1<html lang="en"> 2<head> 3<title>Reentrant Syscalls - Untitled</title> 4<meta http-equiv="Content-Type" content="text/html"> 5<meta name="description" content="Untitled"> 6<meta name="generator" content="makeinfo 4.13"> 7<link title="Top" rel="start" href="index.html#Top"> 8<link rel="up" href="Syscalls.html#Syscalls" title="Syscalls"> 9<link rel="prev" href="Stubs.html#Stubs" title="Stubs"> 10<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> 11<meta http-equiv="Content-Style-Type" content="text/css"> 12<style type="text/css"><!-- 13 pre.display { font-family:inherit } 14 pre.format { font-family:inherit } 15 pre.smalldisplay { font-family:inherit; font-size:smaller } 16 pre.smallformat { font-family:inherit; font-size:smaller } 17 pre.smallexample { font-size:smaller } 18 pre.smalllisp { font-size:smaller } 19 span.sc { font-variant:small-caps } 20 span.roman { font-family:serif; font-weight:normal; } 21 span.sansserif { font-family:sans-serif; font-weight:normal; } 22--></style> 23<link rel="stylesheet" type="text/css" href="../cs.css"> 24</head> 25<body> 26<div class="node"> 27<a name="Reentrant-Syscalls"></a> 28<p> 29Previous: <a rel="previous" accesskey="p" href="Stubs.html#Stubs">Stubs</a>, 30Up: <a rel="up" accesskey="u" href="Syscalls.html#Syscalls">Syscalls</a> 31<hr> 32</div> 33 34<h3 class="section">12.2 Reentrant covers for OS subroutines</h3> 35 36<p>Since the system subroutines are used by other library routines that 37require reentrancy, <samp><span class="file">libc.a</span></samp> provides cover routines (for example, 38the reentrant version of <code>fork</code> is <code>_fork_r</code>). These cover 39routines are consistent with the other reentrant subroutines in this 40library, and achieve reentrancy by using a reserved global data block 41(see <a href="Reentrancy.html#Reentrancy">Reentrancy</a>). 42 43<!-- FIXME!!! The following ignored text specifies how this section ought --> 44<!-- to work; however, both standalone info and Emacs info mode fail when --> 45<!-- confronted with nodes beginning `_' as of 24may93. Restore when Info --> 46<!-- readers fixed! --> 47 <dl> 48<dt><code>_open_r</code><a name="index-g_t_005fopen_005fr-485"></a><dd>A reentrant version of <code>open</code>. It takes a pointer 49to the global data block, which holds <code>errno</code>. 50 51 <pre class="example"> int _open_r(void *<var>reent</var>, 52 const char *<var>file</var>, int <var>flags</var>, int <var>mode</var>); 53</pre> 54 <br><dt><code>_close_r</code><a name="index-g_t_005fclose_005fr-486"></a><dd>A reentrant version of <code>close</code>. It takes a pointer to the global 55data block, which holds <code>errno</code>. 56 57 <pre class="example"> int _close_r(void *<var>reent</var>, int <var>fd</var>); 58</pre> 59 <br><dt><code>_lseek_r</code><a name="index-g_t_005flseek_005fr-487"></a><dd>A reentrant version of <code>lseek</code>. It takes a pointer to the global 60data block, which holds <code>errno</code>. 61 62 <pre class="example"> off_t _lseek_r(void *<var>reent</var>, 63 int <var>fd</var>, off_t <var>pos</var>, int <var>whence</var>); 64</pre> 65 <br><dt><code>_read_r</code><a name="index-g_t_005fread_005fr-488"></a><dd>A reentrant version of <code>read</code>. It takes a pointer to the global 66data block, which holds <code>errno</code>. 67 68 <pre class="example"> long _read_r(void *<var>reent</var>, 69 int <var>fd</var>, void *<var>buf</var>, size_t <var>cnt</var>); 70</pre> 71 <br><dt><code>_write_r</code><a name="index-g_t_005fwrite_005fr-489"></a><dd>A reentrant version of <code>write</code>. It takes a pointer to the global 72data block, which holds <code>errno</code>. 73 74 <pre class="example"> long _write_r(void *<var>reent</var>, 75 int <var>fd</var>, const void *<var>buf</var>, size_t <var>cnt</var>); 76</pre> 77 <br><dt><code>_fork_r</code><a name="index-g_t_005ffork_005fr-490"></a><dd>A reentrant version of <code>fork</code>. It takes a pointer to the global 78data block, which holds <code>errno</code>. 79 80 <pre class="example"> int _fork_r(void *<var>reent</var>); 81</pre> 82 <br><dt><code>_wait_r</code><a name="index-g_t_005fwait_005fr-491"></a><dd>A reentrant version of <code>wait</code>. It takes a pointer to the global 83data block, which holds <code>errno</code>. 84 85 <pre class="example"> int _wait_r(void *<var>reent</var>, int *<var>status</var>); 86</pre> 87 <br><dt><code>_stat_r</code><a name="index-g_t_005fstat_005fr-492"></a><dd>A reentrant version of <code>stat</code>. It takes a pointer to the global 88data block, which holds <code>errno</code>. 89 90 <pre class="example"> int _stat_r(void *<var>reent</var>, 91 const char *<var>file</var>, struct stat *<var>pstat</var>); 92</pre> 93 <br><dt><code>_fstat_r</code><a name="index-g_t_005ffstat_005fr-493"></a><dd>A reentrant version of <code>fstat</code>. It takes a pointer to the global 94data block, which holds <code>errno</code>. 95 96 <pre class="example"> int _fstat_r(void *<var>reent</var>, 97 int <var>fd</var>, struct stat *<var>pstat</var>); 98</pre> 99 <br><dt><code>_link_r</code><a name="index-g_t_005flink_005fr-494"></a><dd>A reentrant version of <code>link</code>. It takes a pointer to the global 100data block, which holds <code>errno</code>. 101 102 <pre class="example"> int _link_r(void *<var>reent</var>, 103 const char *<var>old</var>, const char *<var>new</var>); 104</pre> 105 <br><dt><code>_unlink_r</code><a name="index-g_t_005funlink_005fr-495"></a><dd>A reentrant version of <code>unlink</code>. It takes a pointer to the global 106data block, which holds <code>errno</code>. 107 108 <pre class="example"> int _unlink_r(void *<var>reent</var>, const char *<var>file</var>); 109</pre> 110 <br><dt><code>_sbrk_r</code><a name="index-g_t_005fsbrk_005fr-496"></a><dd>A reentrant version of <code>sbrk</code>. It takes a pointer to the global 111data block, which holds <code>errno</code>. 112 113 <pre class="example"> char *_sbrk_r(void *<var>reent</var>, size_t <var>incr</var>); 114</pre> 115 </dl> 116 117 </body></html> 118 119