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cpython/Modules/_fileio.c

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/* Author: Daniel Stutzbach */
#define PY_SSIZE_T_CLEAN
#include "Python.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stddef.h> /* For offsetof */
/*
* Known likely problems:
*
* - Files larger then 2**32-1
* - Files with unicode filenames
* - Passing numbers greater than 2**32-1 when an integer is expected
* - Making it work on Windows and other oddball platforms
*
* To Do:
*
* - autoconfify header file inclusion
*/
#ifdef MS_WINDOWS
/* can simulate truncate with Win32 API functions; see file_truncate */
#define HAVE_FTRUNCATE
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#endif
typedef struct {
PyObject_HEAD
int fd;
unsigned readable : 1;
unsigned writable : 1;
int seekable : 2; /* -1 means unknown */
int closefd : 1;
PyObject *weakreflist;
} PyFileIOObject;
PyTypeObject PyFileIO_Type;
#define PyFileIO_Check(op) (PyObject_TypeCheck((op), &PyFileIO_Type))
/* Returns 0 on success, errno (which is < 0) on failure. */
static int
internal_close(PyFileIOObject *self)
{
int save_errno = 0;
if (self->fd >= 0) {
int fd = self->fd;
self->fd = -1;
Py_BEGIN_ALLOW_THREADS
if (close(fd) < 0)
save_errno = errno;
Py_END_ALLOW_THREADS
}
return save_errno;
}
static PyObject *
fileio_close(PyFileIOObject *self)
{
if (!self->closefd) {
self->fd = -1;
Py_RETURN_NONE;
}
errno = internal_close(self);
if (errno < 0) {
PyErr_SetFromErrno(PyExc_IOError);
return NULL;
}
Py_RETURN_NONE;
}
static PyObject *
fileio_new(PyTypeObject *type, PyObject *args, PyObject *kews)
{
PyFileIOObject *self;
assert(type != NULL && type->tp_alloc != NULL);
self = (PyFileIOObject *) type->tp_alloc(type, 0);
if (self != NULL) {
self->fd = -1;
self->readable = 0;
self->writable = 0;
self->seekable = -1;
self->closefd = 1;
self->weakreflist = NULL;
}
return (PyObject *) self;
}
/* On Unix, open will succeed for directories.
In Python, there should be no file objects referring to
directories, so we need a check. */
static int
dircheck(PyFileIOObject* self)
{
#if defined(HAVE_FSTAT) && defined(S_IFDIR) && defined(EISDIR)
struct stat buf;
if (self->fd < 0)
return 0;
if (fstat(self->fd, &buf) == 0 && S_ISDIR(buf.st_mode)) {
char *msg = strerror(EISDIR);
PyObject *exc;
internal_close(self);
exc = PyObject_CallFunction(PyExc_IOError, "(is)",
EISDIR, msg);
PyErr_SetObject(PyExc_IOError, exc);
Py_XDECREF(exc);
return -1;
}
#endif
return 0;
}
static int
fileio_init(PyObject *oself, PyObject *args, PyObject *kwds)
{
PyFileIOObject *self = (PyFileIOObject *) oself;
static char *kwlist[] = {"file", "mode", "closefd", NULL};
char *name = NULL;
char *mode = "r";
char *s;
#ifdef MS_WINDOWS
Py_UNICODE *widename = NULL;
#endif
int ret = 0;
int rwa = 0, plus = 0, append = 0;
int flags = 0;
int fd = -1;
int closefd = 1;
assert(PyFileIO_Check(oself));
if (self->fd >= 0) {
/* Have to close the existing file first. */
if (internal_close(self) < 0)
return -1;
}
if (PyArg_ParseTupleAndKeywords(args, kwds, "i|si:fileio",
kwlist, &fd, &mode, &closefd)) {
if (fd < 0) {
PyErr_SetString(PyExc_ValueError,
"Negative filedescriptor");
return -1;
}
}
else {
PyErr_Clear();
#ifdef Py_WIN_WIDE_FILENAMES
if (GetVersion() < 0x80000000) {
/* On NT, so wide API available */
PyObject *po;
if (PyArg_ParseTupleAndKeywords(args, kwds, "U|si:fileio",
kwlist, &po, &mode, &closefd)
) {
widename = PyUnicode_AS_UNICODE(po);
} else {
/* Drop the argument parsing error as narrow
strings are also valid. */
PyErr_Clear();
}
}
if (widename == NULL)
#endif
{
if (!PyArg_ParseTupleAndKeywords(args, kwds, "et|si:fileio",
kwlist,
Py_FileSystemDefaultEncoding,
&name, &mode, &closefd))
return -1;
}
}
s = mode;
while (*s) {
switch (*s++) {
case 'r':
if (rwa) {
bad_mode:
PyErr_SetString(PyExc_ValueError,
"Must have exactly one of read/write/append mode");
goto error;
}
rwa = 1;
self->readable = 1;
break;
case 'w':
if (rwa)
goto bad_mode;
rwa = 1;
self->writable = 1;
flags |= O_CREAT | O_TRUNC;
break;
case 'a':
if (rwa)
goto bad_mode;
rwa = 1;
self->writable = 1;
flags |= O_CREAT;
append = 1;
break;
case '+':
if (plus)
goto bad_mode;
self->readable = self->writable = 1;
plus = 1;
break;
default:
PyErr_Format(PyExc_ValueError,
"invalid mode: %.200s", mode);
goto error;
}
}
if (!rwa)
goto bad_mode;
if (self->readable && self->writable)
flags |= O_RDWR;
else if (self->readable)
flags |= O_RDONLY;
else
flags |= O_WRONLY;
#ifdef O_BINARY
flags |= O_BINARY;
#endif
#ifdef O_APPEND
if (append)
flags |= O_APPEND;
#endif
if (fd >= 0) {
self->fd = fd;
self->closefd = closefd;
}
else {
self->closefd = 1;
if (!closefd) {
PyErr_SetString(PyExc_ValueError,
"Cannot use closefd=False with file name");
goto error;
}
Py_BEGIN_ALLOW_THREADS
errno = 0;
#ifdef MS_WINDOWS
if (widename != NULL)
self->fd = _wopen(widename, flags, 0666);
else
#endif
self->fd = open(name, flags, 0666);
Py_END_ALLOW_THREADS
if (self->fd < 0) {
#ifdef MS_WINDOWS
PyErr_SetFromErrnoWithUnicodeFilename(PyExc_IOError, widename);
#else
PyErr_SetFromErrnoWithFilename(PyExc_IOError, name);
#endif
goto error;
}
if(dircheck(self) < 0)
goto error;
}
goto done;
error:
ret = -1;
done:
PyMem_Free(name);
return ret;
}
static void
fileio_dealloc(PyFileIOObject *self)
{
if (self->weakreflist != NULL)
PyObject_ClearWeakRefs((PyObject *) self);
if (self->fd >= 0 && self->closefd) {
errno = internal_close(self);
if (errno < 0) {
PySys_WriteStderr("close failed: [Errno %d] %s\n",
errno, strerror(errno));
}
}
Py_TYPE(self)->tp_free((PyObject *)self);
}
static PyObject *
err_closed(void)
{
PyErr_SetString(PyExc_ValueError, "I/O operation on closed file");
return NULL;
}
static PyObject *
err_mode(char *action)
{
PyErr_Format(PyExc_ValueError, "File not open for %s", action);
return NULL;
}
static PyObject *
fileio_fileno(PyFileIOObject *self)
{
if (self->fd < 0)
return err_closed();
return PyInt_FromLong((long) self->fd);
}
static PyObject *
fileio_readable(PyFileIOObject *self)
{
if (self->fd < 0)
return err_closed();
return PyBool_FromLong((long) self->readable);
}
static PyObject *
fileio_writable(PyFileIOObject *self)
{
if (self->fd < 0)
return err_closed();
return PyBool_FromLong((long) self->writable);
}
static PyObject *
fileio_seekable(PyFileIOObject *self)
{
if (self->fd < 0)
return err_closed();
if (self->seekable < 0) {
int ret;
Py_BEGIN_ALLOW_THREADS
ret = lseek(self->fd, 0, SEEK_CUR);
Py_END_ALLOW_THREADS
if (ret < 0)
self->seekable = 0;
else
self->seekable = 1;
}
return PyBool_FromLong((long) self->seekable);
}
static PyObject *
fileio_readinto(PyFileIOObject *self, PyObject *args)
{
Py_buffer pbuf;
Py_ssize_t n;
if (self->fd < 0)
return err_closed();
if (!self->readable)
return err_mode("reading");
if (!PyArg_ParseTuple(args, "w*", &pbuf))
return NULL;
Py_BEGIN_ALLOW_THREADS
errno = 0;
n = read(self->fd, pbuf.buf, pbuf.len);
Py_END_ALLOW_THREADS
PyBuffer_Release(&pbuf);
if (n < 0) {
if (errno == EAGAIN)
Py_RETURN_NONE;
PyErr_SetFromErrno(PyExc_IOError);
return NULL;
}
return PyLong_FromSsize_t(n);
}
#define DEFAULT_BUFFER_SIZE (8*1024)
static PyObject *
fileio_readall(PyFileIOObject *self)
{
PyObject *result;
Py_ssize_t total = 0;
int n;
result = PyString_FromStringAndSize(NULL, DEFAULT_BUFFER_SIZE);
if (result == NULL)
return NULL;
while (1) {
Py_ssize_t newsize = total + DEFAULT_BUFFER_SIZE;
if (PyString_GET_SIZE(result) < newsize) {
if (_PyString_Resize(&result, newsize) < 0) {
if (total == 0) {
Py_DECREF(result);
return NULL;
}
PyErr_Clear();
break;
}
}
Py_BEGIN_ALLOW_THREADS
errno = 0;
n = read(self->fd,
PyString_AS_STRING(result) + total,
newsize - total);
Py_END_ALLOW_THREADS
if (n == 0)
break;
if (n < 0) {
if (total > 0)
break;
if (errno == EAGAIN) {
Py_DECREF(result);
Py_RETURN_NONE;
}
Py_DECREF(result);
PyErr_SetFromErrno(PyExc_IOError);
return NULL;
}
total += n;
}
if (PyString_GET_SIZE(result) > total) {
if (_PyString_Resize(&result, total) < 0) {
/* This should never happen, but just in case */
Py_DECREF(result);
return NULL;
}
}
return result;
}
static PyObject *
fileio_read(PyFileIOObject *self, PyObject *args)
{
char *ptr;
Py_ssize_t n;
Py_ssize_t size = -1;
PyObject *bytes;
if (self->fd < 0)
return err_closed();
if (!self->readable)
return err_mode("reading");
if (!PyArg_ParseTuple(args, "|n", &size))
return NULL;
if (size < 0) {
return fileio_readall(self);
}
bytes = PyString_FromStringAndSize(NULL, size);
if (bytes == NULL)
return NULL;
ptr = PyString_AS_STRING(bytes);
Py_BEGIN_ALLOW_THREADS
errno = 0;
n = read(self->fd, ptr, size);
Py_END_ALLOW_THREADS
if (n < 0) {
if (errno == EAGAIN)
Py_RETURN_NONE;
PyErr_SetFromErrno(PyExc_IOError);
return NULL;
}
if (n != size) {
if (_PyString_Resize(&bytes, n) < 0) {
Py_DECREF(bytes);
return NULL;
}
}
return (PyObject *) bytes;
}
static PyObject *
fileio_write(PyFileIOObject *self, PyObject *args)
{
Py_buffer pbuf;
Py_ssize_t n;
if (self->fd < 0)
return err_closed();
if (!self->writable)
return err_mode("writing");
if (!PyArg_ParseTuple(args, "s*", &pbuf))
return NULL;
Py_BEGIN_ALLOW_THREADS
errno = 0;
n = write(self->fd, pbuf.buf, pbuf.len);
Py_END_ALLOW_THREADS
PyBuffer_Release(&pbuf);
if (n < 0) {
if (errno == EAGAIN)
Py_RETURN_NONE;
PyErr_SetFromErrno(PyExc_IOError);
return NULL;
}
return PyLong_FromSsize_t(n);
}
/* XXX Windows support below is likely incomplete */
#if defined(MS_WIN64) || defined(MS_WINDOWS)
typedef PY_LONG_LONG Py_off_t;
#else
typedef off_t Py_off_t;
#endif
/* Cribbed from posix_lseek() */
static PyObject *
portable_lseek(int fd, PyObject *posobj, int whence)
{
Py_off_t pos, res;
#ifdef SEEK_SET
/* Turn 0, 1, 2 into SEEK_{SET,CUR,END} */
switch (whence) {
#if SEEK_SET != 0
case 0: whence = SEEK_SET; break;
#endif
#if SEEK_CUR != 1
case 1: whence = SEEK_CUR; break;
#endif
#if SEEL_END != 2
case 2: whence = SEEK_END; break;
#endif
}
#endif /* SEEK_SET */
if (posobj == NULL)
pos = 0;
else {
if(PyFloat_Check(posobj)) {
PyErr_SetString(PyExc_TypeError, "an integer is required");
return NULL;
}
#if defined(HAVE_LARGEFILE_SUPPORT)
pos = PyLong_AsLongLong(posobj);
#else
pos = PyLong_AsLong(posobj);
#endif
if (PyErr_Occurred())
return NULL;
}
Py_BEGIN_ALLOW_THREADS
#if defined(MS_WIN64) || defined(MS_WINDOWS)
res = _lseeki64(fd, pos, whence);
#else
res = lseek(fd, pos, whence);
#endif
Py_END_ALLOW_THREADS
if (res < 0)
return PyErr_SetFromErrno(PyExc_IOError);
#if defined(HAVE_LARGEFILE_SUPPORT)
return PyLong_FromLongLong(res);
#else
return PyLong_FromLong(res);
#endif
}
static PyObject *
fileio_seek(PyFileIOObject *self, PyObject *args)
{
PyObject *posobj;
int whence = 0;
if (self->fd < 0)
return err_closed();
if (!PyArg_ParseTuple(args, "O|i", &posobj, &whence))
return NULL;
return portable_lseek(self->fd, posobj, whence);
}
static PyObject *
fileio_tell(PyFileIOObject *self, PyObject *args)
{
if (self->fd < 0)
return err_closed();
return portable_lseek(self->fd, NULL, 1);
}
#ifdef HAVE_FTRUNCATE
static PyObject *
fileio_truncate(PyFileIOObject *self, PyObject *args)
{
PyObject *posobj = NULL;
Py_off_t pos;
int ret;
int fd;
fd = self->fd;
if (fd < 0)
return err_closed();
if (!self->writable)
return err_mode("writing");
if (!PyArg_ParseTuple(args, "|O", &posobj))
return NULL;
if (posobj == Py_None || posobj == NULL) {
/* Get the current position. */
posobj = portable_lseek(fd, NULL, 1);
if (posobj == NULL)
return NULL;
}
else {
/* Move to the position to be truncated. */
posobj = portable_lseek(fd, posobj, 0);
}
#if defined(HAVE_LARGEFILE_SUPPORT)
pos = PyLong_AsLongLong(posobj);
#else
pos = PyLong_AsLong(posobj);
#endif
if (PyErr_Occurred())
return NULL;
#ifdef MS_WINDOWS
/* MS _chsize doesn't work if newsize doesn't fit in 32 bits,
so don't even try using it. */
{
HANDLE hFile;
/* Truncate. Note that this may grow the file! */
Py_BEGIN_ALLOW_THREADS
errno = 0;
hFile = (HANDLE)_get_osfhandle(fd);
ret = hFile == (HANDLE)-1;
if (ret == 0) {
ret = SetEndOfFile(hFile) == 0;
if (ret)
errno = EACCES;
}
Py_END_ALLOW_THREADS
}
#else
Py_BEGIN_ALLOW_THREADS
errno = 0;
ret = ftruncate(fd, pos);
Py_END_ALLOW_THREADS
#endif /* !MS_WINDOWS */
if (ret != 0) {
PyErr_SetFromErrno(PyExc_IOError);
return NULL;
}
return posobj;
}
#endif
static char *
mode_string(PyFileIOObject *self)
{
if (self->readable) {
if (self->writable)
return "r+";
else
return "r";
}
else
return "w";
}
static PyObject *
fileio_repr(PyFileIOObject *self)
{
if (self->fd < 0)
return PyString_FromFormat("_fileio._FileIO(-1)");
return PyString_FromFormat("_fileio._FileIO(%d, '%s')",
self->fd, mode_string(self));
}
static PyObject *
fileio_isatty(PyFileIOObject *self)
{
long res;
if (self->fd < 0)
return err_closed();
Py_BEGIN_ALLOW_THREADS
res = isatty(self->fd);
Py_END_ALLOW_THREADS
return PyBool_FromLong(res);
}
PyDoc_STRVAR(fileio_doc,
"file(name: str[, mode: str]) -> file IO object\n"
"\n"
"Open a file. The mode can be 'r', 'w' or 'a' for reading (default),\n"
"writing or appending. The file will be created if it doesn't exist\n"
"when opened for writing or appending; it will be truncated when\n"
"opened for writing. Add a '+' to the mode to allow simultaneous\n"
"reading and writing.");
PyDoc_STRVAR(read_doc,
"read(size: int) -> bytes. read at most size bytes, returned as bytes.\n"
"\n"
"Only makes one system call, so less data may be returned than requested\n"
"In non-blocking mode, returns None if no data is available.\n"
"On end-of-file, returns ''.");
PyDoc_STRVAR(readall_doc,
"readall() -> bytes. read all data from the file, returned as bytes.\n"
"\n"
"In non-blocking mode, returns as much as is immediately available,\n"
"or None if no data is available. On end-of-file, returns ''.");
PyDoc_STRVAR(write_doc,
"write(b: bytes) -> int. Write bytes b to file, return number written.\n"
"\n"
"Only makes one system call, so not all of the data may be written.\n"
"The number of bytes actually written is returned.");
PyDoc_STRVAR(fileno_doc,
"fileno() -> int. \"file descriptor\".\n"
"\n"
"This is needed for lower-level file interfaces, such the fcntl module.");
PyDoc_STRVAR(seek_doc,
"seek(offset: int[, whence: int]) -> None. Move to new file position.\n"
"\n"
"Argument offset is a byte count. Optional argument whence defaults to\n"
"0 (offset from start of file, offset should be >= 0); other values are 1\n"
"(move relative to current position, positive or negative), and 2 (move\n"
"relative to end of file, usually negative, although many platforms allow\n"
"seeking beyond the end of a file)."
"\n"
"Note that not all file objects are seekable.");
#ifdef HAVE_FTRUNCATE
PyDoc_STRVAR(truncate_doc,
"truncate([size: int]) -> None. Truncate the file to at most size bytes.\n"
"\n"
"Size defaults to the current file position, as returned by tell()."
"The current file position is changed to the value of size.");
#endif
PyDoc_STRVAR(tell_doc,
"tell() -> int. Current file position");
PyDoc_STRVAR(readinto_doc,
"readinto() -> Undocumented. Don't use this; it may go away.");
PyDoc_STRVAR(close_doc,
"close() -> None. Close the file.\n"
"\n"
"A closed file cannot be used for further I/O operations. close() may be\n"
"called more than once without error. Changes the fileno to -1.");
PyDoc_STRVAR(isatty_doc,
"isatty() -> bool. True if the file is connected to a tty device.");
PyDoc_STRVAR(seekable_doc,
"seekable() -> bool. True if file supports random-access.");
PyDoc_STRVAR(readable_doc,
"readable() -> bool. True if file was opened in a read mode.");
PyDoc_STRVAR(writable_doc,
"writable() -> bool. True if file was opened in a write mode.");
static PyMethodDef fileio_methods[] = {
{"read", (PyCFunction)fileio_read, METH_VARARGS, read_doc},
{"readall", (PyCFunction)fileio_readall, METH_NOARGS, readall_doc},
{"readinto", (PyCFunction)fileio_readinto, METH_VARARGS, readinto_doc},
{"write", (PyCFunction)fileio_write, METH_VARARGS, write_doc},
{"seek", (PyCFunction)fileio_seek, METH_VARARGS, seek_doc},
{"tell", (PyCFunction)fileio_tell, METH_VARARGS, tell_doc},
#ifdef HAVE_FTRUNCATE
{"truncate", (PyCFunction)fileio_truncate, METH_VARARGS, truncate_doc},
#endif
{"close", (PyCFunction)fileio_close, METH_NOARGS, close_doc},
{"seekable", (PyCFunction)fileio_seekable, METH_NOARGS, seekable_doc},
{"readable", (PyCFunction)fileio_readable, METH_NOARGS, readable_doc},
{"writable", (PyCFunction)fileio_writable, METH_NOARGS, writable_doc},
{"fileno", (PyCFunction)fileio_fileno, METH_NOARGS, fileno_doc},
{"isatty", (PyCFunction)fileio_isatty, METH_NOARGS, isatty_doc},
{NULL, NULL} /* sentinel */
};
/* 'closed' and 'mode' are attributes for backwards compatibility reasons. */
static PyObject *
get_closed(PyFileIOObject *self, void *closure)
{
return PyBool_FromLong((long)(self->fd < 0));
}
static PyObject *
get_closefd(PyFileIOObject *self, void *closure)
{
return PyBool_FromLong((long)(self->closefd));
}
static PyObject *
get_mode(PyFileIOObject *self, void *closure)
{
return PyString_FromString(mode_string(self));
}
static PyGetSetDef fileio_getsetlist[] = {
{"closed", (getter)get_closed, NULL, "True if the file is closed"},
{"closefd", (getter)get_closefd, NULL,
"True if the file descriptor will be closed"},
{"mode", (getter)get_mode, NULL, "String giving the file mode"},
{0},
};
PyTypeObject PyFileIO_Type = {
PyVarObject_HEAD_INIT(NULL, 0)
"_FileIO",
sizeof(PyFileIOObject),
0,
(destructor)fileio_dealloc, /* tp_dealloc */
0, /* tp_print */
0, /* tp_getattr */
0, /* tp_setattr */
0, /* tp_compare */
(reprfunc)fileio_repr, /* tp_repr */
0, /* tp_as_number */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
0, /* tp_call */
0, /* tp_str */
PyObject_GenericGetAttr, /* tp_getattro */
0, /* tp_setattro */
0, /* tp_as_buffer */
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /* tp_flags */
fileio_doc, /* tp_doc */
0, /* tp_traverse */
0, /* tp_clear */
0, /* tp_richcompare */
offsetof(PyFileIOObject, weakreflist), /* tp_weaklistoffset */
0, /* tp_iter */
0, /* tp_iternext */
fileio_methods, /* tp_methods */
0, /* tp_members */
fileio_getsetlist, /* tp_getset */
0, /* tp_base */
0, /* tp_dict */
0, /* tp_descr_get */
0, /* tp_descr_set */
0, /* tp_dictoffset */
fileio_init, /* tp_init */
PyType_GenericAlloc, /* tp_alloc */
fileio_new, /* tp_new */
PyObject_Del, /* tp_free */
};
static PyMethodDef module_methods[] = {
{NULL, NULL}
};
PyMODINIT_FUNC
init_fileio(void)
{
PyObject *m; /* a module object */
m = Py_InitModule3("_fileio", module_methods,
"Fast implementation of io.FileIO.");
if (m == NULL)
return;
if (PyType_Ready(&PyFileIO_Type) < 0)
return;
Py_INCREF(&PyFileIO_Type);
PyModule_AddObject(m, "_FileIO", (PyObject *) &PyFileIO_Type);
}
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