utils-std

which.c (1524B)

// utils-std: Collection of commonly available Unix tools
// SPDX-FileCopyrightText: 2017 Haelwenn (lanodan) Monnier <contact+utils@hacktivis.me>
// SPDX-License-Identifier: MPL-2.0
#define _POSIX_C_SOURCE 200809L
#include <limits.h> // PATH_MAX
#include <stdbool.h>
#include <stdio.h>  // fprintf
#include <stdlib.h> // getenv
#include <string.h> // strtok
#include <unistd.h> // access, getopt
int
main(int argc, char *argv[])
{
	bool opt_a = false, opt_s = false;
	int missing = 0;
	char *path = getenv("PATH");
	if(path == NULL)
	{
		fputs("which: Error: $PATH environment unset", stderr);
		return 1;
	}
	int c = -1;
	while((c = getopt(argc, argv, "as")) != -1)
	{
		switch(c)
		{
		case 'a':
			opt_a = true;
			break;
		case 's':
			opt_s = true;
			break;
		case '?':
			fprintf(stderr, "which: Error: Unrecognised option: '-%c'\n", optopt);
			return 1;
		default:
			abort();
		}
	}
	argc -= optind;
	argv += optind;
	if(argc <= 0) return 1;
	for(int i = 0; i < argc; i++)
	{
		char *cmd = argv[i];
		bool found = false;
		char *state = NULL;
		char *hay = strdup(path);
		if(hay == NULL)
		{
			perror("which: Failed duplicating $PATH");
			return 1;
		}
		for(char *tok = strtok_r(hay, ":", &state); tok != NULL; tok = strtok_r(NULL, ":", &state))
		{
			char buf[PATH_MAX] = "";
			snprintf(buf, PATH_MAX, "%s/%s", tok, cmd);
			if(access(buf, X_OK) == 0)
			{
				if(!opt_s) puts(buf);
				found = true;
				if(!opt_a) break;
			}
		}
		if(!found) missing++;
		free(hay);
	}
	return missing;
}