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 | man pages section 3: Basic Library Functions Oracle Solaris 11 Information Library |
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| man pages section 3: Basic Library Functions Oracle Solaris 11 Information Library |
enable_extended_FILE_stdio(3C)
posix_spawnattr_getschedparam(3C)
posix_spawnattr_getschedpolicy(3C)
posix_spawnattr_getsigdefault(3C)
posix_spawnattr_getsigignore_np(3C)
posix_spawnattr_getsigmask(3C)
posix_spawnattr_setschedparam(3C)
posix_spawnattr_setschedpolicy(3C)
posix_spawnattr_setsigdefault(3C)
posix_spawnattr_setsigignore_np(3C)
posix_spawnattr_setsigmask(3C)
posix_spawn_file_actions_addclose(3C)
posix_spawn_file_actions_addclosefrom_np(3C)
posix_spawn_file_actions_adddup2(3C)
posix_spawn_file_actions_addopen(3C)
posix_spawn_file_actions_destroy(3C)
posix_spawn_file_actions_init(3C)
pthread_attr_getdetachstate(3C)
pthread_attr_getinheritsched(3C)
pthread_attr_getschedparam(3C)
pthread_attr_getschedpolicy(3C)
pthread_attr_setdetachstate(3C)
pthread_attr_setinheritsched(3C)
pthread_attr_setschedparam(3C)
pthread_attr_setschedpolicy(3C)
pthread_barrierattr_destroy(3C)
pthread_barrierattr_getpshared(3C)
pthread_barrierattr_setpshared(3C)
pthread_condattr_getpshared(3C)
pthread_condattr_setpshared(3C)
pthread_cond_reltimedwait_np(3C)
pthread_key_create_once_np(3C)
pthread_mutexattr_getprioceiling(3C)
pthread_mutexattr_getprotocol(3C)
pthread_mutexattr_getpshared(3C)
pthread_mutexattr_getrobust(3C)
pthread_mutexattr_setprioceiling(3C)
pthread_mutexattr_setprotocol(3C)
pthread_mutexattr_setpshared(3C)
pthread_mutexattr_setrobust(3C)
pthread_mutex_getprioceiling(3C)
pthread_mutex_reltimedlock_np(3C)
pthread_mutex_setprioceiling(3C)
pthread_rwlockattr_destroy(3C)
pthread_rwlockattr_getpshared(3C)
pthread_rwlockattr_setpshared(3C)
pthread_rwlock_reltimedrdlock_np(3C)
pthread_rwlock_reltimedwrlock_np(3C)
pthread_rwlock_timedrdlock(3C)
pthread_rwlock_timedwrlock(3C)
rctlblk_get_enforced_value(3C)
- synchronous I/O multiplexing
#include <sys/time.h>intselect(intnfds,fd_set *restrictreadfds,fd_set *restrictwritefds,fd_set *restricterrorfds,struct timeval *restricttimeout);
intpselect(intnfds,fd_set *restrictreadfds,fd_set *restrictwritefds,fd_set *restricterrorfds,const struct timespec *restricttimeout,const sigset_t *restrictsigmask);
voidFD_SET(intfd,fd_set *fdset);
voidFD_CLR(intfd,fd_set *fdset);
intFD_ISSET(intfd,fd_set *fdset);
voidFD_ZERO(fd_set *fdset);
Thepselect() function examines the file descriptor sets whose addresses are passedin thereadfds,writefds, anderrorfds parameters to see if some oftheir descriptors are ready for reading, are ready for writing, or have anexceptional condition pending, respectively.
Theselect() function is equivalent to thepselect() function, except as follows:
For theselect() function, the timeout period is given in seconds and microseconds in an argument of typestruct timeval, whereas for thepselect() function the timeout period is given in seconds and nanoseconds in an argument of typestruct timespec.
Theselect() function has nosigmask argument. It behaves aspselect() does whensigmask is a null pointer.
Upon successful completion, theselect() function might modify the object pointed to by thetimeout argument.
Theselect() andpselect() functions support regular files, terminal and pseudo-terminal devices,STREAMS-based files, FIFOs, pipes, and sockets. The behavior ofselect() andpselect()on file descriptors that refer to other types of file is unspecified.
Thenfds argument specifies the range of file descriptors to be tested.The firstnfds descriptors are checked in each set; that is, thedescriptors from zero throughnfds-1 in the descriptor sets are examined.
If thereadfs argument is not a null pointer, it points toan object of typefd_set that on input specifies the file descriptorsto be checked for being ready to read, and on output indicateswhich file descriptors are ready to read.
If thewritefs argument is not a null pointer, it points toan object of typefd_set that on input specifies the file descriptorsto be checked for being ready to write, and on output indicateswhich file descriptors are ready to write.
If theerrorfds argument is not a null pointer, it points toan object of typefd_set that on input specifies the file descriptorsto be checked for error conditions pending, and on output indicates whichfile descriptors have error conditions pending.
Upon successful completion, the objects pointed to by thereadfs,writefs, anderrorfds arguments are modified to indicate which file descriptors are ready forreading, ready for writing, or have an error condition pending, respectively, and returnthe total number of ready descriptors in all the output sets. Foreach file descriptor less thannfds, the corresponding bit will be seton successful completion if it was set on input and the associatedcondition is true for that file descriptor.
If none of the selected descriptors are ready for the requested operation,theselect() orpselect() function blocks until at least one of therequested operations becomes ready, until the timeout occurs, or until interrupted bya signal. Thetimeout parameter controls how long theselect() orpselect()function takes before timing out. If thetimeout parameter is not anull pointer, it specifies a maximum interval to wait for the selectionto complete. If the specified time interval expires without any requested operation becomingready, the function returns. If thetimeout parameter is a null pointer,then the call toselect() orpselect() blocks indefinitely until at leastone descriptor meets the specified criteria. To effect a poll, thetimeout parametershould not be a null pointer, and should point to a zero-valuedtimespec structure.
The use of atimeout does not affect any pending timers setup byalarm(2),ualarm(3C), orsetitimer(2).
Ifsigmask is not a null pointer, then thepselect() function replacesthe signal mask of the process by the set of signals pointedto bysigmask before examining the descriptors, and restores the signal maskof the process before returning.
A descriptor is considered ready for reading when a call to aninput function withO_NONBLOCK clear would not block, whether or not thefunction would transfer data successfully. (The function might return data, an end-of-fileindication, or an error other than one indicating that it is blocked, andin each of these cases the descriptor will be considered ready forreading.)
A descriptor is considered ready for writing when a call to anoutput function withO_NONBLOCK clear would not block, whether or not thefunction would transfer data successfully.
If a socket has a pending error, it is considered to havean exceptional condition pending. Otherwise, what constitutes an exceptional condition is filetype-specific. For a file descriptor for use with a socket, it isprotocol-specific except as noted below. For other file types, if the operation ismeaningless for a particular file type,select() orpselect() indicates that thedescriptor is ready for read or write operations and indicates that thedescriptor has no exceptional condition pending.
If a descriptor refers to a socket, the implied input function istherecvmsg(3XNET) function with parameters requesting normal and ancillary data, such that thepresence of either type causes the socket to be marked as readable.The presence of out-of-band data is checked if the socket optionSO_OOBINLINEhas been enabled, as out-of-band data is enqueued with normal data. Ifthe socket is currently listening, then it is marked as readable if anincoming connection request has been received, and a call to the acceptfunction completes without blocking.
If a descriptor refers to a socket, the implied output function isthesendmsg(3XNET) function supplying an amount of normal data equal to thecurrent value of theSO_SNDLOWAT option for the socket. If a non-blocking callto the connect function has been made for a socket, and theconnection attempt has either succeeded or failed leaving a pending error, thesocket is marked as writable.
A socket is considered to have an exceptional condition pending if areceive operation withO_NONBLOCK clear for the open file description and withtheMSG_OOB flag set would return out-of-band data without blocking. (It isprotocol-specific whether theMSG_OOB flag would be used to read out-of-band data.) Asocket will also be considered to have an exceptional condition pending ifan out-of-band data mark is present in the receive queue.
A file descriptor for a socket that is listening for connections willindicate that it is ready for reading, when connections are available. A file descriptor for a socket that is connecting asynchronously will indicatethat it is ready for writing, when a connection has been established.
Selecting true for reading on a socket descriptor upon which alisten(3XNET)call has been performed indicates that a subsequentaccept(3XNET) call on thatdescriptor will not block.
If thetimeout argument is not a null pointer, it points toan object of typestruct timeval that specifies a maximum interval to waitfor the selection to complete. If thetimeout argument points to anobject of typestruct timeval whose members are 0,select() does not block.If thetimeout argument is a null pointer,select() blocks until anevent causes one of the masks to be returned with a valid(non-zero) value. If the time limit expires before any event occurs thatwould cause one of the masks to be set to a non-zerovalue,select() completes successfully and returns 0.
If thereadfs,writefs, anderrorfds arguments are all null pointers andthetimeout argument is not a null pointer,select() orpselect() blocksfor the time specified, or until interrupted by a signal. If thereadfs,writefs, anderrorfds arguments are all null pointers and thetimeout argumentis a null pointer,select() blocks until interrupted by a signal.
File descriptors associated with regular files always select true for ready toread, ready to write, and error conditions.
On failure, the objects pointed to by thereadfs,writefs, anderrorfdsarguments are not modified. If the timeout interval expires without thespecified condition being true for any of the specified file descriptors, the objectspointed to by thereadfs,writefs, anderrorfds arguments have all bitsset to 0.
File descriptor masks of typefd_set can be initialized and tested withthe macrosFD_CLR(),FD_ISSET(),FD_SET(), andFD_ZERO().
Clears the bit for the file descriptorfd in the file descriptor setfdset.
Returns a non-zero value if the bit for the file descriptorfd is set in the file descriptor set pointed to byfdset, and 0 otherwise.
Sets the bit for the file descriptorfd in the file descriptor setfdset.
Initializes the file descriptor setfdset to have zero bits for all file descriptors.
The behavior of these macros is undefined if thefd argument isless than 0 or greater than or equal toFD_SETSIZE, or iffd is not a valid file descriptor, or if any of thearguments are expressions with side effects.
On successful completion,select() andpselect() return the total number of bitsset in the bit masks. Otherwise,-1 is returned anderrno isset to indicate the error.
TheFD_CLR(),FD_SET(), andFD_ZERO() macros return no value. TheFD_ISSET()macro returns a non-zero value if the bit for the file descriptorfd is set in the file descriptor set pointed to byfdset, and0 otherwise.
Theselect() andpselect() functions will fail if:
One or more of the file descriptor sets specified a file descriptor that is not a valid open file descriptor.
The function was interrupted before any of the selected events occurred and before the timeout interval expired.
IfSA_RESTART has been set for the interrupting signal, it is implementation-dependent whetherselect() restarts or returns withEINTR.
An invalid timeout interval was specified.
Thenfds argument is less than 0 or greater thanFD_SETSIZE.
One of the specified file descriptors refers to a STREAM or multiplexer that is linked (directly or indirectly) downstream from a multiplexer.
A component of the pointed-to time limit is outside the acceptable range:t_sec must be between0 and 108, inclusive.t_usec must be greater than or equal to0, and less than 106.
Thepoll(2) function is preferred over this function. It must be usedwhen the number of file descriptors exceedsFD_SETSIZE.
The use of a timeout does not affect any pending timers setup byalarm(2),ualarm(3C) orsetitimer(2).
On successful completion, the object pointed to by thetimeout argument maybe modified.
Seeattributes(5) for descriptions of the following attributes:
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alarm(2),fcntl(2),poll(2),read(2),setitimer(2),write(2),accept(3SOCKET),listen(3SOCKET),ualarm(3C),attributes(5),standards(5)
The default value forFD_SETSIZE (currently 1024) is larger than the defaultlimit on the number of open files. To accommodate 32-bit applications that wish to use a larger number of open files withselect(),it is possible to increase this size at compile time by providing alarger definition ofFD_SETSIZE before the inclusion of any system-supplied header. Themaximum supported size forFD_SETSIZE is 65536. The default value is already65536 for 64-bit applications.
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