php method to read only part of remote file

Question

I am working with file_get_contents getting remote files and processing them. Unfortunately the files are quite large and I only need a small segment from each. I know exactly from what offset I would need to read and the length of it but reading the php manual it seems that this is possible with file_get_contents only on local files.

Is there a method which doesn't download the whole file?

Answer 1

you need to use fopen, fseek and fread function instead of file_get contents

here are the links to the documentation of

• fopen
• fseek
• fread

fopen opens the file as a stream of bytes and you can seek into your desired position using fseek and read as much byte as you need using fread

Answer 2

As far as I know there is no way to open a remote file and move the file pointer to a certain point. You need some kind of remote service that provides that feature for you.

Although fopen and fseek seem to work, there is a cullpit. Form the manual:

Not all streams support seeking. For those that do not support seeking, forward seeking from the current position is accomplished by reading and discarding data; other forms of seeking will fail.

As for implementing a service, there a numerous example. I like the rsync solution, that mirrors only changed blocks from a remote to a local machine.