| <html lang="en"> |
| <head> |
| <title>Pathconf - The GNU C Library</title> |
| <meta http-equiv="Content-Type" content="text/html"> |
| <meta name="description" content="The GNU C Library"> |
| <meta name="generator" content="makeinfo 4.13"> |
| <link title="Top" rel="start" href="index.html#Top"> |
| <link rel="up" href="System-Configuration.html#System-Configuration" title="System Configuration"> |
| <link rel="prev" href="File-Minimums.html#File-Minimums" title="File Minimums"> |
| <link rel="next" href="Utility-Limits.html#Utility-Limits" title="Utility Limits"> |
| <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> |
| <!-- |
| This file documents the GNU C library. |
| |
| This is Edition 0.12, last updated 2007-10-27, |
| of `The GNU C Library Reference Manual', for version |
| 2.8 (Sourcery G++ Lite 2011.03-41). |
| |
| Copyright (C) 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2001, 2002, |
| 2003, 2007, 2008, 2010 Free Software Foundation, Inc. |
| |
| Permission is granted to copy, distribute and/or modify this document |
| under the terms of the GNU Free Documentation License, Version 1.3 or |
| any later version published by the Free Software Foundation; with the |
| Invariant Sections being ``Free Software Needs Free Documentation'' |
| and ``GNU Lesser General Public License'', the Front-Cover texts being |
| ``A GNU Manual'', and with the Back-Cover Texts as in (a) below. A |
| copy of the license is included in the section entitled "GNU Free |
| Documentation License". |
| |
| (a) The FSF's Back-Cover Text is: ``You have the freedom to |
| copy and modify this GNU manual. Buying copies from the FSF |
| supports it in developing GNU and promoting software freedom.''--> |
| <meta http-equiv="Content-Style-Type" content="text/css"> |
| <style type="text/css"><!-- |
| pre.display { font-family:inherit } |
| pre.format { font-family:inherit } |
| pre.smalldisplay { font-family:inherit; font-size:smaller } |
| pre.smallformat { font-family:inherit; font-size:smaller } |
| pre.smallexample { font-size:smaller } |
| pre.smalllisp { font-size:smaller } |
| span.sc { font-variant:small-caps } |
| span.roman { font-family:serif; font-weight:normal; } |
| span.sansserif { font-family:sans-serif; font-weight:normal; } |
| --></style> |
| <link rel="stylesheet" type="text/css" href="../cs.css"> |
| </head> |
| <body> |
| <div class="node"> |
| <a name="Pathconf"></a> |
| <p> |
| Next: <a rel="next" accesskey="n" href="Utility-Limits.html#Utility-Limits">Utility Limits</a>, |
| Previous: <a rel="previous" accesskey="p" href="File-Minimums.html#File-Minimums">File Minimums</a>, |
| Up: <a rel="up" accesskey="u" href="System-Configuration.html#System-Configuration">System Configuration</a> |
| <hr> |
| </div> |
| |
| <h3 class="section">31.9 Using <code>pathconf</code></h3> |
| |
| <p>When your machine allows different files to have different values for a |
| file system parameter, you can use the functions in this section to find |
| out the value that applies to any particular file. |
| |
| <p>These functions and the associated constants for the <var>parameter</var> |
| argument are declared in the header file <samp><span class="file">unistd.h</span></samp>. |
| |
| <!-- unistd.h --> |
| <!-- POSIX.1 --> |
| <div class="defun"> |
| — Function: long int <b>pathconf</b> (<var>const char *filename, int parameter</var>)<var><a name="index-pathconf-3665"></a></var><br> |
| <blockquote><p>This function is used to inquire about the limits that apply to |
| the file named <var>filename</var>. |
| |
| <p>The <var>parameter</var> argument should be one of the ‘<samp><span class="samp">_PC_</span></samp>’ constants |
| listed below. |
| |
| <p>The normal return value from <code>pathconf</code> is the value you requested. |
| A value of <code>-1</code> is returned both if the implementation does not |
| impose a limit, and in case of an error. In the former case, |
| <code>errno</code> is not set, while in the latter case, <code>errno</code> is set |
| to indicate the cause of the problem. So the only way to use this |
| function robustly is to store <code>0</code> into <code>errno</code> just before |
| calling it. |
| |
| <p>Besides the usual file name errors (see <a href="File-Name-Errors.html#File-Name-Errors">File Name Errors</a>), |
| the following error condition is defined for this function: |
| |
| <dl> |
| <dt><code>EINVAL</code><dd>The value of <var>parameter</var> is invalid, or the implementation doesn't |
| support the <var>parameter</var> for the specific file. |
| </dl> |
| </p></blockquote></div> |
| |
| <!-- unistd.h --> |
| <!-- POSIX.1 --> |
| <div class="defun"> |
| — Function: long int <b>fpathconf</b> (<var>int filedes, int parameter</var>)<var><a name="index-fpathconf-3666"></a></var><br> |
| <blockquote><p>This is just like <code>pathconf</code> except that an open file descriptor |
| is used to specify the file for which information is requested, instead |
| of a file name. |
| |
| <p>The following <code>errno</code> error conditions are defined for this function: |
| |
| <dl> |
| <dt><code>EBADF</code><dd>The <var>filedes</var> argument is not a valid file descriptor. |
| |
| <br><dt><code>EINVAL</code><dd>The value of <var>parameter</var> is invalid, or the implementation doesn't |
| support the <var>parameter</var> for the specific file. |
| </dl> |
| </p></blockquote></div> |
| |
| <p>Here are the symbolic constants that you can use as the <var>parameter</var> |
| argument to <code>pathconf</code> and <code>fpathconf</code>. The values are all |
| integer constants. |
| |
| <dl> |
| <!-- unistd.h --> |
| <!-- POSIX.1 --> |
| <dt><code>_PC_LINK_MAX</code><dd>Inquire about the value of <code>LINK_MAX</code>. |
| |
| <!-- unistd.h --> |
| <!-- POSIX.1 --> |
| <br><dt><code>_PC_MAX_CANON</code><dd>Inquire about the value of <code>MAX_CANON</code>. |
| |
| <!-- unistd.h --> |
| <!-- POSIX.1 --> |
| <br><dt><code>_PC_MAX_INPUT</code><dd>Inquire about the value of <code>MAX_INPUT</code>. |
| |
| <!-- unistd.h --> |
| <!-- POSIX.1 --> |
| <br><dt><code>_PC_NAME_MAX</code><dd>Inquire about the value of <code>NAME_MAX</code>. |
| |
| <!-- unistd.h --> |
| <!-- POSIX.1 --> |
| <br><dt><code>_PC_PATH_MAX</code><dd>Inquire about the value of <code>PATH_MAX</code>. |
| |
| <!-- unistd.h --> |
| <!-- POSIX.1 --> |
| <br><dt><code>_PC_PIPE_BUF</code><dd>Inquire about the value of <code>PIPE_BUF</code>. |
| |
| <!-- unistd.h --> |
| <!-- POSIX.1 --> |
| <br><dt><code>_PC_CHOWN_RESTRICTED</code><dd>Inquire about the value of <code>_POSIX_CHOWN_RESTRICTED</code>. |
| |
| <!-- unistd.h --> |
| <!-- POSIX.1 --> |
| <br><dt><code>_PC_NO_TRUNC</code><dd>Inquire about the value of <code>_POSIX_NO_TRUNC</code>. |
| |
| <!-- unistd.h --> |
| <!-- POSIX.1 --> |
| <br><dt><code>_PC_VDISABLE</code><dd>Inquire about the value of <code>_POSIX_VDISABLE</code>. |
| |
| <!-- unistd.h --> |
| <!-- POSIX.1 --> |
| <br><dt><code>_PC_SYNC_IO</code><dd>Inquire about the value of <code>_POSIX_SYNC_IO</code>. |
| |
| <!-- unistd.h --> |
| <!-- POSIX.1 --> |
| <br><dt><code>_PC_ASYNC_IO</code><dd>Inquire about the value of <code>_POSIX_ASYNC_IO</code>. |
| |
| <!-- unistd.h --> |
| <!-- POSIX.1 --> |
| <br><dt><code>_PC_PRIO_IO</code><dd>Inquire about the value of <code>_POSIX_PRIO_IO</code>. |
| |
| <!-- unistd.h --> |
| <!-- LFS --> |
| <br><dt><code>_PC_FILESIZEBITS</code><dd>Inquire about the availability of large files on the filesystem. |
| |
| <!-- unistd.h --> |
| <!-- POSIX.1 --> |
| <br><dt><code>_PC_REC_INCR_XFER_SIZE</code><dd>Inquire about the value of <code>POSIX_REC_INCR_XFER_SIZE</code>. |
| |
| <!-- unistd.h --> |
| <!-- POSIX.1 --> |
| <br><dt><code>_PC_REC_MAX_XFER_SIZE</code><dd>Inquire about the value of <code>POSIX_REC_MAX_XFER_SIZE</code>. |
| |
| <!-- unistd.h --> |
| <!-- POSIX.1 --> |
| <br><dt><code>_PC_REC_MIN_XFER_SIZE</code><dd>Inquire about the value of <code>POSIX_REC_MIN_XFER_SIZE</code>. |
| |
| <!-- unistd.h --> |
| <!-- POSIX.1 --> |
| <br><dt><code>_PC_REC_XFER_ALIGN</code><dd>Inquire about the value of <code>POSIX_REC_XFER_ALIGN</code>. |
| </dl> |
| |
| </body></html> |
| |
