69 lines · cpp
1//===-- Linux implementation of recvfrom ----------------------------------===//2//3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.4// See https://llvm.org/LICENSE.txt for license information.5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception6//7//===----------------------------------------------------------------------===//8 9#include "src/sys/socket/recvfrom.h"10 11#include <linux/net.h> // For SYS_SOCKET socketcall number.12#include <sys/syscall.h> // For syscall numbers.13 14#include "hdr/types/socklen_t.h"15#include "hdr/types/ssize_t.h"16#include "hdr/types/struct_sockaddr.h"17#include "src/__support/OSUtil/syscall.h" // For internal syscall function.18#include "src/__support/common.h"19#include "src/__support/libc_errno.h"20#include "src/__support/macros/sanitizer.h"21 22namespace LIBC_NAMESPACE_DECL {23 24LLVM_LIBC_FUNCTION(ssize_t, recvfrom,25 (int sockfd, void *buf, size_t len, int flags,26 sockaddr *__restrict src_addr,27 socklen_t *__restrict addrlen)) {28 // addrlen is a value-result argument. If it's not null, it passes the max29 // size of the buffer src_addr to the syscall. After the syscall, it's updated30 // to the actual size of the source address. This may be larger than the31 // buffer, in which case the buffer contains a truncated result.32 size_t srcaddr_sz;33 if (src_addr)34 srcaddr_sz = *addrlen;35 (void)srcaddr_sz; // prevent "set but not used" warning36 37#ifdef SYS_recvfrom38 ssize_t ret = LIBC_NAMESPACE::syscall_impl<ssize_t>(39 SYS_recvfrom, sockfd, buf, len, flags, src_addr, addrlen);40#elif defined(SYS_socketcall)41 unsigned long sockcall_args[6] = {static_cast<unsigned long>(sockfd),42 reinterpret_cast<unsigned long>(buf),43 static_cast<unsigned long>(len),44 static_cast<unsigned long>(flags),45 reinterpret_cast<unsigned long>(src_addr),46 static_cast<unsigned long>(addrlen)};47 ssize_t ret = LIBC_NAMESPACE::syscall_impl<ssize_t>(48 SYS_socketcall, SYS_RECVFROM, sockcall_args);49#else50#error "socket and socketcall syscalls unavailable for this platform."51#endif52 if (ret < 0) {53 libc_errno = static_cast<int>(-ret);54 return -1;55 }56 57 MSAN_UNPOISON(buf, ret);58 59 if (src_addr) {60 size_t min_src_addr_size = (*addrlen < srcaddr_sz) ? *addrlen : srcaddr_sz;61 (void)min_src_addr_size; // prevent "set but not used" warning62 63 MSAN_UNPOISON(src_addr, min_src_addr_size);64 }65 return ret;66}67 68} // namespace LIBC_NAMESPACE_DECL69