block-reader

read specific chunks of files by offset

npm install block-reader
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block-reader

read specific chunks of files by offset.

``js

var blockReader = require("block-reader")

blockReader("/somefile",1024,function(err,reader,fd,stat){

reader.read(0,function(err,buf){ console.log(buf,toString(),'this is bytes 0-1023 in from somefile'); })

reader.read(5,function(err,buf){

console.log(buf,toString(),'this is bytes 4095-5119 from somefile');

})

reader.read(100,function(err,buf){ // if the offset doesnt exist you should get an error. console.log(err) })

})


in some cases i already have a file descriptor and stat so i use ```fromFD

var blockReader = require("block-reader")
var stat = ..
var fd = ..


var reader = blockReader.fromFD(fd,stat.size,1024)


reader.read(0,function(err,buf){
  console.log(buf,toString(),'this is bytes 0-1023 in from somefile');
})

you may change the size of the file but you shouldn't need to create a new reader. if you want to access those offsets the reader will need to know the new size.


fs.stat('/somefile',function(err,stat){

  reader.size(stat.size);

});
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