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This patch is large, but is almost entirely just adding casts to calls to syscall_impl. Much of the work was done programatically, with human checking when the syntax or types got confusing. Reviewed By: mcgrathr Differential Revision: https://reviews.llvm.org/D156950
73 lines
2.6 KiB
C++
73 lines
2.6 KiB
C++
//===-- Linux implementation of select ------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "src/sys/select/select.h"
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#include "src/__support/CPP/limits.h"
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#include "src/__support/OSUtil/syscall.h" // For internal syscall function.
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#include "src/__support/common.h"
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#include "src/errno/libc_errno.h"
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#include <signal.h>
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#include <stddef.h> // For size_t
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#include <sys/select.h>
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#include <sys/syscall.h> // For syscall numbers.
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namespace __llvm_libc {
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struct pselect6_sigset_t {
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sigset_t *ss;
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size_t ss_len;
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};
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LLVM_LIBC_FUNCTION(int, select,
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(int nfds, fd_set *__restrict read_set,
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fd_set *__restrict write_set, fd_set *__restrict error_set,
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struct timeval *__restrict timeout)) {
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// Linux has a SYS_select syscall but it is not available on all
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// architectures. So, we use the SYS_pselect6 syscall which is more
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// widely available. However, SYS_pselect6 takes a struct timespec argument
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// instead of a struct timeval argument. Also, it takes an additional
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// argument which is a pointer to an object of a type defined above as
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// "pselect6_sigset_t".
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struct timespec ts {
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0, 0
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};
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if (timeout != nullptr) {
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// In general, if the tv_sec and tv_usec in |timeout| are correctly set,
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// then converting tv_usec to nanoseconds will not be a problem. However,
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// if tv_usec in |timeout| is more than a second, it can lead to overflows.
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// So, we detect such cases and adjust.
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constexpr time_t TIME_MAX = cpp::numeric_limits<time_t>::max();
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if ((TIME_MAX - timeout->tv_sec) < (timeout->tv_usec / 1000000)) {
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ts.tv_sec = TIME_MAX;
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ts.tv_nsec = 999999999;
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} else {
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ts.tv_sec = timeout->tv_sec + timeout->tv_usec / 1000000;
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ts.tv_nsec = timeout->tv_usec * 1000;
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}
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}
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pselect6_sigset_t pss{nullptr, sizeof(sigset_t)};
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#if SYS_pselect6
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int ret = __llvm_libc::syscall_impl<int>(SYS_pselect6, nfds, read_set,
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write_set, error_set, &ts, &pss);
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#elif defined(SYS_pselect6_time64)
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int ret = __llvm_libc::syscall_impl<int>(SYS_pselect6_time64, nfds, read_set,
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write_set, error_set, &ts, &pss);
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#else
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#error "SYS_pselect6 and SYS_pselect6_time64 syscalls not available."
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#endif
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if (ret < 0) {
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libc_errno = -ret;
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return -1;
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}
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return ret;
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}
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} // namespace __llvm_libc
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