objcopy

• 複製 .o 檔 (obj file) 的內部內容到另一個檔案中 (.o 檔或是單純地做 hex dump)
• 將一個 binary data (如JPEG 圖片) 做成 .o 檔
• 把執行碼從 ELF 中抽取出來
• 只抽取指定的 section

常用參數

objcopy [`-I' bfdname|`--input-target='bfdname]
        [`-O' bfdname|`--output-target='bfdname]
        [`-B' bfdarch|`--binary-architecture='bfdarch]
        [`-S'|`--strip-all']
        [`-g'|`--strip-debug']
        [`-j' sectionname|`--only-section='sectionname]
        [`-R' sectionname|`--remove-section='sectionname]
        [`--help']
        infile [outfile]

GNU binutil manual

• GNU objcopy manual
• GNU Binary Utilities

使用範例

1. 列出可用的 BFD target

   $ objdump -i
   
   BFD header file version (GNU Binutils for Ubuntu) 2.18
   elf32-i386
    (header little endian, data little endian)
     i386
   a.out-i386-linux
    (header little endian, data little endian)
     i386
   efi-app-ia32
    (header little endian, data little endian)
     i386
   elf32-little
    (header little endian, data little endian)
     i386
   elf32-big
    (header big endian, data big endian)
     i386
   elf64-x86-64
    (header little endian, data little endian)
     i386
   efi-app-x86_64
    (header little endian, data little endian)
     i386
   elf64-little
    (header little endian, data little endian)
     i386
   elf64-big
    (header big endian, data big endian)
     i386
   srec
    (header endianness unknown, data endianness unknown)
     i386
   symbolsrec
    (header endianness unknown, data endianness unknown)
     i386
   tekhex
    (header endianness unknown, data endianness unknown)
     i386
   binary
    (header endianness unknown, data endianness unknown)
     i386
   ihex
    (header endianness unknown, data endianness unknown)
     i386
   trad-core
    (header endianness unknown, data endianness unknown)
   
                  elf32-i386 a.out-i386-linux efi-app-ia32 elf32-little elf32-big
             i386 elf32-i386 a.out-i386-linux efi-app-ia32 elf32-little elf32-big
   
                  elf64-x86-64 efi-app-x86_64 elf64-little elf64-big srec
             i386 elf64-x86-64 efi-app-x86_64 elf64-little elf64-big srec
   
                  symbolsrec tekhex binary ihex trad-core
             i386 symbolsrec tekhex binary ihex ---------
   

2. 將一個 JPEG 圖片檔 做成 .o 檔

   $ objcopy -I binary -O elf32-i386 -B i386  image.jpg  image.o
   

3. 把執行碼從 ELF 中抽取出來，去除 symbol table, relocation information, .comment section, 和 .note section

   $ objcopy -O binary -S -R .comment -R .note  code.o  code.bin
   

4. 只抽取指定的 section

   $ objcopy -O binary -j .text  code.o  code.bin
   

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