
/*
* File: EINTR_wrappers.c
*
* This file implements the wrapper functions for some of the System APIs
*
* Copyright (C) <2019>  <American Megatrends International LLC>
*
*/

#include "EINTR_wrappers.h"
#if defined(__linux__)
#include <sys/msg.h>
#include <sys/file.h>
#endif
#include <errno.h>
#include <unistd.h>

static const int OneSecondasNS = 1000000000;

#ifndef bool
typedef int bool;
#endif

#ifndef TRUE
#define TRUE (1)
#endif

#ifndef FALSE
#define FALSE (0)
#endif

typedef struct
{
    bool OnePoll;
    struct timespec EndTime, Timeout;
} SIGWRAP_TIMEOUT;

static void sigwrap_InitTimeout(SIGWRAP_TIMEOUT *pDst, const struct timespec *timeout)
{
    pDst->Timeout = *timeout;

    if ((timeout->tv_sec == 0) && (timeout->tv_nsec == 0))                  // If both value are zero than only a single poll is requested!
    {
        pDst->OnePoll = 1;
        return;
    }

    pDst->OnePoll = 0;

    struct timespec Now;

    (void)clock_gettime(CLOCK_MONOTONIC_RAW, &Now);                         // CLOCK_MONOTONIC_RAW is not affected by NTP etc.

    pDst->EndTime.tv_sec = Now.tv_sec + pDst->Timeout.tv_sec;               // Check necessary in 2038 due to signed integer variables
    pDst->EndTime.tv_nsec = Now.tv_nsec + pDst->Timeout.tv_nsec;

    if (pDst->EndTime.tv_nsec >= OneSecondasNS)
    {
        pDst->EndTime.tv_sec += (pDst->EndTime.tv_nsec / OneSecondasNS);
        pDst->EndTime.tv_nsec = (pDst->EndTime.tv_nsec % OneSecondasNS);
    }
}


static bool sigwrap_CheckTimeout(SIGWRAP_TIMEOUT *pTo)
{
    if (pTo->OnePoll == TRUE) // Make sure, that in the case that a single poll is requested at least one call is not terminated with EINTR
        return FALSE;

    struct timespec Now;

    (void)clock_gettime(CLOCK_MONOTONIC_RAW, &Now);

    if (Now.tv_sec > pTo->EndTime.tv_sec) // Can become a problem already in 2038 due to signed integer variables
        return TRUE;

    pTo->Timeout.tv_nsec = pTo->EndTime.tv_nsec - Now.tv_nsec;
    pTo->Timeout.tv_sec = pTo->EndTime.tv_sec - Now.tv_sec;

    if (pTo->Timeout.tv_sec == 0)
    {
        if (pTo->Timeout.tv_nsec <= 0)
            return TRUE;
    }
    else if (pTo->Timeout.tv_nsec < 0)
    {
        pTo->Timeout.tv_nsec += OneSecondasNS;
        pTo->Timeout.tv_sec--;
    }

    return FALSE;
}


int sigwrap_semop(int semid, struct sembuf *sops, size_t nsops)
{
    while (1)
    {
        if (semop(semid, sops, nsops) == 0)
            return 0;

        if (errno != EINTR)
            return -1;
    }
}

#if 0
int sigwrap_semtimedop(int semid, struct sembuf *sops, size_t nsops, const struct timespec *timeout)
{
    SIGWRAP_TIMEOUT To;

    if (timeout == NULL)
        return (sigwrap_semop(semid, sops, nsops));

    sigwrap_InitTimeout(&To, timeout);

    while (1)
    {
        if (semtimedop(semid, sops, nsops, &To.Timeout) == 0)
            return 0;

        if (errno != EINTR)
            return -1;

        if (sigwrap_CheckTimeout(&To))
        {
            errno = EAGAIN;
            return -1;
        }
    }
}
#endif

int sigwrap_epoll_wait(int epfd, struct epoll_event *events, int maxevents, int timeout)
{
    SIGWRAP_TIMEOUT To;

    if (timeout != -1)
    {
        struct timespec Timeout;

        Timeout.tv_sec = timeout / 1000;
        Timeout.tv_nsec = (timeout % 1000) * 1000000; // Convert msec to nsec

        sigwrap_InitTimeout(&To, &Timeout);
    }

    while (1)
    {
        int Result = epoll_wait(epfd, events, maxevents, timeout);

        if (Result != -1)
            return Result;

        if (errno != EINTR)
            return Result;

        if (timeout == -1)
            continue;

        if (sigwrap_CheckTimeout(&To))
            return 0;

        timeout = To.Timeout.tv_sec * 1000 + To.Timeout.tv_nsec / 1000000;
    }
}


int sigwrap_epoll_pwait(int epfd, struct epoll_event *events, int maxevents, int timeout, const sigset_t *sigmask)
{
    SIGWRAP_TIMEOUT To;

    if (timeout != -1)
    {
        struct timespec Timeout;

        Timeout.tv_sec = timeout / 1000;
        Timeout.tv_nsec = (timeout % 1000) * 1000000; // Convert msec to nsec

        sigwrap_InitTimeout(&To, &Timeout);
    }

    while (1)
    {
        int Result = epoll_pwait(epfd, events, maxevents, timeout, sigmask);

        if (Result != -1)
            return Result;

        if (errno != EINTR)
            return Result;

        if (timeout == -1)
            continue;

        if (sigwrap_CheckTimeout(&To))
            return 0;

        timeout = To.Timeout.tv_sec * 1000 + To.Timeout.tv_nsec / 1000000;
    }
}


int sigwrap_sigwaitinfo(const sigset_t *set, siginfo_t *info)
{
    while (1)
    {
        int Result = sigwaitinfo(set, info);

        if (Result != -1)
            return Result;

        if (errno != EINTR)
            return Result;
    }
}


int sigwrap_sigtimedwait(const sigset_t *set, siginfo_t *info, const struct timespec *timeout)
{
    SIGWRAP_TIMEOUT To;

    sigwrap_InitTimeout(&To, timeout);

    while (1)
    {
        int Result = sigtimedwait(set, info, &To.Timeout);

        if (Result != -1)
            return Result;

        if (errno != EINTR)
            return Result;

        if (sigwrap_CheckTimeout(&To))
            return 0;
    }
}


int sigwrap_nanosleep(const struct timespec *req, struct timespec *rem)
{
    struct timespec Wait, Remain;

    if (!rem)
        rem = &Remain;

    Wait = *req;

    while (1)
    {
        if (nanosleep(&Wait, rem) == 0)
            return 0;

        if (errno != EINTR)
            return -1;

        Wait = *rem;
    }
}


int sigwrap_clock_nanosleep(clockid_t clock_id, int flags, const struct timespec *request, struct timespec *remain)
{
    struct timespec Wait, Remain;

    if (!remain)
        remain = &Remain;

    Wait = *request;

    while (1)
    {
        int Result = clock_nanosleep(clock_id, flags, &Wait, remain);
        
        if (Result == 0)
            return Result;

        if (Result != EINTR)
            return Result;

        if (flags != TIMER_ABSTIME)
            Wait = *remain;
    }
}


int sigwrap_usleep(useconds_t usec)
{
    SIGWRAP_TIMEOUT To;

    struct timespec Timeout;

    Timeout.tv_sec = usec / 1000000;
    Timeout.tv_nsec = (usec % 1000000) * 1000;

    sigwrap_InitTimeout(&To, &Timeout);

    while (1)
    {
        if (usleep(usec) == 0)
            return 0;

        if (errno != EINTR)
            return -1;

        if (sigwrap_CheckTimeout(&To))
            return 0;

        usec = To.Timeout.tv_sec * 1000000 + To.Timeout.tv_nsec / 1000;
    }
}


int sigwrap_poll(struct pollfd *fds, nfds_t nfds, int timeout)
{
    SIGWRAP_TIMEOUT To;

    if (timeout > 0)
    {
        struct timespec Timeout;

        Timeout.tv_sec = timeout / 1000;
        Timeout.tv_nsec = (timeout % 1000) * 1000000;

        sigwrap_InitTimeout(&To, &Timeout);
    }

    while (1)
    {
        int Result = poll(fds, nfds, timeout);

        if (Result != -1)
            return Result;

        if (errno != EINTR)
            return Result;

        if (timeout < 0) // Specifying a negative value in timeout means an infinite/no timeout. 
            continue;
        else if (timeout == 0)
            continue; // We want to make sure that at least one check was not aborted with EINTR

        if (sigwrap_CheckTimeout(&To))
            return 0;

        timeout = To.Timeout.tv_sec * 1000 + To.Timeout.tv_nsec / 1000000;
    }
}

#if 0
int sigwrap_ppoll(struct pollfd *fds, nfds_t nfds, const struct timespec *tmo_p, const sigset_t *sigmask)
{
    SIGWRAP_TIMEOUT To;

    if (tmo_p != NULL)
    {
        sigwrap_InitTimeout(&To, tmo_p);
        tmo_p = &To.Timeout;
    }

    while (1)
    {
        int Result = ppoll(fds, nfds, tmo_p, sigmask);

        if (Result != -1)
            return Result;

        if (errno != EINTR)
            return Result;

        if (tmo_p == NULL)
            continue;

        if (sigwrap_CheckTimeout(&To))
            return 0;
    }
}
#endif

int sigwrap_select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *timeout)
{
    while (1)
    {
        int Result = select(nfds, readfds, writefds, exceptfds, timeout);

        if (Result != -1)
            return Result;

        if (errno != EINTR)
            return Result;
    }
}


int sigwrap_pselect(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, const struct timespec *timeout,
                    const sigset_t *sigmask)
{
    SIGWRAP_TIMEOUT To;

    if (timeout != NULL)
    {
        sigwrap_InitTimeout(&To, timeout);
        timeout = &To.Timeout;
    }

    while (1)
    {
        int Result = pselect(nfds, readfds, writefds, exceptfds, timeout, sigmask);

        if (Result != -1)
            return Result;

        if (errno != EINTR)
            return Result;

        if (timeout == NULL)
            continue;

        if (sigwrap_CheckTimeout(&To))
            return 0;
    }
}


int sigwrap_msgsnd(int msqid, const void *msgp, size_t msgsz, int msgflg)
{
    while (1)
    {
        int Result = msgsnd(msqid, msgp, msgsz, msgflg);

        if (Result != -1)
            return Result;

        if (errno != EINTR)
            return Result;
    }
}


ssize_t sigwrap_msgrcv(int msqid, void *msgp, size_t msgsz, long msgtyp, int msgflg)
{
    while (1)
    {
        ssize_t Result = msgrcv(msqid, msgp, msgsz, msgtyp, msgflg);

        if (Result != -1)
            return Result;

        if (errno != EINTR)
            return Result;
    }
}


int sigwrap_connect(int sockfd, const struct sockaddr *addr, socklen_t addrlen)
{
    while (1)
    {
        int Result = connect(sockfd, addr, addrlen);

        if (Result != -1)
            return Result;

        if (errno != EINTR)
            return Result;
    }
}


ssize_t sigwrap_send(int sockfd, const void *buf, size_t len, int flags)
{
    while (1)
    {
        ssize_t Result = send(sockfd, buf, len, flags);

        if (Result != -1)
            return Result;

        if (errno != EINTR)
            return Result;
    }
}


ssize_t sigwrap_sendto(int sockfd, const void *buf, size_t len, int flags, const struct sockaddr *dest_addr,
                       socklen_t addrlen)
{
    while (1)
    {
        ssize_t Result = sendto(sockfd, buf, len, flags, dest_addr, addrlen);

        if (Result != -1)
            return Result;

        if (errno != EINTR)
            return Result;
    }
}


ssize_t sigwrap_sendsendmsg(int sockfd, const struct msghdr *msg, int flags)
{
    while (1)
    {
        ssize_t Result = sendmsg(sockfd, msg, flags);

        if (Result != -1)
            return Result;

        if (errno != EINTR)
            return Result;
    }
}


int sigwrap_accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen)
{
    while (1)
    {
        int Result = accept(sockfd, addr, addrlen);

        if (Result != -1)
            return Result;

        if (errno != EINTR)
            return Result;
    }
}

#if 0
int sigwrap_accept4(int sockfd, struct sockaddr *addr, socklen_t *addrlen, int flags)
{
    while (1)
    {
        int Result = accept4(sockfd, addr, addrlen, flags);

        if (Result != -1)
            return Result;

        if (errno != EINTR)
            return Result;
    }
}
#endif

// EINTR wrapper for the standard read() function. Can be used for sockets that are the to non-blocking mode.
// The length of the returned data can be shorter than the requested one!

ssize_t sigwrap_read(int fd, void *buf, size_t count)
{
    while (1)
    {
        ssize_t Result = read(fd, buf, count);

        if (Result != -1)
            return (Result);

        if (errno != EINTR)
            return (Result);
    }
}


// EINTR wrapper for the standard read() function. Waits until ALL requested data is available. Use the non-blocking version (sigwrap_read)
// for sockets that are set to non-blocking mode or when partial data is okay
// Although the description for the read() function describes it differently, it seems possible that the original function may already return
// even though partial data has already been read. This implementation makes sure that all requested data have been read.
// See the comment in the signal description https://linux.die.net/man/7/signal
//* read(2), readv(2), write(2), writev(2), and ioctl(2) calls on "slow" devices. 
//* A "slow" device is one where the I/O call may block for an indefinite time, for example, a terminal, pipe, or socket. 
//* (A disk is not a slow device according to this definition.) If an I/O call on a slow device has already transferred
//* some data by the time it is interrupted by a signal handler, then the call will return a success status (normally, the number of bytes transferred). 

ssize_t sigwrap_blocking_read(int hFile, void *pData, size_t RdLen)
{
    ssize_t Transfered;
    ssize_t Len = RdLen;

    while ((Transfered = read(hFile, pData, Len)) != Len)
    {
        if (Transfered == 0) // EOF reached?
            return 0;

        if (Transfered != -1)
        {
            pData += Transfered;
            Len -= Transfered;
            continue;
        }

        if (errno != EINTR)
            return -1;
    }

    return RdLen;
}


ssize_t sigwrap_readv(int fd, const struct iovec *iov, int iovcnt)
{
    while (1)
    {
        ssize_t Result = readv(fd, iov, iovcnt);

        if (Result != -1)
            return (Result);

        if (errno != EINTR)
            return (Result);
    }
}


ssize_t sigwrap_recv(int sockfd, void *buf, size_t len, int flags)
{
    while (1)
    {
        ssize_t Result = recv(sockfd, buf, len, flags);

        if (Result != -1)
            return (Result);

        if (errno != EINTR)
            return (Result);
    }
}


ssize_t sigwrap_recvfrom(int sockfd, void *buf, size_t len, int flags, struct sockaddr *src_addr, socklen_t *addrlen)
{
    while (1)
    {
        ssize_t Result = recvfrom(sockfd, buf, len, flags, src_addr, addrlen);

        if (Result != -1)
            return (Result);

        if (errno != EINTR)
            return (Result);
    }
}


ssize_t sigwrap_recvmsg(int sockfd, struct msghdr *msg, int flags)
{
    while (1)
    {
        ssize_t Result = recvmsg(sockfd, msg, flags);

        if (Result != -1)
            return (Result);

        if (errno != EINTR)
            return (Result);
    }
}


// EINTR wrapper for the standard write() function. Can be used for sockets that are the to non-blocking mode.
// The length of the effectively written data can be shorter than the length specified at the function call!

ssize_t sigwrap_write(int fd, const void *buf, size_t count)
{
    while (1)
    {
        ssize_t Result = write(fd, buf, count);

        if (Result != -1)
            return (Result);

        if (errno != EINTR)
            return (Result);
    }
}

// EINTR wrapper for the standard write() function. Waits until ALL data is written! Use the non-blocking version (sigwrap_write)
// for sockets that are set to non-blocking mode, or when it is OK to write only partial data.
// Although the description for the write() function describes it differently, it seems possible that the original function may already return
// even though partial data has already been written. This implementation makes sure that all requested data have been written.
// See the comment in the signal description https://linux.die.net/man/7/signal
//* read(2), readv(2), write(2), writev(2), and ioctl(2) calls on "slow" devices. 
//* A "slow" device is one where the I/O call may block for an indefinite time, for example, a terminal, pipe, or socket. 
//* (A disk is not a slow device according to this definition.) If an I/O call on a slow device has already transferred
//* some data by the time it is interrupted by a signal handler, then the call will return a success status (normally, the number of bytes transferred). 
        
ssize_t sigwrap_blocking_write(int hFile, const void *pData, ssize_t WrtLen)
{
    ssize_t Written;
    ssize_t Len = WrtLen;

    while ((Written = write(hFile, pData, Len)) != Len)
    {
        if (Written != -1)
        {
            pData += Written;
            Len -= Written;
            continue;
        }

        if (errno != EINTR)
            return -1;
    }

    return WrtLen;
}


ssize_t sigwrap_writev(int fd, const struct iovec *iov, int iovcnt)
{
    while (1)
    {
        ssize_t Result = writev(fd, iov, iovcnt);

        if (Result != -1)
            return (Result);

        if (errno != EINTR)
            return (Result);
    }
}


int sigwrap_close(int hFile)
{
    while (close(hFile) == -1)
    {
        if (errno != EINTR)
            return -1;
    }

    return 0;
}


int sigwrap_open_mode(const char *pathname, int flags, mode_t mode)
{
    while (1)
    {
        int hFile = open(pathname, flags, mode);
        
        if(hFile != -1)
            return hFile;
        
        if (errno != EINTR)
            return hFile;
    }
}

int sigwrap_open(const char *pathname, int flags)
{
    while (1)
    {
        int hFile = open(pathname, flags);
        
        if(hFile != -1)
            return hFile;
        
        if (errno != EINTR)
            return hFile;
    }
}


pid_t sigwrap_wait(int *status)
{
    while(1)
    {
        pid_t Result = wait(status);
        
        if(Result != -1)
            return Result;
        
        if(errno != EINTR)
            return Result;
    }
}


pid_t sigwrap_waitpid(pid_t pid, int *status, int options)
{
    while(1)
    {
        pid_t Result = waitpid(pid, status, options);
        
        if(Result != -1)
            return Result;
        
        if(errno != EINTR)
            return Result;
    }
}


int sigwrap_waitid(idtype_t idtype, id_t id, siginfo_t *infop, int options)
{
    while(1)
    {
        int Result = waitid(idtype, id, infop, options);
        
        if(Result != -1)
            return Result;
        
        if(errno != EINTR)
            return Result;
    }
}


int sigwrap_flock(int fd, int operation) 
{
    while(1)
    {
        int Result = flock(fd, operation);
        
        if(Result != -1)
            return Result;
        
        if(errno != EINTR)
            return Result;
    }
}