Function validateMimeTypeAndExtensionMatch

packages/components/src/validator.ts:142–170

(filename: string, mimetype: string)

 * @returns {void} Throws an error if validation fails
 */
export const validateMimeTypeAndExtensionMatch = (filename: string, mimetype: string): void => {
    validateFilename(filename)

    if (!mimetype || typeof mimetype !== 'string') {
        throw new Error('Invalid MIME type: MIME type is required and must be a string')
    }

    const normalizedExt = extractFileExtension(filename)

    if (!normalizedExt) {
        // Files without extensions are rejected for security
        throw new Error('File type not allowed: files must have a valid file extension')
    }

    // Get the expected extension from mapMimeTypeToExt (returns extension without dot)
    const expectedExt = mapMimeTypeToExt(mimetype)

    if (!expectedExt) {
        // If mapMimeTypeToExt doesn't recognize the MIME type, it's not supported
        throw new Error(`MIME type "${mimetype}" is not supported or does not have a valid file extension mapping`)
    }

    // Ensure the file extension matches the expected extension for the MIME type
    if (normalizedExt !== expectedExt) {
        throw new Error(
            `MIME type mismatch: file extension "${normalizedExt}" does not match declared MIME type "${mimetype}". Expected: ${expectedExt}`
        )
    }
}

/**
 * Filters an array of MIME type strings to only those allowed for file upload config.