6433ec22b1
Linker --wrap option resolves to __wrap_symbol for undefined symbol. During the compilation of host libportable.a, __HOST__ is defined to rename all portable functions to __wrap_symbol, and the real function to __real_symbol. This way libportable.a can be validated at host w/o changes of user's source code. See http://sourceware.org/binutils/docs/ld/Options.html Change-Id: Idcbe53dd642536f3dc2be85a875f95535b9dc0b1
126 lines
4.5 KiB
C
126 lines
4.5 KiB
C
/*
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* Copyright 2012, The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <portability.h>
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#include <poll.h>
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#include <poll_portable.h>
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/*
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*_XOPEN_SOURCE added the ability to not only poll for data coming in or out
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* but now also the ability to poll for high priority input and output. Though
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* the normal priority is equivalent to the original I/O it was assigned new bits:
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* POLLIN Equivalent to POLLRDNORM
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* POLLOUT Equivalent to POLLWRNORM
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*
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* The Linux kernel sets both POLLIN and POLLRDNORM when data is available and sets
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* both POLLOUT and POLLWRNORM when data can be written; so the new priority BAND bits
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* just supplement the meaning of the prior POLLIN and POLLOUT bits as well as the
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* new POLLRDNORM and POLLWRNORM bits.
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*
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* The DECNet Protocol can set the poll in priority flag, POLLRDBAND.
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* ATM as well as a whole bunch of other protocols can set the poll out priority flag,
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* POLLWRBAND.
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*
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* MIPS and SPARC likely assigned the new XOPEN poll out event flags in UNIX well before
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* UNIX was ported to X86. It appears that Intel chose different bits and that was
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* established by Linus as the the generic case and later also chosen by ARM.
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*
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* POLLWRNORM:0x100 - MIPS used POLLOUT:0x0004, which is equivalent in meaning.
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*
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* POLLWRBAND:0x200 - MIPS used 0x0100. which is POLLWRNORM:0x100.
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*
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* Summary:
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* ========
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* Both Normal and Priority flags can be mapped to MIPS flags (left to right below).
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* Only the Priority poll out flag can be mapped back to portable because MIPS
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* is using the same number as POLLOUT for POLLWRNORM (right to left below).
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*
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* ARM/GENERIC/PORTABLE MIPS
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* ==================== ======
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* POLLIN 0x0001 0x0001
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* POLLPRI 0x0002 0x0002
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* POLLOUT 0x0004 <-----+ 0x0004
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* POLLERR 0x0008 \ 0x0008
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* POLLHUP 0x0010 \ 0x0010
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* POLLNVAL 0x0020 \ 0x0020
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* POLLRDNORM 0x0040 \ 0x0040
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* POLLRDBAND 0x0080 \ 0x0080
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* POLLWRNORM 0x0100 -----------+<----> 0x0004
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* POLLWRBAND 0x0200 <-----------------> 0x0100
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* POLLMSG 0x0400 0x0400
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* POLLREMOVE 0x1000 0x1000
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* POLLRDHUP 0x2000 0x2000
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*
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* The loss of the high priority notice for the polling
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* of output data is likely minor as it was only being used
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* in DECNet. Also, the poll system call and device poll
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* implementations processes POLLOUT and POLLWRNORM event
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* flags the same.
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*/
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#if POLLWRNORM_PORTABLE==POLLWRNORM
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#error Bad build environment
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#endif
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static inline short mips_change_portable_events(short portable_events)
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{
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/* MIPS has different POLLWRNORM and POLLWRBAND. */
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if (portable_events & POLLWRNORM_PORTABLE) {
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portable_events &= ~POLLWRNORM_PORTABLE;
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portable_events |= POLLWRNORM;
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}
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if (portable_events & POLLWRBAND_PORTABLE) {
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portable_events &= ~POLLWRBAND_PORTABLE;
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portable_events |= POLLWRBAND;
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}
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return portable_events;
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}
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static inline short change_mips_events(short mips_events)
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{
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/*
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* MIPS POLLWRNORM equals MIPS POLLOUT, which is the same as POLLOUT_PORTABLE;
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* so we just map POLLWRBAND to POLLWRBAND_PORTABLE.
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*/
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if (mips_events & POLLWRBAND) {
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mips_events &= ~POLLWRBAND;
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mips_events |= POLLWRBAND_PORTABLE;
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}
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return mips_events;
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}
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extern int poll(struct pollfd *, nfds_t, long);
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int WRAP(poll)(struct pollfd *fds, nfds_t nfds, long timeout)
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{
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nfds_t i;
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int ret;
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for (i = 0; i < nfds; i++)
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fds->events = mips_change_portable_events(fds->events);
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ret = REAL(poll)(fds, nfds, timeout);
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for (i = 0; i < nfds; i++) {
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fds->events = change_mips_events(fds->events);
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fds->revents = change_mips_events(fds->revents);
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}
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return ret;
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}
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