Android6.0支持exfat格式内存卡补丁

需求

Android6.0支持exfat格式内存卡.

需要修改的内容

1、kenel；
2、external\e2fsprogs\lib\blkid
3、system\vold

具体修改步骤

1、kernel部分移植的是github上的。链接：https://github.com/dorimanx/exfat-nofuse
2、
external\e2fsprogs\lib\blkid修改内容如下:

diff --git a/lib/blkid/Android.mk b/lib/blkid/Android.mk
index 2fe8f42..9710cf6 100755
--- a/lib/blkid/Android.mk
+++ b/lib/blkid/Android.mk
@@ -8,6 +8,7 @@ libext2_blkid_src_files := \
        getsize.c \
        llseek.c \
        probe.c \
+       probe_exfat.c \
        read.c \
        resolve.c \
        save.c \
@@ -18,7 +19,8 @@ libext2_blkid_src_files := \
 libext2_blkid_shared_libraries := libext2_uuid

 libext2_blkid_system_shared_libraries := libc
-
+libext2_blkid_static_libraries := libext2_uuid_static
+libext2_blkid_system_static_libraries := libc
 libext2_blkid_c_includes := external/e2fsprogs/lib

 libext2_blkid_cflags := -O2 -g -W -Wall -fno-strict-aliasing \
@@ -63,14 +65,12 @@ include $(BUILD_SHARED_LIBRARY)

 include $(CLEAR_VARS)

-LOCAL_STATIC_LIBRARIES := \
-        $(libext2_blkid_system_shared_libraries) \
-        $(libext2_blkid_shared_libraries)
+

 LOCAL_SRC_FILES := $(libext2_blkid_src_files)
+LOCAL_STATIC_LIBRARIES := $(libext2_blkid_static_libraries) $(libext2_blkid_system_static_libraries)
 LOCAL_C_INCLUDES := $(libext2_blkid_c_includes)
 LOCAL_CFLAGS := $(libext2_blkid_cflags) $(libext2_blkid_cflags_linux) -fno-strict-aliasing
-LOCAL_PRELINK_MODULE := true
 LOCAL_MODULE := libext2_blkid
 LOCAL_MODULE_TAGS := optional

diff --git a/lib/blkid/probe.c b/lib/blkid/probe.c
old mode 100644
new mode 100755
index 8215768..0617cf1
--- a/lib/blkid/probe.c
+++ b/lib/blkid/probe.c
@@ -36,6 +36,11 @@
 #include "uuid/uuid.h"
 #include "probe.h"

+extern int probe_exfat(struct blkid_probe *probe,
+       struct blkid_magic *id __BLKID_ATTR((unused)),
+       unsigned char *buf);
+
+
 static int figure_label_len(const unsigned char *label, int len)
 {
        const unsigned char *end = label + len - 1;
@@ -84,7 +89,11 @@ static unsigned char *get_buffer(struct blkid_probe *pr,
                return pr->buf;
        }
 }
-
+unsigned char *blkid_probe_get_buffer(struct blkid_probe *pr,
+                blkid_loff_t off, size_t len)
+{
+        return get_buffer(pr, off, len);
+}

 /*
  * This is a special case code to check for an MDRAID device.  We do
@@ -766,14 +775,41 @@ static int probe_ntfs(struct blkid_probe *probe,
                if (attr_type == MFT_RECORD_ATTR_VOLUME_NAME) {
                        if (val_len > sizeof(label_str))
                                val_len = sizeof(label_str)-1;
-
+/* $_rbox_$_modify_$_huangyonglin: added for mass storage mounting  2012-03-31 */
+#if 0
                        for (i=0, cp=label_str; i < val_len; i+=2,cp++) {
                                val = ((__u8 *) attr) + val_off + i;
                                *cp = val[0];
                                if (val[1])
                                        *cp = '?';
                        }
-                       *cp = 0;
+#else
+            for (i=0, cp=label_str; i < val_len;i+=2,cp++) {
+                __u16 *pval = ((__u8 *) attr) + val_off + i;
+                __u16 val_temp= *pval;
+                 if (val_temp >= 0x00 && val_temp <= 0x7f)
+                 {
+                               val = ((__u8 *) attr) + val_off + i;
+                    *cp =val[0];
+                 }
+                 else if (val_temp >= 0x0080 && val_temp <= 0x07ff)
+                 {
+                    *cp =((val_temp >> 6) & 0x1F) | 0xC0;
+                    cp++;
+                     *cp =(val_temp & 0x3F) | 0x80; ;
+                 }
+                 else if (val_temp >= 0x0800 && val_temp <= 0xffff)
+                 {
+                    *cp = ((val_temp >> 12) & 0x0F) | 0xE0; //0xe0 | (val_temp >> 12);
+                    cp++;
+                    *cp =  ((val_temp >> 6) & 0x3F) | 0x80; //0x80 | (val_temp >> 6 & 0x00ff);
+                    cp++;
+                    *cp =  (val_temp & 0x3F) | 0x80;//0x80 | (val_temp & (0xff >> 2));
+                 }
+            }
+            *cp =0;
+#endif
+/*$_rbox_$_modify_$_end*/
                }
        }

@@ -1428,6 +1464,7 @@ static struct blkid_magic type_array[] = {
   { "vfat",      0,      0,  1, "\353",                 probe_fat_nomagic },
   { "vfat",      0,      0,  1, "\351",                 probe_fat_nomagic },
   { "vfat",      0,  0x1fe,  2, "\125\252",             probe_fat_nomagic },
+  { "exfat",     0,      3,  8, "EXFAT   ",         probe_exfat },
   { "minix",     1,   0x10,  2, "\177\023",             0 },
   { "minix",     1,   0x10,  2, "\217\023",             0 },
   { "minix",    1,   0x10,  2, "\150\044",             0 },

3、vold修改如下：
添加Exfat.cpp和Exfat.h，这个应该系统里面默认有的。

总结

修改完三个部分，烧录kernel，放入libext2_blkid.so和vold就可以了。
附录整个补丁文件：https://download.csdn.net/download/arunboy/12354240
参考文档:https://blog.csdn.net/huolinliang/article/details/86589976