Plasma Note

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int flag = 0;
plasma_contains(conn, id, &flag);
if (flag)
  plasma_delete(conn, id);

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/* Create a buffer. This is creating a temporary file and then
 * immediately unlinking it so we do not leave traces in the system. */
int create_buffer(int64_t size) {
  static char template[] = "/tmp/plasmaXXXXXX";
  char file_name[32];
  strncpy(file_name, template, 32);
  int fd = mkstemp(file_name);
  if (fd < 0)
    return -1;
  FILE *file = fdopen(fd, "a+");
  if (!file) {
    close(fd);
    return -1;
  }
  if (unlink(file_name) != 0) {
    LOG_ERR("unlink error");
    return -1;
  }
  if (ftruncate(fd, (off_t) size) != 0) {
    LOG_ERR("ftruncate error");
    return -1;
  }
  return fd;
}

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#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/types.h>
#include <unistd.h>

int main()
{
  char buf[20] = {0};
  int fd = open("test.txt", O_WRONLY | O_CREAT, 0640);
  // pread(fd,buf,5,2); //10表示要读的字节数,2表示偏移量
  // printf("buf=%s\n",buf);

  char str[10] = "12345";
  // pwrite(fd,str,3,5);//3表示要写入的字节数，2表示偏移量

  close(fd);
  return 0;
}