NetworkManager/shared/nm-glib-aux/nm-json-aux.c

// SPDX-License-Identifier: LGPL-2.1+
/*
 * Copyright (C) 2017 - 2019 Red Hat, Inc.
 */

#include "nm-default.h"

#include "nm-json-aux.h"

#include <dlfcn.h>

/*****************************************************************************/

static void
_gstr_append_string_len (GString *gstr,
                         const char *str,
                         gsize len)
{
	g_string_append_c (gstr, '\"');

	while (len > 0) {
		gsize n;
		const char *end;
		gboolean valid;

		nm_assert (len > 0);

		valid = g_utf8_validate (str, len, &end);

		nm_assert (   end
		           && end >= str
		           && end <= &str[len]);

		if (end > str) {
			const char *s;

			for (s = str; s < end; s++) {
				nm_assert (s[0] != '\0');

				if (s[0] < 0x20) {
					const char *text;

					switch (s[0]) {
					case '\\': text = "\\\\"; break;
					case '\"': text = "\\\""; break;
					case '\b': text = "\\b";  break;
					case '\f': text = "\\f";  break;
					case '\n': text = "\\n";  break;
					case '\r': text = "\\r";  break;
					case '\t': text = "\\t";  break;
					default:
						g_string_append_printf (gstr, "\\u%04X", (guint) s[0]);
						continue;
					}
					g_string_append (gstr, text);
					continue;
				}

				if (NM_IN_SET (s[0], '\\', '\"'))
					g_string_append_c (gstr, '\\');
				g_string_append_c (gstr, s[0]);
			}
		} else
			nm_assert (!valid);

		if (valid) {
			nm_assert (end == &str[len]);
			break;
		}

		nm_assert (end < &str[len]);

		if (end[0] == '\0') {
			/* there is a NUL byte in the string. Technically this is valid UTF-8, so we
			 * encode it there. However, this will likely result in a truncated string when
			 * parsing. */
			g_string_append (gstr, "\\u0000");
		} else {
			/* the character is not valid UTF-8. There is nothing we can do about it, because
			 * JSON can only contain UTF-8 and even the escape sequences can only escape Unicode
			 * codepoints (but not binary).
			 *
			 * The argument is not a string (in any known encoding), hence we cannot represent
			 * it as a JSON string (which are unicode strings).
			 *
			 * Print an underscore instead of the invalid char :) */
			g_string_append_c (gstr, '_');
		}

		n = str - end;
		nm_assert (n < len);
		n++;
		str += n;
		len -= n;
	}

	g_string_append_c (gstr, '\"');
}

void
nm_json_gstr_append_string_len (GString *gstr,
                                const char *str,
                                gsize n)
{
	g_return_if_fail (gstr);

	_gstr_append_string_len (gstr, str, n);
}

void
nm_json_gstr_append_string (GString *gstr,
                            const char *str)
{
	g_return_if_fail (gstr);

	if (!str)
		g_string_append (gstr, "null");
	else
		_gstr_append_string_len (gstr, str, strlen (str));
}

void
nm_json_gstr_append_obj_name (GString *gstr,
                              const char *key,
                              char start_container)
{
	g_return_if_fail (gstr);
	g_return_if_fail (key);

	nm_json_gstr_append_string (gstr, key);

	if (start_container != '\0') {
		nm_assert (NM_IN_SET (start_container, '[', '{'));
		g_string_append_printf (gstr, ": %c ", start_container);
	} else
		g_string_append (gstr, ": ");
}

/*****************************************************************************/

typedef struct {
	NMJsonVt vt;
	void *dl_handle;
} NMJsonVtInternal;

static NMJsonVtInternal *
_nm_json_vt_internal_load (void)
{
	NMJsonVtInternal *v;
	const char *soname;
	void *handle;

	v = g_new0 (NMJsonVtInternal, 1);

#if WITH_JANSSON && defined (JANSSON_SONAME)
	G_STATIC_ASSERT_EXPR (NM_STRLEN (JANSSON_SONAME) > 0);
	nm_assert (strlen (JANSSON_SONAME) > 0);
	soname = JANSSON_SONAME;
#elif !WITH_JANSSON && !defined (JANSSON_SONAME)
	soname = NULL;
#else
#error "WITH_JANSON and JANSSON_SONAME are defined inconsistently."
#endif

	if (!soname)
		return v;

	handle = dlopen (soname,   RTLD_LAZY
	                         | RTLD_LOCAL
	                         | RTLD_NODELETE
#if !defined (ASAN_BUILD)
	                         | RTLD_DEEPBIND
#endif
	                         | 0);
	if (!handle)
		return v;

#define TRY_BIND_SYMBOL(symbol) \
	G_STMT_START { \
		void *_sym = dlsym (handle, #symbol); \
		\
		if (!_sym) \
			goto fail_symbol; \
		v->vt.nm_ ## symbol = _sym; \
	} G_STMT_END

	TRY_BIND_SYMBOL (json_array);
	TRY_BIND_SYMBOL (json_array_append_new);
	TRY_BIND_SYMBOL (json_array_get);
	TRY_BIND_SYMBOL (json_array_size);
	TRY_BIND_SYMBOL (json_delete);
	TRY_BIND_SYMBOL (json_dumps);
	TRY_BIND_SYMBOL (json_false);
	TRY_BIND_SYMBOL (json_integer);
	TRY_BIND_SYMBOL (json_integer_value);
	TRY_BIND_SYMBOL (json_loads);
	TRY_BIND_SYMBOL (json_object);
	TRY_BIND_SYMBOL (json_object_del);
	TRY_BIND_SYMBOL (json_object_get);
	TRY_BIND_SYMBOL (json_object_iter);
	TRY_BIND_SYMBOL (json_object_iter_key);
	TRY_BIND_SYMBOL (json_object_iter_next);
	TRY_BIND_SYMBOL (json_object_iter_value);
	TRY_BIND_SYMBOL (json_object_key_to_iter);
	TRY_BIND_SYMBOL (json_object_set_new);
	TRY_BIND_SYMBOL (json_object_size);
	TRY_BIND_SYMBOL (json_string);
	TRY_BIND_SYMBOL (json_string_value);
	TRY_BIND_SYMBOL (json_true);

	v->vt.loaded = TRUE;
	v->dl_handle = handle;
	return v;

fail_symbol:
	dlclose (&handle);
	*v = (NMJsonVtInternal) { };
	return v;
}

const NMJsonVt *_nm_json_vt_ptr = NULL;

const NMJsonVt *
_nm_json_vt_init (void)
{
	NMJsonVtInternal *v;

again:
	v = g_atomic_pointer_get ((gpointer *) &_nm_json_vt_ptr);
	if (G_UNLIKELY (!v)) {
		v = _nm_json_vt_internal_load ();
		if (!g_atomic_pointer_compare_and_exchange ((gpointer *) &_nm_json_vt_ptr, NULL, v)) {
			if (v->dl_handle)
				dlclose (v->dl_handle);
			g_free (v);
			goto again;
		}

		/* we transfer ownership. */
	}

	nm_assert (v && v == g_atomic_pointer_get ((gpointer *) &_nm_json_vt_ptr));
	return &v->vt;
}

const NMJsonVt *
nmtst_json_vt_reset (gboolean loaded)
{
	NMJsonVtInternal *v_old;
	NMJsonVtInternal *v;

	v_old = g_atomic_pointer_get ((gpointer *) &_nm_json_vt_ptr);

	if (!loaded) {
		/* load a fake instance for testing. */
		v = g_new0 (NMJsonVtInternal, 1);
	} else
		v = _nm_json_vt_internal_load ();

	if (!g_atomic_pointer_compare_and_exchange ((gpointer *) &_nm_json_vt_ptr, v_old, v))
		g_assert_not_reached ();

	if (v_old) {
		if (v_old->dl_handle)
			dlclose (v_old->dl_handle);
		g_free ((gpointer *) v_old);
	}

	return v->vt.loaded ? &v->vt : NULL;
}