[CHDMAN] allow output to special files like /dev/null or /dev/stdout

[alucryd]

Hi there, I'm writing a rom manager in rust inside of which I'm calling chdman to extract chds and verify them against redump.

Right now this involves extracting the chd, then splitting it, then verifying each bin checksum. This could be greatly streamlined if I could output the cue to /dev/null and the chd data to /dev/stdout.

I can trick chdman on the command line using the following:

chdman extractcd -f -i test.chd -o /dev/null -ob /dev/stdout > test.bin

But it does not work when invoking the same command from rust, and all I get is:

Error writing frame 3439 to file (/dev/null): write error

I'm guessing this is because there is a delay between the moment the process is spawned, and the moment stdout is being consumed, and I don't think there is a way to work around that from rust yet as I even tried launching the stdout consumption before spawning the process.

Would it be possible for chdman to handle those special files and don't assume the output will be read right away?

[alucryd]

And I just realized that writing the cue to /dev/null borks the bin file, splitting it afterwards does not check against the redump CRCs.

[angelosa]

I'm not sure why you want to pipe to stdout something that is consumed in binary chunks (which probably don't even work on *nix off the bat?). Plus we have a split tool that can be run afterwards that can be chained with the -ob parameter:

  split -split <bigfile> <basename> [<size>] -- split file into parts
  split -join <splitfile> [<outputfile>] -- join file parts into original file
  split -verify <splitfile> -- verify a split file

Where:
  <bigfile> is the large file you wish to split
  <basename> is the base path and name to assign to the split files
  <size> is the optional split size, in MB (100MB is the default)
  <splitfile> is the name of the <basename>.split generated with -split
  <outputfile> is the name of the file to output (defaults to original name)

Anything else can be done here other than testing split itself?

[cuavas]

The trouble is a number of the formats require seeking back to populate a header. On top of that, MAME’s osd_file precedes every read or write with a seek, so it doesn’t work well with socket-/FIFO-like things. Untangling that stuff is going to be a really big job.

[jeffrey-lebowski]

Plus we have a split tool that can be run afterwards that can be chained with the -ob parameter

Sorry, where can I find this split tool? I can't seem to find it in the current MAME release... Thank you.