#include <errno.h>
#include <string.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>

/* The C Programming Language: 2nd Edition
 *
 * Exercise 8-5: Modify the fsize program to print the other information
 * contained in the inode entry.
 *
 * Notes: The supplied header file examples don't really work well on a
 * GNU/Linux system in 2022. :) This makes 8-5 the only exercise in the book
 * that's broken enough to nearly require the standard library to complete.
 * Despite lacking the homegrown headers, this exercise is still a good example
 * of callbacks.
 *
 * Not all of the information within the stat struct is displayed by this
 * program; this is mostly due to the information not being terribly useful
 * on all systems. Modification time and permission information is relevant
 * to all platforms.
 */

void fsize(char *);
void dirwalk(char *, void (*fcn)(char *));

int main(int argc, char **argv) {
	if (argc == 1) {
		fsize(".");
	} else {
		while (--argc > 0) {
			fsize(*++argv);
		}
	}
	return 0;
}

void fsize(char *name) {
	struct stat stbuf;
	if (stat(name, &stbuf) == -1) {
		fprintf(stderr, "fsize: can't access %s\n", name);
		return;
	}
	if ((stbuf.st_mode & S_IFMT) == S_IFDIR) {
		dirwalk(name, fsize);
	}
	/*
	 * Size, Mode, UID, GID, ModifiedTime, FileName
	 */
	printf("%8ld %6o %d %d %ld %s\n", stbuf.st_size, stbuf.st_mode, stbuf.st_uid, stbuf.st_gid, stbuf.st_mtime, name);
}

void dirwalk(char *dir, void (*fcn)(char *)) {
	char name[PATH_MAX];
	struct dirent *dp;
	DIR *dfd;
	if ((dfd = opendir(dir)) == NULL) {
		fprintf(stderr, "dirwalk: can't open %s\n", dir);
		return;
	}
	while ((dp = readdir(dfd)) != NULL) {
		if (strcmp(dp->d_name, ".") == 0 || strcmp(dp->d_name, "..") == 0) {
			continue;
		}
		if (strlen(dir)+strlen(dp->d_name)+2 > sizeof (name)) {
			fprintf(stderr, "dirwalk: name %s/%s too long\n", dir, dp->d_name);
		} else {
			sprintf(name, "%s/%s", dir, dp->d_name);
			(*fcn)(name);
		}
	}
	closedir(dfd);
}