ast.3

Introduction to Library Functions                          AST(3)

NAME
     ast - miscellaneous libast support

SYNOPSIS
          #include <ast.h>

          char*          astconf(const char* name, const char* path, const char* value);
          Ast_confdisc_t astconfdisc(Ast_confdisc_t new_notify);
          void           astconflist(Sfio_t* stream, const char* path, int flags);
          off_t          astcopy(int rfd, int wfd, off_t n);
          int            astquery(int fd, const char* format , ...);

DESCRIPTION
     astconf is a  string  interface  to  the  confstr(2),  path-
     conf(2),  and sysconf(2) calls.  If value is 0 then the con-
     figuration parameter value for name is returned.  Some  name
     configuration  parameters may consult the path argument.  In
     this case if path is 0 then "/" is used.  Otherwise if  path
     is  not  0  then it must exist.  The string return value for
     name remains unchanged until the next astconf call on  name.
     If  value is 0 then a valid string is always returned; "" is
     returned if name has no configuration value.   This  simpli-
     fies the programming interface:

          if (!strcmp(astconf("PATH_RESOLVE", NiL, NiL), "logical"))
                    /* the logical way ... */

     If value is not 0 then the configuration parameter value for
     name  is set to value.  0 is returned if the value cannot be
     set.  The paradigm is:

          universe = astconf("UNIVERSE", 0, "att");
          astconf("UNIVERSE", 0, universe);

     The settable configuration names are:

     FS_3D
          1 if 3d(1) viewpathing is enabled, 0  otherwise.   This
          is an alternative to the fs3d(3) interface.

     PATH_RESOLVE
          logical if symbolic links are followed during file tree
          traversal,  physical if symbolic links are not followed
          during file tree traversal, and  metaphysical  if  sym-
          bolic  links  are followed at the top level during file
          tree traversal.  These correspond to  the  generic  -L,
          -P, and -H command options.

     UNIVERSE
          ucb for Berkeley style and att otherwise.  This  confi-
          guration  parameter  controls  the  universe setting on
          machines that support  it  (e.g.,  Pyramid).   UNIVERSE

SunOS 5.10                Last change:                          1

Introduction to Library Functions                          AST(3)

          also controls the behavior of some commands like cat(1)
          and echo(1).

     User defined name values may also be set  and  queried,  but
     these  should  probably  have  some form of vendor prefix to
     avoid being stomped by future standards.

     astconfdisc registers a discipline function

          int (*notify)(const char* name, const char* path, const char* value);

     that is called just before the configuration parameter  name
     is  set to value relative to path.  If notify returns 0 then
     the configuration parameter value is not changed.

     astconflist lists the current configuration names and values
     of stream.  If path is 0 then "/" is used where appropriate.
     If flags is 0 or R_OK|W_OK then all configuration parameters
     are  listed.   R_OK lists the readonly configuration parame-
     ters and W_OK lists the settable  configuration  parameters.
     X_OK  lists  the settable configuration parameters in a form
     that can be snarfed for input to the getconf(1) command.

     astcopy efficiently copies up  to  n  bytes  from  the  file
     descriptor  rfd  to  the  file  descriptor  wfd.  The actual
     number of bytes copied is returned; -1 is returned on error.
     If  n is  0 then an optimal number of bytes (with respect to
     both rfd and wfd) is copied.

     If possible mmap(2) is used to do the transfer.  Some imple-
     mentations may bypass user buffer copies usually required by
     the read(2)-write(2) paradigm.

     astquery outputs an sfprintf(3) prompt specified by  format,
     ...  to  the  controlling terminal and reads a response from
     the controlling terminal.  Offirmative response  returns  0,
     EOF  or  quit  response returns -1, otherwise 1 is returned.
     If quit is greater than 0 then exit(quit)  is  called  on  a
     quit  response.   The  responses  will  eventually be locale
     specific.

     astwinsize returns the number  of  rows  in  *rows  and  the
     number  of columns *col for the terminal file descriptor fd.
     If the number of rows or columns cannot be determined or  if
     fd  is not a terminal then *rows and *cols are set to 0.  If
     ioctl (2) methods fail then the environment  variable  LINES
     is used to set *rows and the environment variable COLUMNS is
     used to set *cols.

SEE ALSO
     getconf(1), confstr(2), mmap(2), pathconf(2), read(2),  sys-
     conf(2), write(2)

SunOS 5.10                Last change:                          2

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