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| <title>ioproc(3) - Plan 9 from User Space</title> |
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| <tr><td width=20><td><b>IOPROC(3)</b><td align=right><b>IOPROC(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> |
| |
| closeioproc, iocall, ioclose, iointerrupt, iodial, ioopen, ioproc, |
| ioread, ioread9pmsg, ioreadn, iorecvfd, iosendfd, iosleep, iowrite |
| – slave I/O processes for threaded programs<br> |
| |
| </table> |
| <p><font size=+1><b>SYNOPSIS </b></font><br> |
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| <tt><font size=+1>#include <u.h><br> |
| #include <libc.h><br> |
| #include <thread.h><br> |
| typedef struct Ioproc Ioproc;<br> |
| Ioproc* ioproc(void);<br> |
| int ioclose(Ioproc *io, int fd);<br> |
| int iodial(Ioproc *io, char *addr, char *local, char *dir, char |
| *cdfp);<br> |
| int ioopen(Ioproc *io, char *file, int omode);<br> |
| long ioread(Ioproc *io, int fd, void *a, long n);<br> |
| int ioread9pmsg(Ioproc *io, int fd, void *a, uint n);<br> |
| long ioreadn(Ioproc *io, int fd, void *a, long n);<br> |
| int iorecvfd(int socket);<br> |
| int iosendfd(int socket, int fd);<br> |
| int iosleep(int milli);<br> |
| long iowrite(Ioproc *io, int fd, void *a, long n);<br> |
| void iointerrupt(Ioproc *io);<br> |
| void closeioproc(Ioproc *io);<br> |
| long iocall(Ioproc *io, long (*op)(va_list *arg), ...);<br> |
| </font></tt> |
| </table> |
| <p><font size=+1><b>DESCRIPTION </b></font><br> |
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| These routines provide access to I/O in slave procs. Since the |
| I/O itself is done in a slave proc, other threads in the calling |
| proc can run while the calling thread waits for the I/O to complete. |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> |
| |
| <i>Ioproc</i> forks a new slave proc and returns a pointer to the <tt><font size=+1>Ioproc</font></tt> |
| associated with it. <i>Ioproc</i> uses <i>mallocz</i> and <i>proccreate</i>; if either |
| fails, it calls <i>sysfatal</i> rather than return an error. |
| <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> |
| |
| <i>Ioclose</i>, <i>iodial</i>, <i>ioopen</i>, <i>ioread</i>, <i>ioread9pmsg</i>, <i>ioreadn</i>, <i>iorecvfd</i>, |
| <i>iosendfd</i>, <i>iosleep</i>, and <i>iowrite</i> execute the similarly named library |
| or system calls (see <a href="../man2/close.html"><i>close</i>(2)</a>, <a href="../man3/dial.html"><i>dial</i>(3)</a>, <a href="../man3/open.html"><i>open</i>(3)</a>, <a href="../man3/read.html"><i>read</i>(3)</a>, <a href="../man3/fcall.html"><i>fcall</i>(3)</a>, |
| <a href="../man3/sendfd.html"><i>sendfd</i>(3)</a>, and <a href="../man3/sleep.html"><i>sleep</i>(3)</a>) in the slave process associated with |
| <i>io</i>. It is an error to execute more than one call at a time in |
| an I/O |
| proc. |
| <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> |
| |
| <i>Iointerrupt</i> interrupts the call currently executing in the I/O |
| proc. If no call is executing, <i>iointerrupt</i> is a no-op. |
| <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> |
| |
| <i>Closeioproc</i> terminates the I/O proc and frees the associated <tt><font size=+1>Ioproc |
| . |
| <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> |
| </font></tt> |
| <i>Iocall</i> is a primitive that may be used to implement more slave |
| I/O routines. <i>Iocall</i> arranges for <i>op</i> to be called in <i>io</i>’s proc, |
| with <i>arg</i> set to the variable parameter list, returning the value |
| that <i>op</i> returns.<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> |
| |
| Relay messages between two file descriptors, counting the total |
| number of bytes seen:<br> |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| <tt><font size=+1>int tot;<br> |
| void<br> |
| relaythread(void *v)<br> |
| {<br> |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| int *fd, n;<br> |
| char buf[1024];<br> |
| Ioproc *io;<br> |
| fd = v;<br> |
| io = ioproc();<br> |
| while((n = ioread(io, fd[0], buf, sizeof buf)) > 0){<br> |
| if(iowrite(io, fd[1], buf, n) != n)<br> |
| sysfatal("iowrite: %r");<br> |
| tot += n;<br> |
| }<br> |
| closeioproc(io);<br> |
| |
| </table> |
| }<br> |
| void<br> |
| relay(int fd0, int fd1)<br> |
| {<br> |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| int fd[4];<br> |
| fd[0] = fd[3] = fd0;<br> |
| fd[1] = fd[2] = fd1;<br> |
| threadcreate(relaythread, fd, 8192);<br> |
| threadcreate(relaythread, fd+2, 8192);<br> |
| |
| </table> |
| }<br> |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> |
| </font></tt> |
| |
| </table> |
| If the two <i>relaythread</i> instances were running in different procs, |
| the common access to <i>tot</i> would be unsafe. |
| <table border=0 cellpadding=0 cellspacing=0><tr height=5><td></table> |
| |
| Implement <i>ioread</i>:<br> |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| <tt><font size=+1>static long<br> |
| _ioread(va_list *arg)<br> |
| {<br> |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| int fd;<br> |
| void *a;<br> |
| long n;<br> |
| fd = va_arg(*arg, int);<br> |
| a = va_arg(*arg, void*);<br> |
| n = va_arg(*arg, long);<br> |
| return read(fd, a, n);<br> |
| |
| </table> |
| }<br> |
| long<br> |
| ioread(Ioproc *io, int fd, void *a, long n)<br> |
| {<br> |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| return iocall(io, _ioread, fd, a, n);<br> |
| |
| </table> |
| }<br> |
| </font></tt> |
| </table> |
| |
| </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/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/dial.html"><i>dial</i>(3)</a>, <a href="../man3/open.html"><i>open</i>(3)</a>, <a href="../man3/read.html"><i>read</i>(3)</a>, <a href="../man3/thread.html"><i>thread</i>(3)</a><br> |
| |
| </table> |
| <p><font size=+1><b>BUGS </b></font><br> |
| |
| <table border=0 cellpadding=0 cellspacing=0><tr height=2><td><tr><td width=20><td> |
| |
| <i>Iointerrupt</i> is currently unimplemented.<br> |
| |
| </table> |
| |
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