GetOpt.c

#include "GetOpt.h"
#include <stdio.h>
#include <string.h>
#include <ctype.h>

// How many argument can each option receive at maximum
#define MAX_NBR_ARGS_PER_OPT 10

int GetOpt(int argc, char *argv[], tOptionList optlst)
{
    int err=0;// Will be set to non zero if an error occurs
    int n;// Index to iterate over argv
    int p;// Index to iterate over known options
    int lastopt=0;// 1+index of option in optlst previously found, 0 if no option previously found, -1 for unknown option

    // To store all the arguments of an option
    char optsn[2];// Buffer to render option short name into
    int optargc;
    char* optargv[1+(MAX_NBR_ARGS_PER_OPT)];
    optargc=0;
    optargv[optargc]=NULL;

    // Iterate over all arguments received by main to check for option match
    for(n=0;n<argc;++n)
    {
        int isopt=0;// 0 for no option found, -1 for unknown option, 1..n for option found, corresponding to its 1+index
        char* firstoptarg=NULL;
        // Check for long options, starting with --
        if(argv[n][0]=='-' && argv[n][1]=='-')
        {
            for(p=0;optlst[p].longopt!=NULL;++p)
            {
                if(strcasecmp(&argv[n][2],optlst[p].longopt)==0)
                {
                    if(isopt)
                    {
                        printf("Error: ambiguous option %s\n",argv[n]);
                        ++err;
                    }
                    isopt=1+p;
                }
            }
            if(!isopt)
            {
                printf("Error: Unknown long option %s\n",argv[n]);
                ++err;
                isopt=-1;
            }
        }
        // Check for short options, starting with - or / and one character long
        if((argv[n][0]=='-' || argv[n][0]=='/') && isalnum((int)argv[n][1]))
        {
            for(p=0;optlst[p].longopt!=NULL;++p)
            {
                if(argv[n][1]==optlst[p].shortopt)
                {
                    if(isopt)
                    {
                        printf("Error: ambiguous option %s\n",argv[n]);
                        ++err;
                    }
                    isopt=1+p;
                    if(argv[n][2])
                    {
                        firstoptarg=&argv[n][2];
                    }
                }
            }
            if(!isopt)
            {
                printf("Error: Unknown short option %s\n",argv[n]);
                ++err;
                isopt=-1;
            }
        }
        // If current argument is an option
        if(isopt)
        {
            if(lastopt && lastopt!=-1)
            {
                // Take into account previous option if a new option is found
                (*optlst[lastopt-1].fct)(optargc,optargv);
            }
            // Now that previous opt has been treated, reset opt arg list for the current opt
            optargc=0;
            optargv[optargc]=NULL;
            // First argument is the option name with which it was found
            optargv[optargc++]=optlst[isopt].longopt;
            optargv[optargc]=NULL;
            // If current opt had an arg glued to the option flag
            if(firstoptarg)
            {
                optargv[optargc++]=firstoptarg;
                optargv[optargc]=NULL;
            }
            lastopt=isopt;
        }
        else
        {// Not a new option
            if(lastopt && lastopt!=-1)
            {// Store as arg of previous option
                if(optargc<MAX_NBR_ARGS_PER_OPT)
                {
                    optargv[optargc++]=argv[n];
                    optargv[optargc]=NULL;
                }
                else
                {
                    printf("Error: Option %s has over %d args, ignoring \"%s\".\n",optlst[lastopt-1].longopt,MAX_NBR_ARGS_PER_OPT,argv[n]);
                    ++err;
                }
            }
            else
            {
                if(n>0)// argv[0] is just the name of the program being run, not an option
                {
                    printf("Error: argument ignored: %s\n",argv[n]);
                    ++err;
                }
            }
        }
    }
    // We're done iterating over all argv
    if(lastopt && lastopt!=-1)
    {// If we reach end of argument list with an option hanging, treat it
        (*optlst[lastopt-1].fct)(optargc,optargv);
    }
    // If an error occurred, print help
    if(err)
    {
        PrintOptList(optlst);
    }
    return err;
}

void PrintOptList(tOptionList optlst)
{
    int p;
    static int wasOptListPrinted=0;
    if(wasOptListPrinted)
        return;
    wasOptListPrinted=1;
    printf("\n");
    printf("List of allowed options:\n");
    for(p=0;optlst[p].longopt!=NULL;++p)
    {
        if(isalnum((int)optlst[p].shortopt))
        {
            printf("-%c --%s : %s\n",optlst[p].shortopt,optlst[p].longopt,optlst[p].description);
        }
        else
        {
            printf("   --%s : %s\n",optlst[p].longopt,optlst[p].description);
        }
    }
    printf("Compiled on the %s at %s\n",__DATE__,__TIME__);
    printf("\n");
}