nextcloud / nextcloud/server

`libpng warning: Interlace handling should be turned on when using png_read_image`

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1. to develop 29-feedback bug dependencies feature: previews and thumbnails upstream
Dominant language
PHP
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Description

Steps to reproduce
  1. Upload some png file
  2. Run preview generator with -vvv to create previews for it.
Expected behaviour

Processing without warning.

Actual behaviour

libpng warning: Interlace handling should be turned on when using png_read_image

Server configuration

Operating system: Raspbian Buster

Web server: Apache2 2.4.38

Database: MariaDB 10.3.15

PHP version: PHP 7.3.4

Nextcloud version: 16.0.3

Updated from an older Nextcloud/ownCloud or fresh install: Updated several times

Where did you install Nextcloud from: https://download.nextcloud.com/server/releases/

Signing status:

Signing status 
No errors have been found.

List of activated apps:

App list 
Enabled:
  - activity: 2.9.1
  - apporder: 0.7.1
  - calendar: 1.7.0
  - cloud_federation_api: 0.2.0
  - contacts: 3.1.3
  - dav: 1.9.2
  - federatedfilesharing: 1.6.0
  - files: 1.11.0
  - files_rightclick: 0.13.0
  - files_trashbin: 1.6.0
  - files_versions: 1.9.0
  - gallery: 18.3.0
  - impersonate: 1.3.0
  - logreader: 2.1.0
  - lookup_server_connector: 1.4.0
  - nextcloud_announcements: 1.5.0
  - notes: 3.0.1
  - notifications: 2.4.1
  - oauth2: 1.4.2
  - previewgenerator: 2.1.0
  - provisioning_api: 1.6.0
  - ransomware_protection: 1.4.0
  - survey_client: 1.4.0
  - tasks: 0.11.0
  - twofactor_backupcodes: 1.5.0
  - updatenotification: 1.6.0
  - workflowengine: 1.6.0

Nextcloud configuration:

Config report 
{
    "system": {
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "localhost",
            "micha.gnoedi.org"
        ],
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "mysql",
        "version": "16.0.3.0",
        "memcache.local": "\\OC\\Memcache\\APCu",
        "filelocking.enabled": true,
        "memcache.locking": "\\OC\\Memcache\\Redis",
        "redis": {
            "host": "***REMOVED SENSITIVE VALUE***",
            "port": 0
        },
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbtableprefix": "oc_",
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "installed": true,
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "loglevel": 1,
        "logtimezone": "Europe\/Berlin",
        "trashbin_retention_obligation": "disabled",
        "versions_retention_obligation": "disabled",
        "skeletondirectory": "",
        "defaultapp": "apporder",
        "maintenance": false,
        "overwrite.cli.url": "https:\/\/micha.gnoedi.org\/nextcloud",
        "htaccess.RewriteBase": "\/nextcloud",
        "mail_smtpmode": "smtp",
        "mail_smtpauthtype": "LOGIN",
        "mail_smtpsecure": "ssl",
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "mail_domain": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpauth": 1,
        "mail_smtphost": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpport": "465",
        "mail_smtpname": "***REMOVED SENSITIVE VALUE***",
        "mail_smtppassword": "***REMOVED SENSITIVE VALUE***",
        "theme": "",
        "mysql.utf8mb4": true,
        "updater.release.channel": "beta",
        "tempdirectory": "\/mnt\/sda\/ncdata\/tmp",
        "preview_max_x": "2048",
        "preview_max_y": "2048",
        "jpeg_quality": "60"
    }
}

Are you using external storage, if yes which one: no

Are you using encryption: no

Are you using an external user-backend, if yes which one: no

Nextcloud log (data/nextcloud.log)
Nextcloud log

nothing related

Additional info
ii  libpng16-16:armhf             1.6.37-1                    armhf        PNG library - runtime (version 1.6)

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the preview generator path used by the -vvv command and reproduce the warning with a PNG upload on the reported setup. Trace the PNG processing until the libpng warning appears. Done means previews are generated without this warning while preserving the existing preview behavior.

Written by the indexing model from the issue text.

Assessment

Tech stack
php
Domain
backend
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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