</code>
</a><br>
<a href="#recursive_directory_iterator-members">14.1 <code>recursive_directory_iterator</code> members
</a><br>
<a href="#rec.dir.itr.nonmembers">14.2 <code>recursive_directory_iterator</code> non-member functions
</a><br>
<a href="#Operational-functions">15 Operational functions </a><br>
<a href="#fs.op.absolute">15.1 Absolute </a><br>
<a href="#fs.op.canonical">15.2 Canonical </a><br>
<a href="#fs.op.copy">15.3 Copy </a><br>
<a href="#fs.op.copy_file">15.4 Copy file </a><br>
<a href="#fs.op.copy_symlink">15.5 Copy symlink </a><br>
<a href="#fs.op.create_directories">15.6 Create directories </a><br>
<a href="#fs.op.create_directory">15.7 Create directory </a><br>
<a href="#fs.op.create_dir_symlk">15.8 Create directory symlink </a><br>
<a href="#fs.op.create_hard_lk">15.9 Create hard link </a><br>
<a href="#fs.op.create_symlink">15.10 Create symlink </a><br>
<a href="#fs.op.current_path">15.11 Current path </a><br>
<a href="#fs.op.exists">15.12 Exists </a><br>
<a href="#fs.op.equivalent">15.13 Equivalent </a><br>
<a href="#fs.op.file_size">15.14 File size </a><br>
<a href="#fs.op.hard_lk_ct">15.15 Hard link count </a><br>
<a href="#fs.op.is_block_file">15.16 Is block file </a><br>
<a href="#fs.op.is_char_file">15.17 Is character file </a><br>
<a href="#fs.op.is_directory">15.18 Is directory </a><br>
<a href="#fs.op.is_empty">15.19 Is empty </a><br>
<a href="#fs.op.is_fifo">15.20 Is fifo </a><br>
<a href="#fs.op.is_other">15.21 Is other </a><br>
<a href="#fs.op.is_regular_file">15.22 Is regular file </a><br>
<a href="#fs.op.is_socket">15.23 Is socket </a><br>
<a href="#fs.op.is_symlink">15.24 Is symlink </a><br>
<a href="#fs.op.last_write_time">15.25 Last write time </a><br>
<a href="#fs.op.permissions">15.26 Permissions </a><br>
<a href="#fs.op.read_symlink">15.27 Read symlink </a><br>
<a href="#fs.op.remove">15.28 Remove </a><br>
<a href="#fs.op.remove_all">15.29 Remove all </a><br>
<a href="#fs.op.rename">15.30 Rename </a><br>
<a href="#fs.op.resize_file">15.31 Resize file </a><br>
<a href="#fs.op.space">15.32 Space </a><br>
<a href="#fs.op.status">15.33 Status </a><br>
<a href="#fs.op.status_known">15.34 Status known </a><br>
<a href="#fs.op.symlink_status">15.35 Symlink status </a><br>
<a href="#fs.op.system_complete">15.36 System complete </a><br>
<a href="#fs.op.temp_dir_path">15.37 Temporary directory path </a><br>
<a href="#fs.op.unique_path">15.38 Unique path</a></p>
</blockquote>
<hr>
<h2><a name="Foreword">Foreword</a></h2>
<p><span style="background-color: #E0E0E0"><i>ISO requires a foreword, with most
content supplied by the Central Secretariat of ISO. It will be added by the
editor before the final document is sent to ISO.</i></span></p>
<h2><a name="Introduction">Introduction</a></h2>
<p><span style="background-color: #E0E0E0"><i>ISO specifies "The introduction is
an optional preliminary element used, if required, to give specific information
or commentary about the technical content of the document, and about the reasons
prompting its preparation. It shall not contain requirements."</i></span></p>
<!-- generate-section-numbers=true -->
<h2>1 <a name="Scope">Scope</a> [fs.scope]</h2>
<p>This Technical Specification specifies requirements for implementations of an
interface that computer programs written in the C++ programming language may use
to perform operations on file systems and their components, such as paths,
regular files, and directories. This Technical Specification is applicable to
information technology systems that can access hierarchical file systems, such
as those with operating systems that conform to the POSIX ([fs.norm.ref])
interface. This Technical Specification is applicable only to vendors who wish
to provide the interface it describes.</p>
<h2>2 <a name="Conformance">Conformance</a> [fs.conformance]</h2>
<p>Conformance is specified in terms of behavior. Ideal behavior is not always
implementable, so the conformance sub-clauses take that into account.</p>
<h3>2.1 POSIX conformance [<a name="fs.conform.9945">fs.conform.9945</a>]</h3>
<p>Some behavior is specified by reference to POSIX ([fs.norm.ref]). How such behavior is actually implemented is unspecified.</p>
<blockquote>
<p>[<i>Note:</i> This constitutes an "as if" rule allowing implementations
to call native
operating system or other API's. <i>--end note</i>]</p>
</blockquote>
<p>Implementations are encouraged to provide such behavior as it is defined by
POSIX. Implementations shall document any behavior that differs from the
behavior defined by POSIX. Implementations that do not support exact POSIX
behavior are encouraged to provide behavior as close to POSIX behavior as is reasonable given the
limitations of actual operating systems and file systems. If an implementation cannot provide any
reasonable behavior, the implementation shall report an error in an
implementation-defined manner.</p>
<blockquote>
<p>[<i>Note:</i> Such errors might be reported by an #error directive, a <code>
static_assert</code>, a <code>filesystem_error</code> exception, a special
return value, or some other manner. <i>--end note</i>]</p>
</blockquote>
<p>Implementations are not required to provide behavior that is not supported by
a particular file system.</p>
<blockquote>
<p>[<i>Example:</i> The <a href="http://en.wikipedia.org/wiki/FAT_filesystem">
FAT file system</a> used by some memory cards, camera memory, and floppy discs
does not support hard links, symlinks, and many other features of more capable
file systems, so implementations are not required to support those features
on the FAT file system. <i>-- end example</i>]</p>
</blockquote>
<p>The behavior of functions described in this
Technical Specification
may differ from their specification in
the presence of <a href="#file-system-race">file system races</a> ([fs.def.race]). No diagnostic is required.</p>
<p>If the possibility of a file system race would make it unreliable for a program to
test for a precondition before calling a function described herein, <i>
Requires</i> is not specified for the function.</p>
<blockquote>
<p>[<i>Note:</i> As a design practice, preconditions are not specified when it
is unreasonable for a program to detect them prior to calling the function. <i>
-- end note</i>]</p>
</blockquote>
<h3>2.2 Operating system dependent behavior conformance [<a name="fs.conform.os">fs.conform.os</a>]</h3>
<p>Some behavior is specified as being
operating system dependent ([fs.def.osdep]). The operating system an
implementation is dependent upon is implementation defined.</p>
<p>It is permissible for an implementation to be dependent upon an operating
system emulator rather than the actual underlying operating system.</p>
<h2>3 <a name="Normative-references">Normative references</a> [fs.norm.ref]</h2>
<p>The following referenced documents are indispensable for the application of
this document. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any
amendments) applies. <span style="background-color: #E0E0E0"><i>ISO required
wording.</i></span></p>
<ul>
<li>ISO/IEC 14882, <i>Programming Language C++<br>
</i></li>
<li>ISO/IEC 9945, <i>Information Technology — Portable Operating System
Interface (POSIX)</i></li>
</ul>
<p>[<i>Note:</i> The programming language and library described in ISO/IEC 14882
is herein called <i>the C++ Standard</i>. The operating system interface
described in ISO/IEC 9945 is herein called <i>POSIX</i>. <i>-- end note</i>]<p>This
Technical Specification mentions commercially
available operating systems for purposes of exposition.<sup> <a href="#footnote">
[footnote]</a></sup><p>Unless otherwise specified, the whole of the C++
Standard's Library introduction [lib.library] is included into this Technical
Specification by reference.<p><i><span style="background-color: #E0E0E0">This footnote
is required by ISO/IEC Directives, Part2, section 6.6.3 Use of trade names and
trademarks:</span></i><blockquote>
<p><sup>[<a name="footnote">footnote</a>]</sup> POSIX® is
a registered trademark of The IEEE. MAC OS® is a registered trademark of Apple
Inc. Windows® is a registered trademark of Microsoft Corporation. This information is given for the convenience of
users of this document and does not constitute an endorsement by ISO or IEC of
these products.</blockquote>
<p></p>
<h2>4 <a name="Definitions">Terms and definitions</a> [fs.definitions]</h2>
<p>For the purposes of this document, the terms and definitions given in the C++
Standard and the following apply.</p>
<h3>4.1 <a name="Absolute-path">absolute path</a> [fs.def.absolute-path]</h3>
<p>A path that
unambiguously
identifies the location of a file without reference to an additional starting
location. The elements of a path that determine if it is absolute are
operating system dependent.</p>
<h3>4.2 <a name="canonical-path">canonical path</a> [fs.def.cannonical-path]</h3>
<p>An absolute path that has
no elements that are symbolic links, and no dot or dot-dot elements ([<a href="#path.generic">path.generic</a>]).</p>
<h3>4.3 <a name="directory">directory</a> [fs.def.directory]</h3>
<p>A file within a file system that acts as a container of directory entries
that contain information about
other files, possibly including other directory files.</p>
<h3>4.4 <a name="file">file</a> [fs.def.file]</h3>
<p>An object within a file system that holds user or system data. Files can be written to, or read from, or both. A file
has certain attributes, including type. File types include regular files
and directories. Other types of files, such as symbolic links, may be supported by the
implementation.</p>
<h3>4.5 <a name="file-system">file system</a> [fs.def.filesystem]</h3>
<p>A collection of files and certain of their attributes.</p>
<h3>4.6 <a name="file-system-race">file system race</a> [fs.def.race]</h3>
<p>The condition that occurs
when multiple threads, processes, or computers interleave access and
modification of
the same object within a file system.</p>
<h3>4.7 <a name="filename">filename</a> [fs.def.filename]</h3>
<p>The name of a file. Filenames dot
and dot-dot have special meaning. The following characteristics of
filenames are operating system dependent:</p>
<ul>
<li>
<p>The permitted characters. [<i>Example</i>: Some operating systems prohibit the ASCII control characters (0x00-0x1F)
in filenames. <i>--end example</i>].</p>
</li>
<li>
<p>Filenames that are not permitted.</p>
</li>
<li>
<p>Filenames that have special meaning.</p>
</li>
<li>
<p>Case awareness and sensitivity during path resolution.</p>
</li>
<li>
<p>Special rules that may apply to file types other than regular
files, such as directories.</p>
</li>
</ul>
<h3>4.8 <a name="hard-link">hard link</a> [fs.def.hardlink]</h3>
<p>A link ([fs.def.link]) to an existing file. Some
file systems support multiple hard links to a file. If the last hard link to a
file is removed, the file itself is removed.</p>
<blockquote>
<p>[<i>Note:</i> A hard link can be thought of as a shared-ownership smart
pointer to a file.<i> -- end note</i>]<i> </i></p>
</blockquote>
<h3>4.9 <a name="link">link</a> [fs.def.link]</h3>
<p>A directory entry object that associates a
filename with a file. A link is either a hard link ([fs.def.hardlink]) or a
symbolic link ([fs.def.symlink]).</p>
<h3>4.10 native encoding [<a name="fs.def.native.encode">fs.def.native.encode</a>]</h3>
<p>For narrow character strings, the operating system dependent current encoding
for path names. For wide character strings, the implementation defined execution
wide-character set encoding (C++ standard [lex.charset]).</p>
<h3>4.11 native pathname format [<a name="fs.def.native">fs.def.native</a>]</h3>
<p>The operating system dependent pathname format accepted by the host operating system.</p>
<h3>4.12 <a name="NTCTS">NTCTS</a> [<a name="fs.def.ntcts">fs.def.ntcts</a>]</h3>
<p>Acronym for "null-terminated character-type sequence". Describes a sequence
of values of a given encoded character type terminated by that type's null character. If
the encoded character type is <code>charT</code>, the null character can be constructed
by <code>charT()</code>. <span style="background-color: #E0E0E0"><i>This is an
expansion of the definition in chapter 17; that definition is very hard to
parse. A request for clarification has been sent to the C++ standard project editor.</i></span></p>
<h3>4.13 <a name="operating system dependent">operating system dependent</a> behavior
[fs.def.osdep]</h3>
<p>Behavior that is dependent upon the behavior
and characteristics of an operating system. See [fs.conform.os].</p>
<h3>4.14 parent directory [<a name="fs.def.parent">fs.def.parent</a>]</h3>
<p>When discussing a given directory, the directory that both contains a
directory entry for the given directory and is represented by the pathname
dot-dot in the given directory.</p>
<p>When discussing other types of files, a directory containing a directory
entry for the file under discussion.</p>
<p>This concept does not apply to dot and dot-dot.</p>
<h3>4.15 <a name="path">path</a> [fs.def.path]</h3>
<p>A sequence of elements that identify
the location of a file within a filesystem. The elements are the <i>root-name<sub>opt</sub></i>, <i>
root-directory<sub>opt</sub></i>, and an optional sequence of filenames.</p>
<h3>4.16 pathname [<a name="fs.def.pathname">fs.def.pathname</a>]</h3>
<p>A character string that represents
the name of a
path. Pathnames are formatted according to the generic pathname format grammar
([<a href="#path.generic">path.generic</a>]) or an
operating system dependent
native pathname format.</p>
<h3>4.17 pathname resolution [<a name="fs.def.pathres">fs.def.pathres</a>]</h3>
<p>Pathname resolution is the operating system dependent mechanism for resolving
a pathname to a particular file in a file hierarchy. There may be multiple
pathnames that resolve to the same file. [<i>Example:</i> POSIX specifies the mechanism in section 4.11, Pathname resolution. <i>
--end example]</i></p>
<h3>4.18 <a name="Relative-path">relative path</a> [fs.def.relative-path]</h3>
<p>A path that
is not absolute, and so only
unambiguously
identifies the location of a file when resolved relative to
an implied starting location. The elements of a path that determine if it is
relative are operating system dependent. [<i>Note:</i>
Paths <code>"."</code> and <code>".."</code> are relative paths. <i>--end note</i>]</p>
<h3>4.19 <a name="symbolic-link">symbolic link</a> [fs.def.symlink]</h3>
<p>A link ([fs.def.link]) with the
property that when the file is encountered during pathname resolution, a string
stored by the file is used to modify the pathname resolution.</p>
<blockquote>
<p>[<i>Note:</i> Symbolic links are often called symlinks. A symbolic link can be thought of as a raw pointer to a file.
If the file pointed to does not exist, the symbolic link is said to be a
"dangling" symbolic link.<i> -- end note</i>]<i> </i></p>
</blockquote>
<h2>5 Requirements [<a name="fs.req">fs.req</a>]</h2>
<p>Throughout this Technical Specification, <code>char</code>, <code>wchar_t</code>,
<code>char16_t</code>, and <code>char32_t</code> are collectively called <i>
encoded character types</i>.</p>
<p>Template parameters named <code>charT</code> shall be one of the
encoded character types.</p>
<p>Template parameters named <code>InputIterator</code> shall meet the
C++ Standard's library input iterator requirements ([input.iterators]) and shall
have a value type that is one of the encoded character types.</p>
<blockquote>
<p>[<i>Note:</i> Use of an encoded character type implies an associated
encoding. Since <code>signed char</code> and <code>unsigned char</code> have no
implied encoding, they are not included as permitted types. <i>--end note</i>]</p>
</blockquote>
<h2>6 <a name="Header-filesystem-synopsis">Header <code><filesystem></code> synopsis</a>
[fs.filesystem.synopsis]</h2>
<pre>namespace std { namespace tbd { namespace filesystem {
class <a href="#class-path">path</a>;
void swap(path& lhs, path& rhs) noexcept;
size_t <a href="#hash_value">hash_value</a>(const path& p) noexcept;
bool operator==(const path& lhs, const path& rhs) noexcept;
bool operator!=(const path& lhs, const path& rhs) noexcept;
bool operator< (const path& lhs, const path& rhs) noexcept;
bool operator<=(const path& lhs, const path& rhs) noexcept;
bool operator> (const path& lhs, const path& rhs) noexcept;
bool operator>=(const path& lhs, const path& rhs) noexcept;
path operator/ (const path& lhs, const path& rhs);
template <class charT, class traits>
basic_ostream<charT, traits>&
operator<<(basic_ostream<charT, traits>& os, const path& p);
template <class charT, class traits>
basic_istream<charT, traits>&
operator>>(basic_istream<charT, traits>& is, path& p);
template <class <a href="#Source">Source</a>>
path u8path(Source const& source);
template <class InputIterator>
path u8path(InputIterator begin, InputIterator end);
class <a href="#Class-filesystem_error">filesystem_error</a>;
class <a href="#Class-directory_entry">directory_entry</a>;
class <a href="#Class-directory_iterator">directory_iterator</a>;
// enable directory_iterator range-based for statements
const directory_iterator& <a href="#directory_iterator-non-member-functions">begin</a>(const directory_iterator& iter) noexcept;
directory_iterator <a href="#directory_iterator-non-member-functions">end</a>(const directory_iterator&) noexcept;
class <a href="#Class-recursive_directory_iterator">recursive_directory_iterator</a>;
// enable recursive_directory_iterator range-based for statements
const recursive_directory_iterator& <a href="#rec.dir.itr.nonmembers">begin</a>(const recursive_directory_iterator& iter) noexcept;
recursive_directory_iterator <a href="#rec.dir.itr.nonmembers">end</a>(const recursive_directory_iterator&) noexcept;
enum class file_type; // [<a href="#Enum-file_type">enum.file_type</a>]
enum class perms; // [<a href="#enum.perms">enum.perms</a>]
class <a href="#file_status">file_status</a>;
struct <a name="space_info">space_info</a> // returned by <a href="#space" style="text-decoration: none">space</a> function
{
uintmax_t capacity;
uintmax_t free;
uintmax_t available; // free space available to a non-privileged process
};
enum class <a name="copy_option" href="#enum.copy_options">copy_options</a>; // [<a href="#enum.copy_options">enum.copy_options</a>]
enum class <a name="symlink_option">directory_options</a>
{
none,
follow_directory_symlink,
skip_permission_denied
};
typedef chrono::time_point<<b><i>unspecified-trivial-clock</i></b>> file_time_type;
// <a href="#Operational-functions">operational functions</a>
path <a href="#absolute">absolute</a>(const path& p, const path& base=current_path());
path <a href="#canonical">canonical</a>(const path& p, const path& base = current_path());
path <a href="#canonical">canonical</a>(const path& p, error_code& ec);
path <a href="#canonical">canonical</a>(const path& p, const path& base, error_code& ec);
void <a href="#copy">copy</a>(const path& from, const path& to);
void <a href="#copy">copy</a>(const path& from, const path& to, error_code& ec) noexcept;
void copy(const path& from, const path& to, copy_options options);
void copy(const path& from, const path& to, copy_options options,
error_code& ec) noexcept;
bool <a href="#copy_file">copy_file</a>(const path& from, const path& to);
bool <a href="#copy_file">copy_file</a>(const path& from, const path& to, error_code& ec) noexcept;
bool <a href="#copy_file">copy_file</a>(const path& from, const path& to, <a href="#copy_option">copy_options</a> option);
bool <a href="#copy_file">copy_file</a>(const path& from, const path& to, <a href="#copy_option">copy_options</a> option,
error_code& ec) noexcept;
void <a href="#copy_symlink">copy_symlink</a>(const path& existing_symlink, const path& new_symlink);
void <a href="#copy_symlink">copy_symlink</a>(const path& existing_symlink, const path& new_symlink,
error_code& ec) noexcept;
bool <a href="#create_directories">create_directories</a>(const path& p);
bool <a href="#create_directories">create_directories</a>(const path& p, error_code& ec) noexcept;
bool <a href="#create_directory">create_directory</a>(const path& p);
bool <a href="#create_directory">create_directory</a>(const path& p, error_code& ec) noexcept;
void <a href="#create_directory2">create_directory</a>(const path& p, const path& attributes);
void <a href="#create_directory2">create_directory</a>(const path& p, const path& attributes, error_code& ec) noexcept;
void <a href="#create_directory_symlink">create_directory_symlink</a>(const path& to, const path& new_symlink);
void <a href="#create_directory_symlink">create_directory_symlink</a>(const path& to, const path& new_symlink,
error_code& ec) noexcept;
void <a href="#create_hard_link">create_hard_link</a>(const path& to, const path& new_hard_link);
void <a href="#create_hard_link">create_hard_link</a>(const path& to, const path& new_hard_link,
error_code& ec) noexcept;
void <a href="#create_symlink">create_symlink</a>(const path& to, const path& new_symlink);
void <a href="#create_symlink">create_symlink</a>(const path& to, const path& new_symlink,
error_code& ec) noexcept;
path <a href="#current_path">current_path</a>();
path <a href="#current_path">current_path</a>(error_code& ec);
void <a href="#current_path">current_path</a>(const path& p);
void <a href="#current_path">current_path</a>(const path& p, error_code& ec) noexcept;
bool <a href="#exists">exists</a>(file_status s) noexcept;
bool <a href="#exists">exists</a>(const path& p);
bool <a href="#exists">exists</a>(const path& p, error_code& ec) noexcept;
bool <a href="#equivalent">equivalent</a>(const path& p1, const path& p2);
bool <a href="#equivalent">equivalent</a>(const path& p1, const path& p2, error_code& ec) noexcept;
uintmax_t <a href="#file_size">file_size</a>(const path& p);
uintmax_t <a href="#file_size">file_size</a>(const path& p, error_code& ec) noexcept;
uintmax_t <a href="#hard_link_count">hard_link_count</a>(const path& p);
uintmax_t <a href="#hard_link_count">hard_link_count</a>(const path& p, error_code& ec) noexcept;
bool <a href="#is_block_file">is_block_file</a>(file_status s) noexcept;
bool <a href="#is_block_file">is_block_file</a>(const path& p);
bool <a href="#is_block_file">is_block_file</a>(const path& p, error_code& ec) noexcept;
bool <a href="#is_character_file">is_character_file</a>(file_status s) noexcept;
bool <a href="#is_character_file">is_character_file</a>(const path& p);
bool <a href="#is_character_file">is_character_file</a>(const path& p, error_code& ec) noexcept;
bool <a href="#is_directory">is_directory</a>(file_status s) noexcept;
bool <a href="#is_directory">is_directory</a>(const path& p);
bool <a href="#is_directory">is_directory</a>(const path& p, error_code& ec) noexcept;
bool <a href="#is_empty">is_empty</a>(const path& p);
bool <a href="#is_empty">is_empty</a>(const path& p, error_code& ec) noexcept;
bool <a href="#is_fifo">is_fifo</a>(file_status s) noexcept;
bool <a href="#is_fifo">is_fifo</a>(const path& p);
bool <a href="#is_fifo">is_fifo</a>(const path& p, error_code& ec) noexcept;
bool <a href="#is_other">is_other</a>(file_status s) noexcept;
bool <a href="#is_other2">is_other</a>(const path& p);
bool <a href="#is_other2">is_other</a>(const path& p, error_code& ec) noexcept;
bool <a href="#is_regular_file">is_regular_file</a>(file_status s) noexcept;
bool i<a href="#is_regular_file2">s_regular_file</a>(const path& p);
bool i<a href="#is_regular_file2">s_regular_file</a>(const path& p, error_code& ec) noexcept;
bool <a href="#is_socket">is_socket</a>(file_status s) noexcept;
bool <a href="#is_socket">is_socket</a>(const path& p);
bool <a href="#is_socket">is_socket</a>(const path& p, error_code& ec) noexcept;
bool <a href="#is_symlink">is_symlink</a>(file_status s) noexcept;
bool <a href="#is_symlink2">is_symlink</a>(const path& p);
bool <a href="#is_symlink2">is_symlink</a>(const path& p, error_code& ec) noexcept;
file_time_type <a href="#last_write_time">last_write_time</a>(const path& p);
file_time_type <a href="#last_write_time">last_write_time</a>(const path& p, error_code& ec) noexcept;
void <a href="#last_write_time2">last_write_time</a>(const path& p, file_time_type new_time);
void <a href="#last_write_time2">last_write_time</a>(const path& p, file_time_type new_time,
error_code& ec) noexcept;
path <a href="#read_symlink">read_symlink</a>(const path& p);
path <a href="#read_symlink">read_symlink</a>(const path& p, error_code& ec);
bool <a href="#remove">remove</a>(const path& p);
bool <a href="#remove">remove</a>(const path& p, error_code& ec) noexcept;
uintmax_t <a href="#remove_all">remove_all</a>(const path& p);
uintmax_t <a href="#remove_all">remove_all</a>(const path& p, error_code& ec) noexcept;
void <a href="#rename">rename</a>(const path& from, const path& to);
void <a href="#rename">rename</a>(const path& from, const path& to, error_code& ec) noexcept;
void <a href="#resize_file">resize_file</a>(const path& p, uintmax_t size);
void <a href="#resize_file2">resize_file</a>(const path& p, uintmax_t size, error_code& ec) noexcept;
<a href="#space_info">space_info</a> <a href="#space">space</a>(const path& p);
<a href="#space_info">space_info</a> <a href="#space">space</a>(const path& p, error_code& ec) noexcept;
<a href="#file_status">file_status</a> <a href="#status">status</a>(const path& p);
<a href="#file_status">file_status</a> <a href="#status">status</a>(const path& p, error_code& ec) noexcept;
bool <a href="#status_known">status_known</a>(file_status s) noexcept;
<a href="#file_status">file_status</a> <a href="#symlink_status">symlink_status</a>(const path& p);
<a href="#file_status">file_status</a> <a href="#symlink_status">symlink_status</a>(const path& p, error_code& ec) noexcept;
path <a href="#system_complete">system_complete</a>(const path& p);
path <a href="#system_complete">system_complete</a>(const path& p, error_code& ec);
path <a href="#temp_directory_path">temp_directory_path</a>();
path <a href="#temp_directory_path">temp_directory_path</a>(error_code& ec);
path <a href="#unique_path">unique_path</a>(const path& model="%%%%-%%%%-%%%%-%%%%");
path <a href="#unique_path">unique_path</a>(const path& model, error_code& ec);
} } } // namespaces std::tbd::filesystem</pre>
<p><b><i><code>unspecified-trivial-clock</code></i></b> is an unspecified type
provided by the implementation that satisfies the <code>TrivialClock</code> requirements ([time.clock.req])
and that is capable of representing and measuring file time values.</p>
<h2>7 <a name="Error-reporting">Error reporting</a> [fs.err.report]</h2>
<p>Filesystem library functions often provide two overloads, one that
throws an exception to report file system errors, and another that sets an <code>error_code</code>.</p>
<blockquote>
<p>[<i>Note:</i> This supports two common use cases:</p>
<ul>
<li>Uses where file system
errors are truly exceptional and indicate a serious failure. Throwing an
exception is the most appropriate response. This is the preferred default for
most everyday programming.<br>
</li>
<li>Uses where file system system errors are routine and do not necessarily represent
failure. Returning an error code is the most appropriate response. This allows
application specific error handling, including simply ignoring the error.</li>
</ul>
<p><i>--end note</i>]</p>
</blockquote>
<p>Functions <b>not</b> having an argument of type <code>error_code&</code> report errors as follows, unless otherwise specified:</p>
<ul>
<li>When a call by the
implementation to an operating system or other underlying API results in an
error that prevents the function from meeting its specifications, an exception
of type
<code>filesystem_error</code> shall be thrown. For functions with a single path
argument, that argument shall be passed to the
<code>filesystem_error</code> constructor with a single path argument. For
functions with two path arguments, the first of these arguments shall be
passed to the
<code>filesystem_error</code> constructor as the <code>path1</code> argument,
and the second shall be passed as the <code>path2</code> argument.<br>
</li>
<li>Failure to allocate storage is reported by throwing an exception as described in the C++ standard,
17.6.4.10 [res.on.exception.handling].<br>
</li>
<li>Destructors throw nothing.</li>
</ul>
<p>Functions having an argument of type <code>error_code&</code> report errors as follows, unless otherwise
specified:</p>
<ul>
<li>If a call by the
implementation to an operating system or other underlying API results in an
error that prevents the function from meeting its specifications, the
<code>error_code&</code> argument is set as
appropriate appropriate for the specific error. Otherwise, <code>clear()</code>
is called on the
<code>error_code&</code> argument.</li>
</ul>
<h2>8 <a name="class-path">Class <code>path</code> [class.path]</a></h2>
<p>An object of class <code>path</code> represents a <a href="#class-path">path</a>,
and contains a <a href="#fs.def.pathname">pathname</a> Such an object is concerned only with the lexical and syntactic aspects
of a path. The path does not necessarily exist in external storage, and the
pathname is not necessarily valid for the current operating
system or for a particular file system.</p>
<blockquote>
<pre>namespace std { namespace tbd { namespace filesystem {
class path
{
public:
typedef <b><i><a href="#value_type">see below</a></i></b> value_type;
typedef basic_string<value_type> string_type;
static constexpr value_type preferred_separator = <b><i><a href="#value_type">see below</a></i></b>;
// <a href="#path-constructors">constructors</a> and destructor
path();
path(const path& p);
path(path&& p) noexcept;
template <class <a href="#Source">Source</a>>
path(Source const& source);
template <class InputIterator>
path(InputIterator begin, InputIterator end);
template <class <a href="#Source">Source</a>>
path(Source const& source, const locale& loc);
template <class InputIterator>
path(InputIterator begin, InputIterator end, const locale& loc);
~path() = default;
// <a href="#path-assignments">assignments</a>
path& operator=(const path& p);
path& operator=(path&& p) noexcept;
template <class <a href="#Source">Source</a>>
path& operator=(Source const& source);
template <class <a href="#Source">Source</a>>
path& assign(Source const& source)
template <class InputIterator>
path& assign(InputIterator begin, InputIterator end);
// <a href="#path-appends">appends</a>
path& operator/=(const path& p);
template <class <a href="#Source">Source</a>>
path& operator/=(Source const& source);
template <class <a href="#Source">Source</a>>
path& append(Source const& source);
template <class InputIterator>
path& append(InputIterator begin, InputIterator end);
// <a href="#path-concatenation">concatenation</a>
path& operator+=(const path& x);
path& operator+=(const string_type& x);
path& operator+=(const value_type* x);
path& operator+=(value_type x);
template <class Source>
path& operator+=(Source const& x);
template <class charT>
path& operator+=(charT x);
template <class Source>
path& concat(Source const& x);
template <class InputIterator>
path& concat(InputIterator begin, InputIterator end);
// <a href="#path-modifiers">modifiers</a>
void <a href="#path-clear">clear</a>() noexcept;
path& <a href="#path-make_preferred">make_preferred</a>();
path& <a href="#path-remove_filename">remove_filename</a>();
path& <a href="#replace_filename">replace_filename</a>(const path& replacement);
path& <a href="#path-replace_extension">replace_extension</a>(const path& replacement = path());
void <a href="#path-swap">swap</a>(path& rhs) noexcept;
// <a href="#path-native-format-observers">native format observers</a>
const string_type& <a href="#native">native</a>() const noexcept;
const value_type* <a href="#c_str">c_str</a>() const noexcept;
<a href="#operator-string_type">operator string_type</a>() const;
template <class charT, class traits = char_traits<charT>,
class Allocator = allocator<charT> >
basic_string<charT, traits, Allocator>
<a href="#string-template">string</a>(const Allocator& a = Allocator()) const;
string <a href="#string">string</a>() const;
wstring <a href="#wstring">wstring</a>() const;
string u8string() const;
u16string <a href="#u16string">u16string</a>() const;
u32string <a href="#u32string">u32string</a>() const;
// <a href="#path-generic-format-observers">generic format observers</a>
template <class charT, class traits = char_traits<charT>,
class Allocator = allocator<charT> >
basic_string<charT, traits, Allocator>
<a href="#generic_string-template">generic_string</a>(const Allocator& a = Allocator()) const;
string <a href="#generic_string">generic_string</a>() const;
wstring <a href="#generic_wstring">generic_wstring</a>() const;
string generic_u8string() const;
u16string <a href="#generic_u16string">generic_u16string</a>() const;
u32string <a href="#generic_u32string">generic_u32string</a>() const;
// <a href="#path-compare">compare</a>
int <a href="#path-compare">compare</a>(const path& p) const noexcept;
int <a href="#path-compare">compare</a>(const string& s) const;
int <a href="#path-compare">compare</a>(const value_type* s) const;
// <a href="#path-decomposition">decomposition</a>
path <a href="#path-root_name">root_name</a>() const;
path <a href="#path-root_directory">root_directory</a>() const;
path <a href="#path-root_path">root_path</a>() const;
path <a href="#path-relative_path">relative_path</a>() const;
path <a href="#path-parent_path">parent_path</a>() const;
path <a href="#path-filename">filename</a>() const;
path <a href="#path-stem">stem</a>() const;
path <a href="#path-extension">extension</a>() const;
// <a href="#path-query">query</a>
bool <a href="#path-query">empty</a>() const noexcept;
bool <a href="#path-has_root_name">has_root_name</a>() const;
bool <a href="#path-has_root_directory">has_root_directory</a>() const;
bool <a href="#path-has_root_path">has_root_path</a>() const;
bool <a href="#path-has_relative_path">has_relative_path</a>() const;
bool <a href="#path-has_parent_path">has_parent_path</a>() const;
bool <a href="#path-has_filename">has_filename</a>() const;
bool <a href="#path-has_stem">has_stem</a>() const;
bool <a href="#path-has_extension">has_extension</a>() const;
bool <a href="#path-is_absolute">is_absolute</a>() const;
bool <a href="#path-is_relative">is_relative</a>() const;
// <a href="#path-iterators">iterators</a>
class iterator;
typedef iterator const_iterator;
iterator begin() const;
iterator end() const;
private:
string_type pathname; // <b><i>exposition only</i></b>
};
} } } // namespaces std::tbd::filesystem</pre>
</blockquote>
<p><code><a name="value_type">value_type</a></code> is a <code>typedef</code> for the
operating system dependent encoded character type used to represent pathnames.</p>
<p>The value of <a name="preferred_separator"><code>preferred_separator</code></a>
is the operating system dependent <i>preferred-separator</i> character ([path.generic]).</p>
<blockquote>
[<i>Example:</i> For POSIX based operating
systems, <code>value_type</code> is <code>char</code> and <code>
preferred_separator</code> is the slash character (/). For Windows based
operating systems, <code>value_type</code> is <code>wchar_t</code> and <code>
preferred_separator</code> is the backslash character (\). <i>--end example</i>]
</blockquote>
<h3>8.1 <code>path</code> generic pathname format grammar [<a name="path.generic">path.generic</a>]</h3>
<p><i>pathname:<br>
root-name
root-directory<sub>opt</sub> relative-path<sub>opt<br>
</sub>root-directory relative-path<sub>opt<br>
</sub>relative-path</i></p>
<p><i>root-name:<br>
</i>An
operating system dependent name that identifies the starting location for
absolute paths. </p>
<blockquote>
<blockquote>
<p>[<i>Note:</i> Many operating systems define a name
beginning with two <i>directory-separator</i> characters as a <i>root-name</i>
that identifies network or other resource locations. Some operating systems define a single letter followed by a colon as a drive
specifier - a <i>root-name</i> identifying a specific device such as a disc drive. <i>--end note</i>]</p>
</blockquote>
</blockquote>
<p><i>root-directory:<br>
directory-separator<br>
<br>
relative-path:<br>
filename<br>
relative-path
directory-separator<br>
relative-path
directory-separator filename<br>
<br>
filename:<br>
name<br>
dot<br>
dot-dot<br>
<br>
name:<br>
</i>A
sequence of characters other than <i>directory-separator</i> characters.</p>
<blockquote>
<blockquote>
[<i>Note:</i> Operating systems often place restrictions
on the characters that may be used in a <i>filename</i>. For wide
portability, users may wish to limit <i>filename</i> characters to the POSIX Portable Filename Character Set: <br>
<br>
<tt>A B C D E F G H I J K L M N O P Q R S T U V W X Y Z<br>
a b c d e f g h i j k l m n o p q r s t u v w x y z<br>
0 1 2 3 4 5 6 7 8 9 . _ -
</tt> <i>--end note</i>]
</blockquote>
</blockquote>
<p><i>dot:<br>
</i>The
filename consisting solely of a single period character (.).<br>
<br>
<i>dot-dot:<br>
</i>The
filename consisting solely of two period characters (..).<br>
<br>
<i>directory-separator:<br>
slash<code><br>
</code>slash directory-separator<br>
preferred-separator<br>
preferred-separator directory-separator<br>
<br>
preferred-separator:<br>
</i>An
operating system dependent directory separator character. May be a synonym for
<i>slash</i>.<br>
<br>
<i>slash:<br>
</i>The slash
character (/). </p>
<p>Multiple successive <i>directory-separator</i> characters are considered to
be the same as one <i>directory-separator</i> character.</p>
<p>The filename <i>dot</i> is treated as a reference to the current directory. The filename <i>
dot-dot</i> is treated as a reference to the
parent
directory. Specific filenames may have special meanings for a particular
operating system.</p>
<h3>8.2 <a name="path-Conversions"><code>path</code> conversions</a> [path.cvt]</h3>
<h4>8.2.1 <a name="path-Conversions-to-native-format"><code>path</code> argument format
conversions</a> [path.fmt.cvt]</h4>
<blockquote>
[<i>Note:</i> The format conversions described in this
section are not applied on POSIX or Windows based operating systems
because on these systems:<ul>
<li>The generic format is acceptable as a native path.</li>
<li>There is no need to distinguish between native format and generic
format arguments.</li>
<li>Paths for regular files and paths for directories share the same
syntax.</li>
</ul>
<p> <i>-- end note</i>]
</blockquote>
<p>Functions arguments that take character sequences representing paths
may use the generic pathname format grammar ([<a href="#path.generic">path.generic</a>]) or
the <a href="#fs.def.native">native pathname format</a>. If and only if such
arguments are in the generic format and the generic format is not acceptable to
the operating system as a native path, conversion to native format shall be
performed during the processing of the argument. </p>
<blockquote>
<p>[<i>Note:</i> Some operating systems may have no unambiguous way to distinguish between native format and generic format arguments.
This is by design as it simplifies use for operating systems that do not require
disambiguation. An implementation for an operating system where disambiguation
is required is permitted
as an extension to distinguish between the formats. <i>
-- end note</i>]</p>
</blockquote>
<p>If the native format requires paths for regular files to be formatted
differently from paths for directories, the path shall be treated as a directory
path if last element is <i>directory-separator</i>,
otherwise it shall be treated as a regular file path.</p>
<h4>8.2.2 <code>path</code> type and encoding conversions [<a name="path.arg.convert">path.type.cvt</a>]</h4>