// User-mode smoke test for POSIX dynamic module loading.

#include <stdint.h>
#include <stddef.h>
#include <string.h>
#include <stdbool.h>

#define RTLD_NOW   0x0002
#define RTLD_LOCAL 0x0004

typedef int64_t ssize_t;

extern ssize_t write(int fd, const void* buf, size_t count);
extern void exit(int status);
extern void* dlopen(const char* filename, int flags);
extern void* dlsym(void* handle, const char* symbol);
extern int dlclose(void* handle);
extern char* dlerror(void);

// Writes one NUL-terminated string to stdout.
static void print(const char* s) {
    write(1, s, strlen(s));
}

// Terminates the current process.
static void exit_now(int code) {
    while (true) exit(code);
}

// Fails the smoke test with one message.
static void fail(const char* message) {
    print("posix_module_smoke: ");
    print(message);
    print("\n");
    exit_now(1);
}

// Verifies that dlerror reports and clears one loader error.
static void check_dlerror_clear(void) {
    void* missing = dlsym(0, "definitely_missing");
    if (missing) fail("dlsym unexpectedly succeeded");
    char* first = dlerror();
    if (!first || !first[0]) fail("dlerror did not report the failure");
    char* second = dlerror();
    if (second) fail("dlerror did not clear the failure");
}

// Runs the POSIX dynamic loader smoke test.
int main(void) {
    print("posix_module_smoke: start\n");
    check_dlerror_clear();

    void* module = dlopen("syscall.dll", RTLD_NOW | RTLD_LOCAL);
    if (!module) fail("dlopen syscall.dll failed");

    typedef uint32_t (__stdcall *GETPID_FN)(void);
    GETPID_FN getpid_native = (GETPID_FN)dlsym(module, "SysGetCurrentPid");
    if (!getpid_native) fail("dlsym SysGetCurrentPid failed");
    if (getpid_native() == 0) fail("resolved SysGetCurrentPid returned zero");

    if (dlclose(module) != 0) fail("dlclose syscall.dll failed");

    print("posix_module_smoke: PASS\n");
    exit_now(0);
    return 0;
}