Unix ___domain socket: Difference between revisions

Revision as of 07:52, 19 August 2024

Revision as of 10:40, 22 August 2024

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|page=1150}}</ref>

Two processes may communicate with each other if each obtains a socket. The server process ''binds'' its socket to an ''address'', opens a ''listen'' channel, and then continuously loops — [[Busy waiting|spin waiting]] for a client connection. UponInside ''accepting''the a client connectionloop, the server thenprocess executesis aput [[readto (systemsleep call)|read]]while [[system call]] that will [[Blocking (computing)|block wait]]. The client ''connects''waiting to the server's socket via the server's accept''address''. Thea client process then [[write (system call)|writes]] a [[String (computer science)|message]] for the server process to readconnection. The application's [[algorithm]] may entail multiple read/write interactions. Upon completion of the algorithm, the client executes <code>exit()</code><ref name="lpiunp-p1169p14_quote">{{cite book

|title=Unix Network Programming

|last1=Stevens

|first1=Richard W.

|last2=Fenner

|first2=Bill

|last3=Rudoff

|first3=Andrew M.

|publisher=Pearson Education

|year=2004

|isbn=81-297-0710-1

|quote=Normally, the server process is put to sleep in the call to ''accept'', waiting for a client connection to arrive and be accepted.

|page=14}}</ref> Upon ''accepting'' a client connection, the server then executes a [[read (system call)|read]] [[system call]] that will [[Blocking (computing)|block wait]]. The client ''connects'' to the server's socket via the server's ''address''. The client process then [[write (system call)|writes]] a [[String (computer science)|message]] for the server process to read. The application's [[algorithm]] may entail multiple read/write interactions. Upon completion of the algorithm, the client executes <code>exit()</code><ref name="lpi-p1169">{{cite book

|title=The Linux Programming Interface

|last=Kerrisk

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if ( return_value == -1 ) assert( 0 );

/* Listen and spin waitaccept code omitted. */

}

</syntaxhighlight>

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==Server accept a connection==

After opening a ''listen'' channel, the server enters an infinite loop. Inside the loop is a [[Busysystem waiting|spincall wait]]to <code>accept()</code>, which puts itself to sleep.<ref name="unp-p14_quote"/> The <code>accept()</code> system call will return a file descriptor when a client process executes <code>connect()</code>.<ref>{{cite web

|title=Linux manual page for accept()

|url=https://man7.org/linux/man-pages/man2/accept.2.html}}</ref>