libsigrokdecode  0.5.0
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 static void print_versions(void)
116 {
117  GString *s;
118  GSList *l, *l_orig, *m;
119  char *str;
120  const char *lib, *version;
121 
122  srd_dbg("libsigrokdecode %s/%s (rt: %s/%s).",
125 
126  s = g_string_sized_new(200);
127  g_string_append(s, "Libs: ");
128  l_orig = srd_buildinfo_libs_get();
129  for (l = l_orig; l; l = l->next) {
130  m = l->data;
131  lib = m->data;
132  version = m->next->data;
133  g_string_append_printf(s, "%s %s, ", lib, version);
134  g_slist_free_full(m, g_free);
135  }
136  g_slist_free(l_orig);
137  s->str[s->len - 2] = '.';
138  s->str[s->len - 1] = '\0';
139  srd_dbg("%s", s->str);
140  g_string_free(s, TRUE);
141 
142  str = srd_buildinfo_host_get();
143  srd_dbg("Host: %s.", str);
144  g_free(str);
145 }
146 
147 /**
148  * Initialize libsigrokdecode.
149  *
150  * This initializes the Python interpreter, and creates and initializes
151  * a "sigrokdecode" Python module.
152  *
153  * Then, it searches for sigrok protocol decoders in the "decoders"
154  * subdirectory of the the libsigrokdecode installation directory.
155  * All decoders that are found are loaded into memory and added to an
156  * internal list of decoders, which can be queried via srd_decoder_list().
157  *
158  * The caller is responsible for calling the clean-up function srd_exit(),
159  * which will properly shut down libsigrokdecode and free its allocated memory.
160  *
161  * Multiple calls to srd_init(), without calling srd_exit() in between,
162  * are not allowed.
163  *
164  * @param path Path to an extra directory containing protocol decoders
165  * which will be added to the Python sys.path. May be NULL.
166  *
167  * @return SRD_OK upon success, a (negative) error code otherwise.
168  * Upon Python errors, SRD_ERR_PYTHON is returned. If the decoders
169  * directory cannot be accessed, SRD_ERR_DECODERS_DIR is returned.
170  * If not enough memory could be allocated, SRD_ERR_MALLOC is returned.
171  *
172  * @since 0.1.0
173  */
174 SRD_API int srd_init(const char *path)
175 {
176  const char *const *sys_datadirs;
177  const char *env_path;
178  size_t i;
179  int ret;
180 
181  if (max_session_id != -1) {
182  srd_err("libsigrokdecode is already initialized.");
183  return SRD_ERR;
184  }
185 
186  print_versions();
187 
188  srd_dbg("Initializing libsigrokdecode.");
189 
190  /* Add our own module to the list of built-in modules. */
191  PyImport_AppendInittab("sigrokdecode", PyInit_sigrokdecode);
192 
193  /* Initialize the Python interpreter. */
194  Py_InitializeEx(0);
195 
196  /* Locations relative to the XDG system data directories. */
197  sys_datadirs = g_get_system_data_dirs();
198  for (i = g_strv_length((char **)sys_datadirs); i > 0; i--) {
199  ret = searchpath_add_xdg_dir(sys_datadirs[i-1]);
200  if (ret != SRD_OK) {
201  Py_Finalize();
202  return ret;
203  }
204  }
205 #ifdef DECODERS_DIR
206  /* Hardcoded decoders install location, if defined. */
207  if ((ret = srd_decoder_searchpath_add(DECODERS_DIR)) != SRD_OK) {
208  Py_Finalize();
209  return ret;
210  }
211 #endif
212  /* Location relative to the XDG user data directory. */
213  ret = searchpath_add_xdg_dir(g_get_user_data_dir());
214  if (ret != SRD_OK) {
215  Py_Finalize();
216  return ret;
217  }
218 
219  /* Path specified by the user. */
220  if (path) {
221  if ((ret = srd_decoder_searchpath_add(path)) != SRD_OK) {
222  Py_Finalize();
223  return ret;
224  }
225  }
226 
227  /* Environment variable overrides everything, for debugging. */
228  if ((env_path = g_getenv("SIGROKDECODE_DIR"))) {
229  if ((ret = srd_decoder_searchpath_add(env_path)) != SRD_OK) {
230  Py_Finalize();
231  return ret;
232  }
233  }
234 
235  max_session_id = 0;
236 
237  return SRD_OK;
238 }
239 
240 /**
241  * Shutdown libsigrokdecode.
242  *
243  * This frees all the memory allocated for protocol decoders and shuts down
244  * the Python interpreter.
245  *
246  * This function should only be called if there was a (successful!) invocation
247  * of srd_init() before. Calling this function multiple times in a row, without
248  * any successful srd_init() calls in between, is not allowed.
249  *
250  * @return SRD_OK upon success, a (negative) error code otherwise.
251  *
252  * @since 0.1.0
253  */
254 SRD_API int srd_exit(void)
255 {
256  srd_dbg("Exiting libsigrokdecode.");
257 
258  g_slist_foreach(sessions, (GFunc)srd_session_destroy, NULL);
259 
261  g_slist_free_full(searchpaths, g_free);
262  searchpaths = NULL;
263 
264  /* Py_Finalize() returns void, any finalization errors are ignored. */
265  Py_Finalize();
266 
267  max_session_id = -1;
268 
269  return SRD_OK;
270 }
271 
272 /**
273  * Add an additional search directory for the protocol decoders.
274  *
275  * The specified directory is prepended (not appended!) to Python's sys.path,
276  * in order to search for sigrok protocol decoders in the specified
277  * directories first, and in the generic Python module directories (and in
278  * the current working directory) last. This avoids conflicts if there are
279  * Python modules which have the same name as a sigrok protocol decoder in
280  * sys.path or in the current working directory.
281  *
282  * @param path Path to the directory containing protocol decoders which shall
283  * be added to the Python sys.path, or NULL.
284  *
285  * @return SRD_OK upon success, a (negative) error code otherwise.
286  *
287  * @private
288  *
289  * @since 0.1.0
290  */
291 SRD_PRIV int srd_decoder_searchpath_add(const char *path)
292 {
293  PyObject *py_cur_path, *py_item;
294 
295  srd_dbg("Adding '%s' to module path.", path);
296 
297  py_cur_path = PySys_GetObject("path");
298  if (!py_cur_path)
299  return SRD_ERR_PYTHON;
300 
301  py_item = PyUnicode_FromString(path);
302  if (!py_item) {
303  srd_exception_catch("Failed to create Unicode object");
304  return SRD_ERR_PYTHON;
305  }
306  if (PyList_Insert(py_cur_path, 0, py_item) < 0) {
307  srd_exception_catch("Failed to insert path element");
308  Py_DECREF(py_item);
309  return SRD_ERR_PYTHON;
310  }
311  Py_DECREF(py_item);
312 
313  searchpaths = g_slist_prepend(searchpaths, g_strdup(path));
314 
315  return SRD_OK;
316 }
317 
318 /** @} */
No error.
int srd_init(const char *path)
Initialize libsigrokdecode.
Definition: srd.c:174
#define SRD_API
#define SRD_PACKAGE_VERSION_STRING
The libsigrokdecode package version ("major.minor.micro") as string.
Definition: version.h:51
Generic/unspecified error.
int srd_decoder_unload_all(void)
Unload all loaded protocol decoders.
Definition: decoder.c:1006
GSList * srd_buildinfo_libs_get(void)
Definition: version.c:149
int srd_session_destroy(struct srd_session *sess)
Destroy a decoding session.
Definition: session.c:306
The public libsigrokdecode header file to be used by frontends.
#define SRD_PRIV
char * srd_buildinfo_host_get(void)
Definition: version.c:168
const char * srd_lib_version_string_get(void)
Get the libsigrokdecode library version number as a string.
Definition: version.c:144
#define SRD_LIB_VERSION_STRING
The libsigrokdecode libtool version ("current:revision:age") as string.
Definition: version.h:67
const char * srd_package_version_string_get(void)
Get the libsigrokdecode package version number as a string.
Definition: version.c:95
Python C API error.
int srd_exit(void)
Shutdown libsigrokdecode.
Definition: srd.c:254