getsubopt(3C)															     getsubopt(3C)

NAME

       getsubopt - parse suboption arguments from a string

SYNOPSIS

       #include <stdlib.h>

       int getsubopt(char **optionp, char * const *keylistp, char **valuep);

       The getsubopt() function parses suboption arguments in a flag argument. Such options often result from the use of getopt(3C).

       The  getsubopt()  argument optionp is a pointer to a pointer to the option argument string. The suboption arguments are separated by commas
       and each can consist of either a single token or a token-value pair separated by an equal sign.

       The keylistp argument is a pointer to a vector of strings. The end of the vector is identified by a null pointer. Each entry in the  vector
       is  one of the possible tokens that might be found in *optionp. Since commas delimit suboption arguments in optionp, they should not appear
       in any of the strings pointed to by keylistp. Similarly, because an equal sign separates a token from its value, the application should not
       include an equal sign in any of the strings pointed to by keylistp.

       The valuep argument is the address of a value string pointer.

       If a comma appears in optionp, it is interpreted as a suboption separator. After commas have been processed, if there are one or more equal
       signs in a suboption string, the first equal sign in any suboption string is interpreted as a separator between a token and a value.   Sub-
       sequent equal signs in a suboption string are interpreted as part of the value.

       If the string at *optionp contains only one suboption argument (equivalently, no commas), getsubopt() updates *optionp to point to the null
       character at the end of the string. Otherwise, it isolates the suboption argument by replacing the comma separator with	a  null  character
       and updates *optionp to point to the start of the next suboption argument. If the suboption argument has an associated value (equivalently,
       contains an equal sign), getsubopt() updates *valuep to point to the value's first character. Otherwise, it sets *valuep to a null pointer.
       The calling application can use this information to determine whether the presence or absence of a value for the suboption is an error.

       Additionally,  when  getsubopt()  fails to match the suboption with a token in the keylistp array, the calling application should decide if
       this is an error or if the unrecognized option should be processed in another way.

       The getsubopt() function returns the index of the matched token string or -1 if no token strings were matched.

       No errors are defined.

       Example 1: Use getsubopt() to process options.

       The following example demonstrates the processing of options to the mount(1M) utility using getsubopt().

       #include <stdlib.h>

       char *myopts[] = {
       #define READONLY     0
		   "ro",
       #define READWRITE    1
		   "rw",
       #define WRITESIZE    2
		   "wsize",
       #define READSIZE     3
		   "rsize",
		   NULL};

       main(argc, argv)
	   int	argc;
	   char **argv;
       {
	   int sc, c, errflag;
	   char *options, *value;
	   extern char *optarg;
	   extern int optind;
	   .
	   .
	   .
	   while((c = getopt(argc, argv, "abf:o:")) != -1) {
	       switch (c) {
	       case 'a': /* process a option */
		   break;
	       case 'b': /* process b option */
		   break;
	       case 'f':
		   ofile = optarg;
		   break;
	       case '?':
		   errflag++;
		   break;
	       case 'o':
		   options = optarg;
		   while (*options != '') {
		       switch(getsubopt(&options,myopts,&value)){
		       case READONLY : /* process ro option */
			   break;
		       case READWRITE : /* process rw option */
			   break;
		       case WRITESIZE : /* process wsize option */
			   if (value == NULL) {
			       error_no_arg();
			       errflag++;
			   } else
			       write_size = atoi(value);
			   break;
		       case READSIZE : /* process rsize option */
			   if (value == NULL) {
			       error_no_arg();
			       errflag++;
			   } else
			       read_size = atoi(value);
			   break;
		       default :
			   /* process unknown token */
			   error_bad_token(value);
			   errflag++;
			   break;
			  }
		   }
		     break;
	       }
	   }
	   if (errflag) {
	       /* print usage instructions etc. */
	   }
	   for (; optind<argc; optind++) {
	       /* process remaining arguments */
	   }
	   .
	   .
	   .
       }

       Example 2: Parse suboptions.

       The following example uses the getsubopt() function to parse a value argument in the  optarg  external  variable  returned  by  a  call	to
       getopt(3C).

       #include <stdlib.h>
       ...
       char *tokens[] = {"HOME", "PATH", "LOGNAME", (char *) NULL };
       char *value;
       int opt, index;
       while ((opt = getopt(argc, argv, "e:")) != -1) {
	   switch(opt) {
	   case 'e' :
	       while ((index = getsubopt(&optarg, tokens, &value)) != -1) {
		   switch(index) {
       ...
	       }
	       break;
       ...
	   }
       }

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

       mount(1M), getopt(3C), attributes(5), standards(5)

								    29 Sep 2005 						     getsubopt(3C)