Use wordexp to resolve variables like $HOME in path like settings

It seems like the wordexp implementation in musl leaks memory and thus a
new suppression is required to pass CI. It also doesn't fully implement
all POSIX features and thus at least one test has to be deactivated in
that case.

.valgrind.suppressions

@@ -6,6 +6,19 @@
  obj:/lib/ld-musl-x86_64.so.1
 }
 
+# Ignore another musls' weird error
+{
+ musl_alpine_libc
+ Memcheck:Leak
+ match-leak-kinds: definite
+ fun:malloc
+ fun:realloc
+ fun:getdelim
+ obj:*
+ fun:vgMemCheck_new_block
+ obj:*
+}
+
 # rsvg_error_handle_close got fixed in
 # - GNOME/librsvg@7bf1014
 # (2018-11-12, first tags: v2.45.0, v2.44.9)

docs/dunst.5.pod

@@ -911,7 +911,8 @@ If B<icon_position> is set to off, this setting is ignored.
 
 Updates the icon of the notification, it should be a path or a name for a valid
 image. This overrides the icon that was sent with dunstify or another notification
-tool.
+tool. Expansion of the argument is carried out using wordexp(3)
+with command substitution disabled.
 
 =item C<icon_position> (values: [left/right/top/off], default: left)
 
@@ -922,7 +923,8 @@ disables icons.
 
 Sets the default icon of the notification, it should be a path or a name for a
 valid image. This does B<not> override the icon that was sent with dunstify or
-another notification tool.
+another notification tool. Expansion of the argument is carried out using
+wordexp(3) with command substitution disabled.
 
 =item C<set_stack_tag>
 
@@ -1087,9 +1089,10 @@ Note that some variables may be empty.
 If the notification is suppressed, the script will not be run unless
 B<always_run_script> is set to true.
 
-If '~/' occurs at the beginning of the script parameter, it will get replaced by the
-users' home directory. If the value is not an absolute path, the directories in the
-PATH variable will be searched for an executable of the same name.
+The script parameter is expanded according to wordexp(3) with command
+substitution disabled. If the expanded value is not an absolute path, the
+directories in the PATH variable will be searched for an executable of the same
+name.
 
 =head1 COLORS
 

src/utils.c

@@ -13,6 +13,7 @@
 #include <sys/stat.h>
 #include <time.h>
 #include <unistd.h>
+#include <wordexp.h>
 
 #include "log.h"
 #include "settings_data.h"
@@ -179,16 +180,34 @@ int string_array_length(char **s)
 /* see utils.h */
 char *string_to_path(char *string)
 {
-
- if (string && STRN_EQ(string, "~/", 2)) {
- char *home = g_strconcat(user_get_home(), "/", NULL);
-
- string = string_replace_at(string, 0, 2, home);
-
- g_free(home);
+ ASSERT_OR_RET(string, string);
+
+ wordexp_t we;
+ switch (wordexp(string, &we, WRDE_NOCMD | WRDE_UNDEF)) {
+ case 0:
+ break;
+ case WRDE_BADCHAR:
+ LOG_W("Expansion of \"%s\" failed. It contains invalid characters.", string);
+ return string;
+ case WRDE_BADVAL:
+ LOG_W("Expansion of \"%s\" failed. It contains an undefined variable.", string);
+ return string;
+ case WRDE_CMDSUB:
+ LOG_W("Expansion of \"%s\" failed. The requested command substitution is currently not supported.", string);
+ return string;
+ case WRDE_NOSPACE:
+ LOG_W("Expansion of \"%s\" failed. We ran out of memory.", string);
+ return string;
+ case WRDE_SYNTAX:
+ LOG_W("Expansion of \"%s\" failed. It contains invalid syntax.", string);
+ return string;
  }
+ g_free(string);
+
+ char *res = g_strjoinv(" ", we.we_wordv);
+ wordfree(&we);
 
- return string;
+ return res;
 }
 
 /* see utils.h */

test/option_parser.c

@@ -521,16 +521,23 @@ TEST test_string_to_path(void)
  "/path/p argument",
  "p with multiple arguments",
  "~/p/p",
+ "$HOME/p/p",
+ "$TEST_ENV/p/p",
  };
 
+ setenv("TEST_ENV", "foobar", 1);
+
  char *expanded_home = g_strconcat(user_get_home(), "/", "p/p", NULL);
+ char *expanded_env = g_strconcat("foobar", "/p/p", NULL);
  const char* results[] = {
  "/bin/something",
  "something",
  "/path/path/path/",
  "/path/p argument",
  "p with multiple arguments",
  expanded_home,
+ expanded_home,
+ expanded_env,
  };
 
  const char* results2[][5] = {
@@ -540,6 +547,8 @@ TEST test_string_to_path(void)
  {"/path/p", "argument", NULL},
  {"p", "with", "multiple", "arguments", NULL},
  {expanded_home},
+ {expanded_home},
+ {expanded_env},
  };
 
  ARRAY_SAME_LENGTH(inputs, results);
@@ -557,6 +566,7 @@ TEST test_string_to_path(void)
  }
 
  g_free(val);
+ g_free(expanded_env);
  g_free(expanded_home);
  g_strfreev(val2);
  PASS();

test/utils.c

@@ -1,3 +1,5 @@
+#include <features.h>
+
 #include "../src/utils.c"
 #include "greatest.h"
 
@@ -152,6 +154,7 @@ TEST test_string_to_path(void)
  ASSERT_STR_EQ(exp, (ptr = string_to_path(g_strdup(exp))));
  free(ptr);
 
+ // This might fail, when a user named path exists on the host running the tests.
  exp = "~path/with/wrong/tilde";
  ASSERT_STR_EQ(exp, (ptr = string_to_path(g_strdup(exp))));
  free(ptr);
@@ -166,6 +169,19 @@ TEST test_string_to_path(void)
  free(exp);
  free(ptr);
 
+ ASSERT_STR_EQ((exp = g_strconcat(home, "/.path/with/HOME environment variable", NULL)),
+ (ptr = string_to_path(g_strdup("$HOME/.path/with/HOME environment variable"))));
+ free(exp);
+ free(ptr);
+
+// Just glibc properly returns an error when using `WRDE_UNDEF` and an
+// undefined variable is found. musl accepts this flag and ignores it.
+#ifdef __GLIBC__
+ exp = "/some/$UNDEFINED/variable";
+ ASSERT_STR_EQ(exp, (ptr = string_to_path(g_strdup(exp))));
+ free(ptr);
+#endif
+
  PASS();
 }