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//
// xdg.c: various *nix desktop utilities
//
// Copyright (c) 2021, Přemysl Eric Janouch <p@janouch.name>
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
//
#include <glib.h>
/// Add `element` to the `output` set. `relation` is a map of sets of strings
/// defining is-a relations, and is traversed recursively.
static void
add_applying_transitive_closure(
const char *element, GHashTable *relation, GHashTable *output)
{
// Stop condition.
if (!g_hash_table_add(output, g_strdup(element)))
return;
// TODO(p): Iterate over all aliases of `element` in addition to
// any direct match (and rename this no-longer-generic function).
GHashTable *targets = g_hash_table_lookup(relation, element);
if (!targets)
return;
GHashTableIter iter;
g_hash_table_iter_init(&iter, targets);
gpointer key = NULL, value = NULL;
while (g_hash_table_iter_next(&iter, &key, &value))
add_applying_transitive_closure(key, relation, output);
}
char *
get_xdg_home_dir(const char *var, const char *default_)
{
const char *env = getenv(var);
if (env && g_path_is_absolute(env))
return g_strdup(env);
#ifdef G_OS_WIN32
return g_build_filename(g_get_home_dir(), default_, NULL);
#else
// The specification doesn't handle a missing HOME variable explicitly.
// Implicitly, assuming Bourne shell semantics, it simply resolves empty.
const char *home = getenv("HOME");
return g_build_filename(home ? home : "", default_, NULL);
#endif
}
// Reïmplemented partly due to https://gitlab.gnome.org/GNOME/glib/-/issues/2501
static gchar **
get_xdg_data_dirs(void)
{
// GStrvBuilder is too new, it would help a little bit.
GPtrArray *output = g_ptr_array_new_with_free_func(g_free);
#ifdef G_OS_WIN32
g_ptr_array_add(output, g_strdup(g_get_user_data_dir()));
for (const gchar *const *p = g_get_system_data_dirs(); *p; p++)
g_ptr_array_add(output, g_strdup(*p));
#else
g_ptr_array_add(output, get_xdg_home_dir("XDG_DATA_HOME", ".local/share"));
const char *xdg_data_dirs = "";
if (!(xdg_data_dirs = getenv("XDG_DATA_DIRS")) || !*xdg_data_dirs)
xdg_data_dirs = "/usr/local/share/:/usr/share/";
gchar **candidates = g_strsplit(xdg_data_dirs, G_SEARCHPATH_SEPARATOR_S, 0);
for (gchar **p = candidates; *p; p++) {
if (g_path_is_absolute(*p))
g_ptr_array_add(output, *p);
else
g_free(*p);
}
g_free(candidates);
#endif
g_ptr_array_add(output, NULL);
return (gchar **) g_ptr_array_free(output, FALSE);
}
// --- Filtering ---------------------------------------------------------------
// Derived from shared-mime-info-spec 0.21.
static void
read_mime_subclasses(const char *path, GHashTable *subclass_sets)
{
gchar *data = NULL;
if (!g_file_get_contents(path, &data, NULL /* length */, NULL /* error */))
return;
// The format of this file is unspecified,
// but in practice it's a list of space-separated media types.
gchar *datasave = NULL;
for (gchar *line = strtok_r(data, "\r\n", &datasave); line;
line = strtok_r(NULL, "\r\n", &datasave)) {
gchar *linesave = NULL,
*subclass = strtok_r(line, " ", &linesave),
*superclass = strtok_r(NULL, " ", &linesave);
// Nothing about comments is specified, we're being nice.
if (!subclass || *subclass == '#' || !superclass)
continue;
GHashTable *set = NULL;
if (!(set = g_hash_table_lookup(subclass_sets, superclass))) {
set = g_hash_table_new_full(g_str_hash, g_str_equal, g_free, NULL);
g_hash_table_insert(subclass_sets, g_strdup(superclass), set);
}
g_hash_table_add(set, g_strdup(subclass));
}
g_free(data);
}
static gboolean
filter_mime_globs(const char *path, guint is_globs2, GHashTable *supported_set,
GHashTable *output_set)
{
gchar *data = NULL;
if (!g_file_get_contents(path, &data, NULL /* length */, NULL /* error */))
return FALSE;
gchar *datasave = NULL;
for (const char *line = strtok_r(data, "\r\n", &datasave); line;
line = strtok_r(NULL, "\r\n", &datasave)) {
if (*line == '#')
continue;
// We do not support __NOGLOBS__, nor even parse out the "cs" flag.
// The weight is irrelevant.
gchar **f = g_strsplit(line, ":", 0);
if (g_strv_length(f) >= is_globs2 + 2) {
const gchar *type = f[is_globs2 + 0], *glob = f[is_globs2 + 1];
if (g_hash_table_contains(supported_set, type))
g_hash_table_add(output_set, g_utf8_strdown(glob, -1));
}
g_strfreev(f);
}
g_free(data);
return TRUE;
}
char **
extract_mime_globs(const char **media_types)
{
gchar **data_dirs = get_xdg_data_dirs();
// The mime.cache format is inconvenient to parse,
// we'll do it from the text files manually, and once only.
GHashTable *subclass_sets = g_hash_table_new_full(
g_str_hash, g_str_equal, g_free, (GDestroyNotify) g_hash_table_destroy);
for (gsize i = 0; data_dirs[i]; i++) {
gchar *path =
g_build_filename(data_dirs[i], "mime", "subclasses", NULL);
read_mime_subclasses(path, subclass_sets);
g_free(path);
}
// A hash set of all supported media types, including subclasses,
// but not aliases.
GHashTable *supported =
g_hash_table_new_full(g_str_hash, g_str_equal, g_free, NULL);
while (*media_types) {
add_applying_transitive_closure(
*media_types++, subclass_sets, supported);
}
g_hash_table_destroy(subclass_sets);
// We do not support the distinction of case-sensitive globs (:cs).
GHashTable *globs =
g_hash_table_new_full(g_str_hash, g_str_equal, g_free, NULL);
for (gsize i = 0; data_dirs[i]; i++) {
gchar *path2 = g_build_filename(data_dirs[i], "mime", "globs2", NULL);
gchar *path1 = g_build_filename(data_dirs[i], "mime", "globs", NULL);
if (!filter_mime_globs(path2, TRUE, supported, globs))
filter_mime_globs(path1, FALSE, supported, globs);
g_free(path2);
g_free(path1);
}
g_strfreev(data_dirs);
g_hash_table_destroy(supported);
gchar **result = (gchar **) g_hash_table_get_keys_as_array(globs, NULL);
g_hash_table_steal_all(globs);
g_hash_table_destroy(globs);
return result;
}
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