diff options
Diffstat (limited to 'man2/recv.2')
| -rw-r--r-- | man2/recv.2 | 54 |
1 files changed, 27 insertions, 27 deletions
diff --git a/man2/recv.2 b/man2/recv.2 index 395236d..916cca3 100644 --- a/man2/recv.2 +++ b/man2/recv.2 @@ -10,7 +10,7 @@ .\" Modified 1998,1999 by Andi Kleen .\" 2001-06-19 corrected SO_EE_OFFENDER, bug report by James Hawtin .\" -.TH recv 2 2023-07-18 "Linux man-pages 6.05.01" +.TH recv 2 2024-02-18 "Linux man-pages 6.7" .SH NAME recv, recvfrom, recvmsg \- receive a message from a socket .SH LIBRARY @@ -19,7 +19,7 @@ Standard C library .SH SYNOPSIS .nf .B #include <sys/socket.h> -.PP +.P .BI "ssize_t recv(int " sockfd ", void " buf [. len "], size_t " len , .BI " int " flags ); .BI "ssize_t recvfrom(int " sockfd ", void " buf "[restrict ." len "], size_t " len , @@ -39,7 +39,7 @@ They may be used to receive data on both connectionless and connection-oriented sockets. This page first describes common features of all three system calls, and then describes the differences between the calls. -.PP +.P The only difference between .BR recv () and @@ -54,27 +54,27 @@ is generally equivalent to .BR read (2) (but see NOTES). Also, the following call -.PP +.P .in +4n .EX recv(sockfd, buf, len, flags); .EE .in -.PP +.P is equivalent to -.PP +.P .in +4n .EX recvfrom(sockfd, buf, len, flags, NULL, NULL); .EE .in -.PP +.P All three calls return the length of the message on successful completion. If a message is too long to fit in the supplied buffer, excess bytes may be discarded depending on the type of socket the message is received from. -.PP +.P If no messages are available at the socket, the receive calls wait for a message to arrive, unless the socket is nonblocking (see .BR fcntl (2)), @@ -84,7 +84,7 @@ is set to .BR EAGAIN " or " EWOULDBLOCK . The receive calls normally return any data available, up to the requested amount, rather than waiting for receipt of the full amount requested. -.PP +.P An application can use .BR select (2), .BR poll (2), @@ -123,7 +123,7 @@ is a per-call option, whereas is a setting on the open file description (see .BR open (2)), which will affect all threads in the calling process -and as well as other processes that hold file descriptors +as well as other processes that hold file descriptors referring to the same open file description. .TP .BR MSG_ERRQUEUE " (since Linux 2.2)" @@ -250,7 +250,7 @@ places the received message into the buffer .IR buf . The caller must specify the size of the buffer in .IR len . -.PP +.P If .I src_addr is not NULL, @@ -278,7 +278,7 @@ The returned address is truncated if the buffer provided is too small; in this case, .I addrlen will return a value greater than was supplied to the call. -.PP +.P If the caller is not interested in the source address, .I src_addr and @@ -293,7 +293,7 @@ call is normally used only on a socket (see .BR connect (2)). It is equivalent to the call: -.PP +.P .in +4n .EX recvfrom(fd, buf, len, flags, NULL, 0); @@ -308,7 +308,7 @@ call uses a structure to minimize the number of directly supplied arguments. This structure is defined as follows in .IR <sys/socket.h> : -.PP +.P .in +4n .EX struct msghdr { @@ -322,7 +322,7 @@ struct msghdr { }; .EE .in -.PP +.P The .I msg_name field points to a caller-allocated buffer that is used to @@ -336,14 +336,14 @@ will contain the length of the returned address. If the application does not need to know the source address, .I msg_name can be specified as NULL. -.PP +.P The fields .I msg_iov and .I msg_iovlen describe scatter-gather locations, as discussed in .BR readv (2). -.PP +.P The field .IR msg_control , which has length @@ -358,9 +358,9 @@ should contain the length of the available buffer in .IR msg_control ; upon return from a successful call it will contain the length of the control message sequence. -.PP +.P The messages are of the form: -.PP +.P .in +4n .EX struct cmsghdr { @@ -373,10 +373,10 @@ struct cmsghdr { }; .EE .in -.PP +.P Ancillary data should be accessed only by the macros defined in .BR cmsg (3). -.PP +.P As an example, Linux uses this ancillary data mechanism to pass extended errors, IP options, or file descriptors over UNIX domain sockets. For further information on the use of ancillary data in various @@ -384,7 +384,7 @@ socket domains, see .BR unix (7) and .BR ip (7). -.PP +.P The .I msg_flags field in the @@ -427,14 +427,14 @@ if an error occurred. In the event of an error, .I errno is set to indicate the error. -.PP +.P When a stream socket peer has performed an orderly shutdown, the return value will be 0 (the traditional "end-of-file" return). -.PP +.P Datagram sockets in various domains (e.g., the UNIX and Internet domains) permit zero-length datagrams. When such a datagram is received, the return value is 0. -.PP +.P The value 0 may also be returned if the requested number of bytes to receive from a stream socket was 0. .SH ERRORS @@ -515,7 +515,7 @@ POSIX.1-2008. .SH HISTORY POSIX.1-2001, 4.4BSD (first appeared in 4.2BSD). -.PP +.P POSIX.1 describes only the .BR MSG_OOB , .BR MSG_PEEK , @@ -535,7 +535,7 @@ In this circumstance, has no effect (the datagram remains pending), while .BR recv () consumes the pending datagram. -.PP +.P See .BR recvmmsg (2) for information about a Linux-specific system call |