compress/zopen.3

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  34 .\"     @(#)zopen.3     8.1 (Berkeley) 6/9/93
  35 .\"
  36 .Dd June 9, 1993
  37 .Dt ZOPEN 3
  38 .Os
  39 .Sh NAME
  40 .Nm zopen
  41 .Nd compressed stream open function
  42 .Sh SYNOPSIS
  43 .Fd #include <stdio.h>
  44 .Ft FILE *
  45 .Fn zopen "const char *path" "const char *mode" "int bits"
  46 .Sh DESCRIPTION
  47 The
  48 .Fn zopen
  49 function
  50 opens the compressed file whose name is the string pointed to by
  51 .Fa path
  52 and associates a stream with it.
  53 .Pp
  54 The argument
  55 .Fa mode
  56 points to one of the following one-character strings:
  57 .Bl -tag -width indent
  58 .It Dq Li r
  59 Open compressed file for reading.
  60 The stream is positioned at the beginning of the file.
  61 .It Dq Li w
  62 Truncate file to zero length or create compressed file for writing.
  63 The stream is positioned at the beginning of the file.
  64 .El
  65 .Pp
  66 Any created files will have mode
  67 .Pf \\*q Dv S_IRUSR
  68 \&|
  69 .Dv S_IWUSR
  70 \&|
  71 .Dv S_IRGRP
  72 \&|
  73 .Dv S_IWGRP
  74 \&|
  75 .Dv S_IROTH
  76 \&|
  77 .Dv S_IWOTH Ns \\*q
  78 .Pq Li 0666 ,
  79 as modified by the process'
  80 umask value (see
  81 .Xr umask 2 ) .
  82 .Pp
  83 Files may only be read or written.
  84 Seek operations are not allowed.
  85 .Pp
  86 The
  87 .Fa bits
  88 argument, if non-zero, is set to the bits code limit.
  89 If zero, the default is 16.
  90 See
  91 .Fn compress 1
  92 for more information.
  93 .Sh RETURN VALUES
  94 Upon successful completion
  95 .Fn zopen
  96 returns a
  97 .Tn FILE
  98 pointer.
  99 Otherwise,
 100 .Dv NULL
 101 is returned and the global variable
 102 .Va errno
 103 is set to indicate the error.
 104 .Sh ERRORS
 105 .Bl -tag -width [EINVAL]
 106 .It Bq Er EINVAL
 107 The
 108 .Fa mode
 109 or
 110 .Fa bits
 111 arguments specified to
 112 .Fn zopen
 113 were invalid.
 114 .It Bq Er EFTYPE
 115 The compressed file starts with an invalid header, or the compressed
 116 file is compressed with more bits than can be handled.
 117 .El
 118 .Pp
 119 The
 120 .Fn zopen
 121 function may also fail and set
 122 .Va errno
 123 for any of the errors specified for the routines
 124 .Xr fopen 3
 125 or
 126 .Xr funopen 3 .
 127 .Sh SEE ALSO
 128 .Xr compress 1 ,
 129 .Xr fopen 3 ,
 130 .Xr funopen 3
 131 .Sh HISTORY
 132 The
 133 .Nm zopen
 134 function
 135 first appeared in
 136 .Bx 4.4 .
 137 .Sh BUGS
 138 The
 139 .Fn zopen
 140 function
 141 may not be portable to systems other than
 142 .Bx .