srd.c

   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).",
 123                 SRD_PACKAGE_VERSION_STRING, SRD_LIB_VERSION_STRING,
 124                 srd_package_version_string_get(), srd_lib_version_string_get());
 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 static int print_searchpaths(void)
 148 {
 149         PyObject *py_paths, *py_path, *py_bytes;
 150         PyGILState_STATE gstate;
 151         GString *s;
 152         GSList *l;
 153         int i;
 154
 155         s = g_string_sized_new(500);
 156         g_string_append(s, "Protocol decoder search paths:\n");
 157         for (l = searchpaths; l; l = l->next)
 158                 g_string_append_printf(s, " - %s\n", (const char *)l->data);
 159         s->str[s->len - 1] = '\0';
 160         srd_dbg("%s", s->str);
 161         g_string_free(s, TRUE);
 162
 163         gstate = PyGILState_Ensure();
 164
 165         py_paths = PySys_GetObject("path");
 166         if (!py_paths)
 167                 goto err;
 168
 169         s = g_string_sized_new(500);
 170         g_string_append(s, "Python system search paths:\n");
 171         for (i = 0; i < PyList_Size(py_paths); i++) {
 172                 py_path = PyList_GetItem(py_paths, i);
 173                 py_bytes = PyUnicode_AsUTF8String(py_path);
 174                 g_string_append_printf(s, " - %s\n", PyBytes_AsString(py_bytes));
 175                 Py_DECREF(py_bytes);
 176         }
 177         s->str[s->len - 1] = '\0';
 178         srd_dbg("%s", s->str);
 179         g_string_free(s, TRUE);
 180
 181         PyGILState_Release(gstate);
 182
 183         return SRD_OK;
 184
 185 err:
 186         srd_err("Unable to query Python system search paths.");
 187         PyGILState_Release(gstate);
 188
 189         return SRD_ERR_PYTHON;
 190 }
 191
 192 /**
 193  * Initialize libsigrokdecode.
 194  *
 195  * This initializes the Python interpreter, and creates and initializes
 196  * a "sigrokdecode" Python module.
 197  *
 198  * Then, it searches for sigrok protocol decoders in the "decoders"
 199  * subdirectory of the the libsigrokdecode installation directory.
 200  * All decoders that are found are loaded into memory and added to an
 201  * internal list of decoders, which can be queried via srd_decoder_list().
 202  *
 203  * The caller is responsible for calling the clean-up function srd_exit(),
 204  * which will properly shut down libsigrokdecode and free its allocated memory.
 205  *
 206  * Multiple calls to srd_init(), without calling srd_exit() in between,
 207  * are not allowed.
 208  *
 209  * @param path Path to an extra directory containing protocol decoders
 210  *             which will be added to the Python sys.path. May be NULL.
 211  *
 212  * @return SRD_OK upon success, a (negative) error code otherwise.
 213  *         Upon Python errors, SRD_ERR_PYTHON is returned. If the decoders
 214  *         directory cannot be accessed, SRD_ERR_DECODERS_DIR is returned.
 215  *         If not enough memory could be allocated, SRD_ERR_MALLOC is returned.
 216  *
 217  * @since 0.1.0
 218  */
 219 SRD_API int srd_init(const char *path)
 220 {
 221         const char *const *sys_datadirs;
 222         const char *env_path;
 223         size_t i;
 224         int ret;
 225
 226         if (max_session_id != -1) {
 227                 srd_err("libsigrokdecode is already initialized.");
 228                 return SRD_ERR;
 229         }
 230
 231         print_versions();
 232
 233         srd_dbg("Initializing libsigrokdecode.");
 234
 235         /* Add our own module to the list of built-in modules. */
 236         PyImport_AppendInittab("sigrokdecode", PyInit_sigrokdecode);
 237
 238         /* Initialize the Python interpreter. */
 239         Py_InitializeEx(0);
 240
 241         /* Locations relative to the XDG system data directories. */
 242         sys_datadirs = g_get_system_data_dirs();
 243         for (i = g_strv_length((char **)sys_datadirs); i > 0; i--) {
 244                 ret = searchpath_add_xdg_dir(sys_datadirs[i - 1]);
 245                 if (ret != SRD_OK) {
 246                         Py_Finalize();
 247                         return ret;
 248                 }
 249         }
 250 #ifdef DECODERS_DIR
 251         /* Hardcoded decoders install location, if defined. */
 252         if ((ret = srd_decoder_searchpath_add(DECODERS_DIR)) != SRD_OK) {
 253                 Py_Finalize();
 254                 return ret;
 255         }
 256 #endif
 257         /* Location relative to the XDG user data directory. */
 258         ret = searchpath_add_xdg_dir(g_get_user_data_dir());
 259         if (ret != SRD_OK) {
 260                 Py_Finalize();
 261                 return ret;
 262         }
 263
 264         /* Path specified by the user. */
 265         if (path) {
 266                 if ((ret = srd_decoder_searchpath_add(path)) != SRD_OK) {
 267                         Py_Finalize();
 268                         return ret;
 269                 }
 270         }
 271
 272         /* Environment variable overrides everything, for debugging. */
 273         if ((env_path = g_getenv("SIGROKDECODE_DIR"))) {
 274                 if ((ret = srd_decoder_searchpath_add(env_path)) != SRD_OK) {
 275                         Py_Finalize();
 276                         return ret;
 277                 }
 278         }
 279
 280         /* Initialize the Python GIL (this also happens to acquire it). */
 281         PyEval_InitThreads();
 282
 283         /* Release the GIL (ignore return value, we don't need it here). */
 284         (void)PyEval_SaveThread();
 285
 286         max_session_id = 0;
 287
 288         print_searchpaths();
 289
 290         return SRD_OK;
 291 }
 292
 293 static void srd_session_destroy_cb(void *arg, void *ignored)
 294 {
 295         (void)ignored; // Prevent unused warning
 296         srd_session_destroy((struct srd_session *)arg);
 297 }
 298
 299 /**
 300  * Shutdown libsigrokdecode.
 301  *
 302  * This frees all the memory allocated for protocol decoders and shuts down
 303  * the Python interpreter.
 304  *
 305  * This function should only be called if there was a (successful!) invocation
 306  * of srd_init() before. Calling this function multiple times in a row, without
 307  * any successful srd_init() calls in between, is not allowed.
 308  *
 309  * @return SRD_OK upon success, a (negative) error code otherwise.
 310  *
 311  * @since 0.1.0
 312  */
 313 SRD_API int srd_exit(void)
 314 {
 315         srd_dbg("Exiting libsigrokdecode.");
 316
 317         g_slist_foreach(sessions, srd_session_destroy_cb, NULL);
 318         g_slist_free(sessions);
 319         sessions = NULL;
 320
 321         srd_decoder_unload_all();
 322         g_slist_free_full(searchpaths, g_free);
 323         searchpaths = NULL;
 324
 325         /*
 326          * Acquire the GIL, otherwise Py_Finalize() might have issues.
 327          * Ignore the return value, we don't need it here.
 328          */
 329         if (Py_IsInitialized())
 330                 (void)PyGILState_Ensure();
 331
 332         /* Py_Finalize() returns void, any finalization errors are ignored. */
 333         Py_Finalize();
 334
 335         /* Note: No need to release the GIL since Python is shut down now. */
 336
 337         max_session_id = -1;
 338
 339         return SRD_OK;
 340 }
 341
 342 /**
 343  * Add an additional search directory for the protocol decoders.
 344  *
 345  * The specified directory is prepended (not appended!) to Python's sys.path,
 346  * in order to search for sigrok protocol decoders in the specified
 347  * directories first, and in the generic Python module directories (and in
 348  * the current working directory) last. This avoids conflicts if there are
 349  * Python modules which have the same name as a sigrok protocol decoder in
 350  * sys.path or in the current working directory.
 351  *
 352  * @param path Path to the directory containing protocol decoders which shall
 353  *             be added to the Python sys.path, or NULL.
 354  *
 355  * @return SRD_OK upon success, a (negative) error code otherwise.
 356  *
 357  * @private
 358  */
 359 SRD_PRIV int srd_decoder_searchpath_add(const char *path)
 360 {
 361         PyObject *py_cur_path, *py_item;
 362         PyGILState_STATE gstate;
 363
 364         srd_dbg("Adding '%s' to module path.", path);
 365
 366         gstate = PyGILState_Ensure();
 367
 368         py_cur_path = PySys_GetObject("path");
 369         if (!py_cur_path)
 370                 goto err;
 371
 372         py_item = PyUnicode_FromString(path);
 373         if (!py_item) {
 374                 srd_exception_catch("Failed to create Unicode object");
 375                 goto err;
 376         }
 377         if (PyList_Insert(py_cur_path, 0, py_item) < 0) {
 378                 srd_exception_catch("Failed to insert path element");
 379                 Py_DECREF(py_item);
 380                 goto err;
 381         }
 382         Py_DECREF(py_item);
 383
 384         PyGILState_Release(gstate);
 385
 386         searchpaths = g_slist_prepend(searchpaths, g_strdup(path));
 387
 388         return SRD_OK;
 389
 390 err:
 391         PyGILState_Release(gstate);
 392
 393         return SRD_ERR_PYTHON;
 394 }
 395
 396 /**
 397  * Return the list of protocol decoder search paths.
 398  *
 399  * @return The list of search paths used when loading protocol decoders.
 400  *
 401  * @since 0.5.1
 402  */
 403 SRD_API GSList *srd_searchpaths_get(void)
 404 {
 405         GSList *paths = NULL;
 406
 407         for (GSList *l = searchpaths; l; l = l->next)
 408                 paths = g_slist_append(paths, g_strdup(l->data));
 409
 410         return paths;
 411 }
 412
 413 /** @} */