/*
This is a personal academic project. Dear PVS-Studio, please check it.
PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com
*/
#define _SVID_SOURCE 1
#define _POSIX_C_SOURCE 200112L

#include <sys/shm.h>
#include <semaphore.h>
#include <fcntl.h>
#include <string.h>
#include "error.h"
#include <sys/mman.h>
#include <sys/stat.h>
#include <unistd.h>
#include "shr_mem.h"

sem_t * semEmpty = NULL;
sem_t * semOpen = NULL;

void openSem(char * semName, sem_t ** sem) {
    if (* sem == NULL) {
        if ((* sem = sem_open(semName, O_CREAT | O_RDWR, S_IRWXU, 0)) == SEM_FAILED)
            printSystemError("sem_open() -- ERROR");
    }
}

void closeSem(char * semName, sem_t ** sem) {
    if (sem_close(* sem) < 0)
        printSystemError("sem_close() -- ERROR");
    if (sem_unlink(semName) < 0)
        printSystemError("sem_unlink() -- ERROR");
}

int createShm(int totalSize) {
    openSem(SEM_OPEN_NAME, &semOpen);

    int fd;
    if ((fd = shm_open(SHM_NAME, O_CREAT | O_RDWR, S_IRWXU)) < 0)
        printSystemError("shm_open() -- ERROR");
    ftruncate(fd, totalSize);

    if (sem_post(semOpen) < 0)
        printSystemError("sem_post() --  ERROR");
    return fd;
}

void mapShm(char ** shmPointer, int totalSize, int fd) {
    if ((* shmPointer = mmap(0, totalSize, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0)) == MAP_FAILED)
        printSystemError("mmap() -- ERROR");
}

void writeShm(char * shmPointer, char * str, int len) {
    openSem(SEM_EMPTY_NAME, &semEmpty);

    if (memcpy(shmPointer, str, len) == NULL)
        printError("memcpy() -- ERROR");

    if (sem_post(semEmpty) < 0)
        printSystemError("sem_post() --  ERROR");
}

void terminateShm(const char * name, int fd, char * shmPointer, int totalSize) {
    if (munmap(shmPointer, totalSize) == -1)
        printSystemError("munmap() -- ERROR");
    if (shm_unlink(name) == -1)
        printSystemError("shm_unlink() -- ERROR");
    if (close(fd) == -1)
        printSystemError("close() -- ERROR");
    closeSem(SEM_OPEN_NAME, &semOpen);
    closeSem(SEM_EMPTY_NAME, &semEmpty);
}

int copyShm(char * destPointer, char * srcPointer, int len) {
    int i;
    for (i = 0; i < len && srcPointer[i] != '\n' && srcPointer[i] != '\0'; i++) {
        destPointer[i] = srcPointer[i];
    }
    destPointer[i++] = '\0';

    return i;
}

int readShm(char * shmPointer, char * str, int len) {
    openSem(SEM_EMPTY_NAME, &semEmpty);

    if (sem_wait(semEmpty) < 0)
        printSystemError("sem_wait() -- ERROR");

    return copyShm(str, shmPointer, len);
}

int openCreatedShm(char ** shmPointer, int totalSize) {
    openSem(SEM_OPEN_NAME, &semOpen);
    if (sem_wait(semOpen) < 0)
        printSystemError("sem_wait() -- ERROR");

    int fd;
    if ((fd = shm_open(SHM_NAME, O_RDONLY, S_IRUSR)) < 0)
        printSystemError("shm_open() -- ERROR");

    if ((* shmPointer = mmap(0, totalSize, PROT_READ, MAP_SHARED, fd, 0)) == MAP_FAILED){
        printSystemError("mmap() -- ERROR");
    }

    return fd;
}

void closeCreatedShm(char * shmPointer, int totalSize, int fd) {
    if (munmap(shmPointer, totalSize) == -1)
        printSystemError("munmap() -- ERROR");
    if (close(fd) < 0)
        printSystemError("close() -- ERROR");
    closeSem(SEM_EMPTY_NAME, &semEmpty);
    closeSem(SEM_OPEN_NAME, &semOpen);
}