KasmVNC/unix/kasmvncpasswd/kasmpasswd.c

#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <unistd.h>

#include "kasmpasswd.h"

struct kasmpasswd_t *readkasmpasswd(const char path[]) {

	struct kasmpasswd_t *set = calloc(sizeof(struct kasmpasswd_t), 1);
	FILE *f = fopen(path, "r");
	if (!f)
		return set;

	// Count lines
	unsigned lines = 0;
	char buf[4096];

	while (fgets(buf, 4096, f)) {
		lines++;
	}

	rewind(f);

	set->entries = calloc(sizeof(struct kasmpasswd_entry_t), lines);

	unsigned cur = 0;
	while (fgets(buf, 4096, f)) {
		char *lim = strchr(buf, ':');
		if (!lim)
			continue;
		*lim = '\0';
		lim++;

		const char * const pw = lim;

		lim = strchr(lim, ':');
		if (!lim)
			continue;
		*lim = '\0';
		lim++;

		const char * const perms = lim;

		lim = strchr(lim, '\n');
		if (lim)
			*lim = '\0';

		if (strlen(buf) + 1 > sizeof(((struct kasmpasswd_entry_t *)0)->user)) {
			fprintf(stderr, "Username %s too long\n", buf);
			continue;
		}
		if (strlen(pw) + 1 > sizeof(((struct kasmpasswd_entry_t *)0)->password)) {
			fprintf(stderr, "Password for user %s too long\n", buf);
			continue;
		}

		strcpy(set->entries[cur].user, buf);
		strcpy(set->entries[cur].password, pw);

		if (strchr(perms, 'w'))
			set->entries[cur].write = 1;
		if (strchr(perms, 'o'))
			set->entries[cur].owner = 1;

		cur++;
	}

	fclose(f);

	set->num = cur;

	return set;
}

void writekasmpasswd(const char path[], const struct kasmpasswd_t *set) {
	char tmpname[PATH_MAX];

	if (!set || !set->entries || !set->num)
		return;

	snprintf(tmpname, PATH_MAX, "%s.tmp", path);
	tmpname[PATH_MAX - 1] = '\0';

	FILE *f = fopen(tmpname, "w");
	if (!f) {
		fprintf(stderr, "Failed to open temp file %s\n", tmpname);
		return;
	}

	static const char * const perms[] = {
		"",
		"w",
		"o",
		"ow"
	};

	unsigned i;
	for (i = 0; i < set->num; i++) {
		if (!set->entries[i].user[0])
			continue;

		fprintf(f, "%s:%s:%s\n",
			set->entries[i].user,
			set->entries[i].password,
			perms[set->entries[i].owner * 2 + set->entries[i].write]);
	}

	fsync(fileno(f));
	fclose(f);

	if (rename(tmpname, path))
		fprintf(stderr, "Failed writing the password file %s\n", path);
	chmod(path, S_IRUSR|S_IWUSR);
}