1/* Provide file descriptor control. 2 3 Copyright (C) 2009, 2010 Free Software Foundation, Inc. 4 5 This program is free software: you can redistribute it and/or modify 6 it under the terms of the GNU General Public License as published by 7 the Free Software Foundation; either version 3 of the License, or 8 (at your option) any later version. 9 10 This program is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 GNU General Public License for more details. 14 15 You should have received a copy of the GNU General Public License 16 along with this program. If not, see <http://www.gnu.org/licenses/>. */ 17 18/* Written by Eric Blake <ebb9@byu.net>. */ 19 20#include <config.h> 21 22/* Specification. */ 23#include <fcntl.h> 24 25#include <errno.h> 26#include <limits.h> 27#include <stdarg.h> 28#include <unistd.h> 29 30#if !HAVE_FCNTL 31# define rpl_fcntl fcntl 32#endif 33#undef fcntl 34 35#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__ 36/* Get declarations of the Win32 API functions. */ 37# define WIN32_LEAN_AND_MEAN 38# include <windows.h> 39 40/* Upper bound on getdtablesize(). See lib/getdtablesize.c. */ 41# define OPEN_MAX_MAX 0x10000 42 43/* Duplicate OLDFD into the first available slot of at least NEWFD, 44 which must be positive, with FLAGS determining whether the duplicate 45 will be inheritable. */ 46static int 47dupfd (int oldfd, int newfd, int flags) 48{ 49 /* Mingw has no way to create an arbitrary fd. Iterate until all 50 file descriptors less than newfd are filled up. */ 51 HANDLE curr_process = GetCurrentProcess (); 52 HANDLE old_handle = (HANDLE) _get_osfhandle (oldfd); 53 unsigned char fds_to_close[OPEN_MAX_MAX / CHAR_BIT]; 54 unsigned int fds_to_close_bound = 0; 55 int result; 56 BOOL inherit = flags & O_CLOEXEC ? FALSE : TRUE; 57 int mode; 58 59 if (newfd < 0 || getdtablesize () <= newfd) 60 { 61 errno = EINVAL; 62 return -1; 63 } 64 if (old_handle == INVALID_HANDLE_VALUE 65 || (mode = setmode (oldfd, O_BINARY)) == -1) 66 { 67 /* oldfd is not open, or is an unassigned standard file 68 descriptor. */ 69 errno = EBADF; 70 return -1; 71 } 72 setmode (oldfd, mode); 73 flags |= mode; 74 75 for (;;) 76 { 77 HANDLE new_handle; 78 int duplicated_fd; 79 unsigned int index; 80 81 if (!DuplicateHandle (curr_process, /* SourceProcessHandle */ 82 old_handle, /* SourceHandle */ 83 curr_process, /* TargetProcessHandle */ 84 (PHANDLE) &new_handle, /* TargetHandle */ 85 (DWORD) 0, /* DesiredAccess */ 86 inherit, /* InheritHandle */ 87 DUPLICATE_SAME_ACCESS)) /* Options */ 88 { 89 /* TODO: Translate GetLastError () into errno. */ 90 errno = EMFILE; 91 result = -1; 92 break; 93 } 94 duplicated_fd = _open_osfhandle ((long) new_handle, flags); 95 if (duplicated_fd < 0) 96 { 97 CloseHandle (new_handle); 98 errno = EMFILE; 99 result = -1; 100 break; 101 } 102 if (newfd <= duplicated_fd) 103 { 104 result = duplicated_fd; 105 break; 106 } 107 108 /* Set the bit duplicated_fd in fds_to_close[]. */ 109 index = (unsigned int) duplicated_fd / CHAR_BIT; 110 if (fds_to_close_bound <= index) 111 { 112 if (sizeof fds_to_close <= index) 113 /* Need to increase OPEN_MAX_MAX. */ 114 abort (); 115 memset (fds_to_close + fds_to_close_bound, '\0', 116 index + 1 - fds_to_close_bound); 117 fds_to_close_bound = index + 1; 118 } 119 fds_to_close[index] |= 1 << ((unsigned int) duplicated_fd % CHAR_BIT); 120 } 121 122 /* Close the previous fds that turned out to be too small. */ 123 { 124 int saved_errno = errno; 125 unsigned int duplicated_fd; 126 127 for (duplicated_fd = 0; 128 duplicated_fd < fds_to_close_bound * CHAR_BIT; 129 duplicated_fd++) 130 if ((fds_to_close[duplicated_fd / CHAR_BIT] 131 >> (duplicated_fd % CHAR_BIT)) 132 & 1) 133 close (duplicated_fd); 134 135 errno = saved_errno; 136 } 137 138# if REPLACE_FCHDIR 139 if (0 <= result) 140 result = _gl_register_dup (oldfd, result); 141# endif 142 return result; 143} 144#endif /* W32 */ 145 146/* Perform the specified ACTION on the file descriptor FD, possibly 147 using the argument ARG further described below. This replacement 148 handles the following actions, and forwards all others on to the 149 native fcntl. An unrecognized ACTION returns -1 with errno set to 150 EINVAL. 151 152 F_DUPFD - duplicate FD, with int ARG being the minimum target fd. 153 If successful, return the duplicate, which will be inheritable; 154 otherwise return -1 and set errno. 155 156 F_DUPFD_CLOEXEC - duplicate FD, with int ARG being the minimum 157 target fd. If successful, return the duplicate, which will not be 158 inheritable; otherwise return -1 and set errno. 159 160 F_GETFD - ARG need not be present. If successful, return a 161 non-negative value containing the descriptor flags of FD (only 162 FD_CLOEXEC is portable, but other flags may be present); otherwise 163 return -1 and set errno. */ 164 165int 166rpl_fcntl (int fd, int action, /* arg */...) 167{ 168 va_list arg; 169 int result = -1; 170 va_start (arg, action); 171 switch (action) 172 { 173 174#if !HAVE_FCNTL 175 case F_DUPFD: 176 { 177 int target = va_arg (arg, int); 178 result = dupfd (fd, target, 0); 179 break; 180 } 181#elif FCNTL_DUPFD_BUGGY || REPLACE_FCHDIR 182 case F_DUPFD: 183 { 184 int target = va_arg (arg, int); 185 /* Detect invalid target; needed for cygwin 1.5.x. */ 186 if (target < 0 || getdtablesize () <= target) 187 errno = EINVAL; 188 else 189 { 190 result = fcntl (fd, action, target); 191# if REPLACE_FCHDIR 192 if (0 <= result) 193 result = _gl_register_dup (fd, result); 194# endif 195 } 196 break; 197 } /* F_DUPFD */ 198#endif /* FCNTL_DUPFD_BUGGY || REPLACE_FCHDIR */ 199 200 case F_DUPFD_CLOEXEC: 201 { 202 int target = va_arg (arg, int); 203 204#if !HAVE_FCNTL 205 result = dupfd (fd, target, O_CLOEXEC); 206 break; 207#else /* HAVE_FCNTL */ 208 /* Try the system call first, if the headers claim it exists 209 (that is, if GNULIB_defined_F_DUPFD_CLOEXEC is 0), since we 210 may be running with a glibc that has the macro but with an 211 older kernel that does not support it. Cache the 212 information on whether the system call really works, but 213 avoid caching failure if the corresponding F_DUPFD fails 214 for any reason. 0 = unknown, 1 = yes, -1 = no. */ 215 static int have_dupfd_cloexec = GNULIB_defined_F_DUPFD_CLOEXEC ? -1 : 0; 216 if (0 <= have_dupfd_cloexec) 217 { 218 result = fcntl (fd, action, target); 219 if (0 <= result || errno != EINVAL) 220 { 221 have_dupfd_cloexec = 1; 222# if REPLACE_FCHDIR 223 if (0 <= result) 224 result = _gl_register_dup (fd, result); 225# endif 226 } 227 else 228 { 229 result = rpl_fcntl (fd, F_DUPFD, target); 230 if (result < 0) 231 break; 232 have_dupfd_cloexec = -1; 233 } 234 } 235 else 236 result = rpl_fcntl (fd, F_DUPFD, target); 237 if (0 <= result && have_dupfd_cloexec == -1) 238 { 239 int flags = fcntl (result, F_GETFD); 240 if (flags < 0 || fcntl (result, F_SETFD, flags | FD_CLOEXEC) == -1) 241 { 242 int saved_errno = errno; 243 close (result); 244 errno = saved_errno; 245 result = -1; 246 } 247 } 248 break; 249#endif /* HAVE_FCNTL */ 250 } /* F_DUPFD_CLOEXEC */ 251 252#if !HAVE_FCNTL 253 case F_GETFD: 254 { 255# if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__ 256 HANDLE handle = (HANDLE) _get_osfhandle (fd); 257 DWORD flags; 258 if (handle == INVALID_HANDLE_VALUE 259 || GetHandleInformation (handle, &flags) == 0) 260 errno = EBADF; 261 else 262 result = (flags & HANDLE_FLAG_INHERIT) ? 0 : FD_CLOEXEC; 263# else /* !W32 */ 264 /* Use dup2 to reject invalid file descriptors. No way to 265 access this information, so punt. */ 266 if (0 <= dup2 (fd, fd)) 267 result = 0; 268# endif /* !W32 */ 269 break; 270 } /* F_GETFD */ 271#endif /* !HAVE_FCNTL */ 272 273 /* Implementing F_SETFD on mingw is not trivial - there is no 274 API for changing the O_NOINHERIT bit on an fd, and merely 275 changing the HANDLE_FLAG_INHERIT bit on the underlying handle 276 can lead to odd state. It may be possible by duplicating the 277 handle, using _open_osfhandle with the right flags, then 278 using dup2 to move the duplicate onto the original, but that 279 is not supported for now. */ 280 281 default: 282 { 283#if HAVE_FCNTL 284 void *p = va_arg (arg, void *); 285 result = fcntl (fd, action, p); 286#else 287 errno = EINVAL; 288#endif 289 break; 290 } 291 } 292 va_end (arg); 293 return result; 294} 295