gzContentsInfo

function to get header and trailer info from GZip files
[gz, br] = gzContentsInfo( gzFilePath )
e.g. [gz, br] = gzContentsInfo( 'D:\myfile.ext.gz' );
INPUT:
gzFilePath - name or path as char or cellstr of GZip file(s),
supports wildcards, e.g.
'D:\arc.ext.gz'
'D:\*.gz'
{'D:\arc1.ext.gz' 'D:\arc2.ext.gz'}

OUTPUT:
gz - structured variable modeled after MATLAB's dir(...) with extra
fields related to the GZip file, e.g. gz...
.name = original name of the file*
.date = date string based on MTIME*
.bytes = ISZIE in bytes
.datenum = MATLAB's datenum based on MTIME's format
.ValidID = logical on GZip's header validation
.Compression = string of method (CM) and mode (XFL), e.g. deflate-4
.isText = logical if uncompressed data is likely plaintext
.OS = string of OS declared during compression
.Comment = if declared, plain text comment
.CRC32 = hex string of CRC32 of uncompressed data
* if info NOT explicit, it is inferred from gzFilePath

br - raw (b)inary (r)eads of GZip file and intermediate calculations

(C) Jake D.L. August, 2016/Apr/17
august(dot)jdbl(at)outlook(dot)com