一、bootable/recovery/common.h文件，有如下定义：
#ifndef RECOVERY_COMMON_H
#define RECOVERY_COMMON_H#include <stdio.h>
#include <stdarg.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdbool.h>#ifdef __cplusplus
extern "C" {
#endif// TODO: restore ui_print for LOGE
#define LOGE(...) fprintf(stdout, "E:" __VA_ARGS__)
#define LOGW(...) fprintf(stdout, "W:" __VA_ARGS__)
#define LOGI(...) fprintf(stdout, "I:" __VA_ARGS__)#if 0
#define LOGV(...) fprintf(stdout, "V:" __VA_ARGS__)
#define LOGD(...) fprintf(stdout, "D:" __VA_ARGS__)
#else
#define LOGV(...) do {} while (0)
#define LOGD(...) do {} while (0)
#endif#define STRINGIFY(x) #x
#define EXPAND(x) STRINGIFY(x)１、都是定义的宏；
typedef struct {const char* mount_point; // eg. "/cache". must live in the root directory.const char* fs_type; // "yaffs2" or "ext4" or "vfat"const char* device; // MTD partition name if fs_type == "yaffs"// block device if fs_type == "ext4" or "vfat"const char* device2; // alternative device to try if fs_type// == "ext4" or "vfat" and mounting// 'device' failslong long length; // (ext4 partition only) when// formatting, size to use for the// partition. 0 or negative number// means to format all but the last// (that much).
} Volume;２、定义一个结构体，名为Volume，有挂载点，文件类型，设备， 设备２，长度；//typedef struct fstab_rec Volume;
// fopen a file, mounting volumes and making parent dirs as necessary.
FILE* fopen_path(const char *path, const char *mode);void ui_print(const char* format, ...);bool is_support_gpt(void);３、打开一个路径文件，和ui的打印，以及是否支持gpt
#define PRELOADER_PART "/dev/block/mmcblk0boot0"
#define BOOT_PART "/dev/block/platform/mtk-msdc.0/by-name/boot"
#define CACHE_PART "/dev/block/platform/mtk-msdc.0/by-name/cache"
#define FAT_PART "/dev/block/platform/mtk-msdc.0/by-name/intsd"
#define SYSTEM_PART "/dev/block/platform/mtk-msdc.0/by-name/system"
#define DATA_PART "/dev/block/platform/mtk-msdc.0/by-name/userdata"
#define MISC_PART "/dev/block/platform/mtk-msdc.0/by-name/para"
#define RECOVERY_PART "/dev/block/platform/mtk-msdc.0/by-name/recovery"
#define CUSTOM_PART "/dev/block/platform/mtk-msdc.0/by-name/custom"
#define VENDOR_PART "/dev/block/platform/mtk-msdc.0/by-name/vendor"
#define LOGO_PART "/dev/block/platform/mtk-msdc.0/by-name/logo"
#define LK_PART "/dev/block/platform/mtk-msdc.0/by-name/lk"
#define TEE1_PART "/dev/block/platform/mtk-msdc.0/by-name/tee1"
#define TEE2_PART "/dev/block/platform/mtk-msdc.0/by-name/tee2"
#define PERSIST_PART "/dev/block/platform/mtk-msdc.0/by-name/persist"
#define NVDATA_PART "/dev/block/platform/mtk-msdc.0/by-name/nvdata"static inline bool support_gpt(void) {\int fd = open(MISC_PART, O_RDONLY);\if (fd == -1) {\return false;\} else {\close(fd);\return true;\}\
}4、这个上面也都是定义的宏，供其他文件调用的；
二、分析bootable/recovery/roots.cpp文件；
１、这里有很多引用的.h文件；
#if defined(CACHE_MERGE_SUPPORT)
#include <dirent.h>
#include "backup_restore.h"static int need_clear_cache = 0;
static const char *DATA_CACHE_ROOT = "/data/.cache";#ifndef PATH_MAX
#define PATH_MAX 4096
#endif
static int remove_dir(const char *dirname)
{DIR *dir;struct dirent *entry;char path[PATH_MAX];dir = opendir(dirname);if (dir == NULL) {LOGE("opendir %s failed\n", dirname);return -1;}while ((entry = readdir(dir)) != NULL) {if (strcmp(entry->d_name, ".") && strcmp(entry->d_name, "..")) {snprintf(path, (size_t) PATH_MAX, "%s/%s", dirname, entry->d_name);if (entry->d_type == DT_DIR) {remove_dir(path);} else {// delete fileunlink(path);}}}closedir(dir);// now we can delete the empty dirrmdir(dirname);return 0;
}
#endif２、这个删除目录的方法，涉及到很多的内容需要学习的，比如很多的DIR结构体，opendir方法怎么打开文件夹的，来看下这个DIR结构体：
struct __dirstream
{
void *__fd; /* `struct hurd_fd' pointer for descriptor. */
char *__data; /* Directory block. */
int __entry_data; /* Entry number `__data' corresponds to. */
char *__ptr; /* Current pointer into the block. */
int __entry_ptr; /* Entry number `__ptr' corresponds to. */
size_t __allocation; /* Space allocated for the block. */
size_t __size; /* Total valid data in the block. */
__libc_lock_define (, __lock) /* Mutex lock for this structure. */
};typedef struct __dirstream DIR;３、就是这样定义的一个DIR,还有一个dirent结构体：
struct dirent
{long d_ino; /* inode number 索引节点号 */off_t d_off; /* offset to this dirent 在目录文件中的偏移 */unsigned short d_reclen; /* length of this d_name 文件名长 */unsigned char d_type; /* the type of d_name 文件类型 */char d_name [NAME_MAX+1]; /* file name (null-terminated) 文件名，最长255字符 */
}