strv: introduce new strv_from_stdarg_alloca() macro to generate a string array from stdarg function parameters

This allows us to turn lists of strings passed in easily into string
arrays without having to allocate memory.

src/core/execute.c

@@ -2214,7 +2214,8 @@ int exec_command_set(ExecCommand *c, const char *path, ...) {
         if (!l)
                 return -ENOMEM;
 
-        if (!(p = strdup(path))) {
+        p = strdup(path);
+        if (!p) {
                 strv_free(l);
                 return -ENOMEM;
         }

src/libsystemd-bus/bus-objects.c

@@ -1976,8 +1976,7 @@ int sd_bus_emit_properties_changed(
                 const char *interface,
                 const char *name, ...)  {
 
-        _cleanup_strv_free_ char **names = NULL;
+        char **names;
-        va_list ap;
 
         assert_return(bus, -EINVAL);
         assert_return(object_path_is_valid(path), -EINVAL);
@@ -1988,12 +1987,7 @@ int sd_bus_emit_properties_changed(
         if (!name)
                 return 0;
 
-        va_start(ap, name);
+        names = strv_from_stdarg_alloca(name);
-        names = strv_new_ap(name, ap);
-        va_end(ap);
-
-        if (!names)
-                return -ENOMEM;
 
         return sd_bus_emit_properties_changed_strv(bus, path, interface, names);
 }
@@ -2157,20 +2151,14 @@ int sd_bus_emit_interfaces_added_strv(sd_bus *bus, const char *path, char **inte
 }
 
 int sd_bus_emit_interfaces_added(sd_bus *bus, const char *path, const char *interface, ...) {
-        _cleanup_strv_free_ char **interfaces = NULL;
+        char **interfaces;
-        va_list ap;
 
         assert_return(bus, -EINVAL);
         assert_return(object_path_is_valid(path), -EINVAL);
         assert_return(BUS_IS_OPEN(bus->state), -ENOTCONN);
         assert_return(!bus_pid_changed(bus), -ECHILD);
 
-        va_start(ap, interface);
+        interfaces = strv_from_stdarg_alloca(interface);
-        interfaces = strv_new_ap(interface, ap);
-        va_end(ap);
-
-        if (!interfaces)
-                return -ENOMEM;
 
         return sd_bus_emit_interfaces_added_strv(bus, path, interfaces);
 }
@@ -2203,20 +2191,14 @@ int sd_bus_emit_interfaces_removed_strv(sd_bus *bus, const char *path, char **in
 }
 
 int sd_bus_emit_interfaces_removed(sd_bus *bus, const char *path, const char *interface, ...) {
-        _cleanup_strv_free_ char **interfaces = NULL;
+        char **interfaces;
-        va_list ap;
 
         assert_return(bus, -EINVAL);
         assert_return(object_path_is_valid(path), -EINVAL);
         assert_return(BUS_IS_OPEN(bus->state), -ENOTCONN);
         assert_return(!bus_pid_changed(bus), -ECHILD);
 
-        va_start(ap, interface);
+        interfaces = strv_from_stdarg_alloca(interface);
-        interfaces = strv_new_ap(interface, ap);
-        va_end(ap);
-
-        if (!interfaces)
-                return -ENOMEM;
 
         return sd_bus_emit_interfaces_removed_strv(bus, path, interfaces);
 }

src/shared/conf-files.c

@@ -148,18 +148,12 @@ int conf_files_list_strv(char ***strv, const char *suffix, const char *root, con
 }
 
 int conf_files_list(char ***strv, const char *suffix, const char *root, const char *dir, ...) {
-        _cleanup_strv_free_ char **dirs = NULL;
+        char **dirs;
-        va_list ap;
 
         assert(strv);
         assert(suffix);
 
-        va_start(ap, dir);
+        dirs = strv_from_stdarg_alloca(dir);
-        dirs = strv_new_ap(dir, ap);
-        va_end(ap);
-
-        if (!dirs)
-                return -ENOMEM;
 
         return conf_files_list_strv_internal(strv, suffix, root, dirs);
 }

src/shared/strv.h

@@ -85,3 +85,32 @@ bool strv_overlap(char **a, char **b) _pure_;
 
 char **strv_sort(char **l);
 void strv_print(char **l);
+
+#define strv_from_stdarg_alloca(first)                          \
+        ({                                                      \
+                char **_l;                                      \
+                                                                \
+                if (!first)                                     \
+                        _l = ((char*[1]) { NULL });             \
+                else {                                          \
+                        unsigned _n;                            \
+                        va_list _ap;                            \
+                                                                \
+                        _n = 1;                                 \
+                        va_start(_ap, first);                   \
+                        while (va_arg(_ap, char*))              \
+                                _n++;                           \
+                        va_end(_ap);                            \
+                                                                \
+                        _l = newa(char*, _n+1);                 \
+                        _l[_n = 0] = (char*) first;             \
+                        va_start(_ap, first);                   \
+                        for (;;) {                              \
+                                _l[++_n] = va_arg(_ap, char*);  \
+                                if (!_l[_n])                    \
+                                        break;                  \
+                        }                                       \
+                        va_end(_ap);                            \
+                }                                               \
+                _l;                                             \
+        })

src/test/test-strv.c

@@ -283,31 +283,31 @@ static void test_strv_append(void) {
 }
 
 static void test_strv_foreach(void) {
-	_cleanup_strv_free_ char **a;
+        _cleanup_strv_free_ char **a;
-	unsigned i = 0;
+        unsigned i = 0;
-	char **check;
+        char **check;
 
-	a = strv_new("one", "two", "three", NULL);
+        a = strv_new("one", "two", "three", NULL);
 
-	assert_se(a);
+        assert_se(a);
 
-	STRV_FOREACH(check, a) {
+        STRV_FOREACH(check, a) {
-		assert_se(streq(*check, input_table_multiple[i++]));
+                assert_se(streq(*check, input_table_multiple[i++]));
-	}
+        }
 }
 
 static void test_strv_foreach_backwards(void) {
-	_cleanup_strv_free_ char **a;
+        _cleanup_strv_free_ char **a;
-	unsigned i = 2;
+        unsigned i = 2;
-	char **check;
+        char **check;
 
-	a = strv_new("one", "two", "three", NULL);
+        a = strv_new("one", "two", "three", NULL);
 
-	assert_se(a);
+        assert_se(a);
 
-	STRV_FOREACH_BACKWARDS(check, a) {
+        STRV_FOREACH_BACKWARDS(check, a) {
-		assert_se(streq(*check, input_table_multiple[i--]));
+                assert_se(streq(*check, input_table_multiple[i--]));
-	}
+        }
 }
 
 static void test_strv_foreach_pair(void) {
@@ -324,6 +324,26 @@ static void test_strv_foreach_pair(void) {
         }
 }
 
+static void test_strv_from_stdarg_alloca_one(const char **l, const char *first, ...) {
+        char **j;
+        unsigned i;
+
+        j = strv_from_stdarg_alloca(first);
+
+        for (i = 0;; i++) {
+                assert_se(streq_ptr(l[i], j[i]));
+
+                if (!l[i])
+                        break;
+        }
+}
+
+static void test_strv_from_stdarg_alloca(void) {
+        test_strv_from_stdarg_alloca_one((const char*[]) { "foo", "bar", NULL }, "foo", "bar", NULL);
+        test_strv_from_stdarg_alloca_one((const char*[]) { "foo", "bar", NULL }, "foo", "bar", NULL);
+        test_strv_from_stdarg_alloca_one((const char*[]) { "foo", NULL }, "foo", NULL);
+}
+
 int main(int argc, char *argv[]) {
         test_specifier_printf();
         test_strv_foreach();
@@ -346,6 +366,7 @@ int main(int argc, char *argv[]) {
         test_strv_merge();
         test_strv_merge_concat();
         test_strv_append();
+        test_strv_from_stdarg_alloca();
 
         return 0;
 }