1t_sndv(3NSL) Networking Services Library Functions t_sndv(3NSL)
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6 t_sndv - send data or expedited data, from one or more non-contiguous
7 buffers, on a connection
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10 #include <xti.h>
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14 int t_sndv(int fd, const struct t_iovec *iov, unsigned int iovcount, int flags);
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18 This function is used to send either normal or expedited data. The
19 argument fd identifies the local transport endpoint over which data
20 should be sent, iov points to an array of buffer address/buffer length
21 pairs. t_sndv() sends data contained in buffers iov0 , iov1 ,
22 through iov [iovcount-1]. iovcount contains the number of non-contigu‐
23 ous data buffers which is limited to T_IOV_MAX, an implementation-
24 defined value of at least 16. If the limit is exceeded, the function
25 fails with TBADDATA.
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27 iov(0).iov_len + . . + iov(iovcount-1).iov_len)
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31 Note that the limit on the total number of bytes available in all buf‐
32 fers passed:
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35 may be constrained by implementation limits. If no other constraint
36 applies, it will be limited by INT_MAX. In practice, the availability
37 of memory to an application is likely to impose a lower limit on the
38 amount of data that can be sent or received using scatter/gather func‐
39 tions.
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42 The argument flags specifies any optional flags described below:
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44 T_EXPEDITED If set in flags, the data will be sent as expedited
45 data and will be subject to the interpretations of the
46 transport provider.
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49 T_MORE If set in flags, this indicates to the transport
50 provider that the transport service data unit (TSDU)
51 (or expedited transport service data unit - ETSDU) is
52 being sent through multiple t_sndv() calls. Each
53 t_sndv() with the T_MORE flag set indicates that
54 another t_sndv() or t_snd(3NSL) will follow with more
55 data for the current TSDU (or ETSDU).
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59 The end of the TSDU (or ETSDU) is identified by a t_sndv() call with
60 the T_MORE flag not set. Use of T_MORE enables a user to break up
61 large logical data units without losing the boundaries of those units
62 at the other end of the connection. The flag implies nothing about how
63 the data is packaged for transfer below the transport interface. If
64 the transport provider does not support the concept of a TSDU as indi‐
65 cated in the info argument on return from t_open(3NSL) or t_get‐
66 info(3NSL), the T_MORE flag is not meaningful and will be ignored if
67 set.
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70 The sending of a zero-length fragment of a TSDU or ETSDU is only per‐
71 mitted where this is used to indicate the end of a TSDU or ETSDU, that
72 is, when the T_MORE flag is not set. Some transport providers also
73 forbid zero-length TSDUs and ETSDUs.
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76 If set in flags, requests that the provider transmit all data that it
77 has accumulated but not sent. The request is a local action on the
78 provider and does not affect any similarly named protocol flag (for
79 example, the TCP PUSH flag). This effect of setting this flag is proto‐
80 col‐dependent, and it may be ignored entirely by transport providers
81 which do not support the use of this feature.
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84 The communications provider is free to collect data in a send buffer
85 until it accumulates a sufficient amount for transmission.
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88 By default, t_sndv() operates in synchronous mode and may wait if flow
89 control restrictions prevent the data from being accepted by the local
90 transport provider at the time the call is made. However, if O_NON‐
91 BLOCK is set by means of t_open(3NSL) or fcntl(2), t_sndv() executes
92 in asynchronous mode, and will fail immediately if there are flow con‐
93 trol restrictions. The process can arrange to be informed when the
94 flow control restrictions are cleared via either t_look(3NSL) or the EM
95 interface.
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98 On successful completion, t_sndv() returns the number of bytes
99 accepted by the transport provider. Normally this will equal the total
100 number of bytes to be sent, that is,
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102 (iov0.iov_len + .. + iov[iovcount-1].iov_len)
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106 However, the interface is constrained to send at most INT_MAX bytes in
107 a single send. When t_sndv() has submitted INT_MAX (or lower con‐
108 strained value, see the note above) bytes to the provider for a single
109 call, this value is returned to the user. However, if O_NONBLOCK is
110 set or the function is interrupted by a signal, it is possible that
111 only part of the data has actually been accepted by the communications
112 provider. In this case, t_sndv() returns a value that is less than
113 the value of nbytes. If t_sndv() is interrupted by a signal before it
114 could transfer data to the communications provider, it returns -1 with
115 t_errno set to TSYSERR and errno set to EINTR.
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118 If the number of bytes of data in the iov array is zero and sending of
119 zero octets is not supported by the underlying transport service,
120 t_sndv() returns -1 with t_errno set to TBADDATA.
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123 The size of each TSDU or ETSDU must not exceed the limits of the trans‐
124 port provider as specified by the current values in the TSDU or ETSDU
125 fields in the info argument returned by t_getinfo(3NSL).
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128 The error TLOOK is returned for asynchronous events. It is required
129 only for an incoming disconnect event but may be returned for other
130 events.
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133 On successful completion, t_sndv() returns the number of bytes
134 accepted by the transport provider. Otherwise, -1 is returned on
135 failure and t_errno is set to indicate the error.
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138 Note that in synchronous mode, if more than INT_MAX bytes of data are
139 passed in the iov array, only the first INT_MAX bytes will be passed
140 to the provider.
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143 If the number of bytes accepted by the communications provider is less
144 than the number of bytes requested, this may either indicate that
145 O_NONBLOCK is set and the communications provider is blocked due to
146 flow control, or that O_NONBLOCK is clear and the function was inter‐
147 rupted by a signal.
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150 T_DATAXFER, T_INREL.
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153 On failure, t_errno is set to one of the following:
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155 TBADDATA Illegal amount of data:
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158 TBADF The specified file descriptor does not refer to a trans‐
159 port endpoint.
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161 o A single send was attempted specifying a TSDU
162 (ETSDU) or fragment TSDU (ETSDU) greater than
163 that specified by the current values of the
164 TSDU or ETSDU fields in the info argument.
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166 o A send of a zero byte TSDU (ETSDU) or zero
167 byte fragment of a TSDU (ETSDU) is not sup‐
168 ported by the provider.
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170 o Multiple sends were attempted resulting in a
171 TSDU (ETSDU) larger than that specified by
172 the current value of the TSDU or ETSDU fields
173 in the info argument - the ability of an XTI
174 implementation to detect such an error case
175 is implementation-dependent. See WARNINGS,
176 below.
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178 o iovcount is greater than T_IOV_MAX.
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181 TBADFLAG An invalid flag was specified.
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184 TFLOW O_NONBLOCK was set, but the flow control mechanism pre‐
185 vented the transport provider from accepting any data at
186 this time.
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189 TLOOK An asynchronous event has occurred on this transport
190 endpoint.
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193 TNOTSUPPORT This function is not supported by the underlying trans‐
194 port provider.
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197 TOUTSTATE The communications endpoint referenced by fd is not in
198 one of the states in which a call to this function is
199 valid.
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202 TPROTO This error indicates that a communication problem has
203 been detected between XTI and the transport provider for
204 which there is no other suitable XTI error (t_errno).
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207 TSYSERR A system error has occurred during execution of this
208 function.
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212 In the TLI interface definition, no counterpart of this routine was
213 defined.
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216 See attributes(5) for descriptions of the following attributes:
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221 ┌─────────────────────────────┬─────────────────────────────┐
222 │ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
223 ├─────────────────────────────┼─────────────────────────────┤
224 │MT Level │Safe │
225 └─────────────────────────────┴─────────────────────────────┘
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228 t_getinfo(3NSL), t_open(3NSL), t_rcvv(3NSL) t_rcv(3NSL), t_snd(3NSL),
229 attributes(5)
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232 It is important to remember that the transport provider treats all
233 users of a transport endpoint as a single user. Therefore if several
234 processes issue concurrent t_sndv() or t_snd(3NSL) calls, then the
235 different data may be intermixed.
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238 Multiple sends which exceed the maximum TSDU or ETSDU size may not be
239 discovered by XTI. In this case an implementation-dependent error will
240 result (generated by the transport provider), perhaps on a subsequent
241 XTI call. This error may take the form of a connection abort, a TSY‐
242 SERR, a TBADDATA or a TPROTO error.
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245 If multiple sends which exceed the maximum TSDU or ETSDU size are
246 detected by XTI, t_sndv() fails with TBADDATA.
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250SunOS 5.11 23 Aug 2001 t_sndv(3NSL)