tree-wide: drop a few == NULL and != NULL comparison

Our CODING_STYLE suggests not comparing with NULL, but relying on C's
downgrade-to-bool feature for that. Fix up some code to match these
guidelines. (This is not comprehensive, the coccinelle output for this
is unfortunately kinda borked)

coccinelle/equals-null.cocci

@@ -0,0 +1,14 @@
+@@
+expression e;
+statement s;
+@@
+- if (e == NULL)
++ if (!e)
+s
+@@
+expression e;
+statement s;
+@@
+- if (e != NULL)
++ if (e)
+s

src/analyze/analyze-verify.c

@@ -147,7 +147,7 @@ static int verify_socket(Unit *u) {
 }
 
 static int verify_executable(Unit *u, ExecCommand *exec) {
-        if (exec == NULL)
+        if (!exec)
                 return 0;
 
         if (access(exec->path, X_OK) < 0)

src/analyze/analyze.c

@@ -416,7 +416,7 @@ static int acquire_time_data(sd_bus *bus, struct unit_times **out) {
                         continue;
 
                 t->name = strdup(u.id);
-                if (t->name == NULL) {
+                if (!t->name) {
                         r = log_oom();
                         goto fail;
                 }
@@ -820,7 +820,7 @@ static int list_dependencies_get_dependencies(sd_bus *bus, const char *name, cha
         assert(deps);
 
         path = unit_dbus_path_from_name(name);
-        if (path == NULL)
+        if (!path)
                 return -ENOMEM;
 
         return bus_get_unit_property_strv(bus, path, "After", deps);
@@ -878,7 +878,7 @@ static int list_dependencies_one(sd_bus *bus, const char *name, unsigned int lev
                 }
         }
 
-        if (service_longest == 0 )
+        if (service_longest == 0)
                 return r;
 
         STRV_FOREACH(c, deps) {
@@ -937,7 +937,7 @@ static int list_dependencies(sd_bus *bus, const char *name) {
         assert(bus);
 
         path = unit_dbus_path_from_name(name);
-        if (path == NULL)
+        if (!path)
                 return -ENOMEM;
 
         r = sd_bus_get_property(

src/basic/clock-util.c

@@ -73,7 +73,7 @@ int clock_set_hwclock(const struct tm *tm) {
 int clock_is_localtime(const char* adjtime_path) {
         _cleanup_fclose_ FILE *f;
 
-        if (adjtime_path == NULL)
+        if (!adjtime_path)
                 adjtime_path = "/etc/adjtime";
 
         /*

src/basic/device-nodes.c

@@ -40,7 +40,7 @@ int whitelisted_char_for_devnode(char c, const char *white) {
 int encode_devnode_name(const char *str, char *str_enc, size_t len) {
         size_t i, j;
 
-        if (str == NULL || str_enc == NULL)
+        if (!str || !str_enc)
                 return -EINVAL;
 
         for (i = 0, j = 0; str[i] != '\0'; i++) {

src/basic/ether-addr-util.c

@@ -71,7 +71,7 @@ int ether_addr_from_string(const char *s, struct ether_addr *ret, size_t *offset
                         if (s[pos] == '\0')                     \
                                 break;                          \
                         hexoff = strchr(hex, s[pos]);           \
-                        if (hexoff == NULL)                     \
+                        if (!hexoff)                            \
                                 break;                          \
                         assert(hexoff >= hex);                  \
                         x = hexoff - hex;                       \
@@ -99,7 +99,7 @@ int ether_addr_from_string(const char *s, struct ether_addr *ret, size_t *offset
         sep = s[strspn(s, hex)];
         if (sep == '\n')
                 return -EINVAL;
-        if (strchr(":.-", sep) == NULL)
+        if (!strchr(":.-", sep))
                 return -EINVAL;
 
         if (sep == '.') {

src/basic/fileio.c

@@ -140,7 +140,7 @@ int write_string_file_ts(
 
                 return r;
         } else
-                assert(ts == NULL);
+                assert(!ts);
 
         if (flags & WRITE_STRING_FILE_CREATE) {
                 f = fopen(fn, "we");
@@ -1191,7 +1191,7 @@ int tempfn_xxxxxx(const char *p, const char *extra, char **ret) {
         if (!filename_is_valid(fn))
                 return -EINVAL;
 
-        if (extra == NULL)
+        if (!extra)
                 extra = "";
 
         t = new(char, strlen(p) + 2 + strlen(extra) + 6 + 1);

src/basic/journal-importer.c

@@ -96,7 +96,7 @@ static int get_line(JournalImporter *imp, char **line, size_t *size) {
         assert(imp->state == IMPORTER_STATE_LINE);
         assert(imp->offset <= imp->filled);
         assert(imp->filled <= imp->size);
-        assert(imp->buf == NULL || imp->size > 0);
+        assert(!imp->buf || imp->size > 0);
         assert(imp->fd >= 0);
 
         for (;;) {
@@ -159,8 +159,8 @@ static int fill_fixed_size(JournalImporter *imp, void **data, size_t size) {
         assert(size <= DATA_SIZE_MAX);
         assert(imp->offset <= imp->filled);
         assert(imp->filled <= imp->size);
-        assert(imp->buf != NULL || imp->size == 0);
-        assert(imp->buf == NULL || imp->size > 0);
+        assert(imp->buf || imp->size == 0);
+        assert(!imp->buf || imp->size > 0);
         assert(imp->fd >= 0);
         assert(data);
 

src/basic/path-util.c

@@ -538,7 +538,7 @@ bool paths_check_timestamp(const char* const* paths, usec_t *timestamp, bool upd
 
         assert(timestamp);
 
-        if (paths == NULL)
+        if (!paths)
                 return false;
 
         STRV_FOREACH(i, paths) {

src/basic/time-util.c

@@ -893,7 +893,7 @@ int parse_timestamp(const char *t, usec_t *usec) {
         if (last_space != NULL && timezone_is_valid(last_space + 1))
                 tz = last_space + 1;
 
-        if (tz == NULL || endswith_no_case(t, " UTC"))
+        if (!tz || endswith_no_case(t, " UTC"))
                 return parse_timestamp_impl(t, usec, false);
 
         shared = mmap(NULL, sizeof *shared, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_ANONYMOUS, -1, 0);

src/boot/efi/measure.c

@@ -201,7 +201,7 @@ static EFI_STATUS tpm1_measure_to_pcr_and_event_log(const EFI_TCG *tcg, UINT32 p
 
         tcg_event = AllocateZeroPool(desc_len + sizeof(TCG_PCR_EVENT));
 
-        if (tcg_event == NULL)
+        if (!tcg_event)
                 return EFI_OUT_OF_RESOURCES;
 
         tcg_event->EventSize = desc_len;
@@ -255,7 +255,7 @@ static EFI_STATUS tpm2_measure_to_pcr_and_event_log(const EFI_TCG2 *tcg, UINT32
 
         tcg_event = AllocateZeroPool(sizeof(*tcg_event) - sizeof(tcg_event->Event) + desc_len + 1);
 
-        if (tcg_event == NULL)
+        if (!tcg_event)
                 return EFI_OUT_OF_RESOURCES;
 
         tcg_event->Size = sizeof(*tcg_event) - sizeof(tcg_event->Event) + desc_len + 1;

src/core/execute.c

@@ -3854,7 +3854,7 @@ int exec_context_load_environment(Unit *unit, const ExecContext *c, char ***l) {
                                 p = strv_env_clean_with_callback(p, invalid_env, &info);
                         }
 
-                        if (r == NULL)
+                        if (!r)
                                 r = p;
                         else {
                                 char **m;

src/core/main.c

@@ -1479,7 +1479,7 @@ static int become_shutdown(
         int r;
 
         assert(shutdown_verb);
-        assert(command_line[pos] == NULL);
+        assert(!command_line[pos]);
         env_block = strv_copy(environ);
 
         xsprintf(log_level, "%d", log_get_max_level());

src/coredump/coredump.c

@@ -559,7 +559,7 @@ static int compose_open_fds(pid_t pid, char **open_fds) {
                         continue;
 
                 fdinfo = fdopen(fd, "re");
-                if (fdinfo == NULL) {
+                if (!fdinfo) {
                         close(fd);
                         continue;
                 }

src/vconsole/vconsole-setup.c

@@ -335,7 +335,7 @@ static int find_source_vc(char **ret_path, unsigned *ret_idx) {
         int ret_fd, r, err = 0;
 
         path = new(char, sizeof("/dev/tty63"));
-        if (path == NULL)
+        if (!path)
                 return log_oom();
 
         for (i = 1; i <= 63; i++) {
@@ -396,7 +396,7 @@ static int verify_source_vc(char **ret_path, const char *src_vc) {
                 return log_error_errno(r, "Virtual console %s is not in K_XLATE or K_UNICODE: %m", src_vc);
 
         path = strdup(src_vc);
-        if (path == NULL)
+        if (!path)
                 return log_oom();
 
         *ret_path = path;