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 modification, are permitted provided that the following conditions are met:

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       this list of conditions and the following disclaimer.
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 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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*****************************************************************************/

#include "mp_shared_mem.h"

#if defined(__MINGW32__)

int
shm_destroy(struct shared_memory *sm, const int is_pri)
{
        (void) is_pri;
        sm->name = NULL;
        sm->size = 0;
        sm->ptr = NULL;
        return 0;
}

int
shm_create(struct shared_memory *sm, const int is_pri, const char *name, const size_t size,
           void *mmap_ptr)
{
        (void) is_pri;
        (void) mmap_ptr;
        sm->name = name;
        sm->size = size;
        sm->ptr = NULL;
        return 0;
}

#else

#if defined(__linux__) || defined(__FreeBSD__)
#include <sys/mman.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#endif

#ifdef _WIN32
/*
 * Disable C5105 to workaround warning coming from winbase.h file
 * "Windows Kits\10\include\10.0.19041.0\um\winbase.h(9531): warning
 * C5105: macro expansion producing 'defined' has undefined behavior"
 */
#pragma warning(disable : 5105)

#include <stdint.h>
#include <stdio.h>
#include <windows.h>
#endif

/*
 * =============================================================================
 * =============================================================================
 * Linux & FreeBSD: Shared memory create and destroy
 */

#if defined(__FreeBSD__) || defined(__linux__)
int
shm_destroy(struct shared_memory *sm, const int is_pri)
{
        int ret = 0;

        if (!is_pri)
                if (munmap(sm->ptr, sm->size) != 0) {
                        perror("shm_destroy()");
                        ret = -1;
                }
        sm->ptr = NULL;

        if (is_pri)
                if (shm_unlink(sm->name) != 0) {
                        perror("shm_destroy()");
                        ret = -1;
                }

        sm->name = NULL;
        sm->size = 0;
        return ret;
}

int
shm_create(struct shared_memory *sm, const int is_pri, const char *name, const size_t size,
           void *mmap_ptr)
{
        int fd = -1;

        sm->name = name;
        sm->size = size;
        sm->ptr = MAP_FAILED;

        /* create the shared memory object */
        if (is_pri) {
                fd = shm_open(sm->name, O_RDWR, 0666);
                if (fd != -1) {
                        printf("shm_open(): %s already exists!\n", sm->name);
                        close(fd);
                        return -1;
                }
                fd = shm_open(sm->name, O_CREAT | O_RDWR, 0666);
        } else {
                fd = shm_open(sm->name, O_RDWR, 0666);
        }

        if (fd == -1) {
                perror("shm_create()");
                return -1;
        }

        /* configure the size of the shared memory object */
        if (is_pri) {
                if (ftruncate(fd, sm->size) != 0) {
                        perror("shm_create()");
                        (void) shm_destroy(sm, is_pri);
                        close(fd);
                        return -1;
                }
        }

        /*
         * memory map the shared memory object
         * - secondary process maps shared memory into the same region as the primary process
         */
        if (is_pri) {
#ifdef __FreeBSD__
                static char *base = (char *) 0x900000000; /* arbitrary VA to start mapping from */
                const size_t page_sz = (size_t) (getpagesize() - 1);

                sm->ptr = mmap((void *) base, sm->size, PROT_READ | PROT_WRITE,
                               MAP_FIXED | MAP_PREFAULT_READ | MAP_SHARED, fd, 0);
                base += ((sm->size + page_sz) & (~page_sz));
#else
                sm->ptr = mmap(0, sm->size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
#endif
        } else {
                if (mmap_ptr == NULL) {
#ifdef __FreeBSD__
                        const int flags = MAP_PREFAULT_READ | MAP_SHARED;
#else
                        const int flags = MAP_SHARED;
#endif

                        sm->ptr = mmap(NULL, sm->size, PROT_READ | PROT_WRITE, flags, fd, 0);
                } else {
#ifdef __FreeBSD__
                        const int flags = MAP_PREFAULT_READ | MAP_SHARED | MAP_FIXED;
#else
                        const int flags = MAP_SHARED | MAP_FIXED;
#endif

                        sm->ptr = mmap(mmap_ptr, sm->size, PROT_READ | PROT_WRITE, flags, fd, 0);
                        if (mmap_ptr != sm->ptr) {
                                printf("mmap() %p != mmap_ptr %p\n", sm->ptr, mmap_ptr);
                                (void) shm_destroy(sm, is_pri);
                                return -1;
                        }
                }
        }

        close(fd);

        if (sm->ptr == MAP_FAILED) {
                perror("shm_create()");
                fprintf(stderr, "!mmap() of %s shared memory error\n", sm->name);
                (void) shm_destroy(sm, is_pri);
                return -1;
        }

        return 0;
}
#endif /* __linux__ || __FreeBSD__ */

/*
 * =============================================================================
 * =============================================================================
 * Windows: Shared memory create and destroy
 */

#ifdef _WIN32
static void
printLastError(const DWORD error)
{
        LPSTR message = NULL;

        FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM |
                               FORMAT_MESSAGE_IGNORE_INSERTS,
                       NULL, error, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), (LPSTR) &message, 0,
                       NULL);

        if (message) {
                fprintf(stderr, "ERROR: %s\n", message);
                LocalFree(message);
        }
}

int
shm_destroy(struct shared_memory *sm, const int is_pri)
{
        int ret = 0;

        if (sm->ptr != NULL)
                UnmapViewOfFile(sm->ptr);

        if (sm->fd != INVALID_HANDLE_VALUE)
                CloseHandle(sm->fd);

        sm->ptr = NULL;
        sm->name = NULL;
        sm->size = 0;
        sm->fd = INVALID_HANDLE_VALUE;
        return ret;
}

int
shm_create(struct shared_memory *sm, const int is_pri, const TCHAR *name, const size_t size,
           void *mmap_ptr)
{
        static char *base = NULL;
        static SYSTEM_INFO si;

        if (base == NULL) {
                GetSystemInfo(&si);

                const size_t allocMask = si.dwAllocationGranularity - 1;
                const uintptr_t new_base = (uintptr_t) si.lpMaximumApplicationAddress;

                /* align base mapping address to allocation granularity */
                base = (char *) (new_base & (~allocMask));
        }

        HANDLE fd = INVALID_HANDLE_VALUE;

        sm->name = name;
        sm->size = size;
        sm->ptr = NULL;
        sm->fd = INVALID_HANDLE_VALUE;

        if (is_pri) {
                fd = CreateFileMappingA((HANDLE) INVALID_HANDLE_VALUE, /* Use the page file */
                                        NULL, PAGE_READWRITE, 0, (DWORD) sm->size, sm->name);
        } else {
                fd = OpenFileMappingA(FILE_MAP_ALL_ACCESS, FALSE, sm->name);
        }

        if (fd == INVALID_HANDLE_VALUE) {
                fprintf(stderr, "ERROR: %s failed to create shared memory object (%d)\n", sm->name,
                        GetLastError());
                printLastError(GetLastError());
                return -1;
        }

        /* Map the shared memory object into the address space of the current process */
        if (is_pri) {
                const size_t allocMask = si.dwAllocationGranularity - 1;
                const size_t allocAlignedSize = (size + allocMask) & (~allocMask);

                /* adjust mapping address to allocation size (aligned to allocation granularity) */
                base = base - allocAlignedSize;

                sm->ptr = (void *) MapViewOfFileEx(fd, FILE_MAP_ALL_ACCESS, /* Read/write access */
                                                   0, 0,                    /* offset = 0 */
                                                   0 /* map all object */, (LPVOID) base);

                if (sm->ptr != (void *) base) {
                        fprintf(stderr, "!mmap(%p) = %p %s shared memory error\n", base, sm->ptr,
                                sm->name);
                        printLastError(GetLastError());
                        (void) shm_destroy(sm, is_pri);
                        return -1;
                }
        } else {
                sm->ptr = (void *) MapViewOfFileEx(fd, FILE_MAP_ALL_ACCESS, /* Read/write access */
                                                   0, 0,                    /* Offset = 0 */
                                                   0 /* map all object */, (LPVOID) mmap_ptr);
                if ((mmap_ptr != NULL) && (sm->ptr != mmap_ptr)) {
                        fprintf(stderr, "!mmap(%p) = %p %s shared memory error\n", mmap_ptr,
                                sm->ptr, sm->name);
                        printLastError(GetLastError());
                        (void) shm_destroy(sm, is_pri);
                        return -1;
                }
        }

        if (sm->ptr == NULL) {
                fprintf(stderr, "ERROR: %s failed to map view of shared memory (%d)\n", sm->name,
                        GetLastError());
                printLastError(GetLastError());
                (void) shm_destroy(sm, is_pri);
                return -1;
        }

        sm->fd = fd;
        return 0;
}
#endif

#endif /* _WIN32 || __linux__ || __FreeBSD__ */