man3/catopen.3

   1 .\" Copyright 1993 Mitchum DSouza <m.dsouza@mrc-applied-psychology.cambridge.ac.uk>
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  23 .\" Modified Thu Dec 13 22:51:19 2001 by Martin Schulze <joey@infodrom.org>
  24 .\" Modified 2001-12-14 aeb
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  26 .TH CATOPEN 3 2001-12-14
  27 .SH NAME
  28 catopen, catclose \- open/close a message catalog
  29 .SH SYNOPSIS
  30 .B #include <nl_types.h>
  31 .sp
  32 .BI "nl_catd catopen(const char *" name ", int " flag );
  33 .br
  34 .BI "int catclose(nl_catd " catalog );
  35 .SH DESCRIPTION
  36 The function
  37 .BR catopen ()
  38 opens a message catalog and returns a catalog descriptor.
  39 The descriptor remains valid until
  40 .BR catclose ()
  41 or
  42 .BR exec ().
  43 If a file descriptor is used to implement catalog descriptors
  44 then the FD_CLOEXEC flag will be set.
  45 .LP
  46 The argument
  47 .I name
  48 specifies the name of the message catalog to be opened.
  49 If
  50 .I name
  51 specifies and absolute path (i.e., contains a '/'),
  52 then
  53 .I name
  54 specifies a pathname for the message catalog.
  55 Otherwise, the environment variable
  56 .B NLSPATH
  57 is used with
  58 .I name
  59 substituted for
  60 .B %N
  61 (see
  62 .BR locale (7)).
  63 It is unspecified whether
  64 .B NLSPATH
  65 will be used when the process has root privileges.
  66 If
  67 .B NLSPATH
  68 does not exist in the environment,
  69 or if a message catalog cannot be opened
  70 in any of the paths specified by it,
  71 then an implementation defined path is used.
  72 This latter default path may depend on the
  73 .B LC_MESSAGES
  74 locale setting when the
  75 .I flag
  76 argument is
  77 .B NL_CAT_LOCALE
  78 and on the
  79 .B LANG
  80 environment variable when the
  81 .I flag
  82 argument is 0.
  83 Changing the LC_MESSAGES part of the locale may invalidate
  84 open catalog descriptors.
  85 .LP
  86 The
  87 .I flag
  88 argument to
  89 .BR catopen ()
  90 is used to indicate the source for the language to use.
  91 If it is set to
  92 .B NL_CAT_LOCALE
  93 then it will use the current locale setting for
  94 .BR LC_MESSAGES .
  95 Otherwise it will use the
  96 .B LANG
  97 environment variable.
  98 .LP
  99 The function
 100 .BR catclose ()
 101 closes the message catalog identified by
 102 .IR catalog .
 103 It invalidates any subsequent references to the message catalog
 104 defined by
 105 .IR catalog .
 106 .LP
 107 .SH "RETURN VALUE"
 108 The function
 109 .BR catopen ()
 110 returns a message catalog descriptor of type
 111 .I nl_catd
 112 on success.
 113 On failure, it returns (nl_catd) \-1
 114 and sets
 115 .I errno
 116 to indicate the error. The possible error values include all
 117 possible values for the
 118 .BR open ()
 119 call.
 120 .LP
 121 The function
 122 .BR catclose ()
 123 returns 0 on success, or \-1 on failure.
 124 .SH ENVIRONMENT
 125 .TP
 126 .B LC_MESSAGES
 127 May be the source of the LC_MESSAGES locale setting, and thus
 128 determine the language to use if
 129 .I flag
 130 is set to
 131 .BR NL_CAT_LOCALE .
 132 .TP
 133 .B LANG
 134 The language to use if
 135 .I flag
 136 is 0.
 137 .SH NOTES
 138 The above is the POSIX 1003.1-2001 description.
 139 The glibc value for NL_CAT_LOCALE is 1.
 140 (Compare MCLoadAll below.)
 141 The default path varies, but usually looks at a number of places below
 142 .IR /usr/share/locale .
 143 .SH "NOTES FOR LIBC4 AND LIBC5"
 144 These functions are available for Linux since libc 4.4.4c.
 145 In the case of linux libc4 and libc5, the catalog descriptor
 146 .I nl_catd
 147 is a
 148 .BR mmap ()'ed
 149 area of memory and not a file descriptor.
 150 The
 151 .I flag
 152 argument to
 153 .BR catopen ()
 154 should be either
 155 .B MCLoadBySet
 156 (=0) or
 157 .B MCLoadAll
 158 (=1).
 159 The former value indicates that a set from the catalog is to be
 160 loaded when needed, whereas the latter causes the initial call to
 161 .BR catopen ()
 162 to load the entire catalog into memory.
 163 The default search path varies, but usually looks at a number of places below
 164 .I /etc/locale
 165 and
 166 .IR /usr/lib/locale .
 167 .SH "CONFORMING TO"
 168 POSIX 1003.1-2001.
 169 In XPG 1987, Vol. 3 it says:
 170 .I "The flag argument of catopen is reserved for future use"
 171 .IR "and should be set to 0" .
 172 It is unclear what the source was for the constants MCLoadBySet
 173 and MCLoadAll.
 174 .SH "SEE ALSO"
 175 .BR catgets (3),
 176 .BR setlocale (3)