empty() is NOT your friend for strings

[PVince81]

Basically, empty(0) or empty('0') returns true...

% grep -rie "empty(.*path" apps lib core
apps/files_versions/lib/storage.php:                                            if (empty($userFullPath)) {
apps/files_sharing/lib/sharedstorage.php:               if (empty($path)) {
apps/files_sharing/lib/sharedstorage.php:               if (empty($path)) {
apps/user_ldap/lib/user/user.php:               if(!empty($path)) {
apps/files_trashbin/lib/trashbin.php:           if (\OCP\App::isEnabled('files_versions') && !empty($ownerPath)) {
apps/files_trashbin/lib/trashbin.php:                   if (empty($ownerPath)) {
apps/files_external/3rdparty/Dropbox/API.php:           if(!empty($path)){
apps/files_external/3rdparty/aws-sdk-php/Guzzle/Parser/Cookie/CookieParser.php:        if (empty($path) || substr($path, 0, 1) !== '/') {
lib/base.php:           if (!empty($config_paths)) {
lib/private/appframework/http/request.php:              if (!empty($path)) {
lib/private/helper.php:                         if (empty($paths)) {

And here with "name", probably less critical:

% grep -rie "empty(.*name" apps lib core
apps/dav/lib/carddav/converter.php:             $displayName = empty($displayName ) ? $uid : $displayName;
apps/dav/lib/carddav/converter.php:             if (!empty($displayName)) {
apps/dav/lib/carddav/converter.php:             $displayName = empty($displayName ) ? $uid : $displayName;
apps/dav/lib/comments/entitytypecollection.php:         if(empty($name) || !is_string($name)) {
apps/files_versions/lib/storage.php:            if (empty($filename)) {
apps/files_versions/lib/storage.php:                    if (empty($filename)) {
apps/files_sharing/lib/sharedmount.php:         if ($share['share_type'] === \OCP\Share::SHARE_TYPE_GROUP && empty($share['unique_name'])) {
apps/user_ldap/lib/access.php:                  if(!isset($ldapName[0]) && empty($ldapName[0])) {
apps/user_ldap/lib/access.php:                  if(!empty($usernameAttribute)) {
apps/user_ldap/lib/user/user.php:               if(!empty($displayName)) {
apps/user_ldap/lib/user/user.php:               if(!empty($displayName2)) {
apps/user_ldap/lib/wizard.php:          if(empty($displayName)) {
apps/user_ldap/lib/wizard.php:          if(empty($displayName)) {
apps/files_external/lib/amazons3.php:           $params['hostname'] = empty($params['hostname']) ? 's3.amazonaws.com' : $params['hostname'];
apps/files_external/lib/swift.php:              if (empty($params['service_name'])) {
lib/private/urlgenerator.php:           } elseif (!empty($app) and (!file_exists(\OC::$SERVERROOT . "/themes/$theme/$app/img/$basename.svg")
lib/private/urlgenerator.php:           } elseif (!empty($app) and (!file_exists(\OC::$SERVERROOT . "/$app/img/$basename.svg")
lib/private/setup/abstractdatabase.php:         if(empty($config['dbname'])) {
lib/private/setup/oci.php:              if(empty($config['dbname'])) {
lib/private/user/user.php:                      if (!empty($displayName)) {
lib/private/user/user.php:              if ($this->backend->implementsActions(\OC_User_Backend::SET_DISPLAYNAME) && !empty($displayName)) {
lib/private/systemtag/systemtagmanager.php:             if (!empty($nameSearchPattern)) {
lib/public/util.php:                    if(!empty($ccname)) {
core/command/config/system/getconfig.php:                       if (!empty($configNames)) {

@icewind1991 @nickvergessen @DeepDiver1975 @LukasReschke @schiesbn @rullzer @blizzz

[PVince81]

There might be more...

[nickvergessen]

Maybe each maintainer should grep their source sections for usages?

[PVince81]

Yeah, that's what this ticket is about 😄

[RobinMcCorkell]

As I've mentioned in many places, empty() is completely equivalent to checking a variable's boolean-ness, so if(empty($foo)) is the same as if(!$foo)

[PVince81]

versions: @schiesbn @VicDeo possibly with a file called "0"
trashbin: @schiesbn a $path "0"
user_ldap: @blizzz where display name is "0"
shared storage: @icewind1991 if path is "0"

Assigned to self because I can also help a bit. In the worst case I'll try and create issues while testing with "0" and these will appear as separate issues.

[PVince81]

@blizzz can you have a look at the LDAP ones ? When you're done, pass the ball 😄

[blizzz]

full list:

$ ack -Q "empty(" --type=php  apps/user_ldap/                                            
apps/user_ldap/group_ldap.php
57:             if(!empty($filter) && !empty($gassoc)) {
161:            if (empty($dynamicGroupMemberURL)) {
217:                            if (!empty($nestedGroups)) {
288:            if(empty($result)) {
311:            if(is_array($value) && !empty($value)) {
358:            if(!empty($search)) {
457:            if (!empty($dynamicGroupMemberURL)) {
575:                            if (!empty($nestedGroups)) {
630:            if(!$members && empty($primaryUsers)) {
653:                            if(!empty($search)) {
709:            if(empty($search)) {
823:                    || empty($pagingSize)) {

apps/user_ldap/lib/user/user.php
181:            if(!empty($displayName)) {
268:            if(!empty($path)) {
384:            if(!empty($displayName2)) {
426:                    if(!empty($emailAttribute)) {
456:                    if(!empty($quotaAttribute)) {

apps/user_ldap/lib/connection.php
139:                    if(!empty($this->configID)) {
346:                    if(empty($val)) {
360:                    if(!empty($uuidOverride)) {
380:            if(empty($backupPort)) {
389:                    if(is_array($val) && count($val) === 1 && empty($val[0])) {
417:                    if(empty($val)) {
448:            if((empty($agent) && !empty($pwd)) || (!empty($agent) && empty($pwd))) {
461:            if(empty($base) && empty($baseUsers) && empty($baseGroups)) {
588:            if(empty($host)) {

apps/user_ldap/lib/jobs.php
57:             if(empty($actualGroups) && empty($knownGroups)) {

apps/user_ldap/lib/helper.php
125:            if(empty($prefix)) {

apps/user_ldap/lib/access.php
175:                    if(!empty($attr)) {
182:            if (empty($attr) && ($filter === 'objectclass=*' || $this->ldap->countEntries($cr, $rr) === 1)) {
448:                    if(!isset($ldapName[0]) && empty($ldapName[0])) {
457:                    if(!empty($usernameAttribute)) {
914:            return !empty($cookie) || $cookie === '0';
1156:                   if(!empty($filter) && $filter[0] !== '(') {
1239:                   if(empty($fallbackAttribute)) {
1265:           $result = empty($term) ? '*' :
1315:           if($this->connection->ldapUuidUserAttribute === 'auto' && empty($uuidOverride)) {
1371:           if(!empty($uuidOverride) && !$force) {
1381:                   if(is_array($value) && isset($value[0]) && !empty($value[0])) {
1414:                           && !empty($uuidOverride)
1419:                   if(is_array($uuid) && isset($uuid[0]) && !empty($uuid[0])) {
1513:           if(!is_array($objectSid) || empty($objectSid)) {
1645:           if(empty($this->lastCookie) && $this->lastCookie !== '0') {
1665:           if(!empty($cookie) || $cookie === '0') {
1703:                           if(empty($cookie) && $cookie !== "0" && ($offset > 0)) {
1716:                                   if(empty($cookie) && $cookie !== '0') {
1741:            * So we added "&& !empty($this->lastCookie)" to this test to ignore pagination
1744:           } else if($this->connection->hasPagedResultSupport && $limit === 0 && !empty($this->lastCookie)) {

apps/user_ldap/lib/wizard.php
128:            if(empty($filter)) {
218:            if($attr !== 'displayName' && !empty($attr)) {
260:            if(!empty($attr)) {
314:            if(is_array($selected) && !empty($selected)) {
455:            if(is_array($setFeatures) && !empty($setFeatures)) {
532:                                                            empty($filter));
550:            if(empty($displayName)) {
574:            if(empty($displayName)) {
780:            if(empty($filter)) {
803:                    if(!empty($result)) {
902:                                                    if(empty($dn)) {
921:                            if(empty($filter)) {
972:                                    if(!empty($attr)) {
1097:           return ( (!empty($agent) && !empty($pwd))
1098:                  || (empty($agent) &&  empty($pwd)));
1109:                   if(empty($value)) {
1232:           if(is_array($setFeatures) && !empty($setFeatures)) {
1235:           } else if($po && !empty($maxEntryObjC)) {

apps/user_ldap/lib/configuration.php
158:                                    if(!empty($trimmedVal) && strpos($val, 'attr:') === false) {
274:            if(empty($value)) {
290:            if(empty($value)) {
306:                                    if(!empty($val)) {

apps/user_ldap/user_ldap.php
182:            if(!empty($additionalAttribute)) {
313:            if(isset($this->homesToKill[$uid]) && !empty($this->homesToKill[$uid])) {
362:            if(!empty($additionalAttribute)) {