compress/zopen.3

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  28 .\"     @(#)zopen.3     8.1 (Berkeley) 6/9/93
  29 .\" $FreeBSD: src/usr.bin/compress/zopen.3,v 1.9 2010/12/11 08:32:16 joel Exp $
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  31 .Dd June 9, 1993
  32 .Dt ZOPEN 3
  33 .Os
  34 .Sh NAME
  35 .Nm zopen
  36 .Nd compressed stream open function
  37 .Sh SYNOPSIS
  38 .Fd #include \&"zopen.h\&"
  39 .Ft FILE *
  40 .Fn zopen "const char *path" "const char *mode" "int bits"
  41 .Sh DESCRIPTION
  42 The
  43 .Fn zopen
  44 function
  45 opens the compressed file whose name is the string pointed to by
  46 .Fa path
  47 and associates a stream with it.
  48 .Pp
  49 The argument
  50 .Fa mode
  51 points to one of the following one-character strings:
  52 .Bl -tag -width indent
  53 .It Dq Li r
  54 Open compressed file for reading.
  55 The stream is positioned at the beginning of the file.
  56 .It Dq Li w
  57 Truncate file to zero length or create compressed file for writing.
  58 The stream is positioned at the beginning of the file.
  59 .El
  60 .Pp
  61 Any created files will have mode
  62 .Pf \\*q Dv S_IRUSR
  63 \&|
  64 .Dv S_IWUSR
  65 \&|
  66 .Dv S_IRGRP
  67 \&|
  68 .Dv S_IWGRP
  69 \&|
  70 .Dv S_IROTH
  71 \&|
  72 .Dv S_IWOTH Ns \\*q
  73 .Pq Li 0666 ,
  74 as modified by the process'
  75 umask value (see
  76 .Xr umask 2 ) .
  77 .Pp
  78 Files may only be read or written.
  79 Seek operations are not allowed.
  80 .Pp
  81 The
  82 .Fa bits
  83 argument, if non-zero, is set to the bits code limit.
  84 If zero, the default is 16.
  85 See
  86 .Xr compress 1
  87 for more information.
  88 .Sh RETURN VALUES
  89 Upon successful completion
  90 .Fn zopen
  91 returns a
  92 .Tn FILE
  93 pointer.
  94 Otherwise,
  95 .Dv NULL
  96 is returned and the global variable
  97 .Va errno
  98 is set to indicate the error.
  99 .Sh ERRORS
 100 .Bl -tag -width [EINVAL]
 101 .It Bq Er EINVAL
 102 The
 103 .Fa mode
 104 or
 105 .Fa bits
 106 arguments specified to
 107 .Fn zopen
 108 were invalid.
 109 .It Bq Er EFTYPE
 110 The compressed file starts with an invalid header, or the compressed
 111 file is compressed with more bits than can be handled.
 112 .El
 113 .Pp
 114 The
 115 .Fn zopen
 116 function may also fail and set
 117 .Va errno
 118 for any of the errors specified for the routines
 119 .Xr fopen 3
 120 or
 121 .Xr funopen 3 .
 122 .Sh SEE ALSO
 123 .Xr compress 1 ,
 124 .Xr fopen 3 ,
 125 .Xr funopen 3
 126 .Sh HISTORY
 127 The
 128 .Nm
 129 function
 130 first appeared in
 131 .Bx 4.4 .
 132 .Sh BUGS
 133 The
 134 .Fn zopen
 135 function
 136 may not be portable to systems other than
 137 .Bx .