自定义getMode --- 将mode_t 转换为相应的字符串

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/* * getMode.c * *  Created on: 2011-11-15 *      Author: snape */#include <stdio.h>#include <fcntl.h>#include <sys/types.h>#include <string.h>/* * mode_t 是一个八进制数 * 0777 ---- 111 111 111 * S_IRUSR 代表 100 000 000 * mode_t & S_IRUSR 返回1 说明 具有该权限，返回0 说明不具有 * */int main(int argc, char **argv) {char *getMode(mode_t, char *);int mode = 0666;char buf[9];fprintf(stderr, "mode %d presents %s\n", mode, getMode(mode, buf));return 0;}char * getMode(mode_t mode, char *buf) {if (buf == NULL) {fprintf(stderr, "buf can't be NULL\n");return NULL;}memset(buf, '-', 9);if (mode & S_IRUSR)buf[0] = 'r';if (mode & S_IWUSR)buf[1] = 'w';if (mode & S_IXUSR)buf[2] = 'x';if (mode & S_IRGRP)buf[3] = 'r';if (mode & S_IWGRP)buf[4] = 'w';if (mode & S_IXGRP)buf[5] = 'x';if (mode & S_IROTH)buf[6] = 'r';if (mode & S_IWOTH)buf[7] = 'w';if (mode & S_IXOTH)buf[8] = 'x';buf[9] = NULL;return buf;}