Split out xdg.{c,h}
This commit is contained in:
186
xdg.c
Normal file
186
xdg.c
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//
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// xdg.c: various *nix desktop utilities
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//
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// Copyright (c) 2021, Přemysl Eric Janouch <p@janouch.name>
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//
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// Permission to use, copy, modify, and/or distribute this software for any
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// purpose with or without fee is hereby granted.
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//
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// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
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// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
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// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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//
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#include <glib.h>
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/// Add `element` to the `output` set. `relation` is a map of sets of strings
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/// defining is-a relations, and is traversed recursively.
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static void
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add_applying_transitive_closure(
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const gchar *element, GHashTable *relation, GHashTable *output)
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{
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// Stop condition.
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if (!g_hash_table_add(output, g_strdup(element)))
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return;
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// TODO(p): Iterate over all aliases of `element` in addition to
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// any direct match (and rename this no-longer-generic function).
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GHashTable *targets = g_hash_table_lookup(relation, element);
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if (!targets)
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return;
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GHashTableIter iter;
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g_hash_table_iter_init(&iter, targets);
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gpointer key = NULL, value = NULL;
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while (g_hash_table_iter_next(&iter, &key, &value))
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add_applying_transitive_closure(key, relation, output);
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}
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char *
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get_xdg_home_dir(const char *var, const char *default_)
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{
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const char *env = getenv(var);
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if (env && *env == '/')
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return g_strdup(env);
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// The specification doesn't handle a missing HOME variable explicitly.
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// Implicitly, assuming Bourne shell semantics, it simply resolves empty.
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const char *home = getenv("HOME");
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return g_build_filename(home ? home : "", default_, NULL);
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}
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static gchar **
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get_xdg_data_dirs(void)
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{
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// GStrvBuilder is too new, it would help a little bit.
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GPtrArray *output = g_ptr_array_new_with_free_func(g_free);
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g_ptr_array_add(output, get_xdg_home_dir("XDG_DATA_HOME", ".local/share"));
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const gchar *xdg_data_dirs;
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if (!(xdg_data_dirs = getenv("XDG_DATA_DIRS")) || !*xdg_data_dirs)
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xdg_data_dirs = "/usr/local/share/:/usr/share/";
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gchar **candidates = g_strsplit(xdg_data_dirs, ":", 0);
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for (gchar **p = candidates; *p; p++) {
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if (**p == '/')
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g_ptr_array_add(output, *p);
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else
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g_free(*p);
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}
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g_free(candidates);
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g_ptr_array_add(output, NULL);
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return (gchar **) g_ptr_array_free(output, FALSE);
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}
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// --- Filtering ---------------------------------------------------------------
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// Derived from shared-mime-info-spec 0.21.
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static void
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read_mime_subclasses(const gchar *path, GHashTable *subclass_sets)
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{
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gchar *data = NULL;
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if (!g_file_get_contents(path, &data, NULL /* length */, NULL /* error */))
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return;
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// The format of this file is unspecified,
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// but in practice it's a list of space-separated media types.
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gchar *datasave = NULL;
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for (gchar *line = strtok_r(data, "\r\n", &datasave); line;
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line = strtok_r(NULL, "\r\n", &datasave)) {
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gchar *linesave = NULL,
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*subclass = strtok_r(line, " ", &linesave),
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*superclass = strtok_r(NULL, " ", &linesave);
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// Nothing about comments is specified, we're being nice.
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if (!subclass || *subclass == '#' || !superclass)
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continue;
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GHashTable *set = NULL;
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if (!(set = g_hash_table_lookup(subclass_sets, superclass))) {
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set = g_hash_table_new_full(g_str_hash, g_str_equal, g_free, NULL);
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g_hash_table_insert(subclass_sets, g_strdup(superclass), set);
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}
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g_hash_table_add(set, g_strdup(subclass));
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}
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g_free(data);
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}
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static gboolean
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filter_mime_globs(const gchar *path, guint is_globs2, GHashTable *supported_set,
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GHashTable *output_set)
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{
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gchar *data = NULL;
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if (!g_file_get_contents(path, &data, NULL /* length */, NULL /* error */))
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return FALSE;
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gchar *datasave = NULL;
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for (const gchar *line = strtok_r(data, "\r\n", &datasave); line;
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line = strtok_r(NULL, "\r\n", &datasave)) {
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if (*line == '#')
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continue;
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// We do not support __NOGLOBS__, nor even parse out the "cs" flag.
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// The weight is irrelevant.
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gchar **f = g_strsplit(line, ":", 0);
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if (g_strv_length(f) >= is_globs2 + 2) {
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const gchar *type = f[is_globs2 + 0], *glob = f[is_globs2 + 1];
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if (g_hash_table_contains(supported_set, type))
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g_hash_table_add(output_set, g_utf8_strdown(glob, -1));
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}
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g_strfreev(f);
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}
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g_free(data);
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return TRUE;
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}
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char **
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extract_mime_globs(const char **media_types)
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{
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gchar **data_dirs = get_xdg_data_dirs();
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// The mime.cache format is inconvenient to parse,
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// we'll do it from the text files manually, and once only.
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GHashTable *subclass_sets = g_hash_table_new_full(
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g_str_hash, g_str_equal, g_free, (GDestroyNotify) g_hash_table_destroy);
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for (gsize i = 0; data_dirs[i]; i++) {
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gchar *path =
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g_build_filename(data_dirs[i], "mime", "subclasses", NULL);
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read_mime_subclasses(path, subclass_sets);
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g_free(path);
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}
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// A hash set of all supported media types, including subclasses,
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// but not aliases.
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GHashTable *supported =
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g_hash_table_new_full(g_str_hash, g_str_equal, g_free, NULL);
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while (*media_types) {
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add_applying_transitive_closure(
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*media_types++, subclass_sets, supported);
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}
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g_hash_table_destroy(subclass_sets);
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// We do not support the distinction of case-sensitive globs (:cs).
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GHashTable *globs =
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g_hash_table_new_full(g_str_hash, g_str_equal, g_free, NULL);
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for (gsize i = 0; data_dirs[i]; i++) {
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gchar *path2 = g_build_filename(data_dirs[i], "mime", "globs2", NULL);
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gchar *path1 = g_build_filename(data_dirs[i], "mime", "globs", NULL);
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if (!filter_mime_globs(path2, TRUE, supported, globs))
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filter_mime_globs(path1, FALSE, supported, globs);
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g_free(path2);
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g_free(path1);
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}
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g_strfreev(data_dirs);
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g_hash_table_destroy(supported);
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gchar **result = (gchar **) g_hash_table_get_keys_as_array(globs, NULL);
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g_hash_table_steal_all(globs);
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g_hash_table_destroy(globs);
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return result;
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}
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