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write_metadata()

Description

Writes metadata to a specified file using ExifTool.

Parameters

ColumnTypeDefaultDescription
$path string The file path where the metadata will be written.
$ref int The reference ID of the resource associated with the file.
$uniqid string "" A unique identifier for the temporary file location (optional).

Return

string|bool The path to the temporary file if successful, false otherwise.

Location

include/resource_functions.php lines 4591 to 4788

Definition

 
function write_metadata($path, $ref, $uniqid="")
    {
    debug_function_call('write_metadata', func_get_args());

    if (!is_valid_rs_path($path)) {
        // Not a valid path to a ResourceSpace file source
        return false;
    }

    // copys the file to tmp and runs exiftool on it
    // uniqid tells the tmp file to be placed in an isolated folder within tmp
    global $exiftool_remove_existing, $storagedir, $exiftool_write, $exiftool_write_option, $exiftool_no_process, $mysql_charset, $exiftool_write_omit_utf8_conversion;

    # Fetch file extension and resource type.
    $resource_data=get_resource_data($ref);
    $extension=$resource_data["file_extension"];

    $exiftool_fullpath = get_utility_path("exiftool");

    # Check if an attempt to write the metadata shall be performed.
    if(false != $exiftool_fullpath && $exiftool_write && $exiftool_write_option && !in_array($extension, $exiftool_no_process))
        {
        debug("[write_metadata()][ref={$ref}] Attempting to write metadata...");
        // Trust Exiftool's list of writable formats
        $writable_formats = run_command("{$exiftool_fullpath} -listwf");
        $writable_formats = str_replace("\n", "", $writable_formats);
        $writable_formats_array = explode(" ", $writable_formats);
        if(!in_array(strtoupper((string) $extension), $writable_formats_array))
            {
            debug("[write_metadata()][ref={$ref}] Extension '{$extension}' not in writable_formats_array - " . json_encode($writable_formats_array));
            return false;
            }

        $tmpfile = createTempFile($path, $uniqid, '');
        if($tmpfile === false)
            {
            debug("[write_metadata()][ref={$ref}] Unable to create temp file!");
            return false;
            }

        # Add the call to exiftool and some generic arguments to the command string.
        # Argument -overwrite_original: Now that we have already copied the original file, we can use exiftool's overwrite_original on the tmpfile.
        # Argument -E: Escape values for HTML. Used for handling foreign characters in shells not using UTF-8.
        # Arguments -EXIF:all= -XMP:all= -IPTC:all=: Remove the metadata in the tag groups EXIF, XMP and IPTC.
        $command = $exiftool_fullpath . " -m -overwrite_original -E ";
        if($exiftool_remove_existing)
            {
            $command = stripMetadata(null) . ' ';
            debug("[write_metadata()][ref={$ref}] Removing existing metadata. Command: ". json_encode($command));
            }

        $metadata_all=get_resource_field_data($ref, false,true,null,getval("k","")!=""); // Using get_resource_field_data means we honour field permissions
        $read_only_fields = array_column(array_filter($metadata_all, function($value) {
            return (bool) $value['read_only'] === true;
        }), 'ref');

        $write_to=array();
        foreach($metadata_all as $metadata_item)
            {
            if(trim($metadata_item["exiftool_field"]??"") != "" && !in_array($metadata_item['ref'], $read_only_fields))
                {
                $write_to[] = $metadata_item;
                }
            }

        $writtenfields=array(); // Need to check if we are writing to an embedded field from more than one RS field, in which case subsequent values need to be appended, not replaced

        for($i = 0; $i<count($write_to); $i++) # Loop through all the found fields.
        {
            $fieldtype = $write_to[$i]['type'];
            $writevalue = $write_to[$i]['value']??"";
            # Formatting and cleaning of the value to be written - depending on the RS field type.
            switch ($fieldtype)
                {
                case 2:
                case 3:
                case 9:
                case 12:
                    # Check box list, drop down, radio buttons or dynamic keyword list: remove initial comma if present
                    $writevalue = strip_leading_comma($writevalue);
                    break;
                case 4:
                case 6:
                case 10:
                    # Date / Expiry Date: write datetype fields in exiftool preferred format
                    if($writevalue!='')
                        {
                        $writevalue_to_time=strtotime($writevalue);
                        if($writevalue_to_time!='')
                            {
                            $writevalue = date("Y:m:d H:i:sP", strtotime($writevalue));
                            }
                        }
                    break;
                    # Other types, already set
                }
            $filtervalue=hook("additionalmetadatafilter", "", [$write_to[$i]["exiftool_field"], $writevalue]);
            if ($filtervalue) {
                $writevalue = $filtervalue;
            }
            # Add the tag name(s) and the value to the command string.
            $group_tags = explode(",", $write_to[$i]['exiftool_field']); # Each 'exiftool field' may contain more than one tag.
            foreach ($group_tags as $group_tag)
                {
                $group_tag = strtolower($group_tag); # E.g. IPTC:Keywords -> iptc:keywords
                if (strpos($group_tag,":")===false) {$tag = $group_tag;} # E.g. subject -> subject
                else {$tag = substr($group_tag, strpos($group_tag,":")+1);} # E.g. iptc:keywords -> keywords
                if(strpos($group_tag,"-") !== false && stripos($group_tag,"xmp") !== false)
                    {
                    // Remove the XMP namespace for XMP data if included
                    $group_tag = substr($group_tag,0,(strpos($group_tag,"-")));
                    }
                $exifappend=false; // Need to replace values by default
                if(isset($writtenfields[$group_tag]))
                    {
                    // This embedded field is already being updated, we need to append values from this field
                    $exifappend=true;
                    debug("write_metadata - more than one field mapped to the tag '" . $group_tag . "'. Enabling append mode for this tag. ");
                    }

                switch ($tag)
                    {
                    case "filesize":
                        # Do nothing, no point to try to write the filesize.
                        break;
                    case "filename":
                        # Do nothing, no point to try to write the filename either as ResourceSpace controls this.
                        break;
                    case "directory":
                        # Do nothing, we don't want metadata to control this
                        break;
                    case "keywords":
                        if(substr($group_tag,0,3) != "xmp")
                            {
                            # Only IPTC Keywords are a list type - these are written one at a time and not all together.
                            if(!isset($writtenfields["keywords"])){$writtenfields["keywords"]="";}
                            $keywords = explode(",", $writevalue); # "keyword1,keyword2, keyword3" (with or without spaces)
                            if (implode("", $keywords) != "")
                                {
                                # Only write non-empty keywords/ may be more than one field mapped to keywords so we don't want to overwrite with blank
                                foreach ($keywords as $keyword)
                                    {
                                    $keyword = trim($keyword);
                                    if ($keyword != "")
                                        {
                                        debug("[write_metadata()][ref={$ref}] Writing keyword '{$keyword}'");
                                        $writtenfields["keywords"].="," . $keyword;
                                        # Convert the data to UTF-8 if not already.
                                        if (!$exiftool_write_omit_utf8_conversion && (!isset($mysql_charset) || (isset($mysql_charset) && strtolower($mysql_charset)!="utf8"))){$keyword = mb_convert_encoding($keyword, mb_detect_encoding($keyword), 'UTF-8');}
                                        $command.= escapeshellarg("-" . $group_tag . "-=" . htmlentities($keyword, ENT_QUOTES, "UTF-8")) . " "; // In case value is already embedded, need to manually remove it to prevent duplication
                                        $command.= escapeshellarg("-" . $group_tag . "+=" . htmlentities($keyword, ENT_QUOTES, "UTF-8")) . " ";
                                        }
                                    }
                                }
                            break; // The break is in here so that Non-IPTC keywords continue to be handled by default
                            }
                    default:
                        if($exifappend && ($writevalue=="" || ($writevalue!="" && strpos($writtenfields[$group_tag],$writevalue)!==false)))
                            {
                            // The new value is blank or already included in what is being written, skip to next group tag
                            continue 2; # @see https://www.php.net/manual/en/control-structures.continue.php note
                            }
                        $writtenfields[$group_tag]=$writevalue;
                        debug("[write_metadata()][ref={$ref}] Updating tag '{$group_tag}' with value '{$writevalue}'");
                        # Write as is, convert the data to UTF-8 if not already.

                        global $strip_rich_field_tags;
                        if (!$exiftool_write_omit_utf8_conversion
                            && (!isset($mysql_charset)
                                || (isset($mysql_charset) && strtolower($mysql_charset)!="utf8")))
                            {
                            $writevalue = mb_convert_encoding($writevalue, mb_detect_encoding($writevalue), 'UTF-8');
                            }
                            if ($strip_rich_field_tags)
                            {
                                $command.= escapeshellarg("-" . $group_tag . "=" . trim(strip_tags(i18n_get_translated($writevalue)))) . " ";
                            }
                            else
                            {
                                $command.= escapeshellarg("-" . $group_tag . "=" . htmlentities(i18n_get_translated($writevalue), ENT_QUOTES, "UTF-8")) . " ";
                            }
                    }
                }
            }

            # Add the filename to the command string.
            $command.= " " . escapeshellarg($tmpfile);

            # Perform the actual writing - execute the command string.
            run_command($command);
        return $tmpfile;
       }
    else
        {
        debug("[write_metadata()][ref={$ref}] Did not perform - write metadata!");
        return false;
        }
    }

This article was last updated 15th December 2024 13:35 Europe/London time based on the source file dated 13th December 2024 14:45 Europe/London time.