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diff --git a/man/man3/needstack.html b/man/man3/needstack.html new file mode 100644 index 00000000..bba5fbe8 --- /dev/null +++ b/man/man3/needstack.html @@ -0,0 +1,98 @@ +<head> +<title>needstack(3) - Plan 9 from User Space</title> +<meta content="text/html; charset=utf-8" http-equiv=Content-Type> +</head> +<body bgcolor=#ffffff> +<table border=0 cellpadding=0 cellspacing=0 width=100%> +<tr height=10><td> +<tr><td width=20><td> +<tr><td width=20><td><b>NEEDSTACK(3)</b><td align=right><b>NEEDSTACK(3)</b> +<tr><td width=20><td colspan=2> + <br> +<p><font size=+1><b>NAME </b></font><br> + +<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> + + needstack – check for execution stack overflow<br> + +</table> +<p><font size=+1><b>SYNOPSIS </b></font><br> + +<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> + + <tt><font size=+1>#include <u.h> + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + </font></tt> + <tt><font size=+1>#include <libc.h> + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + </font></tt> + <tt><font size=+1>int needstack(int n)<br> + </font></tt> +</table> +<p><font size=+1><b>DESCRIPTION </b></font><br> + +<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> + + Stack overflow in the thread library leads to bugs that are difficult + to diagnose. The Plan 9 libraries are careful about not allocating + large structures on the stack, so typically four or eight kilobytes + is plenty of stack for a thread. Other libraries are not always + as careful. Calling <i>needstack</i> indicates to the thread library + that an external routine is about to be called that will require + <i>n</i> bytes of stack space. If there is not enough space left on the + stack, the thread library prints an error and terminates the program. + The call <tt><font size=+1>needstack(0)</font></tt> can be used to check whether the stack is + currently overflowed. + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + + <i>Needstack</i> is defined in <tt><font size=+1>libc.h</font></tt> so that library functions used + in threaded and non-threaded contexts can call it. The implementation + of <i>needstack</i> in <tt><font size=+1>lib9</font></tt> is a no-op. + <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> + + <i>Needstack</i> should be thought of as a comment checked at run time, + like <a href="../man3/assert.html"><i>assert</i>(3)</a>.<br> + +</table> +<p><font size=+1><b>EXAMPLE </b></font><br> + +<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> + + The X Window library implementation of <i>XLookupString</i> allocates + some very large buffers on the stack, so <tt><font size=+1>/usr/local/plan9/src/libdraw/x11−itrans.c</font></tt> + calls <tt><font size=+1>needstack(20*1024)</font></tt> before making calls to <i>XLookupString</i>. + If a thread (in this case, the keyboard-reading thread used inside + the <a href="../man3/draw.html"><i>draw</i>(3)</a> + library) does not allocate a large enough stack, the problem is + diagnosed immediately rather than left to corrupt memory.<br> + +</table> +<p><font size=+1><b>SOURCE </b></font><br> + +<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> + + <tt><font size=+1>/usr/local/plan9/src/lib9/needstack.c<br> + /usr/local/plan9/src/libthread<br> + </font></tt> +</table> +<p><font size=+1><b>SEE ALSO </b></font><br> + +<table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> + + <a href="../man3/thread.html"><i>thread</i>(3)</a><br> + +</table> + +<td width=20> +<tr height=20><td> +</table> +<!-- TRAILER --> +<table border=0 cellpadding=0 cellspacing=0 width=100%> +<tr height=15><td width=10><td><td width=10> +<tr><td><td> +<center> +<a href="../../"><img src="../../dist/spaceglenda100.png" alt="Space Glenda" border=1></a> +</center> +</table> +<!-- TRAILER --> +</body></html> |