1 //===-- Implementation of fcntl -------------------------------------------===// 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/fcntl/fcntl.h" 10 11 #include "hdr/fcntl_macros.h" 12 #include "hdr/types/struct_f_owner_ex.h" 13 #include "hdr/types/struct_flock.h" 14 #include "hdr/types/struct_flock64.h" 15 #include "src/__support/OSUtil/syscall.h" // For internal syscall function. 16 #include "src/__support/common.h" 17 #include "src/errno/libc_errno.h" 18 19 #include <stdarg.h> 20 #include <sys/syscall.h> // For syscall numbers. 21 22 // The OFD file locks require special handling for LARGEFILES 23 namespace LIBC_NAMESPACE { 24 LLVM_LIBC_FUNCTION(int, fcntl, (int fd, int cmd, ...)) { 25 void *arg; 26 va_list varargs; 27 va_start(varargs, cmd); 28 arg = va_arg(varargs, void *); 29 va_end(varargs); 30 31 switch (cmd) { 32 case F_SETLKW: 33 return syscall_impl<int>(SYS_fcntl, fd, cmd, arg); 34 case F_OFD_SETLKW: { 35 struct flock *flk = reinterpret_cast<struct flock *>(arg); 36 // convert the struct to a flock64 37 struct flock64 flk64; 38 flk64.l_type = flk->l_type; 39 flk64.l_whence = flk->l_whence; 40 flk64.l_start = flk->l_start; 41 flk64.l_len = flk->l_len; 42 flk64.l_pid = flk->l_pid; 43 // create a syscall 44 return syscall_impl<int>(SYS_fcntl, fd, cmd, &flk64); 45 } 46 case F_OFD_GETLK: 47 case F_OFD_SETLK: { 48 struct flock *flk = reinterpret_cast<struct flock *>(arg); 49 // convert the struct to a flock64 50 struct flock64 flk64; 51 flk64.l_type = flk->l_type; 52 flk64.l_whence = flk->l_whence; 53 flk64.l_start = flk->l_start; 54 flk64.l_len = flk->l_len; 55 flk64.l_pid = flk->l_pid; 56 // create a syscall 57 int retVal = syscall_impl<int>(SYS_fcntl, fd, cmd, &flk64); 58 // On failure, return 59 if (retVal == -1) 60 return -1; 61 // Check for overflow, i.e. the offsets are not the same when cast 62 // to off_t from off64_t. 63 if (static_cast<off_t>(flk64.l_len) != flk64.l_len || 64 static_cast<off_t>(flk64.l_start) != flk64.l_start) { 65 libc_errno = EOVERFLOW; 66 return -1; 67 } 68 // Now copy back into flk, in case flk64 got modified 69 flk->l_type = flk64.l_type; 70 flk->l_whence = flk64.l_whence; 71 flk->l_start = flk64.l_start; 72 flk->l_len = flk64.l_len; 73 flk->l_pid = flk64.l_pid; 74 return retVal; 75 } 76 case F_GETOWN: { 77 struct f_owner_ex fex; 78 int retVal = syscall_impl<int>(SYS_fcntl, fd, F_GETOWN_EX, &fex); 79 if (retVal == -EINVAL) 80 return syscall_impl<int>(SYS_fcntl, fd, cmd, 81 reinterpret_cast<void *>(arg)); 82 if (static_cast<unsigned long>(retVal) <= -4096UL) 83 return fex.type == F_OWNER_PGRP ? -fex.pid : fex.pid; 84 85 libc_errno = -retVal; 86 return -1; 87 } 88 // The general case 89 default: 90 return syscall_impl<int>(SYS_fcntl, fd, cmd, reinterpret_cast<void *>(arg)); 91 } 92 } 93 } // namespace LIBC_NAMESPACE 94