lib/getopt.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * getopt.c - a simple getopt(3) implementation. See getopt.h for explanation.
   4  *
   5  * Copyright (C) 2020 Sean Anderson <seanga2@gmail.com>
   6  * Copyright (c) 2007 Sascha Hauer <s.hauer@pengutronix.de>, Pengutronix
   7  */
   8
   9 #define LOG_CATEGORY LOGC_CORE
  10
  11 #include <getopt.h>
  12 #include <log.h>
  13 #include <linux/string.h>
  14
  15 void getopt_init_state(struct getopt_state *gs)
  16 {
  17         gs->index = 1;
  18         gs->arg_index = 1;
  19 }
  20
  21 int __getopt(struct getopt_state *gs, int argc, char *const argv[],
  22              const char *optstring, bool silent)
  23 {
  24         char curopt;   /* current option character */
  25         const char *curoptp; /* pointer to the current option in optstring */
  26
  27         while (1) {
  28                 log_debug("arg_index: %d index: %d\n", gs->arg_index,
  29                           gs->index);
  30
  31                 /* `--` indicates the end of options */
  32                 if (gs->arg_index == 1 && argv[gs->index] &&
  33                     !strcmp(argv[gs->index], "--")) {
  34                         gs->index++;
  35                         return -1;
  36                 }
  37
  38                 /* Out of arguments */
  39                 if (gs->index >= argc)
  40                         return -1;
  41
  42                 /* Can't parse non-options */
  43                 if (*argv[gs->index] != '-')
  44                         return -1;
  45
  46                 /* We have found an option */
  47                 curopt = argv[gs->index][gs->arg_index];
  48                 if (curopt)
  49                         break;
  50                 /*
  51                  * no more options in current argv[] element; try the next one
  52                  */
  53                 gs->index++;
  54                 gs->arg_index = 1;
  55         }
  56
  57         /* look up current option in optstring */
  58         curoptp = strchr(optstring, curopt);
  59
  60         if (!curoptp) {
  61                 if (!silent)
  62                         printf("%s: invalid option -- %c\n", argv[0], curopt);
  63                 gs->opt = curopt;
  64                 gs->arg_index++;
  65                 return '?';
  66         }
  67
  68         if (*(curoptp + 1) != ':') {
  69                 /* option with no argument. Just return it */
  70                 gs->arg = NULL;
  71                 gs->arg_index++;
  72                 return curopt;
  73         }
  74
  75         if (*(curoptp + 1) && *(curoptp + 2) == ':') {
  76                 /* optional argument */
  77                 if (argv[gs->index][gs->arg_index + 1]) {
  78                         /* optional argument with directly following arg */
  79                         gs->arg = argv[gs->index++] + gs->arg_index + 1;
  80                         gs->arg_index = 1;
  81                         return curopt;
  82                 }
  83                 if (gs->index + 1 == argc) {
  84                         /* We are at the last argv[] element */
  85                         gs->arg = NULL;
  86                         gs->index++;
  87                         return curopt;
  88                 }
  89                 if (*argv[gs->index + 1] != '-') {
  90                         /*
  91                          * optional argument with arg in next argv[] element
  92                          */
  93                         gs->index++;
  94                         gs->arg = argv[gs->index++];
  95                         gs->arg_index = 1;
  96                         return curopt;
  97                 }
  98
  99                 /* no optional argument found */
 100                 gs->arg = NULL;
 101                 gs->arg_index = 1;
 102                 gs->index++;
 103                 return curopt;
 104         }
 105
 106         if (argv[gs->index][gs->arg_index + 1]) {
 107                 /* required argument with directly following arg */
 108                 gs->arg = argv[gs->index++] + gs->arg_index + 1;
 109                 gs->arg_index = 1;
 110                 return curopt;
 111         }
 112
 113         gs->index++;
 114         gs->arg_index = 1;
 115
 116         if (gs->index >= argc || argv[gs->index][0] == '-') {
 117                 if (!silent)
 118                         printf("option requires an argument -- %c\n", curopt);
 119                 gs->opt = curopt;
 120                 return ':';
 121         }
 122
 123         gs->arg = argv[gs->index++];
 124         return curopt;
 125 }