php imagck读取pdf错误：attempt to perform an operation not allowed by the security policy PDF

这是ImageMagic中有权限配置文件，需要修改PDF相关的读写权限。

# 打开policy.xml文件

sudo nano /etc/ImageMagick-6/policy.xml

# 修改PDF相关权限，由none改为read|write

<policy domain="coder" rights="none" pattern="PDF" />

# 改为

<policy domain="coder" rights="read|write" pattern="PDF" />