/*
 * Copyright © 2018 Alexey Dobriyan <adobriyan@gmail.com>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
// Test /proc/*/fd lookup.

#undef NDEBUG
#include <assert.h>
#include <dirent.h>
#include <errno.h>
#include <limits.h>
#include <sched.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#include "proc.h"

/* lstat(2) has more "coverage" in case non-symlink pops up somehow. */
static void test_lookup_pass(const char *pathname)
{
        struct stat st;
        ssize_t rv;

        memset(&st, 0, sizeof(struct stat));
        rv = lstat(pathname, &st);
        assert(rv == 0);
        assert(S_ISLNK(st.st_mode));
}

static void test_lookup_fail(const char *pathname)
{
        struct stat st;
        ssize_t rv;

        rv = lstat(pathname, &st);
        assert(rv == -1 && errno == ENOENT);
}

static void test_lookup(unsigned int fd)
{
        char buf[64];
        unsigned int c;
        unsigned int u;
        int i;

        snprintf(buf, sizeof(buf), "/proc/self/fd/%u", fd);
        test_lookup_pass(buf);

        /* leading junk */
        for (c = 1; c <= 255; c++) {
                if (c == '/')
                        continue;
                snprintf(buf, sizeof(buf), "/proc/self/fd/%c%u", c, fd);
                test_lookup_fail(buf);
        }

        /* trailing junk */
        for (c = 1; c <= 255; c++) {
                if (c == '/')
                        continue;
                snprintf(buf, sizeof(buf), "/proc/self/fd/%u%c", fd, c);
                test_lookup_fail(buf);
        }

        for (i = INT_MIN; i < INT_MIN + 1024; i++) {
                snprintf(buf, sizeof(buf), "/proc/self/fd/%d", i);
                test_lookup_fail(buf);
        }
        for (i = -1024; i < 0; i++) {
                snprintf(buf, sizeof(buf), "/proc/self/fd/%d", i);
                test_lookup_fail(buf);
        }
        for (u = INT_MAX - 1024; u <= (unsigned int)INT_MAX + 1024; u++) {
                snprintf(buf, sizeof(buf), "/proc/self/fd/%u", u);
                test_lookup_fail(buf);
        }
        for (u = UINT_MAX - 1024; u != 0; u++) {
                snprintf(buf, sizeof(buf), "/proc/self/fd/%u", u);
                test_lookup_fail(buf);
        }


}

int main(void)
{
        struct dirent *de;
        unsigned int fd, target_fd;

        if (unshare(CLONE_FILES) == -1)
                return 1;

        /* Wipe fdtable. */
        do {
                DIR *d;

                d = opendir("/proc/self/fd");
                if (!d)
                        return 1;

                de = xreaddir(d);
                assert(de->d_type == DT_DIR);
                assert(streq(de->d_name, "."));

                de = xreaddir(d);
                assert(de->d_type == DT_DIR);
                assert(streq(de->d_name, ".."));
next:
                de = xreaddir(d);
                if (de) {
                        unsigned long long fd_ull;
                        unsigned int fd;
                        char *end;

                        assert(de->d_type == DT_LNK);

                        fd_ull = xstrtoull(de->d_name, &end);
                        assert(*end == '\0');
                        assert(fd_ull == (unsigned int)fd_ull);

                        fd = fd_ull;
                        if (fd == dirfd(d))
                                goto next;
                        close(fd);
                }

                closedir(d);
        } while (de);

        /* Now fdtable is clean. */

        fd = open("/", O_PATH|O_DIRECTORY);
        assert(fd == 0);
        test_lookup(fd);
        close(fd);

        /* Clean again! */

        fd = open("/", O_PATH|O_DIRECTORY);
        assert(fd == 0);
        /* Default RLIMIT_NOFILE-1 */
        target_fd = 1023;
        while (target_fd > 0) {
                if (dup2(fd, target_fd) == target_fd)
                        break;
                target_fd /= 2;
        }
        assert(target_fd > 0);
        close(fd);
        test_lookup(target_fd);
        close(target_fd);

        return 0;
}