Objects/fileobject.c

/* File object implementation */

#include "Python.h"
#include "structmember.h"

#ifndef DONT_HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif /* DONT_HAVE_SYS_TYPES_H */

/* We expect that fstat exists on most systems.
   It's confirmed on Unix, Mac and Windows.
   If you don't have it, add #define DONT_HAVE_FSTAT to your config.h. */
#ifndef DONT_HAVE_FSTAT
#define HAVE_FSTAT

#ifndef DONT_HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif

#ifndef DONT_HAVE_SYS_STAT_H
#include <sys/stat.h>
#else
#ifdef HAVE_STAT_H
#include <stat.h>
#endif
#endif

#endif /* DONT_HAVE_FSTAT */

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#ifdef MS_WIN32
#define fileno _fileno
/* can (almost fully) duplicate with _chsize, see file_truncate */
#define HAVE_FTRUNCATE
#endif

#ifdef macintosh
#ifdef USE_GUSI
#define HAVE_FTRUNCATE
#endif
#endif

#ifdef __MWERKS__
/* Mwerks fopen() doesn't always set errno */
#define NO_FOPEN_ERRNO
#endif

#define BUF(v) PyString_AS_STRING((PyStringObject *)v)

#ifndef DONT_HAVE_ERRNO_H
#include <errno.h>
#endif

/* define the appropriate 64-bit capable tell() function */
#if defined(MS_WIN64)
#define TELL64 _telli64
#elif defined(__NetBSD__) || defined(__OpenBSD__) || defined(_HAVE_BSDI) || defined(__APPLE__)
/* NOTE: this is only used on older
   NetBSD prior to f*o() funcions */
#define TELL64(fd) lseek((fd),0,SEEK_CUR)
#endif


typedef struct {
	PyObject_HEAD
	FILE *f_fp;
	PyObject *f_name;
	PyObject *f_mode;
	int (*f_close)(FILE *);
	int f_softspace; /* Flag used by 'print' command */
	int f_binary; /* Flag which indicates whether the file is open
			 open in binary (1) or test (0) mode */
} PyFileObject;

FILE *
PyFile_AsFile(PyObject *f)
{
	if (f == NULL || !PyFile_Check(f))
		return NULL;
	else
		return ((PyFileObject *)f)->f_fp;
}

PyObject *
PyFile_Name(PyObject *f)
{
	if (f == NULL || !PyFile_Check(f))
		return NULL;
	else
		return ((PyFileObject *)f)->f_name;
}

PyObject *
PyFile_FromFile(FILE *fp, char *name, char *mode, int (*close)(FILE *))
{
	PyFileObject *f = PyObject_NEW(PyFileObject, &PyFile_Type);
	if (f == NULL)
		return NULL;
	f->f_fp = NULL;
	f->f_name = PyString_FromString(name);
	f->f_mode = PyString_FromString(mode);
	f->f_close = close;
	f->f_softspace = 0;
	if (strchr(mode,'b') != NULL)
	    f->f_binary = 1;
	else
	    f->f_binary = 0;
	if (f->f_name == NULL || f->f_mode == NULL) {
		Py_DECREF(f);
		return NULL;
	}
	f->f_fp = fp;
	return (PyObject *) f;
}

PyObject *
PyFile_FromString(char *name, char *mode)
{
	extern int fclose(FILE *);
	PyFileObject *f;
	f = (PyFileObject *) PyFile_FromFile((FILE *)NULL, name, mode, fclose);
	if (f == NULL)
		return NULL;
#ifdef HAVE_FOPENRF
	if (*mode == '*') {
		FILE *fopenRF();
		f->f_fp = fopenRF(name, mode+1);
	}
	else
#endif
	{
		Py_BEGIN_ALLOW_THREADS
		f->f_fp = fopen(name, mode);
		Py_END_ALLOW_THREADS
	}
	if (f->f_fp == NULL) {
#ifdef NO_FOPEN_ERRNO
		/* Metroworks only, not testable, so unchanged */
		if ( errno == 0 ) {
			PyErr_SetString(PyExc_IOError, "Cannot open file");
			Py_DECREF(f);
			return NULL;
		}
#endif
		PyErr_SetFromErrnoWithFilename(PyExc_IOError, name);
		Py_DECREF(f);
		return NULL;
	}
	return (PyObject *)f;
}

void
PyFile_SetBufSize(PyObject *f, int bufsize)
{
	if (bufsize >= 0) {
#ifdef HAVE_SETVBUF
		int type;
		switch (bufsize) {
		case 0:
			type = _IONBF;
			break;
		case 1:
			type = _IOLBF;
			bufsize = BUFSIZ;
			break;
		default:
			type = _IOFBF;
		}
		setvbuf(((PyFileObject *)f)->f_fp, (char *)NULL,
			type, bufsize);
#else /* !HAVE_SETVBUF */
		if (bufsize <= 1)
			setbuf(((PyFileObject *)f)->f_fp, (char *)NULL);
#endif /* !HAVE_SETVBUF */
	}
}

static PyObject *
err_closed(void)
{
	PyErr_SetString(PyExc_ValueError, "I/O operation on closed file");
	return NULL;
}

/* Methods */

static void
file_dealloc(PyFileObject *f)
{
	if (f->f_fp != NULL && f->f_close != NULL) {
		Py_BEGIN_ALLOW_THREADS
		(*f->f_close)(f->f_fp);
		Py_END_ALLOW_THREADS
	}
	if (f->f_name != NULL) {
		Py_DECREF(f->f_name);
	}
	if (f->f_mode != NULL) {
		Py_DECREF(f->f_mode);
	}
	PyObject_DEL(f);
}

static PyObject *
file_repr(PyFileObject *f)
{
	char buf[300];
	sprintf(buf, "<%s file '%.256s', mode '%.10s' at %p>",
		f->f_fp == NULL ? "closed" : "open",
		PyString_AsString(f->f_name),
		PyString_AsString(f->f_mode),
		f);
	return PyString_FromString(buf);
}

static PyObject *
file_close(PyFileObject *f, PyObject *args)
{
	int sts = 0;
	if (!PyArg_NoArgs(args))
		return NULL;
	if (f->f_fp != NULL) {
		if (f->f_close != NULL) {
			Py_BEGIN_ALLOW_THREADS
			errno = 0;
			sts = (*f->f_close)(f->f_fp);
			Py_END_ALLOW_THREADS
		}
		f->f_fp = NULL;
	}
	if (sts == EOF)
		return PyErr_SetFromErrno(PyExc_IOError);
	if (sts != 0)
		return PyInt_FromLong((long)sts);
	Py_INCREF(Py_None);
	return Py_None;
}


/* a portable fseek() function
   return 0 on success, non-zero on failure (with errno set) */
int
#if defined(HAVE_LARGEFILE_SUPPORT) && SIZEOF_OFF_T < 8 && SIZEOF_FPOS_T >= 8 
_portable_fseek(FILE *fp, fpos_t offset, int whence)
#else
_portable_fseek(FILE *fp, off_t offset, int whence)
#endif
{
#if defined(HAVE_FSEEKO)
	return fseeko(fp, offset, whence);
#elif defined(HAVE_FSEEK64)
	return fseek64(fp, offset, whence);
#elif defined(__BEOS__)
	return _fseek(fp, offset, whence);
#elif defined(HAVE_LARGEFILE_SUPPORT) && SIZEOF_FPOS_T >= 8 
	/* lacking a 64-bit capable fseek() (as Win64 does) use a 64-bit capable
		fsetpos() and tell() to implement fseek()*/
	fpos_t pos;
	switch (whence) {
		case SEEK_CUR:
			if (fgetpos(fp, &pos) != 0)
				return -1;
			offset += pos;
			break;
		case SEEK_END:
			/* do a "no-op" seek first to sync the buffering so that
			   the low-level tell() can be used correctly */
			if (fseek(fp, 0, SEEK_END) != 0)
				return -1;
			if ((pos = TELL64(fileno(fp))) == -1L)
				return -1;
			offset += pos;
			break;
		/* case SEEK_SET: break; */
	}
	return fsetpos(fp, &offset);
#else
	return fseek(fp, offset, whence);
#endif
}


/* a portable ftell() function
   Return -1 on failure with errno set appropriately, current file
   position on success */
#if defined(HAVE_LARGEFILE_SUPPORT) && SIZEOF_OFF_T < 8 && SIZEOF_FPOS_T >= 8 
fpos_t
#else
off_t
#endif
_portable_ftell(FILE* fp)
{
#if defined(HAVE_FTELLO) && defined(HAVE_LARGEFILE_SUPPORT)
	return ftello(fp);
#elif defined(HAVE_FTELL64) && defined(HAVE_LARGEFILE_SUPPORT)
	return ftell64(fp);
#elif SIZEOF_FPOS_T >= 8 && defined(HAVE_LARGEFILE_SUPPORT)
	fpos_t pos;
	if (fgetpos(fp, &pos) != 0)
		return -1;
	return pos;
#else
	return ftell(fp);
#endif
}


static PyObject *
file_seek(PyFileObject *f, PyObject *args)
{
	int whence;
	int ret;
#if defined(HAVE_LARGEFILE_SUPPORT) && SIZEOF_OFF_T < 8 && SIZEOF_FPOS_T >= 8 
	fpos_t offset, pos;
#else
	off_t offset;
#endif /* !MS_WIN64 */
	PyObject *offobj;
	
	if (f->f_fp == NULL)
		return err_closed();
	whence = 0;
	if (!PyArg_ParseTuple(args, "O|i:seek", &offobj, &whence))
		return NULL;
#if !defined(HAVE_LARGEFILE_SUPPORT)
	offset = PyInt_AsLong(offobj);
#else
	offset = PyLong_Check(offobj) ?
		PyLong_AsLongLong(offobj) : PyInt_AsLong(offobj);
#endif
	if (PyErr_Occurred())
		return NULL;
	
	Py_BEGIN_ALLOW_THREADS
	errno = 0;
	ret = _portable_fseek(f->f_fp, offset, whence);
	Py_END_ALLOW_THREADS

	if (ret != 0) {
		PyErr_SetFromErrno(PyExc_IOError);
		clearerr(f->f_fp);
		return NULL;
	}
	Py_INCREF(Py_None);
	return Py_None;
}


#ifdef HAVE_FTRUNCATE
static PyObject *
file_truncate(PyFileObject *f, PyObject *args)
{
	int ret;
#if defined(HAVE_LARGEFILE_SUPPORT) && SIZEOF_OFF_T < 8 && SIZEOF_FPOS_T >= 8 
	fpos_t newsize;
#else
	off_t newsize;
#endif
	PyObject *newsizeobj;
	
	if (f->f_fp == NULL)
		return err_closed();
	newsizeobj = NULL;
	if (!PyArg_ParseTuple(args, "|O:truncate", &newsizeobj))
		return NULL;
	if (newsizeobj != NULL) {
#if !defined(HAVE_LARGEFILE_SUPPORT)
		newsize = PyInt_AsLong(newsizeobj);
#else
		newsize = PyLong_Check(newsizeobj) ?
				PyLong_AsLongLong(newsizeobj) :
				PyInt_AsLong(newsizeobj);
#endif
		if (PyErr_Occurred())
			return NULL;
	} else {
		/* Default to current position*/
		Py_BEGIN_ALLOW_THREADS
		errno = 0;
		newsize = _portable_ftell(f->f_fp);
		Py_END_ALLOW_THREADS
		if (newsize == -1) {
		        PyErr_SetFromErrno(PyExc_IOError);
			clearerr(f->f_fp);
			return NULL;
		}
	}
	Py_BEGIN_ALLOW_THREADS
	errno = 0;
	ret = fflush(f->f_fp);
	Py_END_ALLOW_THREADS
	if (ret != 0) goto onioerror;

#ifdef MS_WIN32
	/* can use _chsize; if, however, the newsize overflows 32-bits then
	   _chsize is *not* adequate; in this case, an OverflowError is raised */
	if (newsize > LONG_MAX) {
		PyErr_SetString(PyExc_OverflowError,
			"the new size is too long for _chsize (it is limited to 32-bit values)");
		return NULL;
	} else {
		Py_BEGIN_ALLOW_THREADS
		errno = 0;
		ret = _chsize(fileno(f->f_fp), newsize);
		Py_END_ALLOW_THREADS
		if (ret != 0) goto onioerror;
	}
#else
	Py_BEGIN_ALLOW_THREADS
	errno = 0;
	ret = ftruncate(fileno(f->f_fp), newsize);
	Py_END_ALLOW_THREADS
	if (ret != 0) goto onioerror;
#endif /* !MS_WIN32 */
	
	Py_INCREF(Py_None);
	return Py_None;

onioerror:
	PyErr_SetFromErrno(PyExc_IOError);
	clearerr(f->f_fp);
	return NULL;
}
#endif /* HAVE_FTRUNCATE */

static PyObject *
file_tell(PyFileObject *f, PyObject *args)
{
#if defined(HAVE_LARGEFILE_SUPPORT) && SIZEOF_OFF_T < 8 && SIZEOF_FPOS_T >= 8 
	fpos_t pos;
#else
	off_t pos;
#endif

	if (f->f_fp == NULL)
		return err_closed();
	if (!PyArg_NoArgs(args))
		return NULL;
	Py_BEGIN_ALLOW_THREADS
	errno = 0;
	pos = _portable_ftell(f->f_fp);
	Py_END_ALLOW_THREADS
	if (pos == -1) {
		PyErr_SetFromErrno(PyExc_IOError);
		clearerr(f->f_fp);
		return NULL;
	}
#if !defined(HAVE_LARGEFILE_SUPPORT)
	return PyInt_FromLong(pos);
#else
	return PyLong_FromLongLong(pos);
#endif
}

static PyObject *
file_fileno(PyFileObject *f, PyObject *args)
{
	if (f->f_fp == NULL)
		return err_closed();
	if (!PyArg_NoArgs(args))
		return NULL;
	return PyInt_FromLong((long) fileno(f->f_fp));
}

static PyObject *
file_flush(PyFileObject *f, PyObject *args)
{
	int res;
	
	if (f->f_fp == NULL)
		return err_closed();
	if (!PyArg_NoArgs(args))
		return NULL;
	Py_BEGIN_ALLOW_THREADS
	errno = 0;
	res = fflush(f->f_fp);
	Py_END_ALLOW_THREADS
	if (res != 0) {
		PyErr_SetFromErrno(PyExc_IOError);
		clearerr(f->f_fp);
		return NULL;
	}
	Py_INCREF(Py_None);
	return Py_None;
}

static PyObject *
file_isatty(PyFileObject *f, PyObject *args)
{
	long res;
	if (f->f_fp == NULL)
		return err_closed();
	if (!PyArg_NoArgs(args))
		return NULL;
	Py_BEGIN_ALLOW_THREADS
	res = isatty((int)fileno(f->f_fp));
	Py_END_ALLOW_THREADS
	return PyInt_FromLong(res);
}


#if BUFSIZ < 8192
#define SMALLCHUNK 8192
#else
#define SMALLCHUNK BUFSIZ
#endif

#if SIZEOF_INT < 4
#define BIGCHUNK  (512 * 32)
#else
#define BIGCHUNK  (512 * 1024)
#endif

static size_t
new_buffersize(PyFileObject *f, size_t currentsize)
{
#ifdef HAVE_FSTAT
	long pos, end;
	struct stat st;
	if (fstat(fileno(f->f_fp), &st) == 0) {
		end = st.st_size;
		/* The following is not a bug: we really need to call lseek()
		   *and* ftell().  The reason is that some stdio libraries
		   mistakenly flush their buffer when ftell() is called and
		   the lseek() call it makes fails, thereby throwing away
		   data that cannot be recovered in any way.  To avoid this,
		   we first test lseek(), and only call ftell() if lseek()
		   works.  We can't use the lseek() value either, because we
		   need to take the amount of buffered data into account.
		   (Yet another reason why stdio stinks. :-) */
		pos = lseek(fileno(f->f_fp), 0L, SEEK_CUR);
		if (pos >= 0)
			pos = ftell(f->f_fp);
		if (pos < 0)
			clearerr(f->f_fp);
		if (end > pos && pos >= 0)
			return currentsize + end - pos + 1;
		/* Add 1 so if the file were to grow we'd notice. */
	}
#endif
	if (currentsize > SMALLCHUNK) {
		/* Keep doubling until we reach BIGCHUNK;
		   then keep adding BIGCHUNK. */
		if (currentsize <= BIGCHUNK)
			return currentsize + currentsize;
		else
			return currentsize + BIGCHUNK;
	}
	return currentsize + SMALLCHUNK;
}

static PyObject *
file_read(PyFileObject *f, PyObject *args)
{
	long bytesrequested = -1;
	size_t bytesread, buffersize, chunksize;
	PyObject *v;
	
	if (f->f_fp == NULL)
		return err_closed();
	if (!PyArg_ParseTuple(args, "|l:read", &bytesrequested))
		return NULL;
	if (bytesrequested < 0)
		buffersize = new_buffersize(f, (size_t)0);
	else
		buffersize = bytesrequested;
	if (buffersize > INT_MAX) {
		PyErr_SetString(PyExc_OverflowError,
			"requested number of bytes is more than a Python string can hold");
		return NULL;
	}
	v = PyString_FromStringAndSize((char *)NULL, buffersize);
	if (v == NULL)
		return NULL;
	bytesread = 0;
	for (;;) {
		Py_BEGIN_ALLOW_THREADS
		errno = 0;
		chunksize = fread(BUF(v) + bytesread, 1,
				  buffersize - bytesread, f->f_fp);
		Py_END_ALLOW_THREADS
		if (chunksize == 0) {
			if (!ferror(f->f_fp))
				break;
			PyErr_SetFromErrno(PyExc_IOError);
			clearerr(f->f_fp);
			Py_DECREF(v);
			return NULL;
		}
		bytesread += chunksize;
		if (bytesread < buffersize)
			break;
		if (bytesrequested < 0) {
			buffersize = new_buffersize(f, buffersize);
			if (_PyString_Resize(&v, buffersize) < 0)
				return NULL;
		}
	}
	if (bytesread != buffersize)
		_PyString_Resize(&v, bytesread);
	return v;
}

static PyObject *
file_readinto(PyFileObject *f, PyObject *args)
{
	char *ptr;
	size_t ntodo, ndone, nnow;
	
	if (f->f_fp == NULL)
		return err_closed();
	if (!PyArg_Parse(args, "w#", &ptr, &ntodo))
		return NULL;
	ndone = 0;
	while (ntodo > 0) {
		Py_BEGIN_ALLOW_THREADS
		errno = 0;
		nnow = fread(ptr+ndone, 1, ntodo, f->f_fp);
		Py_END_ALLOW_THREADS
		if (nnow == 0) {
			if (!ferror(f->f_fp))
				break;
			PyErr_SetFromErrno(PyExc_IOError);
			clearerr(f->f_fp);
			return NULL;
		}
		ndone += nnow;
		ntodo -= nnow;
	}
	return PyInt_FromLong((long)ndone);
}


/* Internal routine to get a line.
   Size argument interpretation:
   > 0: max length;
   = 0: read arbitrary line;
   < 0: illegal (use get_line_raw() instead)
*/

#ifdef HAVE_GETC_UNLOCKED
#define GETC(f) getc_unlocked(f)
#define FLOCKFILE(f) flockfile(f)
#define FUNLOCKFILE(f) funlockfile(f)
#else
#define GETC(f) getc(f)
#define FLOCKFILE(f)
#define FUNLOCKFILE(f)
#endif

static PyObject *
get_line(PyFileObject *f, int n)
{
	FILE *fp = f->f_fp;
	int c;
	char *buf, *end;
	size_t n1, n2;
	PyObject *v;

	n2 = n > 0 ? n : 100;
	v = PyString_FromStringAndSize((char *)NULL, n2);
	if (v == NULL)
		return NULL;
	buf = BUF(v);
	end = buf + n2;

	for (;;) {
		Py_BEGIN_ALLOW_THREADS
		FLOCKFILE(fp);
		while ((c = GETC(fp)) != EOF &&
		       (*buf++ = c) != '\n' &&
			buf != end)
			;
		FUNLOCKFILE(fp);
		Py_END_ALLOW_THREADS
		if (c == '\n')
			break;
		if (c == EOF) {
			clearerr(fp);
			if (PyErr_CheckSignals()) {
				Py_DECREF(v);
				return NULL;
			}
			break;
		}
		/* Must be because buf == end */
		if (n > 0)
			break;
		n1 = n2;
		n2 += 1000;
		if (n2 > INT_MAX) {
			PyErr_SetString(PyExc_OverflowError,
			    "line is longer than a Python string can hold");
			return NULL;
		}
		if (_PyString_Resize(&v, n2) < 0)
			return NULL;
		buf = BUF(v) + n1;
		end = BUF(v) + n2;
	}

	n1 = buf - BUF(v);
	if (n1 != n2)
		_PyString_Resize(&v, n1);
	return v;
}

/* Internal routine to get a line for raw_input():
   strip trailing '\n', raise EOFError if EOF reached immediately
*/

static PyObject *
get_line_raw(PyFileObject *f)
{
	PyObject *line;

	line = get_line(f, 0);
	if (line == NULL || PyString_GET_SIZE(line) > 0)
		return line;
	else {
		Py_DECREF(line);
		PyErr_SetString(PyExc_EOFError, "EOF when reading a line");
		return NULL;
	}
}

/* External C interface */

PyObject *
PyFile_GetLine(PyObject *f, int n)
{
	if (f == NULL) {
		PyErr_BadInternalCall();
		return NULL;
	}
	if (!PyFile_Check(f)) {
		PyObject *reader;
		PyObject *args;
		PyObject *result;
		reader = PyObject_GetAttrString(f, "readline");
		if (reader == NULL)
			return NULL;
		if (n <= 0)
			args = Py_BuildValue("()");
		else
			args = Py_BuildValue("(i)", n);
		if (args == NULL) {
			Py_DECREF(reader);
			return NULL;
		}
		result = PyEval_CallObject(reader, args);
		Py_DECREF(reader);
		Py_DECREF(args);
		if (result != NULL && !PyString_Check(result)) {
			Py_DECREF(result);
			result = NULL;
			PyErr_SetString(PyExc_TypeError,
				   "object.readline() returned non-string");
		}
		if (n < 0 && result != NULL) {
			char *s = PyString_AsString(result);
			int len = PyString_Size(result);
			if (len == 0) {
				Py_DECREF(result);
				result = NULL;
				PyErr_SetString(PyExc_EOFError,
					   "EOF when reading a line");
			}
			else if (s[len-1] == '\n') {
				if (result->ob_refcnt == 1)
					_PyString_Resize(&result, len-1);
				else {
					PyObject *v;
					v = PyString_FromStringAndSize(s,
								       len-1);
					Py_DECREF(result);
					result = v;
				}
			}
		}
		return result;
	}
	if (((PyFileObject*)f)->f_fp == NULL)
		return err_closed();
	if (n < 0)
		return get_line_raw((PyFileObject *)f);
	else
		return get_line((PyFileObject *)f, n);
}

/* Python method */

static PyObject *
file_readline(PyFileObject *f, PyObject *args)
{
	int n = -1;

	if (f->f_fp == NULL)
		return err_closed();
	if (!PyArg_ParseTuple(args, "|i:readline", &n))
		return NULL;
	if (n == 0)
		return PyString_FromString("");
	if (n < 0)
		n = 0;
	return get_line(f, n);
}

static PyObject *
file_readlines(PyFileObject *f, PyObject *args)
{
	long sizehint = 0;
	PyObject *list;
	PyObject *line;
	char small_buffer[SMALLCHUNK];
	char *buffer = small_buffer;
	size_t buffersize = SMALLCHUNK;
	PyObject *big_buffer = NULL;
	size_t nfilled = 0;
	size_t nread;
	size_t totalread = 0;
	char *p, *q, *end;
	int err;

	if (f->f_fp == NULL)
		return err_closed();
	if (!PyArg_ParseTuple(args, "|l:readlines", &sizehint))
		return NULL;
	if ((list = PyList_New(0)) == NULL)
		return NULL;
	for (;;) {
		Py_BEGIN_ALLOW_THREADS
		errno = 0;
		nread = fread(buffer+nfilled, 1, buffersize-nfilled, f->f_fp);
		Py_END_ALLOW_THREADS
		if (nread == 0) {
			sizehint = 0;
			if (!ferror(f->f_fp))
				break;
			PyErr_SetFromErrno(PyExc_IOError);
			clearerr(f->f_fp);
		  error:
			Py_DECREF(list);
			list = NULL;
			goto cleanup;
		}
		totalread += nread;
		p = memchr(buffer+nfilled, '\n', nread);
		if (p == NULL) {
			/* Need a larger buffer to fit this line */
			nfilled += nread;
			buffersize *= 2;
			if (buffersize > INT_MAX) {
				PyErr_SetString(PyExc_OverflowError,
					"line is longer than a Python string can hold");
				goto error;
			}
			if (big_buffer == NULL) {
				/* Create the big buffer */
				big_buffer = PyString_FromStringAndSize(
					NULL, buffersize);
				if (big_buffer == NULL)
					goto error;
				buffer = PyString_AS_STRING(big_buffer);
				memcpy(buffer, small_buffer, nfilled);
			}
			else {
				/* Grow the big buffer */
				_PyString_Resize(&big_buffer, buffersize);
				buffer = PyString_AS_STRING(big_buffer);
			}
			continue;
		}
		end = buffer+nfilled+nread;
		q = buffer;
		do {
			/* Process complete lines */
			p++;
			line = PyString_FromStringAndSize(q, p-q);
			if (line == NULL)
				goto error;
			err = PyList_Append(list, line);
			Py_DECREF(line);
			if (err != 0)
				goto error;
			q = p;
			p = memchr(q, '\n', end-q);
		} while (p != NULL);
		/* Move the remaining incomplete line to the start */
		nfilled = end-q;
		memmove(buffer, q, nfilled);
		if (sizehint > 0)
			if (totalread >= (size_t)sizehint)
				break;
	}
	if (nfilled != 0) {
		/* Partial last line */
		line = PyString_FromStringAndSize(buffer, nfilled);
		if (line == NULL)
			goto error;
		if (sizehint > 0) {
			/* Need to complete the last line */
			PyObject *rest = get_line(f, 0);
			if (rest == NULL) {
				Py_DECREF(line);
				goto error;
			}
			PyString_Concat(&line, rest);
			Py_DECREF(rest);
			if (line == NULL)
				goto error;
		}
		err = PyList_Append(list, line);
		Py_DECREF(line);
		if (err != 0)
			goto error;
	}
  cleanup:
	if (big_buffer) {
		Py_DECREF(big_buffer);
	}
	return list;
}

static PyObject *
file_write(PyFileObject *f, PyObject *args)
{
	char *s;
	int n, n2;
	if (f->f_fp == NULL)
		return err_closed();
	if (!PyArg_Parse(args, f->f_binary ? "s#" : "t#", &s, &n))
		return NULL;
	f->f_softspace = 0;
	Py_BEGIN_ALLOW_THREADS
	errno = 0;
	n2 = fwrite(s, 1, n, f->f_fp);
	Py_END_ALLOW_THREADS
	if (n2 != n) {
		PyErr_SetFromErrno(PyExc_IOError);
		clearerr(f->f_fp);
		return NULL;
	}
	Py_INCREF(Py_None);
	return Py_None;
}

static PyObject *
file_writelines(PyFileObject *f, PyObject *args)
{
#define CHUNKSIZE 1000
	PyObject *list, *line;
	PyObject *result;
	int i, j, index, len, nwritten, islist;

	if (f->f_fp == NULL)
		return err_closed();
	if (args == NULL || !PySequence_Check(args)) {
		PyErr_SetString(PyExc_TypeError,
			   "writelines() argument must be a sequence of strings");
		return NULL;
	}
	islist = PyList_Check(args);

	/* Strategy: slurp CHUNKSIZE lines into a private list,
	   checking that they are all strings, then write that list
	   without holding the interpreter lock, then come back for more. */
	index = 0;
	if (islist)
		list = NULL;
	else {
		list = PyList_New(CHUNKSIZE);
		if (list == NULL)
			return NULL;
	}
	result = NULL;

	for (;;) {
		if (islist) {
			Py_XDECREF(list);
			list = PyList_GetSlice(args, index, index+CHUNKSIZE);
			if (list == NULL)
				return NULL;
			j = PyList_GET_SIZE(list);
		}
		else {
			for (j = 0; j < CHUNKSIZE; j++) {
				line = PySequence_GetItem(args, index+j);
				if (line == NULL) {
					if (PyErr_ExceptionMatches(
						PyExc_IndexError)) {
						PyErr_Clear();
						break;
					}
					/* Some other error occurred.
					   XXX We may lose some output. */
					goto error;
				}
				PyList_SetItem(list, j, line);
			}
		}
		if (j == 0)
			break;

		/* Check that all entries are indeed strings. If not,
		   apply the same rules as for file.write() and
		   convert the results to strings. This is slow, but
		   seems to be the only way since all conversion APIs
		   could potentially execute Python code. */
		for (i = 0; i < j; i++) {
			PyObject *v = PyList_GET_ITEM(list, i);
			if (!PyString_Check(v)) {
			    	const char *buffer;
			    	int len;
				if (((f->f_binary && 
				      PyObject_AsReadBuffer(v,
					      (const void**)&buffer,
							    &len)) ||
				     PyObject_AsCharBuffer(v,
							   &buffer,
							   &len))) {
					PyErr_SetString(PyExc_TypeError,
				"writelines() argument must be a sequence of strings");
					goto error;
				}
				line = PyString_FromStringAndSize(buffer,
								  len);
				if (line == NULL)
					goto error;
				Py_DECREF(v);
				PyList_SET_ITEM(list, i, line);
			}
		}

		/* Since we are releasing the global lock, the
		   following code may *not* execute Python code. */
		Py_BEGIN_ALLOW_THREADS
		f->f_softspace = 0;
		errno = 0;
		for (i = 0; i < j; i++) {
		    	line = PyList_GET_ITEM(list, i);
			len = PyString_GET_SIZE(line);
			nwritten = fwrite(PyString_AS_STRING(line),
					  1, len, f->f_fp);
			if (nwritten != len) {
				Py_BLOCK_THREADS
				PyErr_SetFromErrno(PyExc_IOError);
				clearerr(f->f_fp);
				goto error;
			}
		}
		Py_END_ALLOW_THREADS

		if (j < CHUNKSIZE)
			break;
		index += CHUNKSIZE;
	}

	Py_INCREF(Py_None);
	result = Py_None;
  error:
	Py_XDECREF(list);
	return result;
}

static PyMethodDef file_methods[] = {
	{"readline",	(PyCFunction)file_readline, 1},
	{"read",	(PyCFunction)file_read, 1},
	{"write",	(PyCFunction)file_write, 0},
	{"fileno",	(PyCFunction)file_fileno, 0},
	{"seek",	(PyCFunction)file_seek, 1},
#ifdef HAVE_FTRUNCATE
	{"truncate",	(PyCFunction)file_truncate, 1},
#endif
	{"tell",	(PyCFunction)file_tell, 0},
	{"readinto",	(PyCFunction)file_readinto, 0},
	{"readlines",	(PyCFunction)file_readlines, 1},
	{"writelines",	(PyCFunction)file_writelines, 0},
	{"flush",	(PyCFunction)file_flush, 0},
	{"close",	(PyCFunction)file_close, 0},
	{"isatty",	(PyCFunction)file_isatty, 0},
	{NULL,		NULL}		/* sentinel */
};

#define OFF(x) offsetof(PyFileObject, x)

static struct memberlist file_memberlist[] = {
	{"softspace",	T_INT,		OFF(f_softspace)},
	{"mode",	T_OBJECT,	OFF(f_mode),	RO},
	{"name",	T_OBJECT,	OFF(f_name),	RO},
	/* getattr(f, "closed") is implemented without this table */
	{"closed",	T_INT,		0,		RO},
	{NULL}	/* Sentinel */
};

static PyObject *
file_getattr(PyFileObject *f, char *name)
{
	PyObject *res;

	res = Py_FindMethod(file_methods, (PyObject *)f, name);
	if (res != NULL)
		return res;
	PyErr_Clear();
	if (strcmp(name, "closed") == 0)
		return PyInt_FromLong((long)(f->f_fp == 0));
	return PyMember_Get((char *)f, file_memberlist, name);
}

static int
file_setattr(PyFileObject *f, char *name, PyObject *v)
{
	if (v == NULL) {
		PyErr_SetString(PyExc_AttributeError,
				"can't delete file attributes");
		return -1;
	}
	return PyMember_Set((char *)f, file_memberlist, name, v);
}

PyTypeObject PyFile_Type = {
	PyObject_HEAD_INIT(&PyType_Type)
	0,
	"file",
	sizeof(PyFileObject),
	0,
	(destructor)file_dealloc, /*tp_dealloc*/
	0,		/*tp_print*/
	(getattrfunc)file_getattr, /*tp_getattr*/
	(setattrfunc)file_setattr, /*tp_setattr*/
	0,		/*tp_compare*/
	(reprfunc)file_repr, /*tp_repr*/
};

/* Interface for the 'soft space' between print items. */

int
PyFile_SoftSpace(PyObject *f, int newflag)
{
	int oldflag = 0;
	if (f == NULL) {
		/* Do nothing */
	}
	else if (PyFile_Check(f)) {
		oldflag = ((PyFileObject *)f)->f_softspace;
		((PyFileObject *)f)->f_softspace = newflag;
	}
	else {
		PyObject *v;
		v = PyObject_GetAttrString(f, "softspace");
		if (v == NULL)
			PyErr_Clear();
		else {
			if (PyInt_Check(v))
				oldflag = PyInt_AsLong(v);
			Py_DECREF(v);
		}
		v = PyInt_FromLong((long)newflag);
		if (v == NULL)
			PyErr_Clear();
		else {
			if (PyObject_SetAttrString(f, "softspace", v) != 0)
				PyErr_Clear();
			Py_DECREF(v);
		}
	}
	return oldflag;
}

/* Interfaces to write objects/strings to file-like objects */

int
PyFile_WriteObject(PyObject *v, PyObject *f, int flags)
{
	PyObject *writer, *value, *args, *result;
	if (f == NULL) {
		PyErr_SetString(PyExc_TypeError, "writeobject with NULL file");
		return -1;
	}
	else if (PyFile_Check(f)) {
		FILE *fp = PyFile_AsFile(f);
		if (fp == NULL) {
			err_closed();
			return -1;
		}
		return PyObject_Print(v, fp, flags);
	}
	writer = PyObject_GetAttrString(f, "write");
	if (writer == NULL)
		return -1;
	if (flags & Py_PRINT_RAW)
		value = PyObject_Str(v);
	else
		value = PyObject_Repr(v);
	if (value == NULL) {
		Py_DECREF(writer);
		return -1;
	}
	args = Py_BuildValue("(O)", value);
	if (args == NULL) {
		Py_DECREF(value);
		Py_DECREF(writer);
		return -1;
	}
	result = PyEval_CallObject(writer, args);
	Py_DECREF(args);
	Py_DECREF(value);
	Py_DECREF(writer);
	if (result == NULL)
		return -1;
	Py_DECREF(result);
	return 0;
}

int
PyFile_WriteString(char *s, PyObject *f)
{
	if (f == NULL) {
		/* Should be caused by a pre-existing error */
		if (!PyErr_Occurred())
			PyErr_SetString(PyExc_SystemError,
					"null file for PyFile_WriteString");
		return -1;
	}
	else if (PyFile_Check(f)) {
		FILE *fp = PyFile_AsFile(f);
		if (fp == NULL) {
			err_closed();
			return -1;
		}
		fputs(s, fp);
		return 0;
	}
	else if (!PyErr_Occurred()) {
		PyObject *v = PyString_FromString(s);
		int err;
		if (v == NULL)
			return -1;
		err = PyFile_WriteObject(v, f, Py_PRINT_RAW);
		Py_DECREF(v);
		return err;
	}
	else
		return -1;
}

/* Try to get a file-descriptor from a Python object.  If the object
   is an integer or long integer, its value is returned.  If not, the
   object's fileno() method is called if it exists; the method must return
   an integer or long integer, which is returned as the file descriptor value.
   -1 is returned on failure.
*/

int PyObject_AsFileDescriptor(PyObject *o)
{
	int fd;
	PyObject *meth;

	if (PyInt_Check(o)) {
		fd = PyInt_AsLong(o);
	}
	else if (PyLong_Check(o)) {
		fd = PyLong_AsLong(o);
	}
	else if ((meth = PyObject_GetAttrString(o, "fileno")) != NULL)
	{
		PyObject *fno = PyEval_CallObject(meth, NULL);
		Py_DECREF(meth);
		if (fno == NULL)
			return -1;
		
		if (PyInt_Check(fno)) {
			fd = PyInt_AsLong(fno);
			Py_DECREF(fno);
		}
		else if (PyLong_Check(fno)) {
			fd = PyLong_AsLong(fno);
			Py_DECREF(fno);
		}
		else {
			PyErr_SetString(PyExc_TypeError,
					"fileno() returned a non-integer");
			Py_DECREF(fno);
			return -1;
		}
	}
	else {
		PyErr_SetString(PyExc_TypeError,
				"argument must be an int, or have a fileno() method.");
		return -1;
	}

	if (fd < 0) {
		PyErr_Format(PyExc_ValueError,
			     "file descriptor cannot be a negative integer (%i)",
			     fd);
		return -1;
	}
	return fd;
}