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Diffstat (limited to 'gzread.3')
| -rw-r--r-- | gzread.3 | 115 |
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diff --git a/gzread.3 b/gzread.3 new file mode 100644 index 0000000..84439ea --- /dev/null +++ b/gzread.3 @@ -0,0 +1,115 @@ +.Dd January 15, 2017 +.Dt GZREAD 3 +.Os +. +.Sh NAME +.Nm gzread +.Nd read from compressed file +. +.Sh LIBRARY +.Lb libz +. +.Sh SYNOPSIS +.In zlib.h +.Ft int +.Fn gzread "gzFile file" "voidp buf" "unsigned len" +. +.Sh DESCRIPTION +Reads the given number of uncompressed bytes +from the compressed file. +If the input file +is not in gzip format, +.Fn gzread +copies the given number of bytes +into the buffer directly from the file. +. +.Pp +After reaching the end of a gzip stream +in the input, +.Fn gzread +will continue to read, +looking for another gzip stream. +Any number of gzip streams +may be concatenated in the input file, +and will all be decompressed by +.Fn gzread . +If something other than a gzip stream +is encountered after a gzip stream, +that remaining trailing garbage is ignored +(and no error is returned). +. +.Pp +.Fn gzread +can be used to read a gzip file +that is being concurrently written. +Upon reaching the end of the input, +.Fn gzread +will return with the available data. +If the error code returned by +.Xr gzerror 3 +is +.Dv Z_OK +or +.Dv Z_BUF_ERROR , +then +.Xr gzclearerr 3 +can be used +to clear the end of file indicator +in order to permit +.Fn gzread +to be tried again. +.Dv Z_OK +indicates that a gzip stream was completed +on the last +.Fn gzread . +.Dv Z_BUF_ERROR +indicates that the input file +ended in the middle of a gzip stream. +Note that +.Fn gzread +does not return -1 +in the event of an incomplete gzip stream. +This error is deferred until +.Xr gzclose 3 , +which will return +.Dv Z_BUF_ERROR +if the last +.Fn gzread +ended in the middle of a gzip stream. +Alternatively, +.Xr gzerror 3 +can be used before +.Xr gzclose 3 +to detect this case. +. +.Sh RETURN VALUES +.Fn gzread +returns the number of uncompressed bytes actually read, +less than +.Fa len +for end of file, +or -1 for error. +If +.Fa len +is too large to fit in an +.Vt int , +then nothing is read, +-1 is returned, +and the error state is set to +.Dv Z_STREAM_ERROR . +. +.Sh SEE ALSO +.Xr gzeof 3 , +.Xr gzerror 3 , +.Xr gzfread 3 , +.Xr gzopen 3 +. +.Sh HISTORY +This manual page was converted from +.In zlib.h +to mdoc format by +.An C. McEnroe Aq Mt june@causal.agency . +. +.Sh AUTHORS +.An Jean-loup Gailly Aq Mt jloup@gzip.org +.An Mark Adler Aq Mt madler@alumni.caltech.edu |