Created
January 28, 2021 05:17
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A good C main function taken from https://opensource.com/article/19/5/how-write-good-c-main-function
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/* main.c - the complete listing */ | |
#include <stdio.h> | |
#include <stdlib.h> | |
#include <unistd.h> | |
#include <libgen.h> | |
#include <errno.h> | |
#include <string.h> | |
#include <getopt.h> | |
#define OPTSTR "vi:o:f:h" | |
#define USAGE_FMT "%s [-v] [-f hexflag] [-i inputfile] [-o outputfile] [-h]" | |
#define ERR_FOPEN_INPUT "fopen(input, r)" | |
#define ERR_FOPEN_OUTPUT "fopen(output, w)" | |
#define ERR_DO_THE_NEEDFUL "do_the_needful blew up" | |
#define DEFAULT_PROGNAME "george" | |
extern int errno; | |
extern char *optarg; | |
extern int opterr, optind; | |
typedef struct { | |
int verbose; | |
uint32_t flags; | |
FILE *input; | |
FILE *output; | |
} options_t; | |
int dumb_global_variable = -11; | |
void usage(char *progname, int opt); | |
int do_the_needful(options_t *options); | |
int main(int argc, char *argv[]) { | |
int opt; | |
options_t options = { 0, 0x0, stdin, stdout }; | |
opterr = 0; | |
while ((opt = getopt(argc, argv, OPTSTR)) != EOF) | |
switch(opt) { | |
case 'i': | |
if (!(options.input = fopen(optarg, "r")) ){ | |
perror(ERR_FOPEN_INPUT); | |
exit(EXIT_FAILURE); | |
/* NOTREACHED */ | |
} | |
break; | |
case 'o': | |
if (!(options.output = fopen(optarg, "w")) ){ | |
perror(ERR_FOPEN_OUTPUT); | |
exit(EXIT_FAILURE); | |
/* NOTREACHED */ | |
} | |
break; | |
case 'f': | |
options.flags = (uint32_t )strtoul(optarg, NULL, 16); | |
break; | |
case 'v': | |
options.verbose += 1; | |
break; | |
case 'h': | |
default: | |
usage(basename(argv[0]), opt); | |
/* NOTREACHED */ | |
break; | |
} | |
if (do_the_needful(&options) != EXIT_SUCCESS) { | |
perror(ERR_DO_THE_NEEDFUL); | |
exit(EXIT_FAILURE); | |
/* NOTREACHED */ | |
} | |
return EXIT_SUCCESS; | |
} | |
void usage(char *progname, int opt) { | |
fprintf(stderr, USAGE_FMT, progname?progname:DEFAULT_PROGNAME); | |
exit(EXIT_FAILURE); | |
/* NOTREACHED */ | |
} | |
int do_the_needful(options_t *options) { | |
if (!options) { | |
errno = EINVAL; | |
return EXIT_FAILURE; | |
} | |
if (!options->input || !options->output) { | |
errno = ENOENT; | |
return EXIT_FAILURE; | |
} | |
/* XXX do needful stuff */ | |
return EXIT_SUCCESS; | |
} |
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