嵌入式linux文件复制程序

方式一：fgetc fputs 实现

#include <stdio.h>
#include <stdlib.h>


int main(int argc, char **argv)
{
  if (argc != 3)
  {
    fprintf(stderr, "%s <srcfile> <dstfile>\n", argv[0]);
    exit(-1);
  }

  char *srcfile = argv[1];
  char *dstfile =argv[2];

  FILE *srcfp = fopen(srcfile, "r");
  if (NULL == srcfp)
  {
    perror("can't open srcfile");
    exit(-1);
  }

  FILE *dstfp = fopen(dstfile, "w");
  if (NULL == dstfp)
  {
    perror("can't open or create dstfile");
    fclose(srcfp);
    exit(-1);
  }

  char ch;
  while ((ch = fgetc(srcfp)) != EOF)
  {
    fputc(ch, dstfp);
  }

  fclose(srcfp);
  fclose(dstfp);

  return 0;
}

方式二：fgets fputs 实现

#include <stdio.h>
#include <stdlib.h>

#define BUFFER_SIZE 1024

int main(int argc, char **argv)
{
  if (argc != 3)
  {
    fprintf(stderr, "%s <srcfile> <dstfile>\n", argv[0]);
    exit(-1);
  }

  char *srcfile = argv[1];
  char *dstfile =argv[2];

  FILE *srcfp = fopen(srcfile, "r");
  if (NULL == srcfp)
  {
    perror("can't open srcfile");
    exit(-1);
  }

  FILE *dstfp = fopen(dstfile, "w");
  if (NULL == dstfp)
  {
    perror("can't open or create dstfile");
    fclose(srcfp);
    exit(-1);
  }

  char buf[BUFFER_SIZE];
  while (fgets(buf, sizeof(buf), srcfp) != NULL)
  {
    fputs(buf, dstfp);
  }

  fclose(srcfp);
  fclose(dstfp);

  return 0;
}

方式三：fread fwrite 实现

#include <stdio.h>
#include <stdlib.h>

#define BUFFER_SIZE 1024

int main(int argc, char **argv)
{
  if (argc != 3)
  {
    fprintf(stderr, "%s <srcfile> <dstfile>\n", argv[0]);
    exit(-1);
  }

  char *srcfile = argv[1];
  char *dstfile =argv[2];

  FILE *srcfp = fopen(srcfile, "r");
  if (NULL == srcfp)
  {
    perror("can't open srcfile");
    exit(-1);
  }

  FILE *dstfp = fopen(dstfile, "w");
  if (NULL == dstfp)
  {
    perror("can't open or create dstfile");
    fclose(srcfp);
    exit(-1);
  }

  char buf[BUFFER_SIZE];
  int ret;
  while ((ret = fread(buf, sizeof(char), BUFFER_SIZE, srcfp)) != 0)
  {
    fwrite(buf, sizeof(char), ret, dstfp);
  }

  fclose(srcfp);
  fclose(dstfp);

  return 0;
}

方式四：read write 实现

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

#define BUFFER_SIZE 1024

ssize_t mywrite(int fd, const void *buf, size_t count);

ssize_t mywrite(int fd, const void *buf, size_t count)
{

  int ret;
  int num_written = 0;

  while(1)
  {
    ret = write(fd, buf + num_written, count);

    if (ret == -1)
    {
      return -1;
    }
    else if (ret == count)
    {
      return num_written + ret;
    }

    num_written += ret;
    count -= ret;
  }
}

int main(int argc, char **argv)
{
  if (argc != 3)
  {
    fprintf(stderr, "%s <srcfile> <dstfile>\n", argv[0]);
    exit(-1);
  }

  char *srcfile = argv[1];
  char *dstfile =argv[2];

  int srcfd = open(srcfile, O_RDONLY);
  if (-1 == srcfd)
  {
    perror("can't open srcfile");
    exit(-1);
  }

  int dstfd = open(dstfile, O_WRONLY | O_CREAT, 0644);
  if (-1 == dstfd)
  {
    perror("can't open or create dstfile");
    close(srcfd);
    exit(-1);
  }

  char buf[BUFFER_SIZE];
  int ret;
  while (1)
  {
    ret = read(srcfd, buf, sizeof(buf));

    if (ret == -1)
    {
      return -1;
    }
    else if (ret == 0)
    {
      break;
    }

    ret = mywrite(dstfd, buf, ret);
  }

  close(srcfd);
  close(dstfd);

  return 0;
}