MultiMedia/play/getopt.c

   1 /*****************************************************************************
   2  *
   3  *  MODULE NAME : GETOPT.C
   4  *
   5  *  COPYRIGHTS:
   6  *             This module contains code made available by IBM
   7  *             Corporation on an AS IS basis.  Any one receiving the
   8  *             module is considered to be licensed under IBM copyrights
   9  *             to use the IBM-provided source code in any way he or she
  10  *             deems fit, including copying it, compiling it, modifying
  11  *             it, and redistributing it, with or without
  12  *             modifications.  No license under any IBM patents or
  13  *             patent applications is to be implied from this copyright
  14  *             license.
  15  *
  16  *             A user of the module should understand that IBM cannot
  17  *             provide technical support for the module and will not be
  18  *             responsible for any consequences of use of the program.
  19  *
  20  *             Any notices, including this one, are not to be removed
  21  *             from the module without the prior written consent of
  22  *             IBM.
  23  *
  24  *  AUTHOR:   Original author:
  25  *                 G. R. Blair (BOBBLAIR at AUSVM1)
  26  *                 Internet: bobblair@bobblair.austin.ibm.com
  27  *
  28  *            Extensively revised by:
  29  *                 John Q. Walker II, Ph.D. (JOHHQ at RALVM6)
  30  *                 Internet: johnq@ralvm6.vnet.ibm.com
  31  *
  32  */
  33 /******************************************************************************
  34  * getopt()
  35  *
  36  * The getopt() function is a command line parser.  It returns the next
  37  * option character in argv that matches an option character in opstring.
  38  *
  39  * The argv argument points to an array of argc+1 elements containing argc
  40  * pointers to character strings followed by a null pointer.
  41  *
  42  * The opstring argument points to a string of option characters; if an
  43  * option character is followed by a colon, the option is expected to have
  44  * an argument that may or may not be separated from it by white space.
  45  * The external variable optarg is set to point to the start of the option
  46  * argument on return from getopt().
  47  *
  48  * The getopt() function places in optind the argv index of the next argument
  49  * to be processed.  The system initializes the external variable optind to
  50  * 1 before the first call to getopt().
  51  *
  52  * When all options have been processed (that is, up to the first nonoption
  53  * argument), getopt() returns EOF.  The special option "--" may be used to
  54  * delimit the end of the options; EOF will be returned, and "--" will be
  55  * skipped.
  56  *
  57  * The getopt() function returns a question mark (?) when it encounters an
  58  * option character not included in opstring.  This error message can be
  59  * disabled by setting opterr to zero.  Otherwise, it returns the option
  60  * character that was detected.
  61  *
  62  * If the special option "--" is detected, or all options have been
  63  * processed, EOF is returned.
  64  *
  65  * Options are marked by either a minus sign (-) or a slash (/).
  66  *
  67  * No errors are defined.
  68  */
  69 #include <stdio.h>                  /* for EOF */
  70 #include <string.h>                 /* for strchr() */
  71
  72 #ifndef linux
  73
  74 /* static (global) variables that are specified as exported by getopt() */
  75 char *optarg = NULL;    /* pointer to the start of the option argument  */
  76 int   optind = 1;       /* number of the next argv[] to be evaluated    */
  77 int   opterr = 1;       // non-zero if a question mark should be returned
  78                         // when a non-valid option character is detected
  79
  80 /* handle possible future character set concerns by putting this in a macro */
  81 #define _next_char(string)  (char)(*(string+1))
  82
  83 int getopt(int argc, char *argv[], char *opstring)
  84 {
  85     static char *pIndexPosition = NULL; /* place inside current argv string */
  86     char *pArgString = NULL;        /* where to start from next */
  87     char *pOptString;               // the string in our program
  88
  89     if (pIndexPosition != NULL) {
  90         // we last left off inside an argv string
  91         if (*(++pIndexPosition)) {
  92             // there is more to come in the most recent argv
  93             pArgString = pIndexPosition;
  94                 }
  95         }
  96
  97     if (pArgString == NULL) {
  98         // we didn't leave off in the middle of an argv string
  99                 if (optind >= argc) {
 100             // more command-line arguments than the argument count
 101                         pIndexPosition = NULL;  /* not in the middle of anything */
 102             return EOF;             /* used up all command-line arguments */
 103                 }
 104         /*---------------------------------------------------------------------
 105          * If the next argv[] is not an option, there can be no more options.
 106          *-------------------------------------------------------------------*/
 107         pArgString = argv[optind++]; // set this to the next argument ptr
 108
 109         if (('/' != *pArgString) && /* doesn't start with a slash or a dash? */
 110             ('-' != *pArgString)) {
 111             --optind;               /* point to current arg once we're done */
 112             optarg = NULL;          /* no argument follows the option */
 113             pIndexPosition = NULL;  /* not in the middle of anything */
 114             return EOF;             /* used up all the command-line flags */
 115                 }
 116
 117                 // check for special end-of-flags markers
 118         if ((strcmp(pArgString, "-") == 0) ||
 119             (strcmp(pArgString, "--") == 0)) {
 120             optarg = NULL;          /* no argument follows the option */
 121             pIndexPosition = NULL;  /* not in the middle of anything */
 122             return EOF;             /* encountered the special flag */
 123                 }
 124         pArgString++;               /* look past the / or - */
 125         }
 126
 127         if (':' == *pArgString) {       /* is it a colon? */
 128         /*---------------------------------------------------------------------
 129          * Rare case: if opterr is non-zero, return a question mark;
 130          * otherwise, just return the colon we're on.
 131          *-------------------------------------------------------------------*/
 132         return (opterr ? (int)'?' : (int)':');
 133         }
 134     else if ((pOptString = strchr(opstring, *pArgString)) == 0) {
 135         /*---------------------------------------------------------------------
 136          * The letter on the command-line wasn't any good.
 137          *-------------------------------------------------------------------*/
 138         optarg = NULL;              /* no argument follows the option */
 139         pIndexPosition = NULL;      /* not in the middle of anything */
 140         return (opterr ? (int)'?' : (int)*pArgString);
 141         } else {
 142         /*---------------------------------------------------------------------
 143          * The letter on the command-line matches one we expect to see
 144          *-------------------------------------------------------------------*/
 145         if (':' == _next_char(pOptString)) { /* is the next letter a colon? */
 146             /* It is a colon.  Look for an argument string. */
 147             if ('\0' != _next_char(pArgString)) {  /* argument in this argv? */
 148                 optarg = &pArgString[1];   /* Yes, it is */
 149                         } else {
 150                 /*-------------------------------------------------------------
 151                  * The argument string must be in the next argv.
 152                  * But, what if there is none (bad input from the user)?
 153                  * In that case, return the letter, and optarg as NULL.
 154                  *-----------------------------------------------------------*/
 155                 if (optind < argc)
 156                     optarg = argv[optind++];
 157                 else {
 158                     optarg = NULL;
 159                     return (opterr ? (int)'?' : (int)*pArgString);
 160                                 }
 161                         }
 162             pIndexPosition = NULL;  /* not in the middle of anything */
 163                 } else {
 164             /* it's not a colon, so just return the letter */
 165             optarg = NULL;          /* no argument follows the option */
 166             pIndexPosition = pArgString;    /* point to the letter we're on */
 167                 }
 168         return (int)*pArgString;    /* return the letter that matched */
 169         }
 170 }
 171 #endif