#include <errno.h>#include <fcntl.h>#include <stdio.h>#include <stdlib.h>#include <string.h>#include <sys/stat.h>#include <unistd.h> int main(void) {    char directory[] = "/tmp/agentos-open-flags-XXXXXX";    if (mkdtemp(directory) == NULL)        return 1;     char target[512];    char link[512];    char missing[512];    char umask_target[512];    if (snprintf(target, sizeof(target), "%s/target", directory) >= (int)sizeof(target) ||        snprintf(link, sizeof(link), "%s/link", directory) >= (int)sizeof(link) ||        snprintf(missing, sizeof(missing), "%s/missing", directory) >= (int)sizeof(missing) ||        snprintf(umask_target, sizeof(umask_target), "%s/umask", directory) >=            (int)sizeof(umask_target))        return 1;     int fd = open(target, O_WRONLY | O_CREAT | O_TRUNC, 0600);    if (fd < 0 || write(fd, "payload", 7) != 7 || close(fd) != 0 ||        symlink(target, link) != 0)        return 1;     errno = 0;    fd = open(target, O_RDONLY | O_DIRECTORY | O_TRUNC);    int directory_truncate_errno = errno;    if (fd >= 0)        close(fd);     errno = 0;    fd = open(link, O_RDONLY | O_NOFOLLOW | O_TRUNC);    int nofollow_truncate_errno = errno;    if (fd >= 0)        close(fd);     errno = 0;    fd = open(missing, O_RDONLY | O_DIRECTORY | O_CREAT, 0600);    int directory_create_errno = errno;    if (fd >= 0)        close(fd);     char contents[8] = {0};    fd = open(target, O_RDONLY);    int content_intact = fd >= 0 && read(fd, contents, 7) == 7 &&        memcmp(contents, "payload", 7) == 0;    if (fd >= 0)        close(fd);    int missing_absent = access(missing, F_OK) == -1 && errno == ENOENT;     mode_t previous_umask = umask(0077);    fd = open(umask_target, O_WRONLY | O_CREAT | O_EXCL, 0666);    struct stat umask_stat;    int umask_applied = fd >= 0 && close(fd) == 0 &&        stat(umask_target, &umask_stat) == 0 &&        (umask_stat.st_mode & 0777) == 0600;    umask(previous_umask);     int ok = directory_truncate_errno == ENOTDIR &&        nofollow_truncate_errno == ELOOP && directory_create_errno == EINVAL &&        content_intact && missing_absent && umask_applied;    printf("open_directory_truncate_enotdir=%s\n",        directory_truncate_errno == ENOTDIR ? "yes" : "no");    printf("open_nofollow_truncate_eloop=%s\n",        nofollow_truncate_errno == ELOOP ? "yes" : "no");    printf("open_directory_create_einval=%s\n",        directory_create_errno == EINVAL ? "yes" : "no");    printf("open_failure_side_effects_absent=%s\n",        content_intact && missing_absent ? "yes" : "no");    printf("umask_applies_to_kernel_create=%s\n", umask_applied ? "yes" : "no");    printf("open_flags=%s\n", ok ? "ok" : "failed");     unlink(umask_target);    unlink(missing);    unlink(link);    unlink(target);    rmdir(directory);    return ok ? 0 : 1;}