src/platform/shm.c

#include "platform/shm.h"
 
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <sys/mman.h>
#include <unistd.h>
 
int shm_alloc(size_t size, void **outMapped)
{
    if (size == 0 || !outMapped)
        return -1;
 
    int fileDescriptor = -1;
#ifdef __linux__
    fileDescriptor = memfd_create("terminal-shm", MFD_CLOEXEC);
#endif
    if (fileDescriptor < 0) {
        char name[64];
        snprintf(name, sizeof(name), "/terminal-shm-%d", (int)getpid());
        fileDescriptor = shm_open(name, O_RDWR | O_CREAT | O_EXCL, 0600);
        if (fileDescriptor >= 0)
            shm_unlink(name);
    }
    if (fileDescriptor < 0)
        return -1;
 
    if (ftruncate(fileDescriptor, (off_t)size) < 0) {
        close(fileDescriptor);
        return -1;
    }
 
    void *mapped = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fileDescriptor, 0);
    if (mapped == MAP_FAILED) {
        close(fileDescriptor);
        return -1;
    }
 
    memset(mapped, 0, size);
    *outMapped = mapped;
    return fileDescriptor;
}
 
void shm_free(int fileDescriptor, void *mapped, size_t size)
{
    if (mapped && mapped != MAP_FAILED)
        munmap(mapped, size);
    if (fileDescriptor >= 0)
        close(fileDescriptor);
}