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APUE.mm
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<map version="1.0.1">
<!-- To view this file, download free mind mapping software FreeMind from http://freemind.sourceforge.net -->
<node CREATED="1338637055049" ID="ID_143495120" MODIFIED="1498552114655" TEXT="APUE">
<node CREATED="1338637081000" FOLDED="true" ID="ID_640748604" MODIFIED="1503901178469" POSITION="right" TEXT="unbuffered IO (POSIX)">
<font BOLD="true" NAME="Dialog" SIZE="16"/>
<node CREATED="1338638811768" ID="ID_1420511453" MODIFIED="1375431940364" TEXT="header">
<node CREATED="1338637134048" ID="ID_418835484" MODIFIED="1341892737423" TEXT="<unistd.h>">
<node CREATED="1338637168938" ID="ID_425199589" MODIFIED="1338637168938" TEXT="standard symbolic constants and types"/>
<node CREATED="1338637228910" ID="ID_259807824" MODIFIED="1338637249355" TEXT="STDIN_FILENO"/>
<node CREATED="1338637233896" ID="ID_1142684653" MODIFIED="1338637244861" TEXT="STDOUT_FILENO"/>
<node CREATED="1338637215866" ID="ID_1465760884" MODIFIED="1338637225714" TEXT="STDERR_FILENO"/>
</node>
<node CREATED="1338637479192" ID="ID_1989948994" MODIFIED="1341892739605" TEXT="<limits.h>">
<node CREATED="1338637506041" ID="ID_661969641" MODIFIED="1338637506041" TEXT="implementation-defined constants"/>
<node CREATED="1338637562000" ID="ID_671543073" MODIFIED="1338637567436" TEXT="OPEN_MAX">
<node CREATED="1338637571626" ID="ID_582298855" MODIFIED="1338637672588" TEXT="process can open OPEN_MAX+1 files at most"/>
<node CREATED="1338637684700" ID="ID_1710478800" MODIFIED="1338637716267" TEXT="file descriptors range from 0 through OPEN_MAX"/>
</node>
</node>
<node CREATED="1338639047051" ID="ID_1905888153" MODIFIED="1338639074970" TEXT="<sys/types.h>"/>
<node CREATED="1338639045242" ID="ID_1113121751" MODIFIED="1338639060783" TEXT="<sys/stat.h>"/>
<node CREATED="1338637857080" ID="ID_1644592417" MODIFIED="1338728798373" TEXT="<fcntl.h> ">
<node CREATED="1338637878256" ID="ID_1204748916" MODIFIED="1338637878256" TEXT="file control options"/>
<node CREATED="1338638247435" FOLDED="true" ID="ID_1816578570" MODIFIED="1374565372942" TEXT="file open flags">
<node CREATED="1338638362753" ID="ID_1192687196" MODIFIED="1341884928259" TEXT="essential">
<node CREATED="1338638271436" ID="ID_1758951476" MODIFIED="1338638283364" TEXT="O_RDONLY"/>
<node CREATED="1338638290583" ID="ID_624769379" MODIFIED="1338638299982" TEXT="O_WRONLY"/>
<node CREATED="1338638303687" ID="ID_886016896" MODIFIED="1338638307838" TEXT="O_RDWR"/>
</node>
<node CREATED="1338638403470" ID="ID_963865183" MODIFIED="1363191123468" TEXT="optional">
<node CREATED="1338638419932" ID="ID_487678898" MODIFIED="1338638435166" TEXT="O_APPEND"/>
<node CREATED="1338638435587" ID="ID_179847820" MODIFIED="1338638438939" TEXT="O_CREAT"/>
<node CREATED="1338638467715" ID="ID_86886944" MODIFIED="1338638475884" TEXT="O_TRUNC"/>
<node CREATED="1338638439286" ID="ID_1400112512" MODIFIED="1338638456591" TEXT="O_EXCL"/>
<node CREATED="1338638486970" FOLDED="true" ID="ID_1683581176" MODIFIED="1363191126468" TEXT="O_SYNC">
<node CREATED="1363190287716" ID="ID_1660992136" MODIFIED="1363190733761" TEXT="Have each write wait for physical I/O to complete. "/>
<node CREATED="1363190735982" ID="ID_1449205080" MODIFIED="1363190853591" TEXT="This causes each write to wait for the data fo be written to disk before returning. "/>
<node CREATED="1363190858636" ID="ID_1201951453" MODIFIED="1363190955830" TEXT="in other case,copy new data into buffer cache."/>
</node>
<node CREATED="1363190552665" FOLDED="true" ID="ID_734397012" MODIFIED="1363191127475" TEXT="O_ASYNC">
<node CREATED="1363190991507" ID="ID_1975900493" MODIFIED="1363191005931" TEXT="asynchronized IO"/>
</node>
<node CREATED="1338638504692" FOLDED="true" ID="ID_1454998514" MODIFIED="1363191128529" TEXT="O_NOCTTY">
<node CREATED="1363190248943" ID="ID_1119359052" MODIFIED="1363190272312" TEXT="not controling terminal"/>
</node>
<node CREATED="1338638510975" FOLDED="true" ID="ID_614933203" MODIFIED="1363191129428" TEXT="O_NONBLOCK">
<node CREATED="1363190278028" ID="ID_100154832" MODIFIED="1363190285709" TEXT="nonblocking"/>
</node>
</node>
</node>
</node>
</node>
<node CREATED="1338638791151" FOLDED="true" ID="ID_971797200" MODIFIED="1375431960926" TEXT="function">
<node CREATED="1338638914732" ID="ID_981656375" MODIFIED="1341892647265" TEXT="int open(const char *pathname, int oflag .... /* , mode t mode */ );">
<node CREATED="1338640176854" ID="ID_1988766910" MODIFIED="1338640602942" TEXT="open(pathname,O_RDONLY);">
<node CREATED="1338639578699" ID="ID_739055899" MODIFIED="1338640457885" TEXT="open a file for read, generate error if file does not exist"/>
</node>
<node CREATED="1338640268378" ID="ID_41727674" MODIFIED="1341892655663" TEXT="open(pathname,O_WRONLY|O_CREAT,mode);">
<node CREATED="1338639746878" ID="ID_735675190" MODIFIED="1338640363633" TEXT="open a file for write,create it if file does not exists,
otherwise just open file already existing"/>
</node>
<node CREATED="1338640370964" ID="ID_1147658715" MODIFIED="1338640502696" TEXT="open(pathname,O_WRONLY|O_CREAT|O_TRUNC,mode);">
<node CREATED="1338639897696" ID="ID_1864418119" MODIFIED="1338640446342" TEXT="open a file for write,if the file exists,open it and
truncate its size to 0,otherwise create a new file"/>
</node>
<node CREATED="1338640461788" ID="ID_1011631307" MODIFIED="1338640496258" TEXT="open(pathname,O_WRONLY|O_CREAT|O_APPEND,mode);">
<node CREATED="1338639987512" ID="ID_614475156" MODIFIED="1338640546670" TEXT="open a file for write,if the file exists,open it and seek its 
pointor to the end of file,otherwise create a new file"/>
</node>
<node CREATED="1338640549227" ID="ID_1284992251" MODIFIED="1338640622725" TEXT="open(pahtname,O_WRONLY|O_CREAT|O_EXCL,mode);">
<node CREATED="1338640095721" ID="ID_362903588" MODIFIED="1338640599120" TEXT="create a file for write,if the file exists already,
generate error, otherwise create a new file"/>
</node>
</node>
<node CREATED="1338639300549" ID="ID_1890730798" MODIFIED="1341892660681" TEXT="int creat(const char *pathname, mode_t mode);">
<node CREATED="1338639485162" ID="ID_1945980091" MODIFIED="1338639564652" TEXT="equivalent to open(pathname,O_WRONLY|O_CREAT|O_TRUNC,mode);"/>
</node>
<node CREATED="1338640698458" ID="ID_1797736224" MODIFIED="1338640721145" TEXT="int close (int filedes) ; "/>
<node CREATED="1338640801792" ID="ID_382643923" MODIFIED="1341892665658" TEXT="off_t lseek (int filedes, off_t offset, int whence) ; ">
<node CREATED="1338640856498" ID="ID_1469930942" MODIFIED="1338640861923" TEXT="whence">
<node CREATED="1338640876730" ID="ID_1878498146" MODIFIED="1338640880554" TEXT="SEEK_SET">
<node CREATED="1338640912836" ID="ID_672688724" MODIFIED="1338640923261" TEXT="begin of file"/>
</node>
<node CREATED="1338640880920" ID="ID_1242541559" MODIFIED="1338640885834" TEXT="SEEK_CUR">
<node CREATED="1338640927548" ID="ID_1411132779" MODIFIED="1338640935945" TEXT="current position of file"/>
</node>
<node CREATED="1338640886168" ID="ID_679418835" MODIFIED="1338640894350" TEXT="SEEK_END">
<node CREATED="1338640937553" ID="ID_1703838887" MODIFIED="1338640941082" TEXT="end of file"/>
</node>
</node>
</node>
<node CREATED="1338641226270" ID="ID_407834183" MODIFIED="1338641526487" TEXT="int read(int filedes, char *buff, unsigned nbytes); "/>
<node CREATED="1338641740516" ID="ID_1145365765" MODIFIED="1338641795629" TEXT="ssize_t write(int filedes, const void *buff, size_t nbytes);"/>
<node CREATED="1338639315897" ID="ID_431999587" MODIFIED="1338641803979" TEXT="open,create,close,read,write return -1 on error"/>
<node CREATED="1338796847993" ID="ID_807362399" MODIFIED="1338796891891" TEXT="<unistd. h>void sync (void) ;">
<node CREATED="1338796956481" ID="ID_1207894114" MODIFIED="1338797026668" TEXT="write dirty block in buffer cache to disk"/>
</node>
<node CREATED="1338796847993" ID="ID_205764871" MODIFIED="1338796895604" TEXT="<unistd. h>int fsync (int filedes) ;"/>
</node>
<node CREATED="1338642434921" ID="ID_1556299629" MODIFIED="1375431925388" TEXT="file I/O implement">
<node CREATED="1338642498913" ID="ID_1020971923" MODIFIED="1363191425411" TEXT="file descriptor table (u area)">
<icon BUILTIN="full-1"/>
<node CREATED="1338642538633" ID="ID_1126099437" MODIFIED="1363191429040" TEXT="file table">
<icon BUILTIN="full-2"/>
<node CREATED="1338642549384" ID="ID_1672547298" MODIFIED="1363191438724" TEXT="v-node(i-node) list">
<icon BUILTIN="full-3"/>
<node CREATED="1338642567802" ID="ID_1347448214" MODIFIED="1363191445079" TEXT="disk blocks">
<icon BUILTIN="full-4"/>
</node>
</node>
</node>
</node>
<node CREATED="1338642640976" ID="ID_1458417004" MODIFIED="1338642650290" TEXT="file sharing">
<node CREATED="1338642776765" ID="ID_842730631" MODIFIED="1338643150086" TEXT="different file descriptors,same file table entries">
<node CREATED="1338643173252" ID="ID_1900414900" MODIFIED="1338643196471" TEXT="int dup (int filedes) ; ">
<node CREATED="1338643470514" ID="ID_775245686" MODIFIED="1338643564606" TEXT="copy filedes's file table entry pointer to lowest available file descritor"/>
</node>
<node CREATED="1338643198815" ID="ID_626762706" MODIFIED="1338643220065" TEXT="int dup2(int filedes,int filedes2);">
<node CREATED="1338643573349" ID="ID_915453463" MODIFIED="1338643682135" TEXT="close filedes2,then copy filedes's file table entry 
pointer to lowest available file descritor"/>
</node>
<node CREATED="1363191522843" ID="ID_85134465" MODIFIED="1363191524244" TEXT="Both return: new file descriptor if OK, -1 on error "/>
</node>
<node CREATED="1338642712002" ID="ID_1968267083" MODIFIED="1338643151957" TEXT="different file table entres ,same v-node"/>
<node CREATED="1338642680807" ID="ID_1085869172" MODIFIED="1339172881850" TEXT="different pathname(directory entry) ,same inode index"/>
</node>
<node CREATED="1338645252555" ID="ID_127324154" MODIFIED="1338645424627" TEXT="int fcntl(int filedes, int cmd , .../* int arg */ ); ">
<node CREATED="1338645426685" ID="ID_1044661340" MODIFIED="1338645442711" TEXT="duplicate file descriptor">
<node CREATED="1338645820045" ID="ID_847237458" MODIFIED="1338645869205" TEXT="fcntl(fd,F_DUPFD,n)">
<node CREATED="1338645872561" ID="ID_775041607" MODIFIED="1338645926024" TEXT="dup fd to descriptor equal or greater than n"/>
</node>
</node>
<node CREATED="1338645444242" ID="ID_262634947" MODIFIED="1338645699976" TEXT="get/set file descriptor flags">
<node CREATED="1338646023094" ID="ID_648315932" MODIFIED="1338646042220" TEXT="cmd=F_GETFD/F_SETFD"/>
<node CREATED="1338646042720" ID="ID_86506659" MODIFIED="1338646092767" TEXT="only FD_CLOEXEC is defined"/>
</node>
<node CREATED="1338645459027" ID="ID_1405213530" MODIFIED="1338645705629" TEXT="get/set file status flags">
<node CREATED="1338646109988" ID="ID_1179143799" MODIFIED="1363192170122" TEXT="cmd=F_GETFL">
<node CREATED="1338646136931" ID="ID_956846081" MODIFIED="1338646294147" TEXT="O_ACCMODE used to obtain the access mode bit 
O_RDONLY,O_WRONLY,ON_RDWR">
<node CREATED="1363192172462" ID="ID_1072696469" MODIFIED="1363192176556" TEXT="Unfortunately, the three access mode flags (O_RDONLY, O_WRONLY, and O_RDWR) are not separate bits that can be tested. (As we mentioned ear- lier, these three often have the values 0, 1, and 2, respectively, for historical reasons; also these three values are mutually exclusive--a file can have only one of the three enabled.) Therefore we must first use the O_ACCMODE mask fo obtain the access mode bits and then compare the result against any of the three values. "/>
</node>
</node>
<node CREATED="1363192179689" ID="ID_281324774" MODIFIED="1363192190647" TEXT="cmd=F_SETFL">
<node CREATED="1363192191910" ID="ID_871909494" MODIFIED="1363192225678" TEXT="The only flags that can be changed are">
<node CREATED="1363192227556" ID="ID_278981556" MODIFIED="1363192239420" TEXT="O_APPEND"/>
<node CREATED="1363192239832" ID="ID_47134998" MODIFIED="1363192247454" TEXT="O_NONBLOCK"/>
<node CREATED="1363192247794" ID="ID_1884407164" MODIFIED="1363192258864" TEXT="O_SYNC"/>
<node CREATED="1363192259102" ID="ID_1215711035" MODIFIED="1363192264044" TEXT="O_ASYNC"/>
</node>
</node>
</node>
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All three return:next character if OK, EOF on end of file or error  
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<node CREATED="1338820552065" ID="ID_769529621" MODIFIED="1338820578025" TEXT="int vprintf(const char *format, va_list ap);"/>
<node CREATED="1338820552066" ID="ID_1489389107" MODIFIED="1338820578024" TEXT="int vfprintf(FILE *stream, const char *format, va_list ap);"/>
<node CREATED="1338820552066" ID="ID_1834654679" MODIFIED="1338820578023" TEXT="int vsprintf(char *str, const char *format, va_list ap);"/>
<node CREATED="1338820552067" ID="ID_752974167" MODIFIED="1338820578022" TEXT="int vsnprintf(char *str, size_t size, const char *format, va_list ap);"/>
</node>
</node>
<node CREATED="1338820438859" ID="ID_736451510" MODIFIED="1338820441091" TEXT="output">
<node CREATED="1338820744497" ID="ID_269448548" MODIFIED="1338820744497" TEXT="#include <stdio.h>">
<node CREATED="1338820744498" ID="ID_565068543" MODIFIED="1338820744498" TEXT="int scanf(const char *format, ...);"/>
<node CREATED="1338820744499" ID="ID_39576912" MODIFIED="1338820744499" TEXT="int fscanf(FILE *stream, const char *format, ...);"/>
<node CREATED="1338820744500" ID="ID_916205632" MODIFIED="1338820744500" TEXT="int sscanf(const char *str, const char *format, ...);"/>
</node>
<node CREATED="1338820744500" ID="ID_746888925" MODIFIED="1338820744500" TEXT="#include <stdarg.h>">
<node CREATED="1338820744501" ID="ID_1919514439" MODIFIED="1338820744501" TEXT="int vscanf(const char *format, va_list ap);"/>
<node CREATED="1338820744502" ID="ID_1371609697" MODIFIED="1338820744502" TEXT="int vsscanf(const char *str, const char *format, va_list ap);"/>
<node CREATED="1338820744503" ID="ID_1783127301" MODIFIED="1338820744503" TEXT="int vfscanf(FILE *stream, const char *format, va_list ap);"/>
</node>
</node>
</node>
<node CREATED="1338820896265" FOLDED="true" ID="ID_1677705107" MODIFIED="1339853393112" TEXT="fileno">
<node CREATED="1338820916798" ID="ID_1159023612" MODIFIED="1338820916798" TEXT="int fileno(FILE *);"/>
</node>
<node CREATED="1338821181726" FOLDED="true" ID="ID_889499206" MODIFIED="1339853391342" TEXT="temp file">
<node CREATED="1338821225233" ID="ID_482994248" MODIFIED="1338821225233" TEXT="char *tempnam(const char *dir, const char *pfx);"/>
<node CREATED="1338821246051" ID="ID_444252212" MODIFIED="1338821246051" TEXT="char *tmpnam(char *s);"/>
<node CREATED="1338821261635" ID="ID_474254587" MODIFIED="1338821261635" TEXT="FILE *tmpfile(void);"/>
</node>
<node CREATED="1338821680335" FOLDED="true" ID="ID_1007390824" MODIFIED="1457088083097" TEXT="alternatives to standard IO">
<node CREATED="1338821696927" ID="ID_1518971894" MODIFIED="1338821717243" TEXT="fio"/>
<node CREATED="1338821717607" ID="ID_362939942" MODIFIED="1338821724184" TEXT="sfio"/>
<node CREATED="1338821724813" ID="ID_601843360" MODIFIED="1457088077912" TEXT="ASI(mmap)">
<node CREATED="1338821767172" ID="ID_127271931" MODIFIED="1338821782847" TEXT="Alloc Stream Interface"/>
</node>
</node>
</node>
<node CREATED="1341233738980" FOLDED="true" ID="ID_1592264497" MODIFIED="1457088178205" POSITION="right" TEXT="Advanced IO">
<font BOLD="true" NAME="Dialog" SIZE="16"/>
<node CREATED="1363183972035" ID="ID_1877880927" MODIFIED="1363183978609" TEXT="IO mode">
<node CREATED="1363184032875" FOLDED="true" ID="ID_1181800838" MODIFIED="1363184192659" TEXT="busy-wait">
<icon BUILTIN="full-1"/>
<node CREATED="1341233893050" ID="ID_1682300774" MODIFIED="1363184055393" TEXT="monoprogramming"/>
<node CREATED="1363184058925" ID="ID_347234273" MODIFIED="1363184113620" TEXT="IO and computing serialized"/>
</node>
<node CREATED="1363184117289" ID="ID_864814042" MODIFIED="1363184136495" TEXT="blocking">
<icon BUILTIN="full-2"/>
</node>
<node CREATED="1363184139639" ID="ID_1561552708" MODIFIED="1363184150999" TEXT="nonblocking">
<icon BUILTIN="full-3"/>
</node>
<node CREATED="1363184155195" ID="ID_1540465569" MODIFIED="1363184171175" TEXT="asynchronous">
<icon BUILTIN="full-4"/>
</node>
</node>
<node CREATED="1341237063338" FOLDED="true" ID="ID_1977167150" MODIFIED="1381478581369" TEXT="record locking">
<node CREATED="1341238164101" ID="ID_226880162" MODIFIED="1357729409409" TEXT="fcntl">
<node CREATED="1341237086018" ID="ID_478362268" MODIFIED="1341238197524" TEXT="#include<sys/types.h>"/>
<node CREATED="1341237113328" ID="ID_976998802" MODIFIED="1341238197514" TEXT="#include<unistd.h>"/>
<node CREATED="1341237120418" ID="ID_425834071" MODIFIED="1341238197514" TEXT="#include<fcntl.h>"/>
<node CREATED="1341237145798" ID="ID_1525845596" MODIFIED="1341238197514" TEXT="int fcntl (int filedes, int cmd .... /* struct flock *flockptr */ ); ">
<node CREATED="1341237177068" ID="ID_1001218871" MODIFIED="1341237180860" TEXT="cmd">
<node CREATED="1341237182978" ID="ID_1510825903" MODIFIED="1341237322181" TEXT="F_GETLK">
<node CREATED="1341237349419" ID="ID_793402554" MODIFIED="1341237441191" TEXT="Determine if the lock described by flockptr is blocked by some other lock. "/>
<node CREATED="1341237479449" ID="ID_1129974988" MODIFIED="1341237505991" TEXT="if some other lock exists">
<node CREATED="1341237515930" ID="ID_1245707702" MODIFIED="1341237625592" TEXT=" flockptr is overwrited"/>
</node>
<node CREATED="1341237490859" ID="ID_1143214622" MODIFIED="1341237513912" TEXT="otherwise">
<node CREATED="1341237581970" ID="ID_1736869510" MODIFIED="1341237656452" TEXT="flockptr->l_type set to F_UNLCK,others unchanged"/>
</node>
</node>
<node CREATED="1341237322530" ID="ID_1328945968" MODIFIED="1341237328671" TEXT="F_SETLK">
<node CREATED="1341237659900" ID="ID_168468619" MODIFIED="1341237890482" TEXT="obtain lock , returns immediately with errno set to either EACCES or EAGAIN if some other lock prevents from obtaining lock."/>
</node>
<node CREATED="1341237328909" ID="ID_525218682" MODIFIED="1341237336531" TEXT="F_SETLKW">
<node CREATED="1341237874440" ID="ID_678499269" MODIFIED="1341237920902" TEXT="obtain lock, goes to sleep if some other lock prevent from obtaining lock"/>
</node>
</node>
<node CREATED="1341237208558" ID="ID_1881895460" MODIFIED="1357729448819" TEXT="flockptr">
<node CREATED="1341237216108" ID="ID_1888920116" MODIFIED="1363192749006">
<richcontent TYPE="NODE"><html>
<head>
</head>
<body>
<p>
struct flock {
</p>
<p>
    short l_type; /* F_RDLCK, F_WRLCK, or F_UNLCK */
</p>
<p>
    off_t l_start; /* offset in bytes, relative to 1_whence */
</p>
<p>
    short l_whence; /* SEEK_SET, SEEK_CUR, or SEEK_END */
</p>
<p>
    off_t l_len; /* length, in bytes; 0 means lock to EOF */
</p>
<p>
    pid_t l_pid; /* returned with F_GETLK */
</p>
<p>
};
</p>
</body>
</html></richcontent>
</node>
</node>
</node>
<node CREATED="1341237161518" ID="ID_890983105" MODIFIED="1341238197503" TEXT="Returns: depends on cmd if OK,-1 on error "/>
</node>
<node CREATED="1341238202932" ID="ID_1681894481" MODIFIED="1357729755918" TEXT="Locks are associated with a process and a file. This has two implications. The first is obvious: when a process terminates all its locks are released. The second is far from obvious: whenever a descriptor is closed, any locks on the file referenced by that descriptor for that process are released. "/>
<node CREATED="1341238280012" ID="ID_148901281" MODIFIED="1341238282154" TEXT="Locks are never inherited by the child across a fork. "/>
<node CREATED="1341238292542" ID="ID_1693962238" MODIFIED="1341238294344" TEXT="Locks may be inherited by a new program across an exec. "/>
</node>
<node CREATED="1363184228958" FOLDED="true" ID="ID_914696221" MODIFIED="1363192768864" TEXT="IO multiplexing">
<node CREATED="1363184240446" ID="ID_1819502289" MODIFIED="1363184243574" TEXT="select">
<node CREATED="1363184267740" ID="ID_1042354335" MODIFIED="1363184366376" TEXT="#include <sys/types.h> /* fd_set data type */ 
#include <sys/time.h> /* struct timeval */ 
#include <unistd.h> /* function prototype might be here */ 
int select(int maxfdpl, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *tvptr); 
Returns: count of ready descriptors, 0 on timeout, -1 on error 
">
<node CREATED="1363184303749" ID="ID_1724210638" MODIFIED="1363184376229" TEXT="tvptr">
<node CREATED="1363184377403" ID="ID_1434006835" MODIFIED="1363184393471" TEXT="tvptr==NULL">
<node CREATED="1363184394903" ID="ID_912774625" MODIFIED="1363184415452" TEXT="Wait forever. "/>
<node CREATED="1363184418102" ID="ID_1060693959" MODIFIED="1363184477080" TEXT="can be interrupted，then return -1 with errno set to EINTR"/>
</node>
<node CREATED="1363184480416" ID="ID_1107766968" MODIFIED="1363184521131" TEXT="tvptr->tv_sec==0 && tvptr->tv.usec==0">
<node CREATED="1363184523255" ID="ID_1003360748" MODIFIED="1363184567282" TEXT="nonblocking,return immediately if no IO operations are ready"/>
</node>
<node CREATED="1363184601240" ID="ID_1704861950" MODIFIED="1363184622397" TEXT="tvptr->tv_sec!==0 || tvptr->tv.usec!=0">
<node CREATED="1363184623472" ID="ID_704635246" MODIFIED="1363184653345" TEXT="timeout"/>
<node CREATED="1363184694719" ID="ID_67198936" MODIFIED="1363184714892" TEXT="Return is made when one of the specified descriptors is ready or when the rime-out value expires. "/>
<node CREATED="1363184715648" ID="ID_1051164853" MODIFIED="1363184741485" TEXT="0 on time-out value expires"/>
<node CREATED="1363184742313" ID="ID_1074396031" MODIFIED="1363184773598" TEXT="-1 on interruption"/>
</node>
</node>
<node CREATED="1363184889921" FOLDED="true" ID="ID_307735917" MODIFIED="1363185503835" TEXT="fd_set">
<node CREATED="1363184895461" ID="ID_509721850" MODIFIED="1363184978470" TEXT="FD_ZERO(fd_set*fdset)">
<node CREATED="1363185050816" ID="ID_1184306002" MODIFIED="1363185079686" TEXT="clear all bits in fdset(init)"/>
</node>
<node CREATED="1363184979130" ID="ID_854709311" MODIFIED="1363185021749" TEXT="FD_SET(int fd,fd_set *fdset)">
<node CREATED="1363185080978" ID="ID_1465329682" MODIFIED="1363185159602" TEXT="turn on bit for fd in fd_set"/>
</node>
<node CREATED="1363184992721" ID="ID_1271504391" MODIFIED="1363185039266" TEXT="FD_CLR(int fd,fd_set *fdset)">
<node CREATED="1363185087408" ID="ID_1656211882" MODIFIED="1363185180246" TEXT="turn off bit for fd in fd_set"/>
</node>
<node CREATED="1363184997974" ID="ID_604752929" MODIFIED="1363185048557" TEXT="FD_ISSET(int fd,fd_set*fdset)">
<node CREATED="1363185094491" ID="ID_1497366803" MODIFIED="1363185217737" TEXT="test bit for fd in fd_set"/>
</node>
</node>
<node CREATED="1363185333928" ID="ID_365664696" MODIFIED="1363185350115" TEXT="readfds,writefds,exceptfds">
<node CREATED="1363185354861" FOLDED="true" ID="ID_764004916" MODIFIED="1363185362158" TEXT="usleep">
<node CREATED="1363185351305" ID="ID_1450656227" MODIFIED="1363185359502" TEXT="Any (or ail) of the middle three arguments to select (the pointers to the descriptor sets) can be null pointers, if we're not interested in that condition. If all three pointers are NULL, then we have a higher precision timer than provided by sleep. "/>
</node>
</node>
<node CREATED="1363185505791" FOLDED="true" ID="ID_1296494721" MODIFIED="1363185733450" TEXT="maxfdpl">
<node CREATED="1363185518399" ID="ID_848095732" MODIFIED="1363185539577" TEXT="The first argument to select, maxfdpl, stands for "'max fd plus I." We calculate the highest descriptor that we're interested in, in any of the three descriptor sets, add 1, and that's the first argument. We could just set the first argument to FD_SETSIZE, a constant in <sys/types. h> that specifies the maximum number of descriptors (often I/O Multiplexing 399 256 or 1024), but this value is too large for most applications. Indeed, most applications probably use between 3 and 10 descriptors. (There are applications that need many more descriptors, but these aren't the typical Unix program.) By specifying the highest descriptor that we're interested in, the kernel can avoid going through hundreds of unused bits in the three descriptor sets, looking for bits that are turned on. "/>
<node CREATED="1363185583548" ID="ID_1171404557" MODIFIED="1363185584737" TEXT="The reason we have to add 1 to the maximum descriptor number is because descriptors start at 0, and the first argument is really a count of the number of descriptors to check (starting with descriptor 0). "/>
</node>
<node CREATED="1363185734457" ID="ID_848915727" MODIFIED="1363185735659" TEXT=""ready" means. ">
<node CREATED="1363185747834" ID="ID_261087257" MODIFIED="1363185762028" TEXT="1. A descriptor in the read set (readfds) is considered ready if a read from that descriptor won't block. "/>
<node CREATED="1363185776631" ID="ID_1826673171" MODIFIED="1363185777868" TEXT="2. A descriptor in the write set (writefds) is considered ready if a write to that descriptor won't block. "/>
<node CREATED="1363185789991" ID="ID_1825419702" MODIFIED="1363185798628" TEXT="3. A descriptor in the exception set (exceptfds) is considered ready if there is an exception condition pending on that descriptor. Currently an exception condi- tion corresponds to (a) the arrival of out-of-band data on a network connection, or (b) certain conditions occurring on a pseudo terminal that has been placed into packet mode. (Section 15.10 of Stevens [1990] describes this latter condition.) "/>
</node>
<node CREATED="1363185957518" FOLDED="true" ID="ID_360102744" MODIFIED="1363189819487" TEXT="EOF">
<node CREATED="1363185953821" ID="ID_1739882279" MODIFIED="1363185963453" TEXT="If we encounter the end of file on a descriptor, that descriptor is considered readable by select. We then call read and it returns 0, the normal Unix way to signify end of file. (Many people incorrectly assume select indicates an exception condition on a descriptor when the end of file is reached.) "/>
</node>
</node>
</node>
</node>
<node CREATED="1363189830636" ID="ID_889823763" MODIFIED="1363189935881">
<richcontent TYPE="NODE"><html>
<head>
</head>
<body>
<p>
#include <fcntl.h>
</p>
<p>
#include "ourhdr.h"
</p>
<p>
void set_fl(int fd, int flags)
</p>
<p>
{
</p>
<p>
    int val;
</p>
<p>
    /* flags are file status flags to turn on */
</p>
<p>
    if ( (val = fcntl(fd, F_GETFL, 0)) < 0)
</p>
<p>
          err_sys("fcntl F_GETFL error");
</p>
<p>
    val I= flags; /* turn on flags */     
</p>
<p>
    if (fcntl(fd, F_SETFL, val) < 0)
</p>
<p>
         err_sys("fcntl F_SETFL error");
</p>
<p>
}
</p>
</body>
</html></richcontent>
</node>
<node CREATED="1341283732120" ID="ID_1335444766" MODIFIED="1457088083130" TEXT="memory mapped IO">
<node CREATED="1341283750539" ID="ID_731699793" MODIFIED="1457088085969" TEXT="mmap">
<node CREATED="1341283908429" ID="ID_190168221" MODIFIED="1341283930412" TEXT="#include<sys/types.h>"/>
<node CREATED="1341283930823" ID="ID_879360502" MODIFIED="1341283955629" TEXT="#include<sys/mman.h>"/>
<node CREATED="1341283956805" ID="ID_917038823" MODIFIED="1341885344077" TEXT="void *mmap(void *start, size_t length, int prot, int flags, int fd, off_t offset);">
<node CREATED="1341284581178" ID="ID_1994952586" MODIFIED="1341284583457" TEXT="prot">
<node CREATED="1341284591567" ID="ID_97003155" MODIFIED="1341284600383" TEXT="PROT_READ"/>
<node CREATED="1341284600685" ID="ID_1100412528" MODIFIED="1341284606163" TEXT="PROT_WRITE"/>
<node CREATED="1341284622596" ID="ID_205813009" MODIFIED="1341284626685" TEXT="PROT_EXEC"/>
<node CREATED="1341284628438" ID="ID_1950181779" MODIFIED="1341284633822" TEXT="PROT_NONE">
<node CREATED="1341284679863" ID="ID_1789453146" MODIFIED="1341284691331" TEXT="can't be accessed"/>
</node>
</node>
<node CREATED="1341284583759" ID="ID_1122628258" MODIFIED="1341284586913" TEXT="flags">
<node CREATED="1341284700011" ID="ID_689745019" MODIFIED="1341284705208" TEXT="MAP_FIXED">
<node CREATED="1341284715042" ID="ID_1468049440" MODIFIED="1341284768193" TEXT="user specifies start addr for mapped file"/>
</node>
<node CREATED="1341284769915" ID="ID_596995236" MODIFIED="1341284788403" TEXT="MAP_SHARED">
<node CREATED="1341284797160" ID="ID_1097275380" MODIFIED="1341284884162" TEXT="store operations modify orignal mapped file"/>
</node>
<node CREATED="1341284800896" ID="ID_1985585062" MODIFIED="1341284807216" TEXT="MAP_PRIVATE">
<node CREATED="1341284886601" ID="ID_1128526342" MODIFIED="1341284933559" TEXT="a copy created,store operations just modify the copy of orignal mapped file "/>
</node>
</node>
<node CREATED="1341285035598" ID="ID_819831644" MODIFIED="1341285665369" TEXT="offset">
<node CREATED="1341285667546" ID="ID_103009520" MODIFIED="1341285756478" TEXT="offset must be a multiple of the page size">
<node CREATED="1341285667546" ID="ID_1381466438" MODIFIED="1341285789175" TEXT="(SVR4) sysconf(_SC_PAGE_SIZE)."/>
<node CREATED="1341285793175" ID="ID_514436832" MODIFIED="1341285839509" TEXT="(4.3+BSD) constant NBPG in the header <sys/parara. h>"/>
</node>
</node>
</node>
<node CREATED="1341284035858" ID="ID_1085890391" MODIFIED="1341284039963" TEXT="Returns: starting address of mapped region if OK, -1 on error "/>
<node CREATED="1341286120939" ID="ID_553847674" MODIFIED="1341886085468" TEXT="signal triggered">
<node CREATED="1341286152269" ID="ID_1210505940" MODIFIED="1341286172379" TEXT="SIGSEGV">
<node CREATED="1341286193954" ID="ID_190871733" MODIFIED="1341286193954" TEXT="Attempted write into a region mapped as read-only."/>
</node>
<node CREATED="1341286172697" ID="ID_1667818105" MODIFIED="1341286178268" TEXT="SIGBUS">
<node CREATED="1341286234287" ID="ID_627078458" MODIFIED="1341286345064" TEXT="Attempted access to a portion of the buffer that does not correspond to the file (for example, beyond the end of the file, including the case where another process has truncated the file)."/>
</node>
</node>
<node CREATED="1341286374788" ID="ID_343853064" MODIFIED="1457088159344" TEXT="inheritance">
<node CREATED="1341286414815" ID="ID_1505640876" MODIFIED="1341286460845" TEXT="memory mapped region inherited by fork"/>
<node CREATED="1341286461334" ID="ID_1442917312" MODIFIED="1341286470524" TEXT="not inherited by exec"/>
</node>
</node>
<node CREATED="1341283902244" ID="ID_1336146309" MODIFIED="1341283905943" TEXT="munmap">
<node CREATED="1341286503650" ID="ID_1479186748" MODIFIED="1341286503650" TEXT="#include <sys/types.h>"/>
<node CREATED="1341286503650" ID="ID_170058458" MODIFIED="1341286503650" TEXT="#include <sys/mman.h>"/>
<node CREATED="1341286503650" ID="ID_1583422332" MODIFIED="1341286503650" TEXT="int munmap(caddr_t addr, size_t len);"/>
<node CREATED="1341286518429" ID="ID_1312469547" MODIFIED="1341286520066" TEXT="Returns: 0 if OK, -1 on error "/>
<node CREATED="1341286530856" ID="ID_920248923" MODIFIED="1341286546843" TEXT="A memory mapped region is automatically unmapped when the process terminates, or by calling munmap directly. Closing the file descriptor filedes does hot unmap the region. "/>
<node CREATED="1341292519107" ID="ID_563840572" MODIFIED="1341292562196" TEXT="munmap does not affect the object that was mapped,that is, the call to munmap does not cause the contents of the mapped region to be written to the disk file. The updating of the disk file for a MAP_SHARED region happens automatically by the kernel's virtual memory algorithm as we store into the memory mapped region. "/>
</node>
<node CREATED="1341293077169" ID="ID_1720311487" MODIFIED="1341293079433" TEXT="msync">
<node CREATED="1341293096019" ID="ID_284263614" MODIFIED="1341293099056" TEXT="#include <sys/types.h>"/>
<node CREATED="1341293096019" ID="ID_547716544" MODIFIED="1341293099087" TEXT="#include <sys/mman.h>"/>
<node CREATED="1341293081382" ID="ID_975816871" MODIFIED="1341293081382" TEXT="int msync(void *start, size_t length, int flags);">
<node CREATED="1341293149220" ID="ID_51874461" MODIFIED="1341293154337" TEXT="MS_ASYNC"/>
<node CREATED="1341293155341" ID="ID_518465068" MODIFIED="1341293169945" TEXT="MS_SYNC"/>
<node CREATED="1341293170949" ID="ID_1944948368" MODIFIED="1341293172636" TEXT="MS_INVALIDATE"/>
</node>
<node CREATED="1341293196367" ID="ID_151402877" MODIFIED="1341293199005" TEXT="Returns: 0 if OK, -1 on error "/>
</node>
</node>
</node>
<node CREATED="1341293673913" FOLDED="true" ID="ID_1427592362" MODIFIED="1375431903532" POSITION="right" TEXT="IPC(InterProcess Communication)">
<font BOLD="true" NAME="Dialog" SIZE="16"/>
<node CREATED="1341295949046" ID="ID_182899331" MODIFIED="1374565411287" TEXT="System V IPC">
<node CREATED="1341296010736" FOLDED="true" ID="ID_1227441844" MODIFIED="1358084393839" TEXT="getXXX">
<node CREATED="1341300368793" ID="ID_1217472975" MODIFIED="1341300433666" TEXT="creates a new IPC structure or obtains a existed IPC structure"/>
<node CREATED="1341300399147" ID="ID_14596799" MODIFIED="1341300568610" TEXT="specifies key to get a IPC structure identifer ">
<node CREATED="1341300708577" ID="ID_872224181" MODIFIED="1341300719479" TEXT="same key,same identifier"/>
<node CREATED="1341300719793" ID="ID_952146000" MODIFIED="1341300818968" TEXT="a IPC structure has a unique identifier"/>
</node>
<node CREATED="1341300585954" ID="ID_870157002" MODIFIED="1341300588182" TEXT="key">
<node CREATED="1341300614289" ID="ID_1276116549" MODIFIED="1341300614289" TEXT="IPC_PRIVATE">
<node CREATED="1341300626782" ID="ID_102072705" MODIFIED="1341300651360" TEXT="always creates new IPC structure"/>
<node CREATED="1341300657359" ID="ID_61752347" MODIFIED="1341300701815" TEXT="server stores identifer in file system,client fetchs it"/>
</node>
</node>
<node CREATED="1341300588449" ID="ID_315654963" MODIFIED="1341300596208" TEXT="flag">
<node CREATED="1341300861022" ID="ID_818373656" MODIFIED="1341300869272" TEXT="IPC_CREAT"/>
<node CREATED="1341300870026" ID="ID_758367544" MODIFIED="1341300875499" TEXT="IPC_EXCL"/>
</node>
</node>
<node CREATED="1341294978187" ID="ID_1947676420" MODIFIED="1341301682765" TEXT="//#include<sys/ipc.h>
struct ipc_perm {
 key_t key; /* Key supplied to shmget(2) */
 uid_t uid; /* Effective UID of owner */
 gid_t gid; /* Effective GID of owner */
 uid_t cuid; /* Effective UID of creator */
 gid_t cgid; /* Effective GID of creator */
 unsigned short mode; /* Permissions + SHM_DEST
 and SHM_LOCKED flags */ 
 unsigned short seq; /* Sequence number */ 
 };">
<node CREATED="1341301689679" ID="ID_1482105925" MODIFIED="1341301693842" TEXT="mode">
<node CREATED="1341301724955" ID="ID_605630701" MODIFIED="1341301732713" TEXT="message queue"/>
<node CREATED="1341301733006" ID="ID_887119230" MODIFIED="1341301749046" TEXT="semaphore"/>
<node CREATED="1341301750279" ID="ID_1009924503" MODIFIED="1341301765414" TEXT="shared memory">
<node CREATED="1341301821998" ID="ID_235064886" MODIFIED="1341301832933" TEXT="user-read">
<node CREATED="1341301862010" ID="ID_1268183027" MODIFIED="1341301867206" TEXT="SHM_R"/>
</node>
<node CREATED="1341301833187" ID="ID_1897624536" MODIFIED="1341301838466" TEXT="user-write">
<node CREATED="1341301873622" ID="ID_1704187216" MODIFIED="1341301876615" TEXT="SHM_W"/>
</node>
<node CREATED="1341301838703" ID="ID_198621206" MODIFIED="1341301843202" TEXT="group-read">
<node CREATED="1341301883565" ID="ID_1901909274" MODIFIED="1341301892624" TEXT="SHM_R>>3"/>
</node>
<node CREATED="1341301843434" ID="ID_421973819" MODIFIED="1341301847757" TEXT="group-write">
<node CREATED="1341301895105" ID="ID_1297924" MODIFIED="1341301903846" TEXT="SHM_W>>3"/>
</node>
<node CREATED="1341301847950" ID="ID_352316684" MODIFIED="1341301850954" TEXT="other-read">
<node CREATED="1341301905998" ID="ID_421370008" MODIFIED="1341301911347" TEXT="SHM_R>>6"/>
</node>
<node CREATED="1341301851187" ID="ID_1713404653" MODIFIED="1341301856594" TEXT="other-write">
<node CREATED="1341301929294" ID="ID_1470757791" MODIFIED="1341301934169" TEXT="SHM_W>>6"/>
</node>
</node>
</node>
</node>
<node CREATED="1341299854336" ID="ID_1310268124" MODIFIED="1341301976004" TEXT="configuration limits">
<node CREATED="1341302017327" ID="ID_984069510" MODIFIED="1341302025520" TEXT="/etc/conf/cf. d/mtune"/>
</node>
<node CREATED="1341293727522" FOLDED="true" ID="ID_712599293" MODIFIED="1374570580757" TEXT="shared memory">
<icon BUILTIN="full-1"/>
<node CREATED="1341294866748" ID="ID_478450725" MODIFIED="1341295387283" TEXT="//#include<sys/shm.h>
struct shmid ds { 
 struct ipc_perm shm_perm; /* see Section 14.6.2 */ 
 struct anon_map *shm_amp; /* pointer in kernel */ 
 int shm_segsz; /* size of segment in bytes */ 
 ushort shm_Ikcnt; /* number of times segment is being locked */ 
 pid_t shm_Ipid; /* pid of last shmop() */ 
 pid_t shm_cpid; /* pid of creator */ 
 ulong shm_nattch; /* number of current attaches */ 
 ulong shm_cnattch; /* used only for shminfo */ 
 time_t shm_atime; /* last-attach time */ 
 time_t shm_dtime; /* last-detach time */ 
 time_t shm_ctime; /* last-change time */ 
 }; "/>
<node CREATED="1341295175167" FOLDED="true" ID="ID_972102095" MODIFIED="1374570578573" STYLE="fork" TEXT="system limits that affect shared memory ">
<node CREATED="1341302113240" ID="ID_1349606693" MODIFIED="1374565468274" TEXT="SHMALL System wide maximum of shared memory pages.(Linux /proc/sys/kernel/shmall)"/>
<node CREATED="1341295208607" ID="ID_1788937460" MODIFIED="1374565468274" TEXT="SHMMAX The maximum size in bytes of a shared memory segment. (Linux /proc/sys/kernel/shmmax)"/>
<node CREATED="1341295208607" ID="ID_415212494" MODIFIED="1374565468274" TEXT="SHMMIN The minimum size in bytes of a shared memory segment. 1"/>
<node CREATED="1341295208607" ID="ID_1069350097" MODIFIED="1374565468274" TEXT="SHMMNI The maximum number of shared memory segments, systemwide. (Linux /proc/sys/kernel/shmmni)"/>
<node CREATED="1341295208607" ID="ID_294674934" MODIFIED="1374565468274" TEXT="SHMSEG The maximum number of shared memory segments, per process. 6"/>
</node>
<node CREATED="1341295458763" FOLDED="true" ID="ID_1819317811" MODIFIED="1374570574486" TEXT="shmget">
<node CREATED="1341295474175" ID="ID_751004884" MODIFIED="1341295474175" TEXT="#include <sys/types.h>"/>
<node CREATED="1341295474175" ID="ID_176169853" MODIFIED="1341295474175" TEXT="#include <sys/ipc.h>"/>
<node CREATED="1341295474175" ID="ID_997293325" MODIFIED="1341295474175" TEXT="#include <sys/shm.h>"/>
<node CREATED="1341295474175" ID="ID_1596773694" MODIFIED="1341295484146" TEXT="int shmget (key_t key, int size,int flag) ;"/>
<node CREATED="1341295474175" ID="ID_449376456" MODIFIED="1341295474175" TEXT="Returns: shared memory ID if OK, -1 on error"/>
</node>
<node CREATED="1341302420834" ID="ID_865926474" MODIFIED="1374570565906" TEXT="shmctl">
<node CREATED="1341302434595" ID="ID_345207944" MODIFIED="1341302434595" TEXT="#include <sys/types.h>"/>
<node CREATED="1341302434596" ID="ID_796659825" MODIFIED="1341302434596" TEXT="#include <sys/ipc.h>"/>
<node CREATED="1341302434597" ID="ID_600334220" MODIFIED="1341302434597" TEXT="#include <sys/shm.h>"/>
<node CREATED="1341302434598" FOLDED="true" ID="ID_1988080660" MODIFIED="1374570572193" TEXT="int shmctl(int shmid, int cmd, struct shmid_ds *buf);">
<node CREATED="1341302440559" ID="ID_493226867" MODIFIED="1341302442657" TEXT="cmd">
<node CREATED="1341302444084" ID="ID_1395501179" MODIFIED="1341302518344" TEXT="IPC_STAT "/>
<node CREATED="1341302483525" ID="ID_364160896" MODIFIED="1341302521745" TEXT="IPC_SET "/>
<node CREATED="1341302656781" ID="ID_1330211640" MODIFIED="1341302658745" TEXT="IPC RMID "/>
<node CREATED="1341302499125" ID="ID_1652170653" MODIFIED="1341302537962" TEXT="SHM_LOCK "/>
<node CREATED="1341302509497" ID="ID_636642143" MODIFIED="1341302541799" TEXT="SHM_UNLOCK "/>
</node>
</node>
<node CREATED="1341302434599" ID="ID_1338359720" MODIFIED="1341302434599" TEXT="Returns: 0 if OK, -1 on error"/>
</node>
<node CREATED="1341302729185" ID="ID_1168344942" MODIFIED="1341302732106" TEXT="shmat">
<node CREATED="1341302744923" ID="ID_1688908816" MODIFIED="1341302744923" TEXT="#include <sys/types.h>"/>
<node CREATED="1341302744924" ID="ID_281880779" MODIFIED="1341302744924" TEXT="#include <sys/ipc.h>"/>
<node CREATED="1341302744925" ID="ID_536076557" MODIFIED="1341302744925" TEXT="#include <sys/shm.h>"/>
<node CREATED="1341302744926" ID="ID_1074944540" MODIFIED="1341302744926" TEXT="void *shmat(int shmid, void *addr, int flag);">
<node CREATED="1341302894721" ID="ID_213614112" MODIFIED="1341302898700" TEXT="flags">
<node CREATED="1341302900426" ID="ID_215492179" MODIFIED="1341302904353" TEXT="SHM_RND "/>
<node CREATED="1341302987708" ID="ID_29367939" MODIFIED="1341302989138" TEXT="SHM_RDONLY"/>
</node>
</node>
<node CREATED="1341302744927" ID="ID_1587618842" MODIFIED="1341302744927" TEXT="Returns: pointer to shared memory segment if OK, -1 on error"/>
</node>
<node CREATED="1341303325134" ID="ID_980075898" MODIFIED="1341303327836" TEXT="shmdt">
<node CREATED="1341303340260" ID="ID_340535876" MODIFIED="1341303340260" TEXT="#include <sys/types.h>"/>
<node CREATED="1341303340260" ID="ID_1505907721" MODIFIED="1341303340260" TEXT="#include <sys/ipc.h>"/>
<node CREATED="1341303340262" ID="ID_1326253363" MODIFIED="1341303340262" TEXT="#include <sys/shm.h>"/>
<node CREATED="1341303340262" ID="ID_1253895250" MODIFIED="1341303340262" TEXT="int shmdt(void *addr);"/>
<node CREATED="1341303340263" ID="ID_1251339769" MODIFIED="1341303340263" TEXT="Returns: 0 if OK, -1 on error"/>
</node>
</node>
<node CREATED="1341295960343" ID="ID_713621043" MODIFIED="1341296022321" TEXT="message queue">
<icon BUILTIN="full-2"/>
</node>
<node CREATED="1341295980417" ID="ID_507844474" MODIFIED="1374570586046" TEXT="semaphore set">
<icon BUILTIN="full-3"/>
<node CREATED="1341364975888" ID="ID_57600822" MODIFIED="1341365037658" TEXT="struct semid ds {
 struct ipc_perm semerm; /* see Section 14.6.2 */
 struct sem *sem_base; /* ptr to first semaphore in set */
 ushort sem_nsems; /* # of semaphores in set */
 time_t sem_otime; /* last-semop() time */
 time_t sem_ctime; /* last-change time */
 }; ">
<node CREATED="1341365075853" ID="ID_870194815" MODIFIED="1341397771103" TEXT="struct sem {
 ushort semval; /* semaphore value, always >= 0 */
 pid_t sempid; /* pid for last operation */
 ushort semncnt; /* # waiting for increase */
 ushort semzcnt; /* # waiting for zero */
 }; "/>
</node>
<node CREATED="1341365886675" ID="ID_665304680" MODIFIED="1341366898756" TEXT="system limits">
<node BACKGROUND_COLOR="#ccff66" CREATED="1341365917158" ID="ID_702256113" MODIFIED="1341366977377" TEXT="(Redhat Linux)
# man 5 proc
$cat /proc/sys/kernel/sem
250 32000 32 128
semmsl semmns semopm semmni
"/>
<node CREATED="1341366224807" FOLDED="true" ID="ID_604401426" MODIFIED="1341397693851" TEXT="semctl(semid,0, IPC_INFO(or SEM_INFO), struct seminfo*); ">
<node CREATED="1341366653671" ID="ID_479082150" MODIFIED="1341366890239" TEXT=" struct seminfo {
 int semmap; /* # of entries in semaphore map; unused */ 
 int semmni; /* Max. # of semaphore sets */ 
 int semmns; /* Max. # of semaphores in all semaphore sets */ 
 int semmnu; /* System-wide max. # of undo structures; unused */
 int semmsl; /* Max. # of semaphores in a set */ 
 int semopm; /* Max. # of operations for semop() */
 int semume; /* Max. # of undo entries per process; unused */
 int semusz; /* size of struct sem_undo */ 
 int semvmx; /* Maximum semaphore value */
 int semaem; /* Max. value that can be recorded for 
 semaphore adjustment (SEM_UNDO) */ 
 }; "/>
</node>
</node>
<node CREATED="1341314994157" FOLDED="true" ID="ID_1296062728" MODIFIED="1374565423689" TEXT="semget">
<node CREATED="1341364643507" ID="ID_257724758" MODIFIED="1341364686096" TEXT="create a new semaphore set or obtain a existed semphore set"/>
<node CREATED="1341393800623" ID="ID_797339531" MODIFIED="1341393800623" TEXT="#include <sys/types.h>"/>
<node CREATED="1341393800623" ID="ID_89102828" MODIFIED="1341393800623" TEXT="#include <sys/ipc.h>"/>
<node CREATED="1341393800623" ID="ID_1974005653" MODIFIED="1341393800623" TEXT="#include <sys/sem.h>"/>
<node CREATED="1341393800623" ID="ID_934005739" MODIFIED="1341393866478" TEXT="int semget (key_t key, int nsems,int flag) ;">
<node CREATED="1341393825573" ID="ID_169354451" MODIFIED="1341393881532" TEXT="creates a new semaphore set">
<node CREATED="1341393918900" ID="ID_1492989602" MODIFIED="1341394051502" TEXT="semget(key,nsems,IPC_CREAT| O_EXCL|access_permission)"/>
<node CREATED="1341394053053" ID="ID_1532587862" MODIFIED="1341394165952" TEXT="semget(IPC_PRIVATE,nsems,access_permission)"/>
</node>
<node CREATED="1341393842195" ID="ID_1720735928" MODIFIED="1341393885417" TEXT="obtains a existed semaphore set">
<node CREATED="1341394174054" ID="ID_1026980195" MODIFIED="1341394217892" TEXT="semget(key,0,0)"/>
</node>
</node>
<node CREATED="1341393800623" ID="ID_1553865104" MODIFIED="1341393800623" TEXT="Returns: sernaphore ID if OK, -1 on error"/>
</node>
<node CREATED="1341315009162" ID="ID_1125937381" MODIFIED="1358132624679" TEXT="semctl">
<node CREATED="1341364689128" ID="ID_1932316012" MODIFIED="1341364705073" TEXT="initialize semaphore set"/>
<node CREATED="1341364708620" ID="ID_585435116" MODIFIED="1341364743753" TEXT="creating and initializing is not atomic operation"/>
<node CREATED="1341367010096" ID="ID_23107852" MODIFIED="1341367028317" TEXT="#include <sys/types.h>"/>
<node CREATED="1341367030907" ID="ID_1843193242" MODIFIED="1341367044106" TEXT="#include <sys/ipc.h>"/>
<node CREATED="1341367045466" ID="ID_804977132" MODIFIED="1341367056015" TEXT="#include <sys/sem.h>"/>
<node CREATED="1341367057661" ID="ID_327562845" MODIFIED="1374570634164" TEXT="int semctl(int semid, int semnum, int cmd, union semunarg); ">
<node CREATED="1341367148720" ID="ID_1883786859" MODIFIED="1341367281167" TEXT="semnum ">
<node CREATED="1341367283457" ID="ID_763454522" MODIFIED="1341367283457" TEXT="semnum-th semaphore in set (starting at 0)"/>
</node>
<node BACKGROUND_COLOR="#ccff33" CREATED="1341366373249" ID="ID_1597305842" MODIFIED="1341367140930" TEXT="union semun {
 int val; /* Value for SETVAL */
 struct semid_ds *buf; /* Buffer for IPC_STAT, IPC_SET */
 unsigned short *array; /* Array for GETALL, SETALL */
 struct seminfo *__buf; /* Buffer for IPC_INFO (Linux specific) */
 }; "/>
<node CREATED="1341367257658" ID="ID_1315716304" MODIFIED="1341367260326" TEXT="cmd">
<node CREATED="1341394273138" ID="ID_777311892" MODIFIED="1374570615857" TEXT="IPC_STAT "/>
<node CREATED="1341394278340" ID="ID_1971383416" MODIFIED="1341394283522" TEXT="IPC_SET"/>
<node CREATED="1341394283824" ID="ID_1002626438" MODIFIED="1374570605140" TEXT="IPC_RMID "/>
<node CREATED="1341394350225" ID="ID_293792970" MODIFIED="1341394351506" TEXT="GETVAL "/>
<node CREATED="1341394351793" ID="ID_362762063" MODIFIED="1341394365648" TEXT="SETVAL "/>
<node CREATED="1341394386714" ID="ID_706786597" MODIFIED="1341394387964" TEXT="GETPID "/>
<node CREATED="1341394403570" ID="ID_1648181234" MODIFIED="1341394405178" TEXT="GETNCNT "/>
<node CREATED="1341394414763" ID="ID_645828013" MODIFIED="1341394416465" TEXT="GETZCNT "/>
<node CREATED="1341394427718" ID="ID_1881548970" MODIFIED="1341394428797" TEXT="GETALL "/>
<node CREATED="1341394429427" ID="ID_503292806" MODIFIED="1341394432361" TEXT="SETALL"/>
</node>
<node CREATED="1341394236805" ID="ID_1039607944" MODIFIED="1341394249911" TEXT="initialize semphore set">
<node CREATED="1341394530993" ID="ID_399566209" MODIFIED="1341394540891" TEXT="semctl(sem_id, n, SETVAL, init_value);"/>
</node>
</node>
</node>
<node CREATED="1341315013343" FOLDED="true" ID="ID_1804069828" MODIFIED="1358132609303" TEXT="semop">
<node CREATED="1341394556436" ID="ID_1082905639" MODIFIED="1341394556436" TEXT="#include <sys/types.h>"/>
<node CREATED="1341394556436" ID="ID_1410182787" MODIFIED="1341394556436" TEXT="#include <sys/ipc.h>"/>
<node CREATED="1341394556436" ID="ID_291465343" MODIFIED="1341394556436" TEXT="#include <sys/sem.h>"/>
<node CREATED="1341394556436" ID="ID_1483820110" MODIFIED="1341409259000" TEXT="int semop(int semid, struct sembuf semoparray[], size_t nops);">
<node CREATED="1341394563805" ID="ID_53565289" MODIFIED="1341394575460" TEXT="semoparray[]">
<node CREATED="1341394598008" ID="ID_669043662" MODIFIED="1341394630692" TEXT="struct sembuf {
 ushort sem_num; /* member # in set (0, 1 ..... nsems-l) */
 short sem_op; /* operation (negative, 0, or positive) */
 short sem_flg; /* IPC_NOWAIT, SEM_UNDO */
 }; ">
<node CREATED="1341397857065" ID="ID_1495944972" MODIFIED="1341397866068" TEXT="sem_op">
<node CREATED="1341397869131" ID="ID_1176180576" MODIFIED="1341408474341" TEXT="+">
<node CREATED="1341397884349" ID="ID_110424824" MODIFIED="1341398158787" TEXT="requires resources"/>
</node>
<node CREATED="1341397874225" ID="ID_1795673582" MODIFIED="1341409021461" TEXT="0">
<node CREATED="1341398088764" ID="ID_572037533" MODIFIED="1341398094366" TEXT="wait-for-zero"/>
</node>
<node CREATED="1341397876073" ID="ID_196491675" MODIFIED="1341409022261" TEXT="-">
<node CREATED="1341398107273" ID="ID_1372654629" MODIFIED="1341398166540" TEXT="release resources"/>
</node>
</node>
<node CREATED="1341398171257" ID="ID_273482510" MODIFIED="1341398176532" TEXT="sem_flg">
<node CREATED="1341398179049" ID="ID_435909430" MODIFIED="1341398185962" TEXT="IPC_NOWAIT">
<node CREATED="1341398188058" ID="ID_881107607" MODIFIED="1341409087398" TEXT="return with error immediately without waiting for resources become available .errno set to EAGAIN."/>
</node>
<node CREATED="1341398242042" ID="ID_89041707" MODIFIED="1341398250265" TEXT="SEM_UNDO"/>
</node>
</node>
</node>
</node>
<node CREATED="1341394556436" ID="ID_1157365318" MODIFIED="1341394556436" TEXT="Returns: 0 if OK, -1 on error"/>
<node CREATED="1341409125232" ID="ID_1431059437" MODIFIED="1342076349336" TEXT="errno">
<node CREATED="1341409135943" ID="ID_223950750" MODIFIED="1341409142119" TEXT="EAGAIN">
<node CREATED="1341409176026" ID="ID_544812252" MODIFIED="1341409289498" TEXT="sembuf.sem_flg set IPC_NOWAIT"/>
</node>
<node CREATED="1341409315974" FOLDED="true" ID="ID_1181048363" MODIFIED="1342076825980" TEXT="ERMID">
<node CREATED="1341409335255" ID="ID_409156259" MODIFIED="1341409398072" TEXT="semctl(semid,0,IPC_RMID,NULL)"/>
</node>
<node CREATED="1341409404457" ID="ID_1431990391" MODIFIED="1341409410769" TEXT="EINTR">
<node CREATED="1341409415546" ID="ID_1543440677" MODIFIED="1341409478182" TEXT="interrupted by signal"/>
</node>
</node>
</node>
</node>
</node>
</node>
<node CREATED="1338637081684" FOLDED="true" ID="ID_969287546" MODIFIED="1375432086691" POSITION="right" TEXT="file & directory operations">
<font BOLD="true" NAME="Dialog" SIZE="16"/>
<node CREATED="1338647378283" ID="ID_1976735025" MODIFIED="1374567659255" TEXT="stat">
<node CREATED="1338647483842" ID="ID_68683273" MODIFIED="1338647519557" TEXT=":retrieve metadata of a file stored in inode"/>
<node CREATED="1338647522391" ID="ID_1982945353" MODIFIED="1338647537586" TEXT="utility">
<node CREATED="1338647539562" ID="ID_1486925285" MODIFIED="1338647541667" TEXT="stat"/>
</node>
<node CREATED="1338647543089" ID="ID_1890475945" MODIFIED="1338647547470" TEXT="function">
<node CREATED="1338647550066" ID="ID_1171455159" MODIFIED="1363164486295" TEXT="stat <sys/stat.h>">
<node CREATED="1338647597710" ID="ID_1694120859" MODIFIED="1338647597710" TEXT="int stat(const char *path, struct stat *buf);"/>
<node CREATED="1338647597711" ID="ID_1741831704" MODIFIED="1338647597711" TEXT="int fstat(int filedes, struct stat *buf);"/>
<node CREATED="1338647597711" ID="ID_1191552396" MODIFIED="1338647597711" TEXT="int lstat(const char *path, struct stat *buf);">
<node CREATED="1338647616133" ID="ID_1337029910" MODIFIED="1338647762177" TEXT="if path is symbol link, retrieve information of the link,
not the file referenced by link as stat do"/>
</node>
</node>
</node>
<node CREATED="1338647877239" ID="ID_1730061970" MODIFIED="1375432000903">
<richcontent TYPE="NODE"><html>
<head>
</head>
<body>
<p>
struct stat {
</p>
<p>
              dev_t     st_dev;     /* ID of device containing file */
</p>
<p>
              ino_t     st_ino;     /* inode number */
</p>
<p>
              mode_t    st_mode;    /* file type & permission  */
</p>
<p>
              nlink_t   st_nlink;   /* number of hard links */
</p>
<p>
              uid_t     st_uid;     /* user ID of owner */
</p>
<p>
              gid_t     st_gid;     /* group ID of owner */
</p>
<p>
              dev_t     st_rdev;    /* device ID (if special file) */
</p>
<p>
              off_t     st_size;    /* total size, in bytes */
</p>
<p>
              blksize_t st_blksize; /* blocksize for filesystem I/O */
</p>
<p>
              blkcnt_t  st_blocks;  /* number of blocks allocated */
</p>
<p>
              time_t    st_atime;   /* time of last access */
</p>
<p>
              time_t    st_mtime;   /* time of last modification */
</p>
<p>
              time_t    st_ctime;   /* time of last status change */
</p>
<p>