hashmap: fix iterators to not skip entries

Currently, the HASHMAP iterators stop at the first NULL entry in a
hashmap. This is non-obvious and breaks users like sd-device, which
legitimately store NULL values in a hashmap.

Fix all the iterators by taking a pointer to the value storage, instead of
returning it. The iterators now return a boolean that tells whether the
end of the list was reached.

Current users of HASHMAP_FOREACH() are *NOT* changed to explicitly check
for NULL. If it turns out, there were users that inserted NULL into
hashmaps, but didn't properly check for it during iteration, then we
really want to find those and fix them.

3 files changed, 30 insertions, 12 deletions

diff --git a/src/libsystemd/sd-bus/bus-track.c b/src/libsystemd/sd-bus/bus-track.c
index ec9340f8e1..e43891be25 100644
--- a/src/libsystemd/sd-bus/bus-track.c
+++ b/src/libsystemd/sd-bus/bus-track.c
@@ -248,7 +248,7 @@ _public_ const char* sd_bus_track_first(sd_bus_track *track) {
         track->modified = false;
         track->iterator = ITERATOR_FIRST;
 
-        hashmap_iterate(track->names, &track->iterator, (const void**) &n);
+        hashmap_iterate(track->names, &track->iterator, NULL, (const void**) &n);
         return n;
 }
 
@@ -261,7 +261,7 @@ _public_ const char* sd_bus_track_next(sd_bus_track *track) {
         if (track->modified)
                 return NULL;
 
-        hashmap_iterate(track->names, &track->iterator, (const void**) &n);
+        hashmap_iterate(track->names, &track->iterator, NULL, (const void**) &n);
         return n;
 }
 
diff --git a/src/libsystemd/sd-device/sd-device.c b/src/libsystemd/sd-device/sd-device.c
index 8e63b9ef56..b274f71093 100644
--- a/src/libsystemd/sd-device/sd-device.c
+++ b/src/libsystemd/sd-device/sd-device.c
@@ -1371,6 +1371,8 @@ _public_ int sd_device_get_usec_since_initialized(sd_device *device, uint64_t *u
 }
 
 _public_ const char *sd_device_get_tag_first(sd_device *device) {
+        void *v;
+
         assert_return(device, NULL);
 
         (void) device_read_db(device);
@@ -1378,10 +1380,13 @@ _public_ const char *sd_device_get_tag_first(sd_device *device) {
         device->tags_iterator_generation = device->tags_generation;
         device->tags_iterator = ITERATOR_FIRST;
 
-        return set_iterate(device->tags, &device->tags_iterator);
+        set_iterate(device->tags, &device->tags_iterator, &v);
+        return v;
 }
 
 _public_ const char *sd_device_get_tag_next(sd_device *device) {
+        void *v;
+
         assert_return(device, NULL);
 
         (void) device_read_db(device);
@@ -1389,10 +1394,13 @@ _public_ const char *sd_device_get_tag_next(sd_device *device) {
         if (device->tags_iterator_generation != device->tags_generation)
                 return NULL;
 
-        return set_iterate(device->tags, &device->tags_iterator);
+        set_iterate(device->tags, &device->tags_iterator, &v);
+        return v;
 }
 
 _public_ const char *sd_device_get_devlink_first(sd_device *device) {
+        void *v;
+
         assert_return(device, NULL);
 
         (void) device_read_db(device);
@@ -1400,10 +1408,13 @@ _public_ const char *sd_device_get_devlink_first(sd_device *device) {
         device->devlinks_iterator_generation = device->devlinks_generation;
         device->devlinks_iterator = ITERATOR_FIRST;
 
-        return set_iterate(device->devlinks, &device->devlinks_iterator);
+        set_iterate(device->devlinks, &device->devlinks_iterator, &v);
+        return v;
 }
 
 _public_ const char *sd_device_get_devlink_next(sd_device *device) {
+        void *v;
+
         assert_return(device, NULL);
 
         (void) device_read_db(device);
@@ -1411,7 +1422,8 @@ _public_ const char *sd_device_get_devlink_next(sd_device *device) {
         if (device->devlinks_iterator_generation != device->devlinks_generation)
                 return NULL;
 
-        return set_iterate(device->devlinks, &device->devlinks_iterator);
+        set_iterate(device->devlinks, &device->devlinks_iterator, &v);
+        return v;
 }
 
 static int device_properties_prepare(sd_device *device) {
@@ -1482,7 +1494,7 @@ _public_ const char *sd_device_get_property_first(sd_device *device, const char
         device->properties_iterator_generation = device->properties_generation;
         device->properties_iterator = ITERATOR_FIRST;
 
-        value = ordered_hashmap_iterate(device->properties, &device->properties_iterator, (const void**)&key);
+        ordered_hashmap_iterate(device->properties, &device->properties_iterator, (void**)&value, (const void**)&key);
 
         if (_value)
                 *_value = value;
@@ -1504,7 +1516,7 @@ _public_ const char *sd_device_get_property_next(sd_device *device, const char *
         if (device->properties_iterator_generation != device->properties_generation)
                 return NULL;
 
-        value = ordered_hashmap_iterate(device->properties, &device->properties_iterator, (const void**)&key);
+        ordered_hashmap_iterate(device->properties, &device->properties_iterator, (void**)&value, (const void**)&key);
 
         if (_value)
                 *_value = value;
@@ -1562,6 +1574,7 @@ static int device_sysattrs_read_all(sd_device *device) {
 }
 
 _public_ const char *sd_device_get_sysattr_first(sd_device *device) {
+        void *v;
         int r;
 
         assert_return(device, NULL);
@@ -1576,16 +1589,20 @@ _public_ const char *sd_device_get_sysattr_first(sd_device *device) {
 
         device->sysattrs_iterator = ITERATOR_FIRST;
 
-        return set_iterate(device->sysattrs, &device->sysattrs_iterator);
+        set_iterate(device->sysattrs, &device->sysattrs_iterator, &v);
+        return v;
 }
 
 _public_ const char *sd_device_get_sysattr_next(sd_device *device) {
+        void *v;
+
         assert_return(device, NULL);
 
         if (!device->sysattrs_read)
                 return NULL;
 
-        return set_iterate(device->sysattrs, &device->sysattrs_iterator);
+        set_iterate(device->sysattrs, &device->sysattrs_iterator, &v);
+        return v;
 }
 
 _public_ int sd_device_has_tag(sd_device *device, const char *tag) {
diff --git a/src/libsystemd/sd-hwdb/sd-hwdb.c b/src/libsystemd/sd-hwdb/sd-hwdb.c
index 2a0e00f7d2..40aa77ee5c 100644
--- a/src/libsystemd/sd-hwdb/sd-hwdb.c
+++ b/src/libsystemd/sd-hwdb/sd-hwdb.c
@@ -449,7 +449,8 @@ _public_ int sd_hwdb_seek(sd_hwdb *hwdb, const char *modalias) {
 }
 
 _public_ int sd_hwdb_enumerate(sd_hwdb *hwdb, const char **key, const char **value) {
-        const void *k, *v;
+        const void *k;
+        void *v;
 
         assert_return(hwdb, -EINVAL);
         assert_return(key, -EINVAL);
@@ -458,7 +459,7 @@ _public_ int sd_hwdb_enumerate(sd_hwdb *hwdb, const char **key, const char **val
         if (hwdb->properties_modified)
                 return -EAGAIN;
 
-        v = ordered_hashmap_iterate(hwdb->properties, &hwdb->properties_iterator, &k);
+        ordered_hashmap_iterate(hwdb->properties, &hwdb->properties_iterator, &v, &k);
         if (!k)
                 return 0;