/*
 * pfind.c - Search for a binary in $PATH.
 */

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>

#ifndef PATH_MAX
#define PATH_MAX 1024
#endif


char *pfind(const char *name)
{
	char *tok;
	char *sp;
	char *path;
	char fullpath[PATH_MAX+1];

	if (name == NULL) {
		fprintf(stderr, "pfind(): Null argument.\n");
		return NULL;
	}

	/* For absolute namer or name with a path, check if it is an executable.  */
	if (name[0] == '/' || name[0] == '.') {
		if (access(name, X_OK | R_OK) == 0) {
			return strdup(name);
		}
		return NULL;
	}

	/* Search in the PATH environment.  */
	path = getenv("PATH");
	if (path == NULL || strlen(path) <= 0) {
		fprintf(stderr, "Unable to get $PATH.\n");
		return NULL;
	}

	// The value return by getenv() is readonly */
	path = strdup(path);

	tok = strtok_r(path, ":", &sp);
	while (tok != NULL) {
		snprintf(fullpath, sizeof(fullpath) - 1, "%s/%s", tok, name);

		if (access(fullpath, X_OK | R_OK) == 0) {
			free(path);
			return strdup(fullpath);
		}

		tok = strtok_r(NULL, ":", &sp);
	}

	free(path);
	return NULL;
}

#ifdef BUILD_WITH_MAIN
int main(int argc, char **argv)
{
	int i;
	char *fullpath;

	for (i = 1; i<argc; i++) {
		fullpath = pfind(argv[i]);
		if (fullpath == NULL)
			printf("Unable to find %s in $PATH.\n", argv[i]);
		else 
			printf( "Found %s @ %s.\n", argv[i], fullpath );
	}
}
#endif