diff options
Diffstat (limited to 'Python/fileutils.c')
| -rw-r--r-- | Python/fileutils.c | 666 |
1 files changed, 594 insertions, 72 deletions
diff --git a/Python/fileutils.c b/Python/fileutils.c index 31689c047b..63c2571492 100644 --- a/Python/fileutils.c +++ b/Python/fileutils.c @@ -3,6 +3,7 @@ #include <locale.h> #ifdef MS_WINDOWS +# include <malloc.h> # include <windows.h> #endif @@ -29,7 +30,8 @@ extern wchar_t* _Py_DecodeUTF8_surrogateescape(const char *s, Py_ssize_t size); 0: open() ignores O_CLOEXEC flag, ex: Linux kernel older than 2.6.23 1: open() supports O_CLOEXEC flag, close-on-exec is set - The flag is used by _Py_open(), io.FileIO and os.open() */ + The flag is used by _Py_open(), _Py_open_noraise(), io.FileIO + and os.open(). */ int _Py_open_cloexec_works = -1; #endif @@ -82,11 +84,11 @@ extern int _Py_normalize_encoding(const char *, char *, size_t); Values of force_ascii: - 1: the workaround is used: _Py_wchar2char() uses - encode_ascii_surrogateescape() and _Py_char2wchar() uses + 1: the workaround is used: Py_EncodeLocale() uses + encode_ascii_surrogateescape() and Py_DecodeLocale() uses decode_ascii_surrogateescape() - 0: the workaround is not used: _Py_wchar2char() uses wcstombs() and - _Py_char2wchar() uses mbstowcs() + 0: the workaround is not used: Py_EncodeLocale() uses wcstombs() and + Py_DecodeLocale() uses mbstowcs() -1: unknown, need to call check_force_ascii() to get the value */ static int force_ascii = -1; @@ -244,24 +246,26 @@ decode_ascii_surrogateescape(const char *arg, size_t *size) /* Decode a byte string from the locale encoding with the - surrogateescape error handler (undecodable bytes are decoded as characters - in range U+DC80..U+DCFF). If a byte sequence can be decoded as a surrogate + surrogateescape error handler: undecodable bytes are decoded as characters + in range U+DC80..U+DCFF. If a byte sequence can be decoded as a surrogate character, escape the bytes using the surrogateescape error handler instead of decoding them. - Use _Py_wchar2char() to encode the character string back to a byte string. + Return a pointer to a newly allocated wide character string, use + PyMem_RawFree() to free the memory. If size is not NULL, write the number of + wide characters excluding the null character into *size - Return a pointer to a newly allocated wide character string (use - PyMem_RawFree() to free the memory) and write the number of written wide - characters excluding the null character into *size if size is not NULL, or - NULL on error (decoding or memory allocation error). If size is not NULL, - *size is set to (size_t)-1 on memory error and (size_t)-2 on decoding - error. + Return NULL on decoding error or memory allocation error. If *size* is not + NULL, *size is set to (size_t)-1 on memory error or set to (size_t)-2 on + decoding error. + + Decoding errors should never happen, unless there is a bug in the C + library. - Conversion errors should never happen, unless there is a bug in the C - library. */ + Use the Py_EncodeLocale() function to encode the character string back to a + byte string. */ wchar_t* -_Py_char2wchar(const char* arg, size_t *size) +Py_DecodeLocale(const char* arg, size_t *size) { #ifdef __APPLE__ wchar_t *wstr; @@ -399,19 +403,20 @@ oom: #endif /* __APPLE__ */ } -/* Encode a (wide) character string to the locale encoding with the - surrogateescape error handler (characters in range U+DC80..U+DCFF are - converted to bytes 0x80..0xFF). +/* Encode a wide character string to the locale encoding with the + surrogateescape error handler: surrogate characters in the range + U+DC80..U+DCFF are converted to bytes 0x80..0xFF. - This function is the reverse of _Py_char2wchar(). + Return a pointer to a newly allocated byte string, use PyMem_Free() to free + the memory. Return NULL on encoding or memory allocation error. - Return a pointer to a newly allocated byte string (use PyMem_Free() to free - the memory), or NULL on encoding or memory allocation error. + If error_pos is not NULL, *error_pos is set to the index of the invalid + character on encoding error, or set to (size_t)-1 otherwise. - If error_pos is not NULL: *error_pos is the index of the invalid character - on encoding error, or (size_t)-1 otherwise. */ + Use the Py_DecodeLocale() function to decode the bytes string back to a wide + character string. */ char* -_Py_wchar2char(const wchar_t *text, size_t *error_pos) +Py_EncodeLocale(const wchar_t *text, size_t *error_pos) { #ifdef __APPLE__ Py_ssize_t len; @@ -514,23 +519,14 @@ _Py_wchar2char(const wchar_t *text, size_t *error_pos) #endif /* __APPLE__ */ } -/* In principle, this should use HAVE__WSTAT, and _wstat - should be detected by autoconf. However, no current - POSIX system provides that function, so testing for - it is pointless. - Not sure whether the MS_WINDOWS guards are necessary: - perhaps for cygwin/mingw builds? -*/ -#if defined(HAVE_STAT) && !defined(MS_WINDOWS) /* Get file status. Encode the path to the locale encoding. */ - int _Py_wstat(const wchar_t* path, struct stat *buf) { int err; char *fname; - fname = _Py_wchar2char(path, NULL); + fname = Py_EncodeLocale(path, NULL); if (fname == NULL) { errno = EINVAL; return -1; @@ -539,9 +535,139 @@ _Py_wstat(const wchar_t* path, struct stat *buf) PyMem_Free(fname); return err; } + + +#ifdef MS_WINDOWS +static __int64 secs_between_epochs = 11644473600; /* Seconds between 1.1.1601 and 1.1.1970 */ + +static void +FILE_TIME_to_time_t_nsec(FILETIME *in_ptr, time_t *time_out, int* nsec_out) +{ + /* XXX endianness. Shouldn't matter, as all Windows implementations are little-endian */ + /* Cannot simply cast and dereference in_ptr, + since it might not be aligned properly */ + __int64 in; + memcpy(&in, in_ptr, sizeof(in)); + *nsec_out = (int)(in % 10000000) * 100; /* FILETIME is in units of 100 nsec. */ + *time_out = Py_SAFE_DOWNCAST((in / 10000000) - secs_between_epochs, __int64, time_t); +} + +void +_Py_time_t_to_FILE_TIME(time_t time_in, int nsec_in, FILETIME *out_ptr) +{ + /* XXX endianness */ + __int64 out; + out = time_in + secs_between_epochs; + out = out * 10000000 + nsec_in / 100; + memcpy(out_ptr, &out, sizeof(out)); +} + +/* Below, we *know* that ugo+r is 0444 */ +#if _S_IREAD != 0400 +#error Unsupported C library +#endif +static int +attributes_to_mode(DWORD attr) +{ + int m = 0; + if (attr & FILE_ATTRIBUTE_DIRECTORY) + m |= _S_IFDIR | 0111; /* IFEXEC for user,group,other */ + else + m |= _S_IFREG; + if (attr & FILE_ATTRIBUTE_READONLY) + m |= 0444; + else + m |= 0666; + return m; +} + +void +_Py_attribute_data_to_stat(BY_HANDLE_FILE_INFORMATION *info, ULONG reparse_tag, struct _Py_stat_struct *result) +{ + memset(result, 0, sizeof(*result)); + result->st_mode = attributes_to_mode(info->dwFileAttributes); + result->st_size = (((__int64)info->nFileSizeHigh)<<32) + info->nFileSizeLow; + result->st_dev = info->dwVolumeSerialNumber; + result->st_rdev = result->st_dev; + FILE_TIME_to_time_t_nsec(&info->ftCreationTime, &result->st_ctime, &result->st_ctime_nsec); + FILE_TIME_to_time_t_nsec(&info->ftLastWriteTime, &result->st_mtime, &result->st_mtime_nsec); + FILE_TIME_to_time_t_nsec(&info->ftLastAccessTime, &result->st_atime, &result->st_atime_nsec); + result->st_nlink = info->nNumberOfLinks; + result->st_ino = (((__int64)info->nFileIndexHigh)<<32) + info->nFileIndexLow; + if (reparse_tag == IO_REPARSE_TAG_SYMLINK) { + /* first clear the S_IFMT bits */ + result->st_mode ^= (result->st_mode & S_IFMT); + /* now set the bits that make this a symlink */ + result->st_mode |= S_IFLNK; + } + result->st_file_attributes = info->dwFileAttributes; +} +#endif + +/* Return information about a file. + + On POSIX, use fstat(). + + On Windows, use GetFileType() and GetFileInformationByHandle() which support + files larger than 2 GB. fstat() may fail with EOVERFLOW on files larger + than 2 GB because the file size type is an signed 32-bit integer: see issue + #23152. + */ +int +_Py_fstat(int fd, struct _Py_stat_struct *result) +{ +#ifdef MS_WINDOWS + BY_HANDLE_FILE_INFORMATION info; + HANDLE h; + int type; + + if (!_PyVerify_fd(fd)) + h = INVALID_HANDLE_VALUE; + else + h = (HANDLE)_get_osfhandle(fd); + + /* Protocol violation: we explicitly clear errno, instead of + setting it to a POSIX error. Callers should use GetLastError. */ + errno = 0; + + if (h == INVALID_HANDLE_VALUE) { + /* This is really a C library error (invalid file handle). + We set the Win32 error to the closes one matching. */ + SetLastError(ERROR_INVALID_HANDLE); + return -1; + } + memset(result, 0, sizeof(*result)); + + type = GetFileType(h); + if (type == FILE_TYPE_UNKNOWN) { + DWORD error = GetLastError(); + if (error != 0) { + return -1; + } + /* else: valid but unknown file */ + } + + if (type != FILE_TYPE_DISK) { + if (type == FILE_TYPE_CHAR) + result->st_mode = _S_IFCHR; + else if (type == FILE_TYPE_PIPE) + result->st_mode = _S_IFIFO; + return 0; + } + + if (!GetFileInformationByHandle(h, &info)) { + return -1; + } + + _Py_attribute_data_to_stat(&info, 0, result); + /* specific to fstat() */ + result->st_ino = (((__int64)info.nFileIndexHigh)<<32) + info.nFileIndexLow; + return 0; +#else + return fstat(fd, result); #endif +} -#ifdef HAVE_STAT /* Call _wstat() on Windows, or encode the path to the filesystem encoding and call stat() otherwise. Only fill st_mode attribute on Windows. @@ -575,7 +701,6 @@ _Py_stat(PyObject *path, struct stat *statbuf) #endif } -#endif static int get_inheritable(int fd, int raise) @@ -767,40 +892,90 @@ _Py_set_inheritable(int fd, int inheritable, int *atomic_flag_works) return set_inheritable(fd, inheritable, 1, atomic_flag_works); } -/* Open a file with the specified flags (wrapper to open() function). - The file descriptor is created non-inheritable. */ -int -_Py_open(const char *pathname, int flags) +static int +_Py_open_impl(const char *pathname, int flags, int gil_held) { int fd; -#ifdef MS_WINDOWS - fd = open(pathname, flags | O_NOINHERIT); - if (fd < 0) - return fd; -#else - + int async_err = 0; +#ifndef MS_WINDOWS int *atomic_flag_works; -#ifdef O_CLOEXEC +#endif + +#ifdef MS_WINDOWS + flags |= O_NOINHERIT; +#elif defined(O_CLOEXEC) atomic_flag_works = &_Py_open_cloexec_works; flags |= O_CLOEXEC; #else atomic_flag_works = NULL; #endif - fd = open(pathname, flags); - if (fd < 0) - return fd; - if (set_inheritable(fd, 0, 0, atomic_flag_works) < 0) { + if (gil_held) { + do { + Py_BEGIN_ALLOW_THREADS + fd = open(pathname, flags); + Py_END_ALLOW_THREADS + } while (fd < 0 + && errno == EINTR && !(async_err = PyErr_CheckSignals())); + if (async_err) + return -1; + if (fd < 0) { + PyErr_SetFromErrnoWithFilename(PyExc_OSError, pathname); + return -1; + } + } + else { + fd = open(pathname, flags); + if (fd < 0) + return -1; + } + +#ifndef MS_WINDOWS + if (set_inheritable(fd, 0, gil_held, atomic_flag_works) < 0) { close(fd); return -1; } -#endif /* !MS_WINDOWS */ +#endif + return fd; } +/* Open a file with the specified flags (wrapper to open() function). + Return a file descriptor on success. Raise an exception and return -1 on + error. + + The file descriptor is created non-inheritable. + + When interrupted by a signal (open() fails with EINTR), retry the syscall, + except if the Python signal handler raises an exception. + + The GIL must be held. */ +int +_Py_open(const char *pathname, int flags) +{ + /* _Py_open() must be called with the GIL held. */ + assert(PyGILState_Check()); + return _Py_open_impl(pathname, flags, 1); +} + +/* Open a file with the specified flags (wrapper to open() function). + Return a file descriptor on success. Set errno and return -1 on error. + + The file descriptor is created non-inheritable. + + If interrupted by a signal, fail with EINTR. */ +int +_Py_open_noraise(const char *pathname, int flags) +{ + return _Py_open_impl(pathname, flags, 0); +} + /* Open a file. Use _wfopen() on Windows, encode the path to the locale - encoding and use fopen() otherwise. The file descriptor is created - non-inheritable. */ + encoding and use fopen() otherwise. + + The file descriptor is created non-inheritable. + + If interrupted by a signal, fail with EINTR. */ FILE * _Py_wfopen(const wchar_t *path, const wchar_t *mode) { @@ -814,7 +989,7 @@ _Py_wfopen(const wchar_t *path, const wchar_t *mode) errno = EINVAL; return NULL; } - cpath = _Py_wchar2char(path, NULL); + cpath = Py_EncodeLocale(path, NULL); if (cpath == NULL) return NULL; f = fopen(cpath, cmode); @@ -831,7 +1006,11 @@ _Py_wfopen(const wchar_t *path, const wchar_t *mode) return f; } -/* Wrapper to fopen(). The file descriptor is created non-inheritable. */ +/* Wrapper to fopen(). + + The file descriptor is created non-inheritable. + + If interrupted by a signal, fail with EINTR. */ FILE* _Py_fopen(const char *pathname, const char *mode) { @@ -846,20 +1025,29 @@ _Py_fopen(const char *pathname, const char *mode) } /* Open a file. Call _wfopen() on Windows, or encode the path to the filesystem - encoding and call fopen() otherwise. The file descriptor is created - non-inheritable. + encoding and call fopen() otherwise. + + Return the new file object on success. Raise an exception and return NULL + on error. + + The file descriptor is created non-inheritable. + + When interrupted by a signal (open() fails with EINTR), retry the syscall, + except if the Python signal handler raises an exception. - Return the new file object on success, or NULL if the file cannot be open or - (if PyErr_Occurred()) on unicode error. */ + The GIL must be held. */ FILE* _Py_fopen_obj(PyObject *path, const char *mode) { FILE *f; + int async_err = 0; #ifdef MS_WINDOWS wchar_t *wpath; wchar_t wmode[10]; int usize; + assert(PyGILState_Check()); + if (!PyUnicode_Check(path)) { PyErr_Format(PyExc_TypeError, "str file path expected under Windows, got %R", @@ -871,26 +1059,208 @@ _Py_fopen_obj(PyObject *path, const char *mode) return NULL; usize = MultiByteToWideChar(CP_ACP, 0, mode, -1, wmode, sizeof(wmode)); - if (usize == 0) + if (usize == 0) { + PyErr_SetFromWindowsErr(0); return NULL; + } - f = _wfopen(wpath, wmode); + do { + Py_BEGIN_ALLOW_THREADS + f = _wfopen(wpath, wmode); + Py_END_ALLOW_THREADS + } while (f == NULL + && errno == EINTR && !(async_err = PyErr_CheckSignals())); #else PyObject *bytes; + char *path_bytes; + + assert(PyGILState_Check()); + if (!PyUnicode_FSConverter(path, &bytes)) return NULL; - f = fopen(PyBytes_AS_STRING(bytes), mode); + path_bytes = PyBytes_AS_STRING(bytes); + + do { + Py_BEGIN_ALLOW_THREADS + f = fopen(path_bytes, mode); + Py_END_ALLOW_THREADS + } while (f == NULL + && errno == EINTR && !(async_err = PyErr_CheckSignals())); + Py_DECREF(bytes); #endif - if (f == NULL) + if (async_err) return NULL; - if (make_non_inheritable(fileno(f)) < 0) { + + if (f == NULL) { + PyErr_SetFromErrnoWithFilenameObject(PyExc_OSError, path); + return NULL; + } + + if (set_inheritable(fileno(f), 0, 1, NULL) < 0) { fclose(f); return NULL; } return f; } +/* Read count bytes from fd into buf. + * + * On success, return the number of read bytes, it can be lower than count. + * If the current file offset is at or past the end of file, no bytes are read, + * and read() returns zero. + * + * On error, raise an exception, set errno and return -1. + * + * When interrupted by a signal (read() fails with EINTR), retry the syscall. + * If the Python signal handler raises an exception, the function returns -1 + * (the syscall is not retried). + * + * The GIL must be held. */ +Py_ssize_t +_Py_read(int fd, void *buf, size_t count) +{ + Py_ssize_t n; + int err; + int async_err = 0; + + /* _Py_read() must not be called with an exception set, otherwise the + * caller may think that read() was interrupted by a signal and the signal + * handler raised an exception. */ + assert(!PyErr_Occurred()); + + if (!_PyVerify_fd(fd)) { + /* save/restore errno because PyErr_SetFromErrno() can modify it */ + err = errno; + PyErr_SetFromErrno(PyExc_OSError); + errno = err; + return -1; + } + +#ifdef MS_WINDOWS + if (count > INT_MAX) { + /* On Windows, the count parameter of read() is an int */ + count = INT_MAX; + } +#else + if (count > PY_SSIZE_T_MAX) { + /* if count is greater than PY_SSIZE_T_MAX, + * read() result is undefined */ + count = PY_SSIZE_T_MAX; + } +#endif + + do { + Py_BEGIN_ALLOW_THREADS + errno = 0; +#ifdef MS_WINDOWS + n = read(fd, buf, (int)count); +#else + n = read(fd, buf, count); +#endif + /* save/restore errno because PyErr_CheckSignals() + * and PyErr_SetFromErrno() can modify it */ + err = errno; + Py_END_ALLOW_THREADS + } while (n < 0 && err == EINTR && + !(async_err = PyErr_CheckSignals())); + + if (async_err) { + /* read() was interrupted by a signal (failed with EINTR) + * and the Python signal handler raised an exception */ + errno = err; + assert(errno == EINTR && PyErr_Occurred()); + return -1; + } + if (n < 0) { + PyErr_SetFromErrno(PyExc_OSError); + errno = err; + return -1; + } + + return n; +} + +/* Write count bytes of buf into fd. + * + * -On success, return the number of written bytes, it can be lower than count + * including 0 + * - On error, raise an exception, set errno and return -1. + * + * When interrupted by a signal (write() fails with EINTR), retry the syscall. + * If the Python signal handler raises an exception, the function returns -1 + * (the syscall is not retried). + * + * The GIL must be held. */ +Py_ssize_t +_Py_write(int fd, const void *buf, size_t count) +{ + Py_ssize_t n; + int err; + int async_err = 0; + + /* _Py_write() must not be called with an exception set, otherwise the + * caller may think that write() was interrupted by a signal and the signal + * handler raised an exception. */ + assert(!PyErr_Occurred()); + + if (!_PyVerify_fd(fd)) { + /* save/restore errno because PyErr_SetFromErrno() can modify it */ + err = errno; + PyErr_SetFromErrno(PyExc_OSError); + errno = err; + return -1; + } + +#ifdef MS_WINDOWS + if (count > 32767 && isatty(fd)) { + /* Issue #11395: the Windows console returns an error (12: not + enough space error) on writing into stdout if stdout mode is + binary and the length is greater than 66,000 bytes (or less, + depending on heap usage). */ + count = 32767; + } + else if (count > INT_MAX) + count = INT_MAX; +#else + if (count > PY_SSIZE_T_MAX) { + /* write() should truncate count to PY_SSIZE_T_MAX, but it's safer + * to do it ourself to have a portable behaviour. */ + count = PY_SSIZE_T_MAX; + } +#endif + + do { + Py_BEGIN_ALLOW_THREADS + errno = 0; +#ifdef MS_WINDOWS + n = write(fd, buf, (int)count); +#else + n = write(fd, buf, count); +#endif + /* save/restore errno because PyErr_CheckSignals() + * and PyErr_SetFromErrno() can modify it */ + err = errno; + Py_END_ALLOW_THREADS + } while (n < 0 && errno == EINTR && + !(async_err = PyErr_CheckSignals())); + + if (async_err) { + /* write() was interrupted by a signal (failed with EINTR) + * and the Python signal handler raised an exception */ + errno = err; + assert(errno == EINTR && PyErr_Occurred()); + return -1; + } + if (n < 0) { + PyErr_SetFromErrno(PyExc_OSError); + errno = err; + return -1; + } + + return n; +} + #ifdef HAVE_READLINK /* Read value of symbolic link. Encode the path to the locale encoding, decode @@ -905,7 +1275,7 @@ _Py_wreadlink(const wchar_t *path, wchar_t *buf, size_t bufsiz) int res; size_t r1; - cpath = _Py_wchar2char(path, NULL); + cpath = Py_EncodeLocale(path, NULL); if (cpath == NULL) { errno = EINVAL; return -1; @@ -919,7 +1289,7 @@ _Py_wreadlink(const wchar_t *path, wchar_t *buf, size_t bufsiz) return -1; } cbuf[res] = '\0'; /* buf will be null terminated */ - wbuf = _Py_char2wchar(cbuf, &r1); + wbuf = Py_DecodeLocale(cbuf, &r1); if (wbuf == NULL) { errno = EINVAL; return -1; @@ -950,7 +1320,7 @@ _Py_wrealpath(const wchar_t *path, wchar_t *wresolved_path; char *res; size_t r; - cpath = _Py_wchar2char(path, NULL); + cpath = Py_EncodeLocale(path, NULL); if (cpath == NULL) { errno = EINVAL; return NULL; @@ -960,7 +1330,7 @@ _Py_wrealpath(const wchar_t *path, if (res == NULL) return NULL; - wresolved_path = _Py_char2wchar(cresolved_path, &r); + wresolved_path = Py_DecodeLocale(cresolved_path, &r); if (wresolved_path == NULL) { errno = EINVAL; return NULL; @@ -993,7 +1363,7 @@ _Py_wgetcwd(wchar_t *buf, size_t size) if (getcwd(fname, Py_ARRAY_LENGTH(fname)) == NULL) return NULL; - wname = _Py_char2wchar(fname, &len); + wname = Py_DecodeLocale(fname, &len); if (wname == NULL) return NULL; if (size <= len) { @@ -1075,3 +1445,155 @@ _Py_dup(int fd) return fd; } +#ifndef MS_WINDOWS +/* Get the blocking mode of the file descriptor. + Return 0 if the O_NONBLOCK flag is set, 1 if the flag is cleared, + raise an exception and return -1 on error. */ +int +_Py_get_blocking(int fd) +{ + int flags = fcntl(fd, F_GETFL, 0); + if (flags < 0) { + PyErr_SetFromErrno(PyExc_OSError); + return -1; + } + + return !(flags & O_NONBLOCK); +} + +/* Set the blocking mode of the specified file descriptor. + + Set the O_NONBLOCK flag if blocking is False, clear the O_NONBLOCK flag + otherwise. + + Return 0 on success, raise an exception and return -1 on error. */ +int +_Py_set_blocking(int fd, int blocking) +{ +#if defined(HAVE_SYS_IOCTL_H) && defined(FIONBIO) + int arg = !blocking; + if (ioctl(fd, FIONBIO, &arg) < 0) + goto error; +#else + int flags, res; + + flags = fcntl(fd, F_GETFL, 0); + if (flags < 0) + goto error; + + if (blocking) + flags = flags & (~O_NONBLOCK); + else + flags = flags | O_NONBLOCK; + + res = fcntl(fd, F_SETFL, flags); + if (res < 0) + goto error; +#endif + return 0; + +error: + PyErr_SetFromErrno(PyExc_OSError); + return -1; +} +#endif + +#ifdef _MSC_VER +#if _MSC_VER >= 1900 + +/* This function lets the Windows CRT validate the file handle without + terminating the process if it's invalid. */ +int +_PyVerify_fd(int fd) +{ + intptr_t osh; + /* Fast check for the only condition we know */ + if (fd < 0) { + _set_errno(EBADF); + return 0; + } + osh = _get_osfhandle(fd); + return osh != (intptr_t)-1; +} + +#elif _MSC_VER >= 1400 +/* Legacy implementation of _PyVerify_fd while transitioning to + * MSVC 14.0. This should eventually be removed. (issue23524) + */ + +/* Microsoft CRT in VS2005 and higher will verify that a filehandle is + * valid and raise an assertion if it isn't. + * Normally, an invalid fd is likely to be a C program error and therefore + * an assertion can be useful, but it does contradict the POSIX standard + * which for write(2) states: + * "Otherwise, -1 shall be returned and errno set to indicate the error." + * "[EBADF] The fildes argument is not a valid file descriptor open for + * writing." + * Furthermore, python allows the user to enter any old integer + * as a fd and should merely raise a python exception on error. + * The Microsoft CRT doesn't provide an official way to check for the + * validity of a file descriptor, but we can emulate its internal behaviour + * by using the exported __pinfo data member and knowledge of the + * internal structures involved. + * The structures below must be updated for each version of visual studio + * according to the file internal.h in the CRT source, until MS comes + * up with a less hacky way to do this. + * (all of this is to avoid globally modifying the CRT behaviour using + * _set_invalid_parameter_handler() and _CrtSetReportMode()) + */ +/* The actual size of the structure is determined at runtime. + * Only the first items must be present. + */ +typedef struct { + intptr_t osfhnd; + char osfile; +} my_ioinfo; + +extern __declspec(dllimport) char * __pioinfo[]; +#define IOINFO_L2E 5 +#define IOINFO_ARRAYS 64 +#define IOINFO_ARRAY_ELTS (1 << IOINFO_L2E) +#define _NHANDLE_ (IOINFO_ARRAYS * IOINFO_ARRAY_ELTS) +#define FOPEN 0x01 +#define _NO_CONSOLE_FILENO (intptr_t)-2 + +/* This function emulates what the windows CRT does to validate file handles */ +int +_PyVerify_fd(int fd) +{ + const int i1 = fd >> IOINFO_L2E; + const int i2 = fd & ((1 << IOINFO_L2E) - 1); + + static size_t sizeof_ioinfo = 0; + + /* Determine the actual size of the ioinfo structure, + * as used by the CRT loaded in memory + */ + if (sizeof_ioinfo == 0 && __pioinfo[0] != NULL) { + sizeof_ioinfo = _msize(__pioinfo[0]) / IOINFO_ARRAY_ELTS; + } + if (sizeof_ioinfo == 0) { + /* This should not happen... */ + goto fail; + } + + /* See that it isn't a special CLEAR fileno */ + if (fd != _NO_CONSOLE_FILENO) { + /* Microsoft CRT would check that 0<=fd<_nhandle but we can't do that. Instead + * we check pointer validity and other info + */ + if (0 <= i1 && i1 < IOINFO_ARRAYS && __pioinfo[i1] != NULL) { + /* finally, check that the file is open */ + my_ioinfo* info = (my_ioinfo*)(__pioinfo[i1] + i2 * sizeof_ioinfo); + if (info->osfile & FOPEN) { + return 1; + } + } + } + fail: + errno = EBADF; + return 0; +} + +#endif /* _MSC_VER >= 1900 || _MSC_VER >= 1400 */ +#endif /* defined _MSC_VER */ |