75 lines
1.5 KiB
C
75 lines
1.5 KiB
C
/*
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* getopt.c
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*
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* Simple POSIX getopt(), no GNU extensions...
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*/
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#include <stdint.h>
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#include <unistd.h>
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#include <string.h>
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char *optarg;
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int optind = 1;
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int opterr, optopt;
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static const char *__optptr;
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int getopt(int argc, char * const *argv, const char *optstring)
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{
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const char *carg = argv[optind];
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const char *osptr;
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int opt;
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/* We don't actually need argc */
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(void)argc;
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/* First, eliminate all non-option cases */
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if ( !carg || carg[0] != '-' || !carg[1] ) {
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return -1;
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}
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if ( carg[1] == '-' && !carg[2] ) {
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optind++;
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return -1;
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}
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if ( (uintptr_t)(__optptr-carg) > (uintptr_t)strlen(carg) )
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__optptr = carg+1; /* Someone frobbed optind, change to new opt. */
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opt = *__optptr++;
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if ( opt != ':' && (osptr = strchr(optstring, opt)) ) {
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if ( osptr[1] == ':' ) {
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if ( *__optptr ) {
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/* Argument-taking option with attached argument */
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optarg = (char *)__optptr;
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optind++;
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} else {
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/* Argument-taking option with non-attached argument */
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if ( argv[optind+1] ) {
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optarg = (char *)argv[optind+1];
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optind += 2;
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} else {
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/* Missing argument */
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return (optstring[0] == ':') ? ':' : '?';
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}
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}
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return opt;
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} else {
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/* Non-argument-taking option */
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/* __optptr will remember the exact position to resume at */
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if ( ! *__optptr )
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optind++;
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return opt;
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}
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} else {
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/* Unknown option */
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optopt = opt;
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if ( ! *__optptr )
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optind++;
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return '?';
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}
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}
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