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Copy pathfileobject.c
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2402 lines (2229 loc) · 58.9 KB
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/* 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 */
#ifdef MS_WINDOWS
#define fileno _fileno
/* can simulate truncate with Win32 API functions; see file_truncate */
#define HAVE_FTRUNCATE
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#endif
#ifdef _MSC_VER
/* Need GetVersion to see if on NT so safe to use _wfopen */
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#endif /* _MSC_VER */
#ifdef macintosh
#ifdef USE_GUSI
#define HAVE_FTRUNCATE
#endif
#endif
#ifdef __MWERKS__
/* Mwerks fopen() doesn't always set errno */
#define NO_FOPEN_ERRNO
#endif
#if defined(PYOS_OS2) && defined(PYCC_GCC)
#include <io.h>
#endif
#define BUF(v) PyString_AS_STRING((PyStringObject *)v)
#ifndef DONT_HAVE_ERRNO_H
#include <errno.h>
#endif
#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
#ifdef WITH_UNIVERSAL_NEWLINES
/* Bits in f_newlinetypes */
#define NEWLINE_UNKNOWN 0 /* No newline seen, yet */
#define NEWLINE_CR 1 /* \r newline seen */
#define NEWLINE_LF 2 /* \n newline seen */
#define NEWLINE_CRLF 4 /* \r\n newline seen */
#endif
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;
}
/* On Unix, fopen will succeed for directories.
In Python, there should be no file objects referring to
directories, so we need a check. */
static PyFileObject*
dircheck(PyFileObject* f)
{
#if defined(HAVE_FSTAT) && defined(S_IFDIR) && defined(EISDIR)
struct stat buf;
if (f->f_fp == NULL)
return f;
if (fstat(fileno(f->f_fp), &buf) == 0 &&
S_ISDIR(buf.st_mode)) {
#ifdef HAVE_STRERROR
char *msg = strerror(EISDIR);
#else
char *msg = "Is a directory";
#endif
PyObject *exc = PyObject_CallFunction(PyExc_IOError, "(is)",
EISDIR, msg);
PyErr_SetObject(PyExc_IOError, exc);
Py_XDECREF(exc);
return NULL;
}
#endif
return f;
}
static PyObject *
fill_file_fields(PyFileObject *f, FILE *fp, char *name, char *mode,
int (*close)(FILE *), PyObject *wname)
{
assert(f != NULL);
assert(PyFile_Check(f));
assert(f->f_fp == NULL);
Py_DECREF(f->f_name);
Py_DECREF(f->f_mode);
Py_DECREF(f->f_encoding);
#ifdef Py_USING_UNICODE
if (wname)
f->f_name = PyUnicode_FromObject(wname);
else
#endif
f->f_name = PyString_FromString(name);
f->f_mode = PyString_FromString(mode);
f->f_close = close;
f->f_softspace = 0;
f->f_binary = strchr(mode,'b') != NULL;
f->f_buf = NULL;
#ifdef WITH_UNIVERSAL_NEWLINES
f->f_univ_newline = (strchr(mode, 'U') != NULL);
f->f_newlinetypes = NEWLINE_UNKNOWN;
f->f_skipnextlf = 0;
#endif
Py_INCREF(Py_None);
f->f_encoding = Py_None;
if (f->f_name == NULL || f->f_mode == NULL)
return NULL;
f->f_fp = fp;
f = dircheck(f);
return (PyObject *) f;
}
static PyObject *
open_the_file(PyFileObject *f, char *name, char *mode)
{
assert(f != NULL);
assert(PyFile_Check(f));
#ifdef MS_WINDOWS
/* windows ignores the passed name in order to support Unicode */
assert(f->f_name != NULL);
#else
assert(name != NULL);
#endif
assert(mode != NULL);
assert(f->f_fp == NULL);
/* rexec.py can't stop a user from getting the file() constructor --
all they have to do is get *any* file object f, and then do
type(f). Here we prevent them from doing damage with it. */
if (PyEval_GetRestricted()) {
PyErr_SetString(PyExc_IOError,
"file() constructor not accessible in restricted mode");
return NULL;
}
errno = 0;
#ifdef HAVE_FOPENRF
if (*mode == '*') {
FILE *fopenRF();
f->f_fp = fopenRF(name, mode+1);
}
else
#endif
{
#ifdef WITH_UNIVERSAL_NEWLINES
if (strcmp(mode, "U") == 0 || strcmp(mode, "rU") == 0)
mode = "rb";
#else
/* Compatibility: specifying U in a Python without universal
** newlines is allowed, and the file is opened as a normal text
** file.
*/
if (strcmp(mode, "U") == 0 || strcmp(mode, "rU") == 0)
mode = "r";
#endif
#ifdef MS_WINDOWS
if (PyUnicode_Check(f->f_name)) {
PyObject *wmode;
wmode = PyUnicode_DecodeASCII(mode, strlen(mode), NULL);
if (f->f_name && wmode) {
Py_BEGIN_ALLOW_THREADS
/* PyUnicode_AS_UNICODE OK without thread
lock as it is a simple dereference. */
f->f_fp = _wfopen(PyUnicode_AS_UNICODE(f->f_name),
PyUnicode_AS_UNICODE(wmode));
Py_END_ALLOW_THREADS
}
Py_XDECREF(wmode);
}
#endif
if (NULL == f->f_fp && NULL != name) {
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, wich does not always sets errno */
if (errno == 0) {
PyObject *v;
v = Py_BuildValue("(is)", 0, "Cannot open file");
if (v != NULL) {
PyErr_SetObject(PyExc_IOError, v);
Py_DECREF(v);
}
return NULL;
}
#endif
#ifdef _MSC_VER
/* MSVC 6 (Microsoft) leaves errno at 0 for bad mode strings,
* across all Windows flavors. When it sets EINVAL varies
* across Windows flavors, the exact conditions aren't
* documented, and the answer lies in the OS's implementation
* of Win32's CreateFile function (whose source is secret).
* Seems the best we can do is map EINVAL to ENOENT.
*/
if (errno == 0) /* bad mode string */
errno = EINVAL;
else if (errno == EINVAL) /* unknown, but not a mode string */
errno = ENOENT;
#endif
if (errno == EINVAL)
PyErr_Format(PyExc_IOError, "invalid mode: %s",
mode);
else
#ifdef MS_WINDOWS
PyErr_SetFromErrnoWithFilenameObject(PyExc_IOError, f->f_name);
#else
PyErr_SetFromErrnoWithFilename(PyExc_IOError, name);
#endif /* MS_WINDOWS */
f = NULL;
}
if (f != NULL)
f = dircheck(f);
return (PyObject *)f;
}
PyObject *
PyFile_FromFile(FILE *fp, char *name, char *mode, int (*close)(FILE *))
{
PyFileObject *f = (PyFileObject *)PyFile_Type.tp_new(&PyFile_Type,
NULL, NULL);
if (f != NULL) {
if (fill_file_fields(f, fp, name, mode, close, NULL) == NULL) {
Py_DECREF(f);
f = NULL;
}
}
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) {
if (open_the_file(f, name, mode) == NULL) {
Py_DECREF(f);
f = NULL;
}
}
return (PyObject *)f;
}
void
PyFile_SetBufSize(PyObject *f, int bufsize)
{
PyFileObject *file = (PyFileObject *)f;
if (bufsize >= 0) {
int type;
switch (bufsize) {
case 0:
type = _IONBF;
break;
#ifdef HAVE_SETVBUF
case 1:
type = _IOLBF;
bufsize = BUFSIZ;
break;
#endif
default:
type = _IOFBF;
#ifndef HAVE_SETVBUF
bufsize = BUFSIZ;
#endif
break;
}
fflush(file->f_fp);
if (type == _IONBF) {
PyMem_Free(file->f_setbuf);
file->f_setbuf = NULL;
} else {
file->f_setbuf = PyMem_Realloc(file->f_setbuf, bufsize);
}
#ifdef HAVE_SETVBUF
setvbuf(file->f_fp, file->f_setbuf, type, bufsize);
#else /* !HAVE_SETVBUF */
setbuf(file->f_fp, file->f_setbuf);
#endif /* !HAVE_SETVBUF */
}
}
/* Set the encoding used to output Unicode strings.
Returh 1 on success, 0 on failure. */
int
PyFile_SetEncoding(PyObject *f, const char *enc)
{
PyFileObject *file = (PyFileObject*)f;
PyObject *str = PyString_FromString(enc);
if (!str)
return 0;
Py_DECREF(file->f_encoding);
file->f_encoding = str;
return 1;
}
static PyObject *
err_closed(void)
{
PyErr_SetString(PyExc_ValueError, "I/O operation on closed file");
return NULL;
}
static void drop_readahead(PyFileObject *);
/* 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
}
PyMem_Free(f->f_setbuf);
Py_XDECREF(f->f_name);
Py_XDECREF(f->f_mode);
Py_XDECREF(f->f_encoding);
drop_readahead(f);
f->ob_type->tp_free((PyObject *)f);
}
static PyObject *
file_repr(PyFileObject *f)
{
if (PyUnicode_Check(f->f_name)) {
#ifdef Py_USING_UNICODE
PyObject *ret = NULL;
PyObject *name;
name = PyUnicode_AsUnicodeEscapeString(f->f_name);
ret = PyString_FromFormat("<%s file u'%s', mode '%s' at %p>",
f->f_fp == NULL ? "closed" : "open",
PyString_AsString(name),
PyString_AsString(f->f_mode),
f);
Py_XDECREF(name);
return ret;
#endif
} else {
return PyString_FromFormat("<%s file '%s', mode '%s' at %p>",
f->f_fp == NULL ? "closed" : "open",
PyString_AsString(f->f_name),
PyString_AsString(f->f_mode),
f);
}
}
static PyObject *
file_close(PyFileObject *f)
{
int sts = 0;
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;
}
PyMem_Free(f->f_setbuf);
f->f_setbuf = NULL;
if (sts == EOF)
return PyErr_SetFromErrno(PyExc_IOError);
if (sts != 0)
return PyInt_FromLong((long)sts);
Py_INCREF(Py_None);
return Py_None;
}
/* Our very own off_t-like type, 64-bit if possible */
#if !defined(HAVE_LARGEFILE_SUPPORT)
typedef off_t Py_off_t;
#elif SIZEOF_OFF_T >= 8
typedef off_t Py_off_t;
#elif SIZEOF_FPOS_T >= 8
typedef fpos_t Py_off_t;
#else
#error "Large file support, but neither off_t nor fpos_t is large enough."
#endif
/* a portable fseek() function
return 0 on success, non-zero on failure (with errno set) */
static int
_portable_fseek(FILE *fp, Py_off_t offset, int whence)
{
#if !defined(HAVE_LARGEFILE_SUPPORT)
return fseek(fp, offset, whence);
#elif defined(HAVE_FSEEKO) && SIZEOF_OFF_T >= 8
return fseeko(fp, offset, whence);
#elif defined(HAVE_FSEEK64)
return fseek64(fp, offset, whence);
#elif defined(__BEOS__)
return _fseek(fp, offset, whence);
#elif SIZEOF_FPOS_T >= 8
/* lacking a 64-bit capable fseek(), use a 64-bit capable fsetpos()
and fgetpos() to implement fseek()*/
fpos_t pos;
switch (whence) {
case SEEK_END:
#ifdef MS_WINDOWS
fflush(fp);
if (_lseeki64(fileno(fp), 0, 2) == -1)
return -1;
#else
if (fseek(fp, 0, SEEK_END) != 0)
return -1;
#endif
/* fall through */
case SEEK_CUR:
if (fgetpos(fp, &pos) != 0)
return -1;
offset += pos;
break;
/* case SEEK_SET: break; */
}
return fsetpos(fp, &offset);
#else
#error "Large file support, but no way to fseek."
#endif
}
/* a portable ftell() function
Return -1 on failure with errno set appropriately, current file
position on success */
static Py_off_t
_portable_ftell(FILE* fp)
{
#if !defined(HAVE_LARGEFILE_SUPPORT)
return ftell(fp);
#elif defined(HAVE_FTELLO) && SIZEOF_OFF_T >= 8
return ftello(fp);
#elif defined(HAVE_FTELL64)
return ftell64(fp);
#elif SIZEOF_FPOS_T >= 8
fpos_t pos;
if (fgetpos(fp, &pos) != 0)
return -1;
return pos;
#else
#error "Large file support, but no way to ftell."
#endif
}
static PyObject *
file_seek(PyFileObject *f, PyObject *args)
{
int whence;
int ret;
Py_off_t offset;
PyObject *offobj;
if (f->f_fp == NULL)
return err_closed();
drop_readahead(f);
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;
}
#ifdef WITH_UNIVERSAL_NEWLINES
f->f_skipnextlf = 0;
#endif
Py_INCREF(Py_None);
return Py_None;
}
#ifdef HAVE_FTRUNCATE
static PyObject *
file_truncate(PyFileObject *f, PyObject *args)
{
int ret;
Py_off_t newsize;
PyObject *newsizeobj;
if (f->f_fp == NULL)
return err_closed();
newsizeobj = NULL;
if (!PyArg_UnpackTuple(args, "truncate", 0, 1, &newsizeobj))
return NULL;
/* Set newsize to current postion if newsizeobj NULL, else to the
specified value. */
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)
goto onioerror;
}
/* Flush the file. */
Py_BEGIN_ALLOW_THREADS
errno = 0;
ret = fflush(f->f_fp);
Py_END_ALLOW_THREADS
if (ret != 0)
goto onioerror;
#ifdef MS_WINDOWS
/* MS _chsize doesn't work if newsize doesn't fit in 32 bits,
so don't even try using it. */
{
Py_off_t current; /* current file position */
HANDLE hFile;
int error;
/* current <- current file postion. */
if (newsizeobj == NULL)
current = newsize;
else {
Py_BEGIN_ALLOW_THREADS
errno = 0;
current = _portable_ftell(f->f_fp);
Py_END_ALLOW_THREADS
if (current == -1)
goto onioerror;
}
/* Move to newsize. */
if (current != newsize) {
Py_BEGIN_ALLOW_THREADS
errno = 0;
error = _portable_fseek(f->f_fp, newsize, SEEK_SET)
!= 0;
Py_END_ALLOW_THREADS
if (error)
goto onioerror;
}
/* Truncate. Note that this may grow the file! */
Py_BEGIN_ALLOW_THREADS
errno = 0;
hFile = (HANDLE)_get_osfhandle(fileno(f->f_fp));
error = hFile == (HANDLE)-1;
if (!error) {
error = SetEndOfFile(hFile) == 0;
if (error)
errno = EACCES;
}
Py_END_ALLOW_THREADS
if (error)
goto onioerror;
/* Restore original file position. */
if (current != newsize) {
Py_BEGIN_ALLOW_THREADS
errno = 0;
error = _portable_fseek(f->f_fp, current, SEEK_SET)
!= 0;
Py_END_ALLOW_THREADS
if (error)
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_WINDOWS */
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)
{
Py_off_t pos;
if (f->f_fp == NULL)
return err_closed();
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;
}
#ifdef WITH_UNIVERSAL_NEWLINES
if (f->f_skipnextlf) {
int c;
c = GETC(f->f_fp);
if (c == '\n') {
pos++;
f->f_skipnextlf = 0;
} else if (c != EOF) ungetc(c, f->f_fp);
}
#endif
#if !defined(HAVE_LARGEFILE_SUPPORT)
return PyInt_FromLong(pos);
#else
return PyLong_FromLongLong(pos);
#endif
}
static PyObject *
file_fileno(PyFileObject *f)
{
if (f->f_fp == NULL)
return err_closed();
return PyInt_FromLong((long) fileno(f->f_fp));
}
static PyObject *
file_flush(PyFileObject *f)
{
int res;
if (f->f_fp == NULL)
return err_closed();
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)
{
long res;
if (f->f_fp == NULL)
return err_closed();
Py_BEGIN_ALLOW_THREADS
res = isatty((int)fileno(f->f_fp));
Py_END_ALLOW_THREADS
return PyBool_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
off_t 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. :-) */
#ifdef USE_GUSI2
pos = lseek(fileno(f->f_fp), 1L, SEEK_CUR);
pos = lseek(fileno(f->f_fp), -1L, SEEK_CUR);
#else
pos = lseek(fileno(f->f_fp), 0L, SEEK_CUR);
#endif
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;
}
#if defined(EWOULDBLOCK) && defined(EAGAIN) && EWOULDBLOCK != EAGAIN
#define BLOCKED_ERRNO(x) ((x) == EWOULDBLOCK || (x) == EAGAIN)
#else
#ifdef EWOULDBLOCK
#define BLOCKED_ERRNO(x) ((x) == EWOULDBLOCK)
#else
#ifdef EAGAIN
#define BLOCKED_ERRNO(x) ((x) == EAGAIN)
#else
#define BLOCKED_ERRNO(x) 0
#endif
#endif
#endif
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 = Py_UniversalNewlineFread(BUF(v) + bytesread,
buffersize - bytesread, f->f_fp, (PyObject *)f);
Py_END_ALLOW_THREADS
if (chunksize == 0) {
if (!ferror(f->f_fp))
break;
clearerr(f->f_fp);
/* When in non-blocking mode, data shouldn't
* be discarded if a blocking signal was
* received. That will also happen if
* chunksize != 0, but bytesread < buffersize. */
if (bytesread > 0 && BLOCKED_ERRNO(errno))
break;
PyErr_SetFromErrno(PyExc_IOError);
Py_DECREF(v);
return NULL;
}
bytesread += chunksize;
if (bytesread < buffersize) {
clearerr(f->f_fp);
break;
}
if (bytesrequested < 0) {
buffersize = new_buffersize(f, buffersize);
if (_PyString_Resize(&v, buffersize) < 0)
return NULL;
} else {
/* Got what was requested. */
break;
}
}
if (bytesread != buffersize)
_PyString_Resize(&v, bytesread);
return v;
}
static PyObject *
file_readinto(PyFileObject *f, PyObject *args)
{
char *ptr;
int ntodo;
size_t ndone, nnow;
if (f->f_fp == NULL)
return err_closed();
if (!PyArg_ParseTuple(args, "w#", &ptr, &ntodo))
return NULL;
ndone = 0;
while (ntodo > 0) {
Py_BEGIN_ALLOW_THREADS
errno = 0;
nnow = Py_UniversalNewlineFread(ptr+ndone, ntodo, f->f_fp,
(PyObject *)f);
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);
}
/**************************************************************************
Routine to get next line using platform fgets().
Under MSVC 6:
+ MS threadsafe getc is very slow (multiple layers of function calls before+
after each character, to lock+unlock the stream).
+ The stream-locking functions are MS-internal -- can't access them from user
code.
+ There's nothing Tim could find in the MS C or platform SDK libraries that
can worm around this.
+ MS fgets locks/unlocks only once per line; it's the only hook we have.
So we use fgets for speed(!), despite that it's painful.
MS realloc is also slow.
Reports from other platforms on this method vs getc_unlocked (which MS doesn't
have):
Linux a wash
Solaris a wash
Tru64 Unix getline_via_fgets significantly faster
CAUTION: The C std isn't clear about this: in those cases where fgets
writes something into the buffer, can it write into any position beyond the
required trailing null byte? MSVC 6 fgets does not, and no platform is (yet)
known on which it does; and it would be a strange way to code fgets. Still,
getline_via_fgets may not work correctly if it does. The std test
test_bufio.py should fail if platform fgets() routinely writes beyond the
trailing null byte. #define DONT_USE_FGETS_IN_GETLINE to disable this code.
**************************************************************************/
/* Use this routine if told to, or by default on non-get_unlocked()
* platforms unless told not to. Yikes! Let's spell that out:
* On a platform with getc_unlocked():
* By default, use getc_unlocked().
* If you want to use fgets() instead, #define USE_FGETS_IN_GETLINE.
* On a platform without getc_unlocked():
* By default, use fgets().
* If you don't want to use fgets(), #define DONT_USE_FGETS_IN_GETLINE.
*/
#if !defined(USE_FGETS_IN_GETLINE) && !defined(HAVE_GETC_UNLOCKED)
#define USE_FGETS_IN_GETLINE
#endif
#if defined(DONT_USE_FGETS_IN_GETLINE) && defined(USE_FGETS_IN_GETLINE)
#undef USE_FGETS_IN_GETLINE
#endif
#ifdef USE_FGETS_IN_GETLINE
static PyObject*
getline_via_fgets(FILE *fp)
{
/* INITBUFSIZE is the maximum line length that lets us get away with the fast
* no-realloc, one-fgets()-call path. Boosting it isn't free, because we have
* to fill this much of the buffer with a known value in order to figure out
* how much of the buffer fgets() overwrites. So if INITBUFSIZE is larger
* than "most" lines, we waste time filling unused buffer slots. 100 is
* surely adequate for most peoples' email archives, chewing over source code,
* etc -- "regular old text files".
* MAXBUFSIZE is the maximum line length that lets us get away with the less
* fast (but still zippy) no-realloc, two-fgets()-call path. See above for
* cautions about boosting that. 300 was chosen because the worst real-life
* text-crunching job reported on Python-Dev was a mail-log crawler where over
* half the lines were 254 chars.
*/
#define INITBUFSIZE 100
#define MAXBUFSIZE 300
char* p; /* temp */
char buf[MAXBUFSIZE];
PyObject* v; /* the string object result */
char* pvfree; /* address of next free slot */
char* pvend; /* address one beyond last free slot */
size_t nfree; /* # of free buffer slots; pvend-pvfree */
size_t total_v_size; /* total # of slots in buffer */
size_t increment; /* amount to increment the buffer */
/* Optimize for normal case: avoid _PyString_Resize if at all
* possible via first reading into stack buffer "buf".
*/
total_v_size = INITBUFSIZE; /* start small and pray */
pvfree = buf;
for (;;) {
Py_BEGIN_ALLOW_THREADS
pvend = buf + total_v_size;
nfree = pvend - pvfree;
memset(pvfree, '\n', nfree);
p = fgets(pvfree, nfree, fp);
Py_END_ALLOW_THREADS
if (p == NULL) {
clearerr(fp);
if (PyErr_CheckSignals())
return NULL;
v = PyString_FromStringAndSize(buf, pvfree - buf);
return v;
}
/* fgets read *something* */
p = memchr(pvfree, '\n', nfree);
if (p != NULL) {
/* Did the \n come from fgets or from us?
* Since fgets stops at the first \n, and then writes
* \0, if it's from fgets a \0 must be next. But if
* that's so, it could not have come from us, since
* the \n's we filled the buffer with have only more
* \n's to the right.
*/
if (p+1 < pvend && *(p+1) == '\0') {
/* It's from fgets: we win! In particular,
* we haven't done any mallocs yet, and can
* build the final result on the first try.
*/
++p; /* include \n from fgets */
}