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| -rw-r--r-- | gzseek.3 | 108 |
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diff --git a/gzseek.3 b/gzseek.3 new file mode 100644 index 00000000..a14b2db6 --- /dev/null +++ b/gzseek.3 @@ -0,0 +1,108 @@ +.Dd January 15, 2017 +.Dt GZSEEK 3 +.Os +. +.Sh NAME +.Nm gzseek , +.Nm gzrewind , +.Nm gztell +.Nd seek compressed file +. +.Sh LIBRARY +.Lb libz +. +.Sh SYNOPSIS +.In zlib.h +.Ft z_off_t +.Fn gzseek "gzFile file" "z_off_t offset" "int whence" +.Ft int +.Fn gzrewind "gzFile file" +.Ft z_off_t +.Fn gztell "gzFile file" +. +.Sh DESCRIPTION +Sets the starting position +for the next +.Xr gzread 3 +or +.Xr gzwrite 3 +on the given compressed file. +The +.Fa offset +represents a number of bytes +in the uncompressed data stream. +The +.Fa whence +parameter +is defined as in +.Xr lseek 2 ; +the value +.Dv SEEK_END +is not supported. +. +.Pp +If the file is opened for reading, +this function is emulated +but can be extremely slow. +If the file is opened for writing, +only forward seeks are supported; +.Fn gzseek +then compresses a sequence of zeroes +up to the new starting position. +. +.Pp +.Fn gzrewind +rewinds the given file. +This function is supported +only for reading. +. +.Pp +.Fn gzrewind file +is equivalent to +.Li (int) Ns Fn gzseek file 0L SEEK_SET . +. +.Pp +.Fn gztell +returns the starting position +for the next +.Xr gzread 3 +or +.Xr gzwrite 3 +on the given compressed file. +This position represents a number of bytes +in the uncompressed data stream, +and is zero when starting, +even if appending or reading +a gzip stream from the middle of a file using +.Xr gzdopen 3 . +. +.Pp +.Fn gztell file +is equivalent to +.Fn gzseek file 0L SEEK_CUR . +. +.Sh RETURN VALUES +.Fn gzseek +returns the resulting offset location +as measured in bytes +from the beginning of the uncompressed stream, +or -1 in case of error, +in particular if the file +is opened for writing +and the new starting position +would be before the current position. +. +.Sh SEE ALSO +.Xr gzerror 3 , +.Xr gzoffset 3 , +.Xr gzopen 3 +. +.Sh HISTORY +This manual page was converted from +.In zlib.h +to mdoc format by +.An June 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 |