bsdiff是一个差异包比较工具,可以用来实现增量更新.

下载地址:http://www.daemonology.net/bsdiff

编译

Mac环境

版本：macOS 10.12

1.解压下载的bsdiff-4.3.tar.gz

tar -zxvf bsdiff-4.3.tar.gz

2.进入bsdiff-4.3目录，在终端下执行构建

cd bsdiff-4.3

make

此时报错： Makefile:13: *** missing separator.  Stop.

这是makefile文件的内容的格式不对，修改Makefile文件，修改后的文件内容如下：

CFLAGS        +=    -O3 -lbz2

PREFIX        ?=    /usr/local
INSTALL_PROGRAM    ?=    ${INSTALL} -c -s -m 555
INSTALL_MAN    ?=    ${INSTALL} -c -m 444

all:        bsdiff bspatch
bsdiff:        bsdiff.c
bspatch:    bspatch.c

install:
    ${INSTALL_PROGRAM} bsdiff bspatch ${PREFIX}/bin
    .ifndef WITHOUT_MAN
    ${INSTALL_MAN} bsdiff.1 bspatch.1 ${PREFIX}/man/man1
    .endif

即.ifndef WITHOUT_MAN，.endi语句f前面加TAB键进行缩进

然后再执行make，此时又报错：

bspatch.c:39:21: error: unknown type name ‘u_char‘; did you mean ‘char‘?
static off_t offtin(u_char *buf)
                    ^~~~~~
                    char
bspatch.c:65:8: error: expected ‘;‘ after expression
        u_char header[32],buf[8];
              ^
              ;
bspatch.c:65:2: error: use of undeclared identifier ‘u_char‘; did you mean ‘putchar‘?
        u_char header[32],buf[8];
        ^~~~~~
        putchar
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk/usr/include/stdio.h:261:6: note:
      ‘putchar‘ declared here
int      putchar(int);
         ^
bspatch.c:65:9: error: use of undeclared identifier ‘header‘
        u_char header[32],buf[8];
               ^
bspatch.c:65:20: error: use of undeclared identifier ‘buf‘
        u_char header[32],buf[8];
                          ^
bspatch.c:66:2: error: use of undeclared identifier ‘u_char‘; did you mean ‘putchar‘?
        u_char *old, *new;
        ^~~~~~
        putchar
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.12.sdk/usr/include/stdio.h:261:6: note:
      ‘putchar‘ declared here
int      putchar(int);
         ^
bspatch.c:66:10: error: use of undeclared identifier ‘old‘
        u_char *old, *new;
                ^
bspatch.c:66:16: error: use of undeclared identifier ‘new‘
        u_char *old, *new;
                      ^
bspatch.c:93:12: error: use of undeclared identifier ‘header‘
        if (fread(header, 1, 32, f) < 32) {
                  ^
bspatch.c:100:13: error: use of undeclared identifier ‘header‘
        if (memcmp(header, "BSDIFF40", 8) != 0)
                   ^
bspatch.c:104:19: error: use of undeclared identifier ‘header‘
        bzctrllen=offtin(header+8);
                         ^
bspatch.c:105:19: error: use of undeclared identifier ‘header‘
        bzdatalen=offtin(header+16);
                         ^
bspatch.c:106:17: error: use of undeclared identifier ‘header‘
        newsize=offtin(header+24);
                       ^
bspatch.c:137:5: error: use of undeclared identifier ‘old‘
                ((old=malloc(oldsize+1))==NULL) ||
                  ^
bspatch.c:139:12: error: use of undeclared identifier ‘old‘
                (read(fd,old,oldsize)!=oldsize) ||
                         ^
bspatch.c:141:6: error: use of undeclared identifier ‘new‘
        if((new=malloc(newsize+1))==NULL) err(1,NULL);
            ^
bspatch.c:147:43: error: use of undeclared identifier ‘buf‘
                        lenread = BZ2_bzRead(&cbz2err, cpfbz2, buf, 8);
                                                               ^
bspatch.c:151:19: error: use of undeclared identifier ‘buf‘
                        ctrl[i]=offtin(buf);
                                       ^
bspatch.c:159:42: error: use of undeclared identifier ‘new‘
                lenread = BZ2_bzRead(&dbz2err, dpfbz2, new + newpos, ctrl[0]);
                                                       ^
fatal error: too many errors emitted, stopping now [-ferror-limit=]
20 errors generated.
make: *** [bspatch] Error 1

在bspatch.c文件中加入#include <sys/types.h>

然后再执行make命令，此时命令执行成功，会在当前目录下生成bsdiff,bspatch文件

使用

生成差异文件，常用于服务端生成差异包

bsdiff oldfile newfile patchfile

oldfile: 旧的文件

newfile:新的文件

patchfile:生成的差异文件

合并文件，常用于客户端根据差异包合并生成新的文件

bspatch oldfile newfile2 patchfile

oldfile:旧的文件

newfile2:生成的新的文件

patchfile:差异文件

举个例子，测试一下使用bsdiff进行增量更新

./bsdiff old.apk new.apk old-new.patch

./bspatch old.apk new2.apk old-new.patch

md5 new.apk

MD5 (new.apk) = fc8bdb15f80abef22eb25f9601063cf0

md5 new2.apk

MD5 (new2.apk) = fc8bdb15f80abef22eb25f9601063cf0

此时new.apk和new2.apk的md5值是一致的