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<div class="ChapSects"><a href="chap3.html#X85DE7F82801DDA50">3 <span class="Heading">Functions directly available from the C library</span></a>
<div class="ContSect"><span class="tocline"><span class="nocss"> </span><a href="chap3.html#X85D3551379BA32FC">3.1 <span class="Heading">Differences in arguments - an overview</span></a>
</span>
</div>
<div class="ContSect"><span class="tocline"><span class="nocss"> </span><a href="chap3.html#X800F9F3E810A7228">3.2 <span class="Heading">The low-level functions in detail</span></a>
</span>
<div class="ContSSBlock">
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7E474E9787012FE4">3.2-1 IO_accept</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X791A6341852001F8">3.2-2 IO_bind</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X790139B37E87FA61">3.2-3 IO_chdir</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X83D4CB2681674FA4">3.2-4 IO_chmod</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X85C0617479E4D952">3.2-5 IO_chown</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X820DA9C97C2E80BA">3.2-6 IO_close</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X8078699B84F082A4">3.2-7 IO_closedir</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7DE9D8B387D3A3D5">3.2-8 IO_connect</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X78FCF69C7FCF3BD7">3.2-9 IO_creat</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7DAAD93A80F76681">3.2-10 IO_dup</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7F7B8FAC7ABA285B">3.2-11 IO_dup2</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7B30A7FA84692EC5">3.2-12 IO_execv</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X875D9A9E8201D461">3.2-13 IO_execve</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X818044D07C64A412">3.2-14 IO_execvp</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X843634347E88C357">3.2-15 IO_exit</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7F08E1187BDB619A">3.2-16 IO_fchmod</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X791C4B4A81059A88">3.2-17 IO_fchown</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7870647E866D29A4">3.2-18 IO_fcntl</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X86C819F37D07ECF7">3.2-19 IO_fork</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7E27748983EC7B5C">3.2-20 IO_fstat</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X826D86AF8013F184">3.2-21 IO_getcwd</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X84AECCE17832D6D8">3.2-22 IO_getenv</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7DD25BDC79EE65AD">3.2-23 IO_gethostbyname</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7B7164EF8307D26B">3.2-24 IO_gethostname</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7ECF948083E38BD0">3.2-25 IO_getpid</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7EC6ABAB7AB9F40F">3.2-26 IO_getppid</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X877A161482FC1769">3.2-27 IO_getsockname</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X790213D885BAB495">3.2-28 IO_getsockopt</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7BC965198011083B">3.2-29 IO_gettimeofday</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7DC156EA86F3F356">3.2-30 IO_gmtime</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7D0439128512FBF6">3.2-31 IO_kill</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X8305F97C87FE448E">3.2-32 IO_lchown</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7E1C65EB84497185">3.2-33 IO_link</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7957063B807025C7">3.2-34 IO_listen</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7B7D3D64805F335F">3.2-35 IO_localtime</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X85C475187C824830">3.2-36 IO_lseek</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7A8C75038517A55A">3.2-37 IO_lstat</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X83D968AB84F00ABF">3.2-38 IO_mkdir</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X80BFF17A8099815F">3.2-39 IO_mkfifo</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7928F1DB8379F850">3.2-40 IO_mknod</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X82B09BF27D5AA458">3.2-41 IO_mkstemp</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7F9C9F4B7CB7977A">3.2-42 IO_mkdtemp</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X8731A44E8032D9D2">3.2-43 IO_open</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X78E234797EB01883">3.2-44 IO_opendir</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7C8F0A44837BBE8C">3.2-45 IO_pipe</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X84F3D862836BF17C">3.2-46 IO_read</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X8410C6F17DE9302D">3.2-47 IO_readdir</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7943F25E7EBA9A6B">3.2-48 IO_readlink</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X78EB295E78B363B2">3.2-49 IO_recv</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X84C617887EE02EB4">3.2-50 IO_recvfrom</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X78EC95007A92AB69">3.2-51 IO_rename</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7F86DBEB7876FBA5">3.2-52 IO_rewinddir</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7FA4DD537C83A199">3.2-53 IO_rmdir</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X84A98D2380BF6574">3.2-54 IO_seekdir</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X81CA6EE88062010E">3.2-55 IO_select</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X87019FD887F55C27">3.2-56 IO_send</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X8388B0147B5745EC">3.2-57 IO_sendto</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7D2AB8E985C56AD4">3.2-58 IO_setenv</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7BE641C1784D0899">3.2-59 IO_setsockopt</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X852B16CF82B96C84">3.2-60 IO_socket</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7F7D23867B45D525">3.2-61 IO_stat</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7B0D9CEF7A3CD431">3.2-62 IO_symlink</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X81FF8B678748900B">3.2-63 IO_telldir</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X78C93B6587B478C2">3.2-64 IO_unlink</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X8103218E7C5CF577">3.2-65 IO_unsetenv</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X80737A008450184F">3.2-66 IO_WaitPid</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X84295FC77CCB1066">3.2-67 IO_IgnorePid</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X84EB06707D1BD3F1">3.2-68 IO_write</a></span>
</div></div>
<div class="ContSect"><span class="tocline"><span class="nocss"> </span><a href="chap3.html#X85065AD381BD8E0F">3.3 <span class="Heading">Further C level functions</span></a>
</span>
<div class="ContSSBlock">
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X878007A67E806CEF">3.3-1 IO_make_sockaddr_in</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7F3E88AD7EFD52F4">3.3-2 IO_environ</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X8383E62D86BE30C6">3.3-3 IO_InstallSIGCHLDHandler</a></span>
<span class="ContSS"><br /><span class="nocss"> </span><a href="chap3.html#X7EEB7471816B64DF">3.3-4 IO_RestoreSIGCHLDHandler</a></span>
</div></div>
</div>
<h3>3 <span class="Heading">Functions directly available from the C library</span></h3>
<p>The following functions from the C library are made available as <strong class="pkg">GAP</strong> functions:</p>
<p><code class="code">accept</code>, <code class="code">bind</code>, <code class="code">chdir</code>, <code class="code">chmod</code>, <code class="code">chown</code>, <code class="code">close</code>, <code class="code">closedir</code>, <code class="code">connect</code>, <code class="code">creat</code>, <code class="code">dup</code>, <code class="code">dup2</code>, <code class="code">execv</code>, <code class="code">execve</code>, <code class="code">execvp</code>, <code class="code">exit</code>, <code class="code">fchmod</code>, <code class="code">fchown</code>, <code class="code">fcntl</code>, <code class="code">fork</code>, <code class="code">fstat</code>, <code class="code">getcwd</code>, <code class="code">getenv</code>, <code class="code">gethostbyname</code>, <code class="code">gethostname</code>, <code class="code">getpid</code>, <code class="code">getppid</code>, <code class="code">getsockname</code>, <code class="code">getsockopt</code>, <code class="code">gettimeofday</code>, <code class="code">gmtime</code>, <code class="code">kill</code>, <code class="code">lchown</code>, <code class="code">link</code>, <code class="code">listen</code>, <code class="code">localtime</code>, <code class="code">lseek</code>, <code class="code">lstat</code>, <code class="code">mkdir</code>, <code class="code">mkfifo</code>, <code class="code">mknod</code>, <code class="code">mkstemp</code>, <code class="code">mkdtemp</code>, <code class="code">open</code>, <code class="code">opendir</code>, <code class="code">pipe</code>, <code class="code">read</code>, <code class="code">readdir</code>, <code class="code">readlink</code>, <code class="code">recv</code>, <code class="code">recvfrom</code>, <code class="code">rename</code>, <code class="code">rewinddir</code>, <code class="code">rmdir</code>, <code class="code">seekdir</code>, <code class="code">select</code>, <code class="code">send</code>, <code class="code">sendto</code>, <code class="code">setenv</code>, <code class="code">setsockopt</code>, <code class="code">socket</code>, <code class="code">stat</code>, <code class="code">symlink</code>, <code class="code">telldir</code>, <code class="code">unlink</code>, <code class="code">unsetenv</code>, <code class="code">write</code>.</p>
<p>Use the <code class="code">man</code> command in your shell to get information about these functions.</p>
<p>For each of these functions there is a corresponding <strong class="pkg">GAP</strong> global function with the prefix <code class="code">IO_</code> before its name. Apart from minor differences (see below) they take exactly the same arguments as their C counterparts. Strings must be specified as <strong class="pkg">GAP</strong> strings and integers as <strong class="pkg">GAP</strong> immediate integers. Return values are in general the same as for the C counterparts. However, an error condition is indicated by the value <code class="code">fail</code> instead of -1, and if the result can only be success or failure, <code class="code">true</code> indicates success.</p>
<p>All errors are reported via the <code class="func">LastSystemError</code> (<a href="../../../doc/ref/chap9_mj.html#X87D278437A916905"><span class="RefLink">Reference: LastSystemError</span></a>) function.</p>
<p>In the C library a lot of integers are defined as macros in header files. All the necessary values for the above functions are bound to their name in the global <code class="code">IO</code> record.</p>
<p><em>Warning:</em> Existence of many of these functions and constants is platform dependent. The compilation process checks existence and this leads to the situation that on the <strong class="pkg">GAP</strong> levels the functions and constants are there or not. If you want to develop platform independent <strong class="pkg">GAP</strong> code using this package, then you have to check for existence of the functions and constants you need.</p>
<p><a id="X85D3551379BA32FC" name="X85D3551379BA32FC"></a></p>
<h4>3.1 <span class="Heading">Differences in arguments - an overview</span></h4>
<p>The <code class="code">open</code> function has to be called with three arguments. The version with two arguments is not available on the <strong class="pkg">GAP</strong> level.</p>
<p>The <code class="code">read</code> function takes four arguments: <var class="Arg">fd</var> is an integer file descriptor, <var class="Arg">st</var> is a <strong class="pkg">GAP</strong> string, <var class="Arg">offset</var> is an offset within this string (zero based), and <var class="Arg">count</var> is the maximal number of bytes to read. The data is read and stored into the string <var class="Arg">st</var>, starting at position <span class="SimpleMath"><var class="Arg">offset</var>+1</span>. The string <var class="Arg">st</var> is made long enough, such that <var class="Arg">count</var> bytes would fit into it, beginning at position <span class="SimpleMath"><var class="Arg">offset</var>+1</span>. The number of bytes read is returned or <code class="code">fail</code> in case of an error.</p>
<p>The <code class="code">write</code> function is similar, it also takes four arguments: <var class="Arg">fd</var> is an integer file descriptor, <var class="Arg">st</var> is a <strong class="pkg">GAP</strong> string, <var class="Arg">offset</var> is an offset within this string (zero based), and <var class="Arg">count</var> is the number of bytes to write, starting from position <span class="SimpleMath"><var class="Arg">offset</var>+1</span> in the string <var class="Arg">st</var>. The number of bytes written is returned, or a <code class="code">fail</code> in case of an error.</p>
<p>The <code class="code">opendir</code> function only returns <code class="code">true</code> or <code class="code">fail</code>.</p>
<p>The <code class="code">readdir</code> function takes no argument. It reads the directory that was specified in the last call to <code class="code">opendir</code>. It just returns a string, which is the name of a file or subdirectory in the corresponding directory. It returns <code class="code">false</code> after the last file name in the directory or <code class="code">fail</code> in case of an error.</p>
<p>The <code class="code">closedir</code> function takes no argument. It should be called after <code class="code">readdir</code> returned <code class="code">false</code> or <code class="code">fail</code> to avoid excessive use of file descriptors.</p>
<p>The functions <code class="code">stat</code>, <code class="code">fstat</code>, and <code class="code">lstat</code> only take one argument and return a <strong class="pkg">GAP</strong> record that has the same entries as a <code class="code">struct stat</code>.</p>
<p>The function <code class="code">socket</code> can optionally take a string as third argument. In that case it automatically calls <code class="code">getprotobyname</code> to look up the protocol name.</p>
<p>The functions <code class="code">bind</code> and <code class="code">connect</code> take only one string argument as address field, because the string already encodes the length.</p>
<p>There are two convenience functions <code class="func">IO_make_sockaddr_in</code> (<a href="chap3.html#X878007A67E806CEF"><span class="RefLink">3.3-1</span></a>) and <code class="func">IO_MakeIPAddressPort</code> (<a href="chap4.html#X8568CE6684C90CE5"><span class="RefLink">4.3-6</span></a>) to create such addresses. The first takes two arguments <var class="Arg">addr</var> and <var class="Arg">port</var>, where <var class="Arg">addr</var> is a string of length 4, containing the 4 bytes of the IP address and <var class="Arg">port</var> is a port number as <strong class="pkg">GAP</strong> integer. The function <code class="func">IO_MakeIPAddressPort</code> (<a href="chap4.html#X8568CE6684C90CE5"><span class="RefLink">4.3-6</span></a>) takes the same arguments, but the first can be a string containing an IP address in dot notation like <q>137.226.152.77</q> or a hostname to be looked up.</p>
<p>The <code class="code">setsockopt</code> function has no argument <var class="Arg">optlen</var>. The length of the string <var class="Arg">optval</var> is taken.</p>
<p>The <code class="code">select</code> function works as the function <code class="code">UNIXSelect</code> in the <strong class="pkg">GAP</strong> library.</p>
<p>As of now, the file locking mechanisms of <code class="code">fcntl</code> using <code class="code">struct flock</code> are not yet implemented on the <strong class="pkg">GAP</strong> level.</p>
<p><a id="X800F9F3E810A7228" name="X800F9F3E810A7228"></a></p>
<h4>3.2 <span class="Heading">The low-level functions in detail</span></h4>
<p>Nearly all of this functions return an integer result in the C library. On the <strong class="pkg">GAP</strong> level this is either returned as a non-negative integer in case of success or as <code class="keyw">fail</code> in case of an error (where on the C level <span class="SimpleMath">-1</span> would be returned). If the integer can only be <span class="SimpleMath">0</span> for <q>no error</q> this is changed to <code class="keyw">true</code> on the <strong class="pkg">GAP</strong> level.</p>
<p><a id="X7E474E9787012FE4" name="X7E474E9787012FE4"></a></p>
<h5>3.2-1 IO_accept</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_accept</code>( <var class="Arg">fd</var>, <var class="Arg">addr</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: an integer or <code class="keyw">fail</code></p>
<p>Accepts an incoming network connection. For details see <q><code class="code">man 2 accept</code></q>. The argument <var class="Arg">addr</var> can be made with <code class="func">IO_make_sockaddr_in</code> (<a href="chap3.html#X878007A67E806CEF"><span class="RefLink">3.3-1</span></a>) and contains its length such that no third argument is necessary.</p>
<p><a id="X791A6341852001F8" name="X791A6341852001F8"></a></p>
<h5>3.2-2 IO_bind</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_bind</code>( <var class="Arg">fd</var>, <var class="Arg">my_addr</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: an integer or <code class="keyw">fail</code></p>
<p>Binds a local address to a socket. For details see <q><code class="code">man 2 bind</code></q>. The argument <var class="Arg">my_addr</var> can be made with <code class="func">IO_make_sockaddr_in</code> (<a href="chap3.html#X878007A67E806CEF"><span class="RefLink">3.3-1</span></a>) and contains its length such that no third argument is necessary.</p>
<p><a id="X790139B37E87FA61" name="X790139B37E87FA61"></a></p>
<h5>3.2-3 IO_chdir</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_chdir</code>( <var class="Arg">path</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: <code class="keyw">true</code> or <code class="keyw">fail</code></p>
<p>Changes the current working directory. For details see <q><code class="code">man 2 chdir</code></q>.</p>
<p><a id="X83D4CB2681674FA4" name="X83D4CB2681674FA4"></a></p>
<h5>3.2-4 IO_chmod</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_chmod</code>( <var class="Arg">pathname</var>, <var class="Arg">mode</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: <code class="keyw">true</code> or <code class="keyw">fail</code></p>
<p>Changes the mode of a file. For details see <q><code class="code">man 2 chmod</code></q>.</p>
<p><a id="X85C0617479E4D952" name="X85C0617479E4D952"></a></p>
<h5>3.2-5 IO_chown</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_chown</code>( <var class="Arg">path</var>, <var class="Arg">owner</var>, <var class="Arg">group</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: <code class="keyw">true</code> or <code class="keyw">fail</code></p>
<p>Sets owner and/or group of file. For details see <q><code class="code">man 2 chown</code></q>.</p>
<p><a id="X820DA9C97C2E80BA" name="X820DA9C97C2E80BA"></a></p>
<h5>3.2-6 IO_close</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_close</code>( <var class="Arg">fd</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: <code class="keyw">true</code> or <code class="keyw">fail</code></p>
<p>Closes a file descriptor. For details see <q><code class="code">man 2 close</code></q>.</p>
<p><a id="X8078699B84F082A4" name="X8078699B84F082A4"></a></p>
<h5>3.2-7 IO_closedir</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_closedir</code>( )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: <code class="keyw">true</code> or <code class="keyw">fail</code></p>
<p>Closes a directory. For details see <q><code class="code">man 3 closedir</code></q>. Has no arguments, because we only have one <code class="code">DIR</code> struct in the C part.</p>
<p><a id="X7DE9D8B387D3A3D5" name="X7DE9D8B387D3A3D5"></a></p>
<h5>3.2-8 IO_connect</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_connect</code>( <var class="Arg">fd</var>, <var class="Arg">serv_addr</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: <code class="keyw">true</code> or <code class="keyw">fail</code></p>
<p>Connects to a remote socket. For details see <q><code class="code">man 2 connect</code></q>. The argument <var class="Arg">serv_addr</var> can be made with <code class="func">IO_make_sockaddr_in</code> (<a href="chap3.html#X878007A67E806CEF"><span class="RefLink">3.3-1</span></a>) and contains its length such that no third argument is necessary.</p>
<p><a id="X78FCF69C7FCF3BD7" name="X78FCF69C7FCF3BD7"></a></p>
<h5>3.2-9 IO_creat</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_creat</code>( <var class="Arg">pathname</var>, <var class="Arg">mode</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: an integer or <code class="keyw">fail</code></p>
<p>Creates a new file. For details see <q><code class="code">man 2 creat</code></q>.</p>
<p><a id="X7DAAD93A80F76681" name="X7DAAD93A80F76681"></a></p>
<h5>3.2-10 IO_dup</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_dup</code>( <var class="Arg">oldfd</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: an integer or <code class="keyw">fail</code></p>
<p>Duplicates a file descriptor. For details see <q><code class="code">man 2 dup</code></q>.</p>
<p><a id="X7F7B8FAC7ABA285B" name="X7F7B8FAC7ABA285B"></a></p>
<h5>3.2-11 IO_dup2</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_dup2</code>( <var class="Arg">oldfd</var>, <var class="Arg">newfd</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: <code class="keyw">true</code> or <code class="keyw">fail</code></p>
<p>Duplicates a file descriptor to a new one. For details see <q><code class="code">man 2 dup2</code></q>.</p>
<p><a id="X7B30A7FA84692EC5" name="X7B30A7FA84692EC5"></a></p>
<h5>3.2-12 IO_execv</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_execv</code>( <var class="Arg">path</var>, <var class="Arg">argv</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: <code class="keyw">fail</code> or does not return</p>
<p>Replaces the process with another process. For details see <q><code class="code">man 3 execv</code></q>. The argument <var class="Arg">argv</var> is a list of strings. The called program does not have to be the first argument in this list.</p>
<p><a id="X875D9A9E8201D461" name="X875D9A9E8201D461"></a></p>
<h5>3.2-13 IO_execve</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_execve</code>( <var class="Arg">path</var>, <var class="Arg">argv</var>, <var class="Arg">envp</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: <code class="keyw">fail</code> or does not return</p>
<p>Replaces the process with another process. For details see <q><code class="code">man 3 execve</code></q>. The arguments <var class="Arg">argv</var> and <var class="Arg">envp</var> are both lists of strings. The called program does not have to be the first argument in <var class="Arg">argv</var>. The list <var class="Arg">envp</var> can be made with <code class="func">IO_MakeEnvList</code> (<a href="chap4.html#X7CF3DB5081A91600"><span class="RefLink">4.3-8</span></a>) from a record acquired from <code class="func">IO_Environment</code> (<a href="chap4.html#X7F9AAE018474E1D8"><span class="RefLink">4.3-7</span></a>) and modified later.</p>
<p><a id="X818044D07C64A412" name="X818044D07C64A412"></a></p>
<h5>3.2-14 IO_execvp</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_execvp</code>( <var class="Arg">path</var>, <var class="Arg">argv</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: <code class="keyw">fail</code> or does not return</p>
<p>Replaces the process with another process. For details see <q><code class="code">man 3 execvp</code></q>. The argument <var class="Arg">argv</var> is a list of strings. The called program does not have to be the first argument in this list.</p>
<p><a id="X843634347E88C357" name="X843634347E88C357"></a></p>
<h5>3.2-15 IO_exit</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_exit</code>( <var class="Arg">status</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Stops process immediately with return code <var class="Arg">status</var>. For details see <q><code class="code">man 2 exit</code></q>. The argument <var class="Arg">status</var> must be an integer. Does not return.</p>
<p><a id="X7F08E1187BDB619A" name="X7F08E1187BDB619A"></a></p>
<h5>3.2-16 IO_fchmod</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_fchmod</code>( <var class="Arg">fd</var>, <var class="Arg">mode</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: <code class="keyw">true</code> or <code class="keyw">fail</code></p>
<p>Changes mode of an opened file. For details see <q><code class="code">man 2 fchmod</code></q>.</p>
<p><a id="X791C4B4A81059A88" name="X791C4B4A81059A88"></a></p>
<h5>3.2-17 IO_fchown</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_fchown</code>( <var class="Arg">fd</var>, <var class="Arg">owner</var>, <var class="Arg">group</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: <code class="keyw">true</code> or <code class="keyw">fail</code></p>
<p>Changes owner and/or group of an opened file. For details see <q><code class="code">man 2 fchown</code></q>.</p>
<p><a id="X7870647E866D29A4" name="X7870647E866D29A4"></a></p>
<h5>3.2-18 IO_fcntl</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_fcntl</code>( <var class="Arg">fd</var>, <var class="Arg">cmd</var>, <var class="Arg">arg</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: an integer or <code class="keyw">fail</code></p>
<p>Does various things to control the behaviour of a file descriptor. For details see <q><code class="code">man 2 fcntl</code></q>.</p>
<p><a id="X86C819F37D07ECF7" name="X86C819F37D07ECF7"></a></p>
<h5>3.2-19 IO_fork</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_fork</code>( )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: an integer or <code class="keyw">fail</code></p>
<p>Forks off a child process, which is an identical copy. For details see <q><code class="code">man 2 fork</code></q>. Note that <code class="func">IO_fork</code> activates our SIGCHLD handler (see <code class="func">IO_InstallSIGCHLDHandler</code> (<a href="chap3.html#X8383E62D86BE30C6"><span class="RefLink">3.3-3</span></a>)). Note that you must use the <code class="func">IO_WaitPid</code> (<a href="chap3.html#X80737A008450184F"><span class="RefLink">3.2-66</span></a>) function to wait or check for the termination of child processes, or call <code class="func">IO_IgnorePid</code> (<a href="chap3.html#X84295FC77CCB1066"><span class="RefLink">3.2-67</span></a>) to ignore the child.</p>
<p><a id="X7E27748983EC7B5C" name="X7E27748983EC7B5C"></a></p>
<h5>3.2-20 IO_fstat</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_fstat</code>( <var class="Arg">fd</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: a record or <code class="keyw">fail</code></p>
<p>Returns the file meta data for an opened file. For details see <q><code class="code">man 2 fstat</code></q>. A <strong class="pkg">GAP</strong> record is returned with the same entries than a <code class="code">struct stat</code>.</p>
<p><a id="X826D86AF8013F184" name="X826D86AF8013F184"></a></p>
<h5>3.2-21 IO_getcwd</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_getcwd</code>( )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: a string or <code class="keyw">fail</code></p>
<p>Returns the current working directory. For details see <q><code class="code">man 3 getcwd</code></q>.</p>
<p><a id="X84AECCE17832D6D8" name="X84AECCE17832D6D8"></a></p>
<h5>3.2-22 IO_getenv</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_getenv</code>( <var class="Arg">name</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: a string or <code class="keyw">fail</code></p>
<p>Return the current value of the environment variable <var class="Arg">name</var>. If the variable is not in the current environment, <code class="code">fail</code> is returned. For details see <q><code class="code">man 3 getenv</code></q>.</p>
<p><a id="X7DD25BDC79EE65AD" name="X7DD25BDC79EE65AD"></a></p>
<h5>3.2-23 IO_gethostbyname</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_gethostbyname</code>( <var class="Arg">name</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: a record or <code class="keyw">fail</code></p>
<p>Return host information by name. For details see <q><code class="code">man 3 gethostbyname</code></q>. A <strong class="pkg">GAP</strong> record is returned with all the relevant information about the host.</p>
<p><a id="X7B7164EF8307D26B" name="X7B7164EF8307D26B"></a></p>
<h5>3.2-24 IO_gethostname</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_gethostname</code>( )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: a string or <code class="keyw">fail</code></p>
<p>Return host name. For details see <q><code class="code">man 3 gethostname</code></q>.</p>
<p><a id="X7ECF948083E38BD0" name="X7ECF948083E38BD0"></a></p>
<h5>3.2-25 IO_getpid</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_getpid</code>( )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: an integer</p>
<p>Returns the process ID of the current process as an integer. For details see <q><code class="code">man 2 getpid</code></q>.</p>
<p><a id="X7EC6ABAB7AB9F40F" name="X7EC6ABAB7AB9F40F"></a></p>
<h5>3.2-26 IO_getppid</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_getppid</code>( )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: an integer</p>
<p>Returns the process ID of the parent of the current process as an integer. For details see <q><code class="code">man 2 getppid</code></q>.</p>
<p><a id="X877A161482FC1769" name="X877A161482FC1769"></a></p>
<h5>3.2-27 IO_getsockname</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_getsockname</code>( <var class="Arg">fd</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: a string or <code class="keyw">fail</code></p>
<p>Get a socket name. For details see <q><code class="code">man 2 getsockname</code></q>.</p>
<p><a id="X790213D885BAB495" name="X790213D885BAB495"></a></p>
<h5>3.2-28 IO_getsockopt</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_getsockopt</code>( <var class="Arg">fd</var>, <var class="Arg">level</var>, <var class="Arg">optname</var>, <var class="Arg">optval</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: <code class="keyw">true</code> or <code class="keyw">false</code></p>
<p>Get a socket option. For details see <q><code class="code">man 2 getsockopt</code></q>. Note that the argument <var class="Arg">optval</var> carries its length around, such that no 5th argument is necessary.</p>
<p><a id="X7BC965198011083B" name="X7BC965198011083B"></a></p>
<h5>3.2-29 IO_gettimeofday</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_gettimeofday</code>( )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: A record with components <code class="code">tv_sec</code> and <code class="code">tv_usec</code></p>
<p>This returns the time elapsed since 1.1.1970, 0:00 GMT. The component <code class="code">tv_sec</code> contains the number of full seconds and the number <code class="code">tv_usec</code> the additional microseconds.</p>
<p><a id="X7DC156EA86F3F356" name="X7DC156EA86F3F356"></a></p>
<h5>3.2-30 IO_gmtime</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_gmtime</code>( <var class="Arg">seconds</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: A record</p>
<p>The argument is the number of seconds that have elapsed since 1.1.1970, 0:00 GMT. The result is a record with the current Greenwich mean time broken down into date and time as in the C-library function <code class="code">gmtime</code>.</p>
<p><a id="X7D0439128512FBF6" name="X7D0439128512FBF6"></a></p>
<h5>3.2-31 IO_kill</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_kill</code>( <var class="Arg">pid</var>, <var class="Arg">sig</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: <code class="keyw">true</code> or <code class="keyw">fail</code></p>
<p>Sends the signal <var class="Arg">sig</var> to the process with process ID <var class="Arg">pid</var>. For details see <q><code class="code">man 2 kill</code></q>. The signal numbers available can be found in the global <code class="code">IO</code> record with names like <code class="code">SIGTERM</code>.</p>
<p><a id="X8305F97C87FE448E" name="X8305F97C87FE448E"></a></p>
<h5>3.2-32 IO_lchown</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_lchown</code>( <var class="Arg">path</var>, <var class="Arg">owner</var>, <var class="Arg">group</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: <code class="keyw">true</code> or <code class="keyw">false</code></p>
<p>Changes owner and/or group of a file not following links. For details see <q><code class="code">man 2 lchown</code></q>.</p>
<p><a id="X7E1C65EB84497185" name="X7E1C65EB84497185"></a></p>
<h5>3.2-33 IO_link</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_link</code>( <var class="Arg">oldpath</var>, <var class="Arg">newpath</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: <code class="keyw">true</code> or <code class="keyw">false</code></p>
<p>Create a hard link. For details see <q><code class="code">man 2 link</code></q>.</p>
<p><a id="X7957063B807025C7" name="X7957063B807025C7"></a></p>
<h5>3.2-34 IO_listen</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_listen</code>( <var class="Arg">fd</var>, <var class="Arg">backlog</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: <code class="keyw">true</code> or <code class="keyw">false</code></p>
<p>Switch a socket to listening. For details see <q><code class="code">man 2 listen</code></q>.</p>
<p><a id="X7B7D3D64805F335F" name="X7B7D3D64805F335F"></a></p>
<h5>3.2-35 IO_localtime</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_localtime</code>( <var class="Arg">seconds</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: A record</p>
<p>The argument is the number of seconds that have elapsed since 1.1.1970, 0:00 GMT. The result is a record with the current local time broken down into date and time as in the C-library function <code class="code">localtime</code>.</p>
<p><a id="X85C475187C824830" name="X85C475187C824830"></a></p>
<h5>3.2-36 IO_lseek</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_lseek</code>( <var class="Arg">fd</var>, <var class="Arg">offset</var>, <var class="Arg">whence</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: an integer or <code class="keyw">fail</code></p>
<p>Seeks within an open file. For details see <q><code class="code">man 2 lseek</code></q>.</p>
<p><a id="X7A8C75038517A55A" name="X7A8C75038517A55A"></a></p>
<h5>3.2-37 IO_lstat</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_lstat</code>( <var class="Arg">name</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: a record or <code class="keyw">fail</code></p>
<p>Returns the file meta data for a file not following links. For details see <q><code class="code">man 2 lstat</code></q>. A <strong class="pkg">GAP</strong> record is returned with the same entries than a <code class="code">struct stat</code>.</p>
<p><a id="X83D968AB84F00ABF" name="X83D968AB84F00ABF"></a></p>
<h5>3.2-38 IO_mkdir</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_mkdir</code>( <var class="Arg">pathname</var>, <var class="Arg">mode</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: <code class="keyw">true</code> or <code class="keyw">false</code></p>
<p>Creates a directory. For details see <q><code class="code">man 2 mkdir</code></q>.</p>
<p><a id="X80BFF17A8099815F" name="X80BFF17A8099815F"></a></p>
<h5>3.2-39 IO_mkfifo</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_mkfifo</code>( <var class="Arg">pathname</var>, <var class="Arg">mode</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: <code class="keyw">true</code> or <code class="keyw">false</code></p>
<p>Creates a FIFO special file (a named pipe). For details see <q><code class="code">man 3 mkfifo</code></q>.</p>
<p><a id="X7928F1DB8379F850" name="X7928F1DB8379F850"></a></p>
<h5>3.2-40 IO_mknod</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_mknod</code>( <var class="Arg">pathname</var>, <var class="Arg">mode</var>, <var class="Arg">dev</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: <code class="keyw">true</code> or <code class="keyw">false</code></p>
<p>Create a special or ordinary file. For details see <q><code class="code">man 2 mknod</code></q>.</p>
<p><a id="X82B09BF27D5AA458" name="X82B09BF27D5AA458"></a></p>
<h5>3.2-41 IO_mkstemp</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_mkstemp</code>( <var class="Arg">template</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: an integer or <code class="keyw">fail</code></p>
<p>Create a special or ordinary file. For details see <q><code class="code">man 3 mkstemp</code></q>.</p>
<p><a id="X7F9C9F4B7CB7977A" name="X7F9C9F4B7CB7977A"></a></p>
<h5>3.2-42 IO_mkdtemp</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_mkdtemp</code>( <var class="Arg">template</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: a string or <code class="keyw">fail</code></p>
<p>Create a temporary directory. For details see <q><code class="code">man 3 mkdtemp</code></q>.</p>
<p><a id="X8731A44E8032D9D2" name="X8731A44E8032D9D2"></a></p>
<h5>3.2-43 IO_open</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_open</code>( <var class="Arg">pathname</var>, <var class="Arg">flags</var>, <var class="Arg">mode</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: an integer or <code class="keyw">fail</code></p>
<p>Open and possibly create a file or device. For details see <q><code class="code">man 2 open</code></q>. Only the variant with 3 arguments can be used.</p>
<p><a id="X78E234797EB01883" name="X78E234797EB01883"></a></p>
<h5>3.2-44 IO_opendir</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_opendir</code>( <var class="Arg">name</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: <code class="keyw">true</code> or <code class="keyw">false</code></p>
<p>Opens a directory. For details see <q><code class="code">man 3 opendir</code></q>. Note that only <code class="keyw">true</code> is returned if everything is OK, since only one <code class="code">DIR</code> struct is stored on the C level and thus only one directory can be open at any time.</p>
<p><a id="X7C8F0A44837BBE8C" name="X7C8F0A44837BBE8C"></a></p>
<h5>3.2-45 IO_pipe</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_pipe</code>( )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: a record or <code class="keyw">fail</code></p>
<p>Create a pair of file descriptors with a pipe between them. For details see <q><code class="code">man 2 pipe</code></q>. Note that no arguments are needed. The result is either <code class="keyw">fail</code> in case of an error or a record with two components <code class="code">toread</code> and <code class="code">towrite</code> bound to the two filedescriptors for reading and writing respectively.</p>
<p><a id="X84F3D862836BF17C" name="X84F3D862836BF17C"></a></p>
<h5>3.2-46 IO_read</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_read</code>( <var class="Arg">fd</var>, <var class="Arg">st</var>, <var class="Arg">offset</var>, <var class="Arg">count</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: an integer or <code class="keyw">fail</code></p>
<p>Reads from file descriptor. For details see <q><code class="code">man 2 read</code></q>. Note that there is one more argument <var class="Arg">offset</var> to specify at which position in the string <var class="Arg">st</var> the read data should be stored. Note that <var class="Arg">offset</var> zero means at the beginning of the string, which is position 1 in <strong class="pkg">GAP</strong>. The number of bytes read or <code class="keyw">fail</code> in case of an error is returned.</p>
<p><a id="X8410C6F17DE9302D" name="X8410C6F17DE9302D"></a></p>
<h5>3.2-47 IO_readdir</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_readdir</code>( )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: a string or <code class="keyw">fail</code> or <code class="keyw">false</code></p>
<p>Reads from a directory. For details see <q><code class="code">man 2 readdir</code></q>. Note that no argument is required as we have only one <code class="code">DIR</code> struct on the C level. If the directory is read completely <code class="keyw">false</code> is returned, and otherwise a string. An error is indicated by <code class="keyw">fail</code>.</p>
<p><a id="X7943F25E7EBA9A6B" name="X7943F25E7EBA9A6B"></a></p>
<h5>3.2-48 IO_readlink</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_readlink</code>( <var class="Arg">path</var>, <var class="Arg">buf</var>, <var class="Arg">bufsize</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: an integer or <code class="keyw">fail</code></p>
<p>Reads the value of a symbolic link. For details see <q><code class="code">man 2 readlink</code></q>. <var class="Arg">buf</var> is modified. The new length of <var class="Arg">buf</var> is returned or <code class="keyw">fail</code> in case of an error.</p>
<p><a id="X78EB295E78B363B2" name="X78EB295E78B363B2"></a></p>
<h5>3.2-49 IO_recv</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_recv</code>( <var class="Arg">fd</var>, <var class="Arg">st</var>, <var class="Arg">offset</var>, <var class="Arg">len</var>, <var class="Arg">flags</var> )</td><td class="tdright">( function )</td></tr></table></div>
<p>Returns: an integer or <code class="keyw">fail</code></p>
<p>Receives data from a socket. For details see <q><code class="code">man 2 recv</code></q>. Note the additional argument <var class="Arg">offset</var> which plays the same role as for the <code class="func">IO_read</code> (<a href="chap3.html#X84F3D862836BF17C"><span class="RefLink">3.2-46</span></a>) function.</p>
<p><a id="X84C617887EE02EB4" name="X84C617887EE02EB4"></a></p>
<h5>3.2-50 IO_recvfrom</h5>
<div class="func"><table class="func" width="100%"><tr><td class="tdleft"><code class="func">‣ IO_recvfrom</code>( <var class="Arg">fd</var>, <var class="Arg">st</var>, <var class="Arg">offset</var>, <var class="Arg">len</var>, <var class="Arg">flags</var>, <var class="Arg">addr</var> )</td><td class= | |
