tcl7.6 C API - GetOpnFl






NAME

     Tcl_GetOpenFile - Get a standard IO File  *  handle  from  a
     channel.


SYNOPSIS

     #include <tcl.h>

     int
     Tcl_GetOpenFile(interp, string, write, checkUsage, filePtr)



ARGUMENTS

     Tcl_Interp   *interp      (in)      Tcl   interpreter   from
                                         which  file handle is to
                                         be obtained.

     char         *string      (in)      String identifying chan-
                                         nel,  such  as  stdin or
                                         file4.

     int          write        (in)      Non-zero means the  file
                                         will  be  used for writ-
                                         ing, zero means it  will
                                         be used for reading.

     int          checkUsage   (in)      If  non-zero,  then   an
                                         error  will be generated
                                         if   the   file   wasn't
                                         opened  for  the  access
                                         indicated by write.

     ClientData   *filePtr     (out)     Points to word in  which
                                         to store pointer to FILE
                                         structure for  the  file
                                         given by string.





DESCRIPTION

     Tcl_GetOpenFile takes as argument a file identifier  of  the
     form  returned by the open command and returns at *filePtr a
     pointer to the FILE structure for the file.  The write argu-
     ment  indicates  whether  the  FILE pointer will be used for
     reading or writing.  In some cases, such as a  channel  that
     connects  to  a  pipeline  of  subprocesses,  different FILE
     pointers  will  be  returned  for   reading   and   writing.
     Tcl_GetOpenFile normally returns TCL_OK.  If an error occurs
     in Tcl_GetOpenFile (e.g. string didn't  make  any  sense  or
     checkUsage was set and the file wasn't opened for the access
     specified by write) then TCL_ERROR is returned  and  interp-
     >result  will  contain  an  error  message.   In the current
     implementation checkUsage is ignored and consistency  checks
     are always performed.



KEYWORDS

     channel, file handle, permissions, pipeline, read, write