fcntlmodule.c

/* fcntl module */

#definePY_SSIZE_T_CLEAN

#include"Python.h"

#ifdefHAVE_SYS_FILE_H
#include<sys/file.h>
#endif

#include<sys/ioctl.h>
#include<fcntl.h>
#ifdefHAVE_STROPTS_H
#include<stropts.h>
#endif

staticint
conv_descriptor(PyObject*object, int*target)
{
intfd=PyObject_AsFileDescriptor(object);

if (fd<0)
return0;
*target=fd;
return1;
}


/* fcntl(fd, op, [arg]) */

staticPyObject*
fcntl_fcntl(PyObject*self, PyObject*args)
{
intfd;
intcode;
intarg;
intret;
char*str;
Py_ssize_tlen;
charbuf[1024];

if (PyArg_ParseTuple(args, "O&is#:fcntl",
conv_descriptor, &fd, &code, &str, &len)) {
if (len>sizeofbuf) {
PyErr_SetString(PyExc_ValueError,
"fcntl string arg too long");
returnNULL;
 }
memcpy(buf, str, len);
Py_BEGIN_ALLOW_THREADS
ret=fcntl(fd, code, buf);
Py_END_ALLOW_THREADS
if (ret<0) {
PyErr_SetFromErrno(PyExc_IOError);
returnNULL;
 }
returnPyString_FromStringAndSize(buf, len);
 }

PyErr_Clear();
arg=0;
if (!PyArg_ParseTuple(args,
"O&i|I;fcntl requires a file or file descriptor,"
" an integer and optionally a third integer or a string",
conv_descriptor, &fd, &code, &arg)) {
returnNULL;
 }
Py_BEGIN_ALLOW_THREADS
ret=fcntl(fd, code, arg);
Py_END_ALLOW_THREADS
if (ret<0) {
PyErr_SetFromErrno(PyExc_IOError);
returnNULL;
 }
returnPyInt_FromLong((long)ret);
}

PyDoc_STRVAR(fcntl_doc,
"fcntl(fd, op, [arg])\n\
\n\
Perform the operation op on file descriptor fd. The values used\n\
for op are operating system dependent, and are available\n\
as constants in the fcntl module, using the same names as used in\n\
the relevant C header files. The argument arg is optional, and\n\
defaults to 0; it may be an int or a string. If arg is given as a string,\n\
the return value of fcntl is a string of that length, containing the\n\
resulting value put in the arg buffer by the operating system. The length\n\
of the arg string is not allowed to exceed 1024 bytes. If the arg given\n\
is an integer or if none is specified, the result value is an integer\n\
corresponding to the return value of the fcntl call in the C code.");


/* ioctl(fd, op, [arg]) */

staticPyObject*
fcntl_ioctl(PyObject*self, PyObject*args)
{
#defineIOCTL_BUFSZ 1024
intfd;
/* In PyArg_ParseTuple below, we use the unsigned non-checked 'I'
 format for the 'code' parameter because Python turns 0x8000000
 into either a large positive number (PyLong or PyInt on 64-bit
 platforms) or a negative number on others (32-bit PyInt)
 whereas the system expects it to be a 32bit bit field value
 regardless of it being passed as an int or unsigned long on
 various platforms. See the termios.TIOCSWINSZ constant across
 platforms for an example of this.

 If any of the 64bit platforms ever decide to use more than 32bits
 in their unsigned long ioctl codes this will break and need
 special casing based on the platform being built on.
 */
unsigned intcode;
intarg;
intret;
char*str;
Py_ssize_tlen;
intmutate_arg=1;
charbuf[IOCTL_BUFSZ+1]; /* argument plus NUL byte */

if (PyArg_ParseTuple(args, "O&Iw#|i:ioctl",
conv_descriptor, &fd, &code,
&str, &len, &mutate_arg)) {
char*arg;

if (mutate_arg) {
if (len <= IOCTL_BUFSZ) {
memcpy(buf, str, len);
buf[len] ='\0';
arg=buf;
 }
else {
arg=str;
 }
 }
else {
if (len>IOCTL_BUFSZ) {
PyErr_SetString(PyExc_ValueError,
"ioctl string arg too long");
returnNULL;
 }
else {
memcpy(buf, str, len);
buf[len] ='\0';
arg=buf;
 }
 }
if (buf==arg) {
Py_BEGIN_ALLOW_THREADS/* think array.resize() */
ret=ioctl(fd, code, arg);
Py_END_ALLOW_THREADS
 }
else {
ret=ioctl(fd, code, arg);
 }
if (mutate_arg&& (len <= IOCTL_BUFSZ)) {
memcpy(str, buf, len);
 }
if (ret<0) {
PyErr_SetFromErrno(PyExc_IOError);
returnNULL;
 }
if (mutate_arg) {
returnPyInt_FromLong(ret);
 }
else {
returnPyString_FromStringAndSize(buf, len);
 }
 }

PyErr_Clear();
if (PyArg_ParseTuple(args, "O&Is#:ioctl",
conv_descriptor, &fd, &code, &str, &len)) {
if (len>IOCTL_BUFSZ) {
PyErr_SetString(PyExc_ValueError,
"ioctl string arg too long");
returnNULL;
 }
memcpy(buf, str, len);
buf[len] ='\0';
Py_BEGIN_ALLOW_THREADS
ret=ioctl(fd, code, buf);
Py_END_ALLOW_THREADS
if (ret<0) {
PyErr_SetFromErrno(PyExc_IOError);
returnNULL;
 }
returnPyString_FromStringAndSize(buf, len);
 }

PyErr_Clear();
arg=0;
if (!PyArg_ParseTuple(args,
"O&I|i;ioctl requires a file or file descriptor,"
" an integer and optionally an integer or buffer argument",
conv_descriptor, &fd, &code, &arg)) {
returnNULL;
 }
Py_BEGIN_ALLOW_THREADS
#ifdef__VMS
ret=ioctl(fd, code, (void*)arg);
#else
ret=ioctl(fd, code, arg);
#endif
Py_END_ALLOW_THREADS
if (ret<0) {
PyErr_SetFromErrno(PyExc_IOError);
returnNULL;
 }
returnPyInt_FromLong((long)ret);
#undef IOCTL_BUFSZ
}

PyDoc_STRVAR(ioctl_doc,
"ioctl(fd, op[, arg[, mutate_flag]])\n\
\n\
Perform the operation op on file descriptor fd. The values used for op\n\
are operating system dependent, and are available as constants in the\n\
fcntl or termios library modules, using the same names as used in the\n\
relevant C header files.\n\
\n\
The argument arg is optional, and defaults to 0; it may be an int or a\n\
buffer containing character data (most likely a string or an array). \n\
\n\
If the argument is a mutable buffer (such as an array) and if the\n\
mutate_flag argument (which is only allowed in this case) is true then the\n\
buffer is (in effect) passed to the operating system and changes made by\n\
the OS will be reflected in the contents of the buffer after the call has\n\
returned. The return value is the integer returned by the ioctl system\n\
call.\n\
\n\
If the argument is a mutable buffer and the mutable_flag argument is not\n\
passed or is false, the behavior is as if a string had been passed. This\n\
behavior will change in future releases of Python.\n\
\n\
If the argument is an immutable buffer (most likely a string) then a copy\n\
of the buffer is passed to the operating system and the return value is a\n\
string of the same length containing whatever the operating system put in\n\
the buffer. The length of the arg buffer in this case is not allowed to\n\
exceed 1024 bytes.\n\
\n\
If the arg given is an integer or if none is specified, the result value is\n\
an integer corresponding to the return value of the ioctl call in the C\n\
code.");


/* flock(fd, operation) */

staticPyObject*
fcntl_flock(PyObject*self, PyObject*args)
{
intfd;
intcode;
intret;

if (!PyArg_ParseTuple(args, "O&i:flock",
conv_descriptor, &fd, &code))
returnNULL;

#ifdefHAVE_FLOCK
Py_BEGIN_ALLOW_THREADS
ret=flock(fd, code);
Py_END_ALLOW_THREADS
#else

#ifndefLOCK_SH
#defineLOCK_SH 1 /* shared lock */
#defineLOCK_EX 2 /* exclusive lock */
#defineLOCK_NB 4 /* don't block when locking */
#defineLOCK_UN 8 /* unlock */
#endif
 {
structflockl;
if (code==LOCK_UN)
l.l_type=F_UNLCK;
elseif (code&LOCK_SH)
l.l_type=F_RDLCK;
elseif (code&LOCK_EX)
l.l_type=F_WRLCK;
else {
PyErr_SetString(PyExc_ValueError,
"unrecognized flock argument");
returnNULL;
 }
l.l_whence=l.l_start=l.l_len=0;
Py_BEGIN_ALLOW_THREADS
ret=fcntl(fd, (code&LOCK_NB) ? F_SETLK : F_SETLKW, &l);
Py_END_ALLOW_THREADS
 }
#endif/* HAVE_FLOCK */
if (ret<0) {
PyErr_SetFromErrno(PyExc_IOError);
returnNULL;
 }
Py_INCREF(Py_None);
returnPy_None;
}

PyDoc_STRVAR(flock_doc,
"flock(fd, operation)\n\
\n\
Perform the lock operation op on file descriptor fd. See the Unix \n\
manual page for flock(2) for details. (On some systems, this function is\n\
emulated using fcntl().)");


/* lockf(fd, operation) */
staticPyObject*
fcntl_lockf(PyObject*self, PyObject*args)
{
intfd, code, ret, whence=0;
PyObject*lenobj=NULL, *startobj=NULL;

if (!PyArg_ParseTuple(args, "O&i|OOi:lockf",
conv_descriptor, &fd, &code,
&lenobj, &startobj, &whence))
returnNULL;

#if defined(PYOS_OS2) && defined(PYCC_GCC)
PyErr_SetString(PyExc_NotImplementedError,
"lockf not supported on OS/2 (EMX)");
returnNULL;
#else
#ifndefLOCK_SH
#defineLOCK_SH 1 /* shared lock */
#defineLOCK_EX 2 /* exclusive lock */
#defineLOCK_NB 4 /* don't block when locking */
#defineLOCK_UN 8 /* unlock */
#endif/* LOCK_SH */
 {
structflockl;
if (code==LOCK_UN)
l.l_type=F_UNLCK;
elseif (code&LOCK_SH)
l.l_type=F_RDLCK;
elseif (code&LOCK_EX)
l.l_type=F_WRLCK;
else {
PyErr_SetString(PyExc_ValueError,
"unrecognized lockf argument");
returnNULL;
 }
l.l_start=l.l_len=0;
if (startobj!=NULL) {
#if !defined(HAVE_LARGEFILE_SUPPORT)
l.l_start=PyInt_AsLong(startobj);
#else
l.l_start=PyLong_Check(startobj) ?
PyLong_AsLongLong(startobj) :
PyInt_AsLong(startobj);
#endif
if (PyErr_Occurred())
returnNULL;
 }
if (lenobj!=NULL) {
#if !defined(HAVE_LARGEFILE_SUPPORT)
l.l_len=PyInt_AsLong(lenobj);
#else
l.l_len=PyLong_Check(lenobj) ?
PyLong_AsLongLong(lenobj) :
PyInt_AsLong(lenobj);
#endif
if (PyErr_Occurred())
returnNULL;
 }
l.l_whence=whence;
Py_BEGIN_ALLOW_THREADS
ret=fcntl(fd, (code&LOCK_NB) ? F_SETLK : F_SETLKW, &l);
Py_END_ALLOW_THREADS
 }
if (ret<0) {
PyErr_SetFromErrno(PyExc_IOError);
returnNULL;
 }
Py_INCREF(Py_None);
returnPy_None;
#endif/* defined(PYOS_OS2) && defined(PYCC_GCC) */
}

PyDoc_STRVAR(lockf_doc,
"lockf (fd, operation, length=0, start=0, whence=0)\n\
\n\
This is essentially a wrapper around the fcntl() locking calls. fd is the\n\
file descriptor of the file to lock or unlock, and operation is one of the\n\
following values:\n\
\n\
 LOCK_UN - unlock\n\
 LOCK_SH - acquire a shared lock\n\
 LOCK_EX - acquire an exclusive lock\n\
\n\
When operation is LOCK_SH or LOCK_EX, it can also be bitwise ORed with\n\
LOCK_NB to avoid blocking on lock acquisition. If LOCK_NB is used and the\n\
lock cannot be acquired, an IOError will be raised and the exception will\n\
have an errno attribute set to EACCES or EAGAIN (depending on the operating\n\
system -- for portability, check for either value).\n\
\n\
length is the number of bytes to lock, with the default meaning to lock to\n\
EOF. start is the byte offset, relative to whence, to that the lock\n\
starts. whence is as with fileobj.seek(), specifically:\n\
\n\
 0 - relative to the start of the file (SEEK_SET)\n\
 1 - relative to the current buffer position (SEEK_CUR)\n\
 2 - relative to the end of the file (SEEK_END)");

/* List of functions */

staticPyMethodDeffcntl_methods[] = {
 {"fcntl", fcntl_fcntl, METH_VARARGS, fcntl_doc},
 {"ioctl", fcntl_ioctl, METH_VARARGS, ioctl_doc},
 {"flock", fcntl_flock, METH_VARARGS, flock_doc},
 {"lockf", fcntl_lockf, METH_VARARGS, lockf_doc},
 {NULL, NULL} /* sentinel */
};


PyDoc_STRVAR(module_doc,
"This module performs file control and I/O control on file \n\
descriptors. It is an interface to the fcntl() and ioctl() Unix\n\
routines. File descriptors can be obtained with the fileno() method of\n\
a file or socket object.");

/* Module initialisation */

staticint
ins(PyObject*d, char*symbol, longvalue)
{
PyObject*v=PyInt_FromLong(value);
if (!v||PyDict_SetItemString(d, symbol, v) <0)
return-1;

Py_DECREF(v);
return0;
}

#defineINS(x) if (ins(d, #x, (long)x)) return -1

staticint
all_ins(PyObject*d)
{
if (ins(d, "LOCK_SH", (long)LOCK_SH)) return-1;
if (ins(d, "LOCK_EX", (long)LOCK_EX)) return-1;
if (ins(d, "LOCK_NB", (long)LOCK_NB)) return-1;
if (ins(d, "LOCK_UN", (long)LOCK_UN)) return-1;
/* GNU extensions, as of glibc 2.2.4 */
#ifdefLOCK_MAND
if (ins(d, "LOCK_MAND", (long)LOCK_MAND)) return-1;
#endif
#ifdefLOCK_READ
if (ins(d, "LOCK_READ", (long)LOCK_READ)) return-1;
#endif
#ifdefLOCK_WRITE
if (ins(d, "LOCK_WRITE", (long)LOCK_WRITE)) return-1;
#endif
#ifdefLOCK_RW
if (ins(d, "LOCK_RW", (long)LOCK_RW)) return-1;
#endif

#ifdefF_DUPFD
if (ins(d, "F_DUPFD", (long)F_DUPFD)) return-1;
#endif
#ifdefF_GETFD
if (ins(d, "F_GETFD", (long)F_GETFD)) return-1;
#endif
#ifdefF_SETFD
if (ins(d, "F_SETFD", (long)F_SETFD)) return-1;
#endif
#ifdefF_GETFL
if (ins(d, "F_GETFL", (long)F_GETFL)) return-1;
#endif
#ifdefF_SETFL
if (ins(d, "F_SETFL", (long)F_SETFL)) return-1;
#endif
#ifdefF_GETLK
if (ins(d, "F_GETLK", (long)F_GETLK)) return-1;
#endif
#ifdefF_SETLK
if (ins(d, "F_SETLK", (long)F_SETLK)) return-1;
#endif
#ifdefF_SETLKW
if (ins(d, "F_SETLKW", (long)F_SETLKW)) return-1;
#endif
#ifdefF_GETOWN
if (ins(d, "F_GETOWN", (long)F_GETOWN)) return-1;
#endif
#ifdefF_SETOWN
if (ins(d, "F_SETOWN", (long)F_SETOWN)) return-1;
#endif
#ifdefF_GETSIG
if (ins(d, "F_GETSIG", (long)F_GETSIG)) return-1;
#endif
#ifdefF_SETSIG
if (ins(d, "F_SETSIG", (long)F_SETSIG)) return-1;
#endif
#ifdefF_RDLCK
if (ins(d, "F_RDLCK", (long)F_RDLCK)) return-1;
#endif
#ifdefF_WRLCK
if (ins(d, "F_WRLCK", (long)F_WRLCK)) return-1;
#endif
#ifdefF_UNLCK
if (ins(d, "F_UNLCK", (long)F_UNLCK)) return-1;
#endif
/* LFS constants */
#ifdefF_GETLK64
if (ins(d, "F_GETLK64", (long)F_GETLK64)) return-1;
#endif
#ifdefF_SETLK64
if (ins(d, "F_SETLK64", (long)F_SETLK64)) return-1;
#endif
#ifdefF_SETLKW64
if (ins(d, "F_SETLKW64", (long)F_SETLKW64)) return-1;
#endif
/* GNU extensions, as of glibc 2.2.4. */
#ifdefFASYNC
if (ins(d, "FASYNC", (long)FASYNC)) return-1;
#endif
#ifdefF_SETLEASE
if (ins(d, "F_SETLEASE", (long)F_SETLEASE)) return-1;
#endif
#ifdefF_GETLEASE
if (ins(d, "F_GETLEASE", (long)F_GETLEASE)) return-1;
#endif
#ifdefF_NOTIFY
if (ins(d, "F_NOTIFY", (long)F_NOTIFY)) return-1;
#endif
/* Old BSD flock(). */
#ifdefF_EXLCK
if (ins(d, "F_EXLCK", (long)F_EXLCK)) return-1;
#endif
#ifdefF_SHLCK
if (ins(d, "F_SHLCK", (long)F_SHLCK)) return-1;
#endif

/* OS X (and maybe others) let you tell the storage device to flush to physical media */
#ifdefF_FULLFSYNC
if (ins(d, "F_FULLFSYNC", (long)F_FULLFSYNC)) return-1;
#endif

/* For F_{GET|SET}FL */
#ifdefFD_CLOEXEC
if (ins(d, "FD_CLOEXEC", (long)FD_CLOEXEC)) return-1;
#endif

/* For F_NOTIFY */
#ifdefDN_ACCESS
if (ins(d, "DN_ACCESS", (long)DN_ACCESS)) return-1;
#endif
#ifdefDN_MODIFY
if (ins(d, "DN_MODIFY", (long)DN_MODIFY)) return-1;
#endif
#ifdefDN_CREATE
if (ins(d, "DN_CREATE", (long)DN_CREATE)) return-1;
#endif
#ifdefDN_DELETE
if (ins(d, "DN_DELETE", (long)DN_DELETE)) return-1;
#endif
#ifdefDN_RENAME
if (ins(d, "DN_RENAME", (long)DN_RENAME)) return-1;
#endif
#ifdefDN_ATTRIB
if (ins(d, "DN_ATTRIB", (long)DN_ATTRIB)) return-1;
#endif
#ifdefDN_MULTISHOT
if (ins(d, "DN_MULTISHOT", (long)DN_MULTISHOT)) return-1;
#endif

#ifdefHAVE_STROPTS_H
/* Unix 98 guarantees that these are in stropts.h. */
INS(I_PUSH);
INS(I_POP);
INS(I_LOOK);
INS(I_FLUSH);
INS(I_FLUSHBAND);
INS(I_SETSIG);
INS(I_GETSIG);
INS(I_FIND);
INS(I_PEEK);
INS(I_SRDOPT);
INS(I_GRDOPT);
INS(I_NREAD);
INS(I_FDINSERT);
INS(I_STR);
INS(I_SWROPT);
#ifdefI_GWROPT
/* despite the comment above, old-ish glibcs miss a couple... */
INS(I_GWROPT);
#endif
INS(I_SENDFD);
INS(I_RECVFD);
INS(I_LIST);
INS(I_ATMARK);
INS(I_CKBAND);
INS(I_GETBAND);
INS(I_CANPUT);
INS(I_SETCLTIME);
#ifdefI_GETCLTIME
INS(I_GETCLTIME);
#endif
INS(I_LINK);
INS(I_UNLINK);
INS(I_PLINK);
INS(I_PUNLINK);
#endif

return0;
}

PyMODINIT_FUNC
initfcntl(void)
{
PyObject*m, *d;

/* Create the module and add the functions and documentation */
m=Py_InitModule3("fcntl", fcntl_methods, module_doc);
if (m==NULL)
return;

/* Add some symbolic constants to the module */
d=PyModule_GetDict(m);
all_ins(d);
}