libsigrokdecode  0.4.1
sigrok protocol decoding library
srd.c
Go to the documentation of this file.
1 /*
2  * This file is part of the libsigrokdecode project.
3  *
4  * Copyright (C) 2010 Uwe Hermann <uwe@hermann-uwe.de>
5  * Copyright (C) 2013 Bert Vermeulen <bert@biot.com>
6  *
7  * This program is free software: you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License as published by
9  * the Free Software Foundation, either version 3 of the License, or
10  * (at your option) any later version.
11  *
12  * This program is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15  * GNU General Public License for more details.
16  *
17  * You should have received a copy of the GNU General Public License
18  * along with this program. If not, see <http://www.gnu.org/licenses/>.
19  */
20 
21 #include <config.h>
22 #include "libsigrokdecode-internal.h" /* First, so we avoid a _POSIX_C_SOURCE warning. */
23 #include "libsigrokdecode.h"
24 #include <glib.h>
25 
26 /** @cond PRIVATE */
27 
28 /* Python module search paths */
29 SRD_PRIV GSList *searchpaths = NULL;
30 
31 /* session.c */
32 extern SRD_PRIV GSList *sessions;
33 extern SRD_PRIV int max_session_id;
34 
35 /** @endcond */
36 
37 /**
38  * @mainpage libsigrokdecode API
39  *
40  * @section sec_intro Introduction
41  *
42  * The <a href="http://sigrok.org">sigrok</a> project aims at creating a
43  * portable, cross-platform, Free/Libre/Open-Source signal analysis software
44  * suite that supports various device types (such as logic analyzers,
45  * oscilloscopes, multimeters, and more).
46  *
47  * <a href="http://sigrok.org/wiki/Libsigrokdecode">libsigrokdecode</a> is a
48  * shared library written in C which provides the basic API for (streaming)
49  * protocol decoding functionality.
50  *
51  * The <a href="http://sigrok.org/wiki/Protocol_decoders">protocol decoders</a>
52  * are written in Python (>= 3.0).
53  *
54  * @section sec_api API reference
55  *
56  * See the "Modules" page for an introduction to various libsigrokdecode
57  * related topics and the detailed API documentation of the respective
58  * functions.
59  *
60  * You can also browse the API documentation by file, or review all
61  * data structures.
62  *
63  * @section sec_mailinglists Mailing lists
64  *
65  * There is one mailing list for sigrok/libsigrokdecode: <a href="https://lists.sourceforge.net/lists/listinfo/sigrok-devel">sigrok-devel</a>.
66  *
67  * @section sec_irc IRC
68  *
69  * You can find the sigrok developers in the
70  * <a href="irc://chat.freenode.net/sigrok">\#sigrok</a>
71  * IRC channel on Freenode.
72  *
73  * @section sec_website Website
74  *
75  * <a href="http://sigrok.org/wiki/Libsigrokdecode">sigrok.org/wiki/Libsigrokdecode</a>
76  */
77 
78 /**
79  * @file
80  *
81  * Initializing and shutting down libsigrokdecode.
82  */
83 
84 /**
85  * @defgroup grp_init Initialization
86  *
87  * Initializing and shutting down libsigrokdecode.
88  *
89  * Before using any of the libsigrokdecode functionality, srd_init() must
90  * be called to initialize the library.
91  *
92  * When libsigrokdecode functionality is no longer needed, srd_exit() should
93  * be called.
94  *
95  * @{
96  */
97 
98 static int searchpath_add_xdg_dir(const char *datadir)
99 {
100  char *decdir;
101  int ret;
102 
103  decdir = g_build_filename(datadir, PACKAGE_TARNAME, "decoders", NULL);
104 
105  if (g_file_test(decdir, G_FILE_TEST_IS_DIR))
106  ret = srd_decoder_searchpath_add(decdir);
107  else
108  ret = SRD_OK; /* just ignore non-existing directory */
109 
110  g_free(decdir);
111 
112  return ret;
113 }
114 
115 /**
116  * Initialize libsigrokdecode.
117  *
118  * This initializes the Python interpreter, and creates and initializes
119  * a "sigrokdecode" Python module.
120  *
121  * Then, it searches for sigrok protocol decoders in the "decoders"
122  * subdirectory of the the libsigrokdecode installation directory.
123  * All decoders that are found are loaded into memory and added to an
124  * internal list of decoders, which can be queried via srd_decoder_list().
125  *
126  * The caller is responsible for calling the clean-up function srd_exit(),
127  * which will properly shut down libsigrokdecode and free its allocated memory.
128  *
129  * Multiple calls to srd_init(), without calling srd_exit() in between,
130  * are not allowed.
131  *
132  * @param path Path to an extra directory containing protocol decoders
133  * which will be added to the Python sys.path. May be NULL.
134  *
135  * @return SRD_OK upon success, a (negative) error code otherwise.
136  * Upon Python errors, SRD_ERR_PYTHON is returned. If the decoders
137  * directory cannot be accessed, SRD_ERR_DECODERS_DIR is returned.
138  * If not enough memory could be allocated, SRD_ERR_MALLOC is returned.
139  *
140  * @since 0.1.0
141  */
142 SRD_API int srd_init(const char *path)
143 {
144  const char *const *sys_datadirs;
145  const char *env_path;
146  size_t i;
147  int ret;
148 
149  if (max_session_id != -1) {
150  srd_err("libsigrokdecode is already initialized.");
151  return SRD_ERR;
152  }
153 
154  srd_dbg("Initializing libsigrokdecode.");
155 
156  /* Add our own module to the list of built-in modules. */
157  PyImport_AppendInittab("sigrokdecode", PyInit_sigrokdecode);
158 
159  /* Initialize the Python interpreter. */
160  Py_InitializeEx(0);
161 
162  /* Locations relative to the XDG system data directories. */
163  sys_datadirs = g_get_system_data_dirs();
164  for (i = g_strv_length((char **)sys_datadirs); i > 0; i--) {
165  ret = searchpath_add_xdg_dir(sys_datadirs[i-1]);
166  if (ret != SRD_OK) {
167  Py_Finalize();
168  return ret;
169  }
170  }
171 #ifdef DECODERS_DIR
172  /* Hardcoded decoders install location, if defined. */
173  if ((ret = srd_decoder_searchpath_add(DECODERS_DIR)) != SRD_OK) {
174  Py_Finalize();
175  return ret;
176  }
177 #endif
178  /* Location relative to the XDG user data directory. */
179  ret = searchpath_add_xdg_dir(g_get_user_data_dir());
180  if (ret != SRD_OK) {
181  Py_Finalize();
182  return ret;
183  }
184 
185  /* Path specified by the user. */
186  if (path) {
187  if ((ret = srd_decoder_searchpath_add(path)) != SRD_OK) {
188  Py_Finalize();
189  return ret;
190  }
191  }
192 
193  /* Environment variable overrides everything, for debugging. */
194  if ((env_path = g_getenv("SIGROKDECODE_DIR"))) {
195  if ((ret = srd_decoder_searchpath_add(env_path)) != SRD_OK) {
196  Py_Finalize();
197  return ret;
198  }
199  }
200 
201  max_session_id = 0;
202 
203  return SRD_OK;
204 }
205 
206 /**
207  * Shutdown libsigrokdecode.
208  *
209  * This frees all the memory allocated for protocol decoders and shuts down
210  * the Python interpreter.
211  *
212  * This function should only be called if there was a (successful!) invocation
213  * of srd_init() before. Calling this function multiple times in a row, without
214  * any successful srd_init() calls in between, is not allowed.
215  *
216  * @return SRD_OK upon success, a (negative) error code otherwise.
217  *
218  * @since 0.1.0
219  */
220 SRD_API int srd_exit(void)
221 {
222  srd_dbg("Exiting libsigrokdecode.");
223 
224  g_slist_foreach(sessions, (GFunc)srd_session_destroy, NULL);
225 
227  g_slist_free_full(searchpaths, g_free);
228  searchpaths = NULL;
229 
230  /* Py_Finalize() returns void, any finalization errors are ignored. */
231  Py_Finalize();
232 
233  max_session_id = -1;
234 
235  return SRD_OK;
236 }
237 
238 /**
239  * Add an additional search directory for the protocol decoders.
240  *
241  * The specified directory is prepended (not appended!) to Python's sys.path,
242  * in order to search for sigrok protocol decoders in the specified
243  * directories first, and in the generic Python module directories (and in
244  * the current working directory) last. This avoids conflicts if there are
245  * Python modules which have the same name as a sigrok protocol decoder in
246  * sys.path or in the current working directory.
247  *
248  * @param path Path to the directory containing protocol decoders which shall
249  * be added to the Python sys.path, or NULL.
250  *
251  * @return SRD_OK upon success, a (negative) error code otherwise.
252  *
253  * @private
254  *
255  * @since 0.1.0
256  */
257 SRD_PRIV int srd_decoder_searchpath_add(const char *path)
258 {
259  PyObject *py_cur_path, *py_item;
260 
261  srd_dbg("Adding '%s' to module path.", path);
262 
263  py_cur_path = PySys_GetObject("path");
264  if (!py_cur_path)
265  return SRD_ERR_PYTHON;
266 
267  py_item = PyUnicode_FromString(path);
268  if (!py_item) {
269  srd_exception_catch("Failed to create Unicode object");
270  return SRD_ERR_PYTHON;
271  }
272  if (PyList_Insert(py_cur_path, 0, py_item) < 0) {
273  srd_exception_catch("Failed to insert path element");
274  Py_DECREF(py_item);
275  return SRD_ERR_PYTHON;
276  }
277  Py_DECREF(py_item);
278 
279  searchpaths = g_slist_prepend(searchpaths, g_strdup(path));
280 
281  return SRD_OK;
282 }
283 
284 /** @} */
No error.
int srd_init(const char *path)
Initialize libsigrokdecode.
Definition: srd.c:142
#define SRD_API
Generic/unspecified error.
int srd_decoder_unload_all(void)
Unload all loaded protocol decoders.
Definition: decoder.c:993
int srd_session_destroy(struct srd_session *sess)
Destroy a decoding session.
Definition: session.c:270
The public libsigrokdecode header file to be used by frontends.
#define SRD_PRIV
Python C API error.
int srd_exit(void)
Shutdown libsigrokdecode.
Definition: srd.c:220