diff options
Diffstat (limited to 'man2/msgop.2')
| -rw-r--r-- | man2/msgop.2 | 48 |
1 files changed, 24 insertions, 24 deletions
diff --git a/man2/msgop.2 b/man2/msgop.2 index 381875e..e09c632 100644 --- a/man2/msgop.2 +++ b/man2/msgop.2 @@ -17,7 +17,7 @@ .\" Language and formatting clean-ups .\" Added notes on /proc files .\" -.TH MSGOP 2 2023-05-03 "Linux man-pages 6.05.01" +.TH MSGOP 2 2023-10-31 "Linux man-pages 6.7" .SH NAME msgrcv, msgsnd \- System V message queue operations .SH LIBRARY @@ -26,10 +26,10 @@ Standard C library .SH SYNOPSIS .nf .B #include <sys/msg.h> -.PP +.P .BI "int msgsnd(int " msqid ", const void " msgp [. msgsz "], size_t " msgsz , .BI " int " msgflg ); -.PP +.P .BI "ssize_t msgrcv(int " msqid ", void " msgp [. msgsz "], size_t " msgsz \ ", long " msgtyp , .BI " int " msgflg ); @@ -43,12 +43,12 @@ system calls are used to send messages to, and receive messages from, a System\ V message queue. The calling process must have write permission on the message queue in order to send a message, and read permission to receive a message. -.PP +.P The .I msgp argument is a pointer to a caller-defined structure of the following general form: -.PP +.P .in +4n .EX struct msgbuf { @@ -57,7 +57,7 @@ struct msgbuf { }; .EE .in -.PP +.P The .I mtext field is an array (or other structure) whose size is specified by @@ -82,7 +82,7 @@ system call appends a copy of the message pointed to by to the message queue whose identifier is specified by .IR msqid . -.PP +.P If sufficient space is available in the queue, .BR msgsnd () succeeds immediately. @@ -109,7 +109,7 @@ This check is necessary to prevent an unlimited number of zero-length messages being placed on the queue. Although such messages contain no data, they nevertheless consume (locked) kernel memory. -.PP +.P If insufficient space is available in the queue, then the default behavior of .BR msgsnd () @@ -120,7 +120,7 @@ is specified in .IR msgflg , then the call instead fails with the error .BR EAGAIN . -.PP +.P A blocked .BR msgsnd () call may also fail if: @@ -143,7 +143,7 @@ is never automatically restarted after being interrupted by a signal handler, regardless of the setting of the .B SA_RESTART flag when establishing a signal handler.) -.PP +.P Upon successful completion the message queue data structure is updated as follows: .IP \[bu] 3 @@ -163,7 +163,7 @@ system call removes a message from the queue specified by and places it in the buffer pointed to by .IR msgp . -.PP +.P The argument .I msgsz specifies the maximum size in bytes for the member @@ -189,7 +189,7 @@ the system call fails returning \-1 with .I errno set to .BR E2BIG . -.PP +.P Unless .B MSG_COPY is specified in @@ -225,7 +225,7 @@ then the first message in the queue with the lowest type less than or equal to the absolute value of .I msgtyp will be read. -.PP +.P The .I msgflg argument is a bit mask constructed by ORing together zero or more @@ -279,7 +279,7 @@ from To truncate the message text if longer than .I msgsz bytes. -.PP +.P If no message of the requested type is available and .B IPC_NOWAIT isn't specified in @@ -304,7 +304,7 @@ is never automatically restarted after being interrupted by a signal handler, regardless of the setting of the .B SA_RESTART flag when establishing a signal handler.) -.PP +.P Upon successful completion the message queue data structure is updated as follows: .IP @@ -372,7 +372,7 @@ value (less than 0 or greater than the system value The system does not have enough memory to make a copy of the message pointed to by .IR msgp . -.PP +.P .BR msgrcv () can fail with the following errors: .TP @@ -451,7 +451,7 @@ and this kernel was configured without .BR CONFIG_CHECKPOINT_RESTORE . .SH STANDARDS POSIX.1-2008. -.PP +.P The .B MSG_EXCEPT and @@ -463,7 +463,7 @@ their definitions can be obtained by defining the feature test macro. .SH HISTORY POSIX.1-2001, SVr4. -.PP +.P The .I msgp argument is declared as \fIstruct msgbuf\ *\fP in @@ -495,7 +495,7 @@ using the .BR msgctl (2) .B IPC_SET operation. -.PP +.P The implementation has no intrinsic system-wide limits on the number of message headers .RB ( MSGTQL ) @@ -521,7 +521,7 @@ of whether that message was at the ordinal position This bug is fixed .\" commit 4f87dac386cc43d5525da7a939d4b4e7edbea22c in Linux 3.14. -.PP +.P Specifying both .B MSG_COPY and @@ -542,18 +542,18 @@ The program below demonstrates the use of .BR msgsnd () and .BR msgrcv (). -.PP +.P The example program is first run with the \fB\-s\fP option to send a message and then run again with the \fB\-r\fP option to receive a message. -.PP +.P The following shell session shows a sample run of the program: -.PP +.P .in +4n .EX .RB "$" " ./a.out \-s" sent: a message at Wed Mar 4 16:25:45 2015 -.PP +.P .RB "$" " ./a.out \-r" message received: a message at Wed Mar 4 16:25:45 2015 .EE |