fopen.html

IEEE 1003.1-2003, Single Unix Specification v3

<dd><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
The named file is a character special or block special file, and the device associated with this special file does not exist. <img
src="../images/opt-end.gif" alt="[Option End]" border="0"></dd>

<dt>[EOVERFLOW]</dt>

<dd><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
The named file is a regular file and the size of the file cannot be represented correctly in an object of type <b>off_t</b>. <img
src="../images/opt-end.gif" alt="[Option End]" border="0"></dd>

<dt>[EROFS]</dt>

<dd><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
The named file resides on a read-only file system and <i>mode</i> requires write access. <img src="../images/opt-end.gif" alt=
"[Option End]" border="0"></dd>
</dl>

<p>The <i>fopen</i>() function may fail if:</p>

<dl compact>
<dt>[EINVAL]</dt>

<dd><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
The value of the <i>mode</i> argument is not valid. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></dd>

<dt>[ELOOP]</dt>

<dd><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
More than {SYMLOOP_MAX} symbolic links were encountered during resolution of the <i>path</i> argument. <img src=
"../images/opt-end.gif" alt="[Option End]" border="0"></dd>

<dt>[EMFILE]</dt>

<dd><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
{FOPEN_MAX} streams are currently open in the calling process. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></dd>

<dt>[EMFILE]</dt>

<dd><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
{STREAM_MAX} streams are currently open in the calling process. <img src="../images/opt-end.gif" alt="[Option End]" border=
"0"></dd>

<dt>[ENAMETOOLONG]</dt>

<dd><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border=
"0"><br>
Pathname resolution of a symbolic link produced an intermediate result whose length exceeds {PATH_MAX}. <img src=
"../images/opt-end.gif" alt="[Option End]" border="0"></dd>

<dt>[ENOMEM]</dt>

<dd><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
Insufficient storage space is available. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></dd>

<dt>[ETXTBSY]</dt>

<dd><sup>[<a href="javascript:open_code('CX')">CX</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
The file is a pure procedure (shared text) file that is being executed and <i>mode</i> requires write access. <img src=
"../images/opt-end.gif" alt="[Option End]" border="0"></dd>
</dl>
</blockquote>

<hr>
<div class="box"><em>The following sections are informative.</em></div>

<h4><a name="tag_03_176_06"></a>EXAMPLES</h4>

<blockquote>
<h5><a name="tag_03_176_06_01"></a>Opening a File</h5>

<p>The following example tries to open the file named <b>file</b> for reading. The <i>fopen</i>() function returns a file pointer
that is used in subsequent <a href="../functions/fgets.html"><i>fgets</i>()</a> and <a href=
"../functions/fclose.html"><i>fclose</i>()</a> calls. If the program cannot open the file, it just ignores it.</p>

<pre>
<tt>#include &lt;stdio.h&gt;
...
FILE *fp;
...
void rgrep(const char *file)
{
...
    if ((fp = fopen(file, "r")) == NULL)
        return;
...
}
</tt>
</pre>
</blockquote>

<h4><a name="tag_03_176_07"></a>APPLICATION USAGE</h4>

<blockquote>
<p>None.</p>
</blockquote>

<h4><a name="tag_03_176_08"></a>RATIONALE</h4>

<blockquote>
<p>None.</p>
</blockquote>

<h4><a name="tag_03_176_09"></a>FUTURE DIRECTIONS</h4>

<blockquote>
<p>None.</p>
</blockquote>

<h4><a name="tag_03_176_10"></a>SEE ALSO</h4>

<blockquote>
<p><a href="fclose.html"><i>fclose</i>()</a> , <a href="fdopen.html"><i>fdopen</i>()</a> , <a href=
"freopen.html"><i>freopen</i>()</a> , the Base Definitions volume of IEEE&nbsp;Std&nbsp;1003.1-2001, <a href=
"../basedefs/stdio.h.html"><i>&lt;stdio.h&gt;</i></a></p>
</blockquote>

<h4><a name="tag_03_176_11"></a>CHANGE HISTORY</h4>

<blockquote>
<p>First released in Issue 1. Derived from Issue 1 of the SVID.</p>
</blockquote>

<h4><a name="tag_03_176_12"></a>Issue 5</h4>

<blockquote>
<p>Large File Summit extensions are added.</p>
</blockquote>

<h4><a name="tag_03_176_13"></a>Issue 6</h4>

<blockquote>
<p>Extensions beyond the ISO&nbsp;C standard are marked.</p>

<p>The following new requirements on POSIX implementations derive from alignment with the Single UNIX Specification:</p>

<ul>
<li>
<p>In the DESCRIPTION, text is added to indicate setting of the offset maximum in the open file description. This change is to
support large files.</p>
</li>

<li>
<p>In the ERRORS section, the [EOVERFLOW] condition is added. This change is to support large files.</p>
</li>

<li>
<p>The [ELOOP] mandatory error condition is added.</p>
</li>

<li>
<p>The [EINVAL], [EMFILE], [ENAMETOOLONG], [ENOMEM], and [ETXTBSY] optional error conditions are added.</p>
</li>
</ul>

<p>The DESCRIPTION is updated to avoid use of the term &quot;must&quot; for application requirements.</p>

<p>The following changes are made for alignment with the ISO/IEC&nbsp;9899:1999 standard:</p>

<ul>
<li>
<p>The prototype for <i>fopen</i>() is updated.</p>
</li>

<li>
<p>The DESCRIPTION is updated to note that if the argument <i>mode</i> points to a string other than those listed, then the
behavior is undefined.</p>
</li>
</ul>

<p>The wording of the mandatory [ELOOP] error condition is updated, and a second optional [ELOOP] error condition is added.</p>
</blockquote>

<div class="box"><em>End of informative text.</em></div>

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