124 lines
2.5 KiB
C
124 lines
2.5 KiB
C
/*
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* 代码清单：文件读写例子
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*
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* 这个例子演示了如何读写一个文件，特别是写的时候应该如何操作。
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*/
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#include <rtthread.h>
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#include <dfs_posix.h> /* 当需要使用文件操作时，需要包含这个头文件 */
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#define TEST_FN "/test.dat"
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/* 测试用的数据和缓冲 */
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static char test_data[120], buffer[120];
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/* 文件读写测试 */
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void readwrite(const char* filename)
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{
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int fd;
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int index, length;
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/* 只写 & 创建 打开 */
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fd = open(TEST_FN, O_WRONLY | O_CREAT | O_TRUNC, 0);
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if (fd < 0)
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{
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rt_kprintf("open file for write failed\n");
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return;
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}
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/* 准备写入数据 */
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for (index = 0; index < sizeof(test_data); index ++)
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{
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test_data[index] = index + 27;
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}
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/* 写入数据 */
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length = write(fd, test_data, sizeof(test_data));
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if (length != sizeof(test_data))
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{
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rt_kprintf("write data failed\n");
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close(fd);
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return;
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}
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/* 关闭文件 */
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close(fd);
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/* 只写并在末尾添加打开 */
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fd = open(TEST_FN, O_WRONLY | O_CREAT | O_APPEND, 0);
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if (fd < 0)
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{
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rt_kprintf("open file for append write failed\n");
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return;
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}
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length = write(fd, test_data, sizeof(test_data));
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if (length != sizeof(test_data))
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{
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rt_kprintf("append write data failed\n");
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close(fd);
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return;
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}
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/* 关闭文件 */
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close(fd);
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/* 只读打开进行数据校验 */
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fd = open(TEST_FN, O_RDONLY, 0);
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if (fd < 0)
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{
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rt_kprintf("check: open file for read failed\n");
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return;
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}
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/* 读取数据(应该为第一次写入的数据) */
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length = read(fd, buffer, sizeof(buffer));
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if (length != sizeof(buffer))
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{
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rt_kprintf("check: read file failed\n");
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close(fd);
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return;
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}
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/* 检查数据是否正确 */
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for (index = 0; index < sizeof(test_data); index ++)
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{
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if (test_data[index] != buffer[index])
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{
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rt_kprintf("check: check data failed at %d\n", index);
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close(fd);
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return;
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}
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}
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/* 读取数据(应该为第二次写入的数据) */
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length = read(fd, buffer, sizeof(buffer));
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if (length != sizeof(buffer))
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{
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rt_kprintf("check: read file failed\n");
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close(fd);
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return;
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}
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/* 检查数据是否正确 */
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for (index = 0; index < sizeof(test_data); index ++)
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{
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if (test_data[index] != buffer[index])
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{
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rt_kprintf("check: check data failed at %d\n", index);
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close(fd);
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return;
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}
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}
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/* 检查数据完毕，关闭文件 */
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close(fd);
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/* 打印结果 */
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rt_kprintf("read/write done.\n");
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}
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#ifdef RT_USING_FINSH
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#include <finsh.h>
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/* 输出函数到finsh shell命令行中 */
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FINSH_FUNCTION_EXPORT(readwrite, perform file read and write test);
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#endif
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