File size: 10,246 Bytes
859a779 |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 |
/*
* lock.cc - Context managers for implementing locking.
*
* Copyright 2009 Julian Andres Klode <[email protected]>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*/
#include <Python.h>
#include <apt-pkg/init.h>
#include <apt-pkg/error.h>
#include <apt-pkg/fileutl.h>
#include <apt-pkg/pkgsystem.h>
#include "generic.h"
static PyObject *systemlock_exit(PyObject *self, PyObject *args)
{
PyObject *exc_type = 0;
PyObject *exc_value = 0;
PyObject *traceback = 0;
if (!PyArg_UnpackTuple(args, "__exit__", 3, 3, &exc_type, &exc_value,
&traceback)) {
return 0;
}
if (_system->UnLock() == 0) {
// The unlock failed. If no exception happened within the suite, we
// will raise an error here. Otherwise, we just display the error, so
// Python can handle the original exception instead.
HandleErrors();
if (exc_type == Py_None)
return NULL;
else
PyErr_WriteUnraisable(self);
}
// Return False, as required by the context manager protocol.
Py_RETURN_FALSE;
}
static PyObject *systemlock_enter(PyObject *self, PyObject *args)
{
if (!PyArg_ParseTuple(args, ""))
return NULL;
if (!_system->Lock())
return HandleErrors();
Py_INCREF(self);
return self;
}
static PyObject *systemlock_new(PyTypeObject *type, PyObject *args,
PyObject *kwds)
{
if (_system == 0) {
PyErr_SetString(PyExc_ValueError,"_system not initialized");
return 0;
}
return PyType_GenericNew(type,args,kwds);
}
static PyMethodDef systemlock_methods[] = {
{"__enter__",systemlock_enter,METH_VARARGS,"Lock the system."},
{"__exit__",systemlock_exit,METH_VARARGS,"Unlock the system."},
{NULL}
};
static char *systemlock_doc = "SystemLock()\n\n"
"Context manager for locking the package system. The lock is established\n"
"as soon as the method __enter__() is called. It is released when\n"
"__exit__() is called.\n\n"
"This should be used via the 'with' statement, for example:\n\n"
" with apt_pkg.SystemLock():\n"
" ...\n\n"
"Once the block is left, the lock is released automatically. The object\n"
"can be used multiple times:\n\n"
" lock = apt_pkg.SystemLock()\n"
" with lock:\n"
" ...\n"
" with lock:\n"
" ...\n\n";
PyTypeObject PySystemLock_Type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
"apt_pkg.SystemLock", // tp_name
0, // tp_basicsize
0, // tp_itemsize
// Methods
0, // tp_dealloc
0, // tp_print
0, // tp_getattr
0, // tp_setattr
0, // tp_compare
0, // tp_repr
0, // tp_as_number
0, // tp_as_sequence
0, // tp_as_mapping
0, // tp_hash
0, // tp_call
0, // tp_str
0, // tp_getattro
0, // tp_setattro
0, // tp_as_buffer
(Py_TPFLAGS_DEFAULT | // tp_flags
Py_TPFLAGS_BASETYPE),
systemlock_doc, // tp_doc
0, // tp_traverse
0, // tp_clear
0, // tp_richcompare
0, // tp_weaklistoffset
0, // tp_iter
0, // tp_iternext
systemlock_methods, // tp_methods
0, // tp_members
0, // tp_getset
0, // tp_base
0, // tp_dict
0, // tp_descr_get
0, // tp_descr_set
0, // tp_dictoffset
0, // tp_init
0, // tp_alloc
systemlock_new, // tp_new
};
/**
* File Based locking.
*
* The counter is increased by every call to filelock_enter() and decreased by
* every call to filelock_exit(). When the counter reaches 0, the underlying
* file descriptor is closed.
*
* Members:
* @member char* filename The name of the file
* @member int lock_count How many times we have locked it.
* @member int fd The filedescriptor returned by GetLock() or 0.
*/
struct filelock_object {
PyObject_HEAD
char *filename;
int lock_count;
int fd;
};
static PyObject *filelock_enter(filelock_object *self, PyObject *args)
{
self->lock_count++;
// If we have no lock yet, get a lock.
if (self->lock_count == 1) {
self->fd = GetLock(self->filename, true);
if (self->fd == -1) {
self->lock_count--;
return HandleErrors();
}
}
Py_INCREF(self);
return (PyObject *)self;
}
static PyObject *filelock_exit(filelock_object *self, PyObject *args)
{
// Count down the lock_count, if it is less than 0, reset it to 0.
self->lock_count--;
if (self->lock_count < 0)
self->lock_count = 0;
if (self->lock_count == 0 && self->fd != 0 && close(self->fd) == -1) {
return PyErr_SetFromErrno(PyExc_OSError);
}
Py_RETURN_FALSE;
}
static PyObject *filelock_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
PyApt_Filename filename;
char *kwlist[] = {"filename", NULL};
if (PyArg_ParseTupleAndKeywords(args, kwds, "O&:__init__", kwlist,
PyApt_Filename::Converter,
&filename) == 0) {
return NULL;
}
filelock_object *self = (filelock_object *)type->tp_alloc(type, 0);
// Copy the string into the object.
self->filename = new char[strlen(filename) + 1];
strcpy(self->filename, filename);
return (PyObject *)self;
}
static void filelock_dealloc(filelock_object *self)
{
delete[] self->filename;
((PyObject*)self)->ob_type->tp_free(self);
}
static PyMethodDef filelock_methods[] = {
{"__enter__",(PyCFunction)filelock_enter,METH_VARARGS,"Lock the system."},
{"__exit__",(PyCFunction)filelock_exit,METH_VARARGS,"Unlock the system."},
{NULL}
};
static char *filelock_doc = "SystemLock(filename: str)\n\n"
"Context manager for locking using a file. The lock is established\n"
"as soon as the method __enter__() is called. It is released when\n"
"__exit__() is called.\n\n"
"This should be used via the 'with' statement, for example:\n\n"
" with apt_pkg.FileLock(filename):\n"
" ...\n\n"
"Once the block is left, the lock is released automatically. The object\n"
"can be used multiple times:\n\n"
" lock = apt_pkg.FileLock(filename)\n"
" with lock:\n"
" ...\n"
" with lock:\n"
" ...\n\n";
PyTypeObject PyFileLock_Type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
"apt_pkg.FileLock", // tp_name
sizeof(filelock_object), // tp_basicsize
0, // tp_itemsize
// Methods
destructor(filelock_dealloc), // tp_dealloc
0, // tp_print
0, // tp_getattr
0, // tp_setattr
0, // tp_compare
0, // tp_repr
0, // tp_as_number
0, // tp_as_sequence
0, // tp_as_mapping
0, // tp_hash
0, // tp_call
0, // tp_str
0, // tp_getattro
0, // tp_setattro
0, // tp_as_buffer
(Py_TPFLAGS_DEFAULT | // tp_flags
Py_TPFLAGS_BASETYPE),
filelock_doc, // tp_doc
0, // tp_traverse
0, // tp_clear
0, // tp_richcompare
0, // tp_weaklistoffset
0, // tp_iter
0, // tp_iternext
filelock_methods, // tp_methods
0, // tp_members
0, // tp_getset
0, // tp_base
0, // tp_dict
0, // tp_descr_get
0, // tp_descr_set
0, // tp_dictoffset
0, // tp_init
0, // tp_alloc
filelock_new, // tp_new
};
|