libc/src/unistd/linux/read.cpp

   1 //===-- Linux implementation of read --------------------------------------===//
   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-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "src/unistd/read.h"
  10
  11 #include "src/__support/OSUtil/syscall.h" // For internal syscall function.
  12 #include "src/__support/common.h"
  13 #include "src/__support/macros/config.h"
  14 #include "src/__support/macros/sanitizer.h" // for MSAN_UNPOISON
  15 #include "src/errno/libc_errno.h"
  16 #include <sys/syscall.h> // For syscall numbers.
  17
  18 namespace LIBC_NAMESPACE_DECL {
  19
  20 LLVM_LIBC_FUNCTION(ssize_t, read, (int fd, void *buf, size_t count)) {
  21   ssize_t ret = LIBC_NAMESPACE::syscall_impl<ssize_t>(SYS_read, fd, buf, count);
  22   if (ret < 0) {
  23     libc_errno = static_cast<int>(-ret);
  24     return -1;
  25   }
  26   // The cast is important since there is a check that dereferences the pointer
  27   // which fails on void*.
  28   MSAN_UNPOISON(reinterpret_cast<char *>(buf), count);
  29   return ret;
  30 }
  31
  32 } // namespace LIBC_NAMESPACE_DECL