I am looking to run a program on a target that is in memory.
For example I would like to call LaTeX on a set of characters in the memory instead of in file.
I realise I can set a file pointer in C to target memory and read/write to and from memory.
However I don’t know if there is any way to pass LaTeX a file pointer or a wrapper to do so?
Running on Arch Linux, I don’t care if I just get environment dependent solution for now – just need a starting point.
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Answer
The easiest way is to create a file in /tmp. On most modern systems, /tmp is mounted using the “tmpfs” filesystem, which stores files in memory.
Maybe you don’t want to rely on /tmp being a tmpfs. In that case, you can use memfd_create to create a file descriptor which is only stored in memory. If LaTeX needs a filename, you could make it open the file directly from your process, using /proc/<your pid>/fd/<fd number>.
A third solution is to use a pipe (which is what popen uses internally). This doesn’t work if LaTeX wants to seek backwards or forwards in the file – you can’t seek in a pipe. On the other hand, the pipe doesn’t have to store the entire file at once.