diff options
Diffstat (limited to 'lib/fcntl.c')
| -rw-r--r-- | lib/fcntl.c | 308 |
1 files changed, 308 insertions, 0 deletions
diff --git a/lib/fcntl.c b/lib/fcntl.c new file mode 100644 index 0000000..d6a328c --- /dev/null +++ b/lib/fcntl.c @@ -0,0 +1,308 @@ +/* Provide file descriptor control. + + Copyright (C) 2009-2011 Free Software Foundation, Inc. + + This program is free software: you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see <http://www.gnu.org/licenses/>. */ + +/* Written by Eric Blake <ebb9@byu.net>. */ + +#include <config.h> + +/* Specification. */ +#include <fcntl.h> + +#include <errno.h> +#include <limits.h> +#include <stdarg.h> +#include <unistd.h> + +#if !HAVE_FCNTL +# define rpl_fcntl fcntl +#endif +#undef fcntl + +#if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__ +/* Get declarations of the Win32 API functions. */ +# define WIN32_LEAN_AND_MEAN +# include <windows.h> + +/* Upper bound on getdtablesize(). See lib/getdtablesize.c. */ +# define OPEN_MAX_MAX 0x10000 + +/* Duplicate OLDFD into the first available slot of at least NEWFD, + which must be positive, with FLAGS determining whether the duplicate + will be inheritable. */ +static int +dupfd (int oldfd, int newfd, int flags) +{ + /* Mingw has no way to create an arbitrary fd. Iterate until all + file descriptors less than newfd are filled up. */ + HANDLE curr_process = GetCurrentProcess (); + HANDLE old_handle = (HANDLE) _get_osfhandle (oldfd); + unsigned char fds_to_close[OPEN_MAX_MAX / CHAR_BIT]; + unsigned int fds_to_close_bound = 0; + int result; + BOOL inherit = flags & O_CLOEXEC ? FALSE : TRUE; + int mode; + + if (newfd < 0 || getdtablesize () <= newfd) + { + errno = EINVAL; + return -1; + } + if (old_handle == INVALID_HANDLE_VALUE + || (mode = setmode (oldfd, O_BINARY)) == -1) + { + /* oldfd is not open, or is an unassigned standard file + descriptor. */ + errno = EBADF; + return -1; + } + setmode (oldfd, mode); + flags |= mode; + + for (;;) + { + HANDLE new_handle; + int duplicated_fd; + unsigned int index; + + if (!DuplicateHandle (curr_process, /* SourceProcessHandle */ + old_handle, /* SourceHandle */ + curr_process, /* TargetProcessHandle */ + (PHANDLE) &new_handle, /* TargetHandle */ + (DWORD) 0, /* DesiredAccess */ + inherit, /* InheritHandle */ + DUPLICATE_SAME_ACCESS)) /* Options */ + { + /* TODO: Translate GetLastError () into errno. */ + errno = EMFILE; + result = -1; + break; + } + duplicated_fd = _open_osfhandle ((long) new_handle, flags); + if (duplicated_fd < 0) + { + CloseHandle (new_handle); + errno = EMFILE; + result = -1; + break; + } + if (newfd <= duplicated_fd) + { + result = duplicated_fd; + break; + } + + /* Set the bit duplicated_fd in fds_to_close[]. */ + index = (unsigned int) duplicated_fd / CHAR_BIT; + if (fds_to_close_bound <= index) + { + if (sizeof fds_to_close <= index) + /* Need to increase OPEN_MAX_MAX. */ + abort (); + memset (fds_to_close + fds_to_close_bound, '\0', + index + 1 - fds_to_close_bound); + fds_to_close_bound = index + 1; + } + fds_to_close[index] |= 1 << ((unsigned int) duplicated_fd % CHAR_BIT); + } + + /* Close the previous fds that turned out to be too small. */ + { + int saved_errno = errno; + unsigned int duplicated_fd; + + for (duplicated_fd = 0; + duplicated_fd < fds_to_close_bound * CHAR_BIT; + duplicated_fd++) + if ((fds_to_close[duplicated_fd / CHAR_BIT] + >> (duplicated_fd % CHAR_BIT)) + & 1) + close (duplicated_fd); + + errno = saved_errno; + } + +# if REPLACE_FCHDIR + if (0 <= result) + result = _gl_register_dup (oldfd, result); +# endif + return result; +} +#endif /* W32 */ + +/* Perform the specified ACTION on the file descriptor FD, possibly + using the argument ARG further described below. This replacement + handles the following actions, and forwards all others on to the + native fcntl. An unrecognized ACTION returns -1 with errno set to + EINVAL. + + F_DUPFD - duplicate FD, with int ARG being the minimum target fd. + If successful, return the duplicate, which will be inheritable; + otherwise return -1 and set errno. + + F_DUPFD_CLOEXEC - duplicate FD, with int ARG being the minimum + target fd. If successful, return the duplicate, which will not be + inheritable; otherwise return -1 and set errno. + + F_GETFD - ARG need not be present. If successful, return a + non-negative value containing the descriptor flags of FD (only + FD_CLOEXEC is portable, but other flags may be present); otherwise + return -1 and set errno. */ + +int +rpl_fcntl (int fd, int action, /* arg */...) +{ + va_list arg; + int result = -1; + va_start (arg, action); + switch (action) + { + +#if !HAVE_FCNTL + case F_DUPFD: + { + int target = va_arg (arg, int); + result = dupfd (fd, target, 0); + break; + } +#elif FCNTL_DUPFD_BUGGY || REPLACE_FCHDIR + case F_DUPFD: + { + int target = va_arg (arg, int); + /* Detect invalid target; needed for cygwin 1.5.x. */ + if (target < 0 || getdtablesize () <= target) + errno = EINVAL; + else + { + /* Haiku alpha 2 loses fd flags on original. */ + int flags = fcntl (fd, F_GETFD); + if (flags < 0) + { + result = -1; + break; + } + result = fcntl (fd, action, target); + if (0 <= result && fcntl (fd, F_SETFD, flags) == -1) + { + int saved_errno = errno; + close (result); + result = -1; + errno = saved_errno; + } +# if REPLACE_FCHDIR + if (0 <= result) + result = _gl_register_dup (fd, result); +# endif + } + break; + } /* F_DUPFD */ +#endif /* FCNTL_DUPFD_BUGGY || REPLACE_FCHDIR */ + + case F_DUPFD_CLOEXEC: + { + int target = va_arg (arg, int); + +#if !HAVE_FCNTL + result = dupfd (fd, target, O_CLOEXEC); + break; +#else /* HAVE_FCNTL */ + /* Try the system call first, if the headers claim it exists + (that is, if GNULIB_defined_F_DUPFD_CLOEXEC is 0), since we + may be running with a glibc that has the macro but with an + older kernel that does not support it. Cache the + information on whether the system call really works, but + avoid caching failure if the corresponding F_DUPFD fails + for any reason. 0 = unknown, 1 = yes, -1 = no. */ + static int have_dupfd_cloexec = GNULIB_defined_F_DUPFD_CLOEXEC ? -1 : 0; + if (0 <= have_dupfd_cloexec) + { + result = fcntl (fd, action, target); + if (0 <= result || errno != EINVAL) + { + have_dupfd_cloexec = 1; +# if REPLACE_FCHDIR + if (0 <= result) + result = _gl_register_dup (fd, result); +# endif + } + else + { + result = rpl_fcntl (fd, F_DUPFD, target); + if (result < 0) + break; + have_dupfd_cloexec = -1; + } + } + else + result = rpl_fcntl (fd, F_DUPFD, target); + if (0 <= result && have_dupfd_cloexec == -1) + { + int flags = fcntl (result, F_GETFD); + if (flags < 0 || fcntl (result, F_SETFD, flags | FD_CLOEXEC) == -1) + { + int saved_errno = errno; + close (result); + errno = saved_errno; + result = -1; + } + } + break; +#endif /* HAVE_FCNTL */ + } /* F_DUPFD_CLOEXEC */ + +#if !HAVE_FCNTL + case F_GETFD: + { +# if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__ + HANDLE handle = (HANDLE) _get_osfhandle (fd); + DWORD flags; + if (handle == INVALID_HANDLE_VALUE + || GetHandleInformation (handle, &flags) == 0) + errno = EBADF; + else + result = (flags & HANDLE_FLAG_INHERIT) ? 0 : FD_CLOEXEC; +# else /* !W32 */ + /* Use dup2 to reject invalid file descriptors. No way to + access this information, so punt. */ + if (0 <= dup2 (fd, fd)) + result = 0; +# endif /* !W32 */ + break; + } /* F_GETFD */ +#endif /* !HAVE_FCNTL */ + + /* Implementing F_SETFD on mingw is not trivial - there is no + API for changing the O_NOINHERIT bit on an fd, and merely + changing the HANDLE_FLAG_INHERIT bit on the underlying handle + can lead to odd state. It may be possible by duplicating the + handle, using _open_osfhandle with the right flags, then + using dup2 to move the duplicate onto the original, but that + is not supported for now. */ + + default: + { +#if HAVE_FCNTL + void *p = va_arg (arg, void *); + result = fcntl (fd, action, p); +#else + errno = EINVAL; +#endif + break; + } + } + va_end (arg); + return result; +} |