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Commit 57bed6d8 authored by Tianjie Xu's avatar Tianjie Xu
Browse files

updater: Add a function to check first block 

Add and register a function to check if the device has been remounted
since last update during incremental OTA. This function reads block 0
and executes before partition recovery for version >= 4.

Bug: 21124327
Change-Id: I8b915b9f1d4736b3609daa9d16bd123225be357f
(cherry picked from commit 30bf4765)
parent 8e150a5b

updater/blockimg.cpp

+55 −0
Original line number Diff line number Diff line
@@ -42,6 +42,7 @@ 


#include "applypatch/applypatch.h"

#include "edify/expr.h"

#include "install.h"

#include "mincrypt/sha.h"

#include "minzip/Hash.h"

#include "print_sha1.h"
@@ -1650,6 +1651,59 @@ Value* RangeSha1Fn(const char* name, State* state, int /* argc */, Expr* argv[]) 
    return StringValue(strdup(print_sha1(digest).c_str()));

}



// This function checks if a device has been remounted R/W prior to an incremental

// OTA update. This is an common cause of update abortion. The function reads the

// 1st block of each partition and check for mounting time/count. It return string "t"

// if executes successfully and an empty string otherwise.



Value* CheckFirstBlockFn(const char* name, State* state, int argc, Expr* argv[]) {

    Value* arg_filename;



    if (ReadValueArgs(state, argv, 1, &arg_filename) < 0) {

        return nullptr;

    }

    std::unique_ptr<Value, decltype(&FreeValue)> filename(arg_filename, FreeValue);



    if (filename->type != VAL_STRING) {

        ErrorAbort(state, "filename argument to %s must be string", name);

        return StringValue(strdup(""));

    }



    int fd = open(arg_filename->data, O_RDONLY);

    unique_fd fd_holder(fd);

    if (fd == -1) {

        ErrorAbort(state, "open \"%s\" failed: %s", arg_filename->data, strerror(errno));

        return StringValue(strdup(""));

    }



    RangeSet blk0 {1 /*count*/, 1/*size*/, std::vector<size_t> {0, 1}/*position*/};

    std::vector<uint8_t> block0_buffer(BLOCKSIZE);



    if (ReadBlocks(blk0, block0_buffer, fd) == -1) {

        ErrorAbort(state, "failed to read %s: %s", arg_filename->data,

                strerror(errno));

        return StringValue(strdup(""));

    }



    // https://ext4.wiki.kernel.org/index.php/Ext4_Disk_Layout

    // Super block starts from block 0, offset 0x400

    //   0x2C: len32 Mount time

    //   0x30: len32 Write time

    //   0x34: len16 Number of mounts since the last fsck

    //   0x38: len16 Magic signature 0xEF53



    time_t mount_time = *reinterpret_cast<uint32_t*>(&block0_buffer[0x400+0x2C]);

    uint16_t mount_count = *reinterpret_cast<uint16_t*>(&block0_buffer[0x400+0x34]);



    if (mount_count > 0) {

        uiPrintf(state, "Device was remounted R/W %d times\n", mount_count);

        uiPrintf(state, "Last remount happened on %s", ctime(&mount_time));

    }



    return StringValue(strdup("t"));

}





Value* BlockImageRecoverFn(const char* name, State* state, int argc, Expr* argv[]) {

    Value* arg_filename;

    Value* arg_ranges;
@@ -1731,5 +1785,6 @@ void RegisterBlockImageFunctions() { 
    RegisterFunction("block_image_verify", BlockImageVerifyFn);

    RegisterFunction("block_image_update", BlockImageUpdateFn);

    RegisterFunction("block_image_recover", BlockImageRecoverFn);

    RegisterFunction("check_first_block", CheckFirstBlockFn);

    RegisterFunction("range_sha1", RangeSha1Fn);

}

updater/install.h

+3 −0
Original line number Diff line number Diff line
@@ -19,6 +19,9 @@ 


void RegisterInstallFunctions();



// uiPrintf function prints msg to screen as well as logs

void uiPrintf(State* state, const char* format, ...);



static int make_parents(char* name);



#endif