/* test_dir.c — dir backend: host passthrough + path containment
 * (Section 6.2): a normalized ".." can't reach it (blocked in the
 * virtual namespace, Section 6.1), and an absolute symlink planted
 * inside the mount cannot be used to read outside it. */

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

#include "packfs.h"
#include "test_harness.h"

int main(void) {
    char root[] = "/tmp/packfs_test_dir_XXXXXX";
    CHECK(mkdtemp(root) != NULL);
    char outside_dir[480];
    snprintf(outside_dir, sizeof(outside_dir), "/tmp/packfs_secret_%d", (int)getpid());
    mkdir(outside_dir, 0755);
    char secret_file[512];
    snprintf(secret_file, sizeof(secret_file), "%s/secret.txt", outside_dir);
    FILE *sf = fopen(secret_file, "w");
    CHECK(sf != NULL);
    fputs("top secret", sf);
    fclose(sf);

    /* a symlink INSIDE root pointing OUTSIDE it */
    char link_path[512];
    snprintf(link_path, sizeof(link_path), "%s/escape", root);
    CHECK(symlink(outside_dir, link_path) == 0);

    Vfs *v = vfs_new();
    int derr = 0;
    Backend *dir = backend_dir_new(root, &derr);
    CHECK(dir != NULL);
    CHECK_EQ_INT(vfs_mount(v, "/", dir), VFS_OK);

    int err = 0;
    VfsFile *f = vfs_open(v, "/a.txt", VFS_O_WRONLY | VFS_O_CREAT, &err);
    CHECK(f != NULL);
    CHECK_EQ_INT(vfs_write(f, "abc", 3), 3);
    CHECK_EQ_INT(vfs_close(f), VFS_OK);

    f = vfs_open(v, "/a.txt", VFS_O_RDONLY, &err);
    char buf[8] = {0};
    CHECK_EQ_INT(vfs_read(f, buf, sizeof(buf)), 3);
    CHECK_STR_EQ(buf, "abc");
    CHECK_EQ_INT(vfs_close(f), VFS_OK);

    /* virtual-namespace ".." escape: rejected before any backend is reached */
    f = vfs_open(v, "/../etc/shadow", VFS_O_RDONLY, &err);
    CHECK(f == NULL);
    CHECK_EQ_INT(err, VFS_ERR_INVAL);

    /* symlink escape through the dir backend itself: openat2/O_NOFOLLOW
     * containment (Section 6.2) must refuse to follow it. */
    f = vfs_open(v, "/escape/secret.txt", VFS_O_RDONLY, &err);
    CHECK(f == NULL);

    vfs_unmount(v, "/");
    backend_free(dir);
    vfs_free(v);
    TEST_MAIN_END();
}