// SPDX-License-Identifier: WTFPL

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

#define MAX_ID	65536

static char *loadfile(char *filename)
{
	FILE *fp;
	size_t size;
	char *buf;

	fp = fopen(filename, "r");
	if (fp == NULL)
		return NULL;

	fseek(fp, 0, SEEK_END);
	size = ftell(fp);
	fseek(fp, 0, SEEK_SET);

	// treat as string, add '\0' at last
	buf = calloc(size + 1, 1);
	if (buf == NULL)
		goto fin0;

	fread(buf, size, 1, fp);
fin0:
	fclose(fp);

	return buf;
}

static void tokenize(char *table[], char *buf)
{
	int i, id;
	char *p, *n, *d;

	d = NULL;

	for (i = 1, p = buf; p != NULL && *p; i++, p = n) {
		n = strchr(p, ':');
		if (n != NULL) {
			*n = '\0';
			n++;
		}

		// extract 3rd (ID) field
		if (i == 3) {
			d = p;
			break; // no need to tokenize more
		}
	}

	if (d != NULL) {
		id = atoi(d);
		if (id >= 0 && id < MAX_ID)
			table[id] = buf; // 1st field: name
	}
}

static void parse_lines(char *table[], char *buf)
{
	char *p, *n;

	for (p = buf; p != NULL && *p; p = n) {
		n = strchr(p, '\n');
		if (n != NULL) {
			*n = '\0';
			n++;
		}

		tokenize(table, p);
	}
}

static void match_tables(char *src[], char *dest[], int entry)
{
	int i, j;

	// NFS mapping for client
	// uid/gid remote local

	for (i = 0; i < entry; i++) {
		if (src[i] == NULL)
			continue;

		for (j = 0; j < entry; j++) {
			if (dest[j] == NULL)
				continue;

			if (!strcmp(src[i], dest[j])) {
				printf("gid	%5d %5d # %s\n",
				       j, i, src[i]);
				break;
			}
		}
	}
}

int main(int argc, char *argv[])
{
	char *local, *remote;
	char *local_id[MAX_ID];
	char *remote_id[MAX_ID];

	memset(local_id, 0, sizeof(local_id));
	memset(remote_id, 0, sizeof(remote_id));

	if (argc < 3) {
		printf("%s [local] [remote]\n", argv[0]);
		return 0;
	}

	local = loadfile(argv[1]);
	if (local == NULL) {
		printf("file open error(local)\n");
		goto fin0;
	}

	remote = loadfile(argv[2]);
	if (remote == NULL) {
		printf("file open error(remote)\n");
		goto fin1;
	}

	parse_lines(local_id, local);
	parse_lines(remote_id, remote);

	match_tables(local_id, remote_id, MAX_ID);

//fin2:
	free(remote);
fin1:
	free(local);
fin0:
	return 0;
}