如何在删除部分后删除 ELF 部分之间无用的空白 space？
How to remove useless empty space between ELF sections after removing section?
我尝试使用 --remove-section 选项将二进制大小减小 objcopy。删除节后，在删除节的原始位置保留一些空白space。有什么方法可以调整该部分的偏移量以避免这些空 space?
对于emxaple，我删除了.eh_frame_hdr部分，并且在剥离的二进制文件中从0x0764开始有0x03c空space。
There are 35 section headers, starting at offset 0x1c78:
Section Headers:
[Nr] Name Type Address Off Size ES Flg Lk Inf Al
[ 0] NULL 0000000000000000 000000 000000 00 0 0 0
[ 1] .interp PROGBITS 0000000000400238 000238 00001c 00 A 0 0 1
[ 2] .note.ABI-tag NOTE 0000000000400254 000254 000020 00 A 0 0 4
[ 3] .note.gnu.build-id NOTE 0000000000400274 000274 000024 00 A 0 0 4
[ 4] .gnu.hash GNU_HASH 0000000000400298 000298 00001c 00 A 5 0 8
[ 5] .dynsym DYNSYM 00000000004002b8 0002b8 000078 18 A 6 1 8
[ 6] .dynstr STRTAB 0000000000400330 000330 000060 00 A 0 0 1
[ 7] .gnu.version VERSYM 0000000000400390 000390 00000a 02 A 5 0 2
[ 8] .gnu.version_r VERNEED 00000000004003a0 0003a0 000040 00 A 6 2 8
[ 9] .rela.dyn RELA 00000000004003e0 0003e0 000030 18 A 5 0 8
[10] .rela.plt RELA 0000000000400410 000410 000030 18 AI 5 27 8
[11] .init PROGBITS 0000000000400440 000440 000017 00 AX 0 0 4
[12] .rela.init RELA 0000000000000000 0018c0 000018 18 I 32 11 8
[13] .plt PROGBITS 0000000000400460 000460 000030 10 AX 0 0 16
[14] .text PROGBITS 0000000000400490 000490 0002c2 00 AX 0 0 16
[15] .rela.text RELA 0000000000000000 0018d8 0001c8 18 I 32 14 8
[16] .fini PROGBITS 0000000000400754 000754 000009 00 AX 0 0 4
[17] .rodata PROGBITS 0000000000400760 000760 000004 04 AM 0 0 4
[18] .eh_frame_hdr PROGBITS 0000000000400764 000764 00003c 00 A 0 0 4
[19] .eh_frame PROGBITS 00000000004007a0 0007a0 000100 00 A 0 0 8
[20] .rela.eh_frame RELA 0000000000000000 001aa0 000078 18 I 32 19 8
[21] .init_array INIT_ARRAY 0000000000600e00 000e00 000008 08 WA 0 0 8
[22] .rela.init_array RELA 0000000000000000 001b18 000018 18 I 32 21 8
[23] .fini_array FINI_ARRAY 0000000000600e08 000e08 000008 08 WA 0 0 8
[24] .rela.fini_array RELA 0000000000000000 001b30 000018 18 I 32 23 8
[25] .dynamic DYNAMIC 0000000000600e10 000e10 0001e0 10 WA 6 0 8
[26] .got PROGBITS 0000000000600ff0 000ff0 000010 08 WA 0 0 8
[27] .got.plt PROGBITS 0000000000601000 001000 000028 08 WA 0 0 8
[28] .data PROGBITS 0000000000601028 001028 000010 00 WA 0 0 8
[29] .tm_clone_table PROGBITS 0000000000601038 001038 000000 00 WA 0 0 8
[30] .bss NOBITS 0000000000601038 001038 000008 00 WA 0 0 1
[31] .comment PROGBITS 0000000000000000 001038 000029 01 MS 0 0 1
[32] .symtab SYMTAB 0000000000000000 001068 000630 18 33 45 8
[33] .strtab STRTAB 0000000000000000 001698 000227 00 0 0 1
[34] .shstrtab STRTAB 0000000000000000 001b48 00012c 00 0 0 1
Key to Flags:
W (write), A (alloc), X (execute), M (merge), S (strings), I (info),
L (link order), O (extra OS processing required), G (group), T (TLS),
C (compressed), x (unknown), o (OS specific), E (exclude),
l (large), p (processor specific)
剥离后：
There are 34 section headers, starting at offset 0x1c28:
Section Headers:
[Nr] Name Type Address Off Size ES Flg Lk Inf Al
[ 0] NULL 0000000000000000 000000 000000 00 0 0 0
[ 1] .interp PROGBITS 0000000000400238 000238 00001c 00 A 0 0 1
[ 2] .note.ABI-tag NOTE 0000000000400254 000254 000020 00 A 0 0 4
[ 3] .note.gnu.build-id NOTE 0000000000400274 000274 000024 00 A 0 0 4
[ 4] .gnu.hash GNU_HASH 0000000000400298 000298 00001c 00 A 5 0 8
[ 5] .dynsym DYNSYM 00000000004002b8 0002b8 000078 18 A 6 1 8
[ 6] .dynstr STRTAB 0000000000400330 000330 000060 00 A 0 0 1
[ 7] .gnu.version VERSYM 0000000000400390 000390 00000a 02 A 5 0 2
[ 8] .gnu.version_r VERNEED 00000000004003a0 0003a0 000040 00 A 6 2 8
[ 9] .rela.dyn RELA 00000000004003e0 0003e0 000030 18 A 5 0 8
[10] .rela.plt RELA 0000000000400410 000410 000030 18 AI 5 26 8
[11] .init PROGBITS 0000000000400440 000440 000017 00 AX 0 0 4
[12] .rela.init RELA 0000000000000000 001880 000018 18 I 31 11 8
[13] .plt PROGBITS 0000000000400460 000460 000030 10 AX 0 0 16
[14] .text PROGBITS 0000000000400490 000490 0002c2 00 AX 0 0 16
[15] .rela.text RELA 0000000000000000 001898 0001c8 18 I 31 14 8
[16] .fini PROGBITS 0000000000400754 000754 000009 00 AX 0 0 4
[17] .rodata PROGBITS 0000000000400760 000760 000004 04 AM 0 0 4
[18] .eh_frame PROGBITS 00000000004007a0 0007a0 000100 00 A 0 0 8
[19] .rela.eh_frame RELA 0000000000000000 001a60 000078 18 I 31 18 8
[20] .init_array INIT_ARRAY 0000000000600e00 000e00 000008 08 WA 0 0 8
[21] .rela.init_array RELA 0000000000000000 001ad8 000018 18 I 31 20 8
[22] .fini_array FINI_ARRAY 0000000000600e08 000e08 000008 08 WA 0 0 8
[23] .rela.fini_array RELA 0000000000000000 001af0 000018 18 I 31 22 8
[24] .dynamic DYNAMIC 0000000000600e10 000e10 0001e0 10 WA 6 0 8
[25] .got PROGBITS 0000000000600ff0 000ff0 000010 08 WA 0 0 8
[26] .got.plt PROGBITS 0000000000601000 001000 000028 08 WA 0 0 8
[27] .data PROGBITS 0000000000601028 001028 000010 00 WA 0 0 8
[28] .tm_clone_table PROGBITS 0000000000601038 001038 000000 00 WA 0 0 8
[29] .bss NOBITS 0000000000601038 001038 000008 00 WA 0 0 1
[30] .comment PROGBITS 0000000000000000 001038 000029 01 MS 0 0 1
[31] .symtab SYMTAB 0000000000000000 001068 000600 18 32 43 8
[32] .strtab STRTAB 0000000000000000 001668 000214 00 0 0 1
[33] .shstrtab STRTAB 0000000000000000 001b08 00011e 00 0 0 1
Key to Flags:
W (write), A (alloc), X (execute), M (merge), S (strings), I (info),
L (link order), O (extra OS processing required), G (group), T (TLS),
C (compressed), x (unknown), o (OS specific), E (exclude),
l (large), p (processor specific)
链接是一个有损过程。 .o 中的重定位可以在链接图像中解决。 objcopy 不知道是否隐藏了引用。因此，它只是试图非常保守：在 --remove-section.
之后不更改地址
如果你想避免.eh_frame_hdr和.eh_frame，最好是使用-fno-exceptions -fno-asynchronous-unwind-tables.
我尝试使用 --remove-section 选项将二进制大小减小 objcopy。删除节后，在删除节的原始位置保留一些空白space。有什么方法可以调整该部分的偏移量以避免这些空 space?
对于emxaple，我删除了.eh_frame_hdr部分，并且在剥离的二进制文件中从0x0764开始有0x03c空space。
There are 35 section headers, starting at offset 0x1c78:
Section Headers:
[Nr] Name Type Address Off Size ES Flg Lk Inf Al
[ 0] NULL 0000000000000000 000000 000000 00 0 0 0
[ 1] .interp PROGBITS 0000000000400238 000238 00001c 00 A 0 0 1
[ 2] .note.ABI-tag NOTE 0000000000400254 000254 000020 00 A 0 0 4
[ 3] .note.gnu.build-id NOTE 0000000000400274 000274 000024 00 A 0 0 4
[ 4] .gnu.hash GNU_HASH 0000000000400298 000298 00001c 00 A 5 0 8
[ 5] .dynsym DYNSYM 00000000004002b8 0002b8 000078 18 A 6 1 8
[ 6] .dynstr STRTAB 0000000000400330 000330 000060 00 A 0 0 1
[ 7] .gnu.version VERSYM 0000000000400390 000390 00000a 02 A 5 0 2
[ 8] .gnu.version_r VERNEED 00000000004003a0 0003a0 000040 00 A 6 2 8
[ 9] .rela.dyn RELA 00000000004003e0 0003e0 000030 18 A 5 0 8
[10] .rela.plt RELA 0000000000400410 000410 000030 18 AI 5 27 8
[11] .init PROGBITS 0000000000400440 000440 000017 00 AX 0 0 4
[12] .rela.init RELA 0000000000000000 0018c0 000018 18 I 32 11 8
[13] .plt PROGBITS 0000000000400460 000460 000030 10 AX 0 0 16
[14] .text PROGBITS 0000000000400490 000490 0002c2 00 AX 0 0 16
[15] .rela.text RELA 0000000000000000 0018d8 0001c8 18 I 32 14 8
[16] .fini PROGBITS 0000000000400754 000754 000009 00 AX 0 0 4
[17] .rodata PROGBITS 0000000000400760 000760 000004 04 AM 0 0 4
[18] .eh_frame_hdr PROGBITS 0000000000400764 000764 00003c 00 A 0 0 4
[19] .eh_frame PROGBITS 00000000004007a0 0007a0 000100 00 A 0 0 8
[20] .rela.eh_frame RELA 0000000000000000 001aa0 000078 18 I 32 19 8
[21] .init_array INIT_ARRAY 0000000000600e00 000e00 000008 08 WA 0 0 8
[22] .rela.init_array RELA 0000000000000000 001b18 000018 18 I 32 21 8
[23] .fini_array FINI_ARRAY 0000000000600e08 000e08 000008 08 WA 0 0 8
[24] .rela.fini_array RELA 0000000000000000 001b30 000018 18 I 32 23 8
[25] .dynamic DYNAMIC 0000000000600e10 000e10 0001e0 10 WA 6 0 8
[26] .got PROGBITS 0000000000600ff0 000ff0 000010 08 WA 0 0 8
[27] .got.plt PROGBITS 0000000000601000 001000 000028 08 WA 0 0 8
[28] .data PROGBITS 0000000000601028 001028 000010 00 WA 0 0 8
[29] .tm_clone_table PROGBITS 0000000000601038 001038 000000 00 WA 0 0 8
[30] .bss NOBITS 0000000000601038 001038 000008 00 WA 0 0 1
[31] .comment PROGBITS 0000000000000000 001038 000029 01 MS 0 0 1
[32] .symtab SYMTAB 0000000000000000 001068 000630 18 33 45 8
[33] .strtab STRTAB 0000000000000000 001698 000227 00 0 0 1
[34] .shstrtab STRTAB 0000000000000000 001b48 00012c 00 0 0 1
Key to Flags:
W (write), A (alloc), X (execute), M (merge), S (strings), I (info),
L (link order), O (extra OS processing required), G (group), T (TLS),
C (compressed), x (unknown), o (OS specific), E (exclude),
l (large), p (processor specific)
剥离后：
There are 34 section headers, starting at offset 0x1c28:
Section Headers:
[Nr] Name Type Address Off Size ES Flg Lk Inf Al
[ 0] NULL 0000000000000000 000000 000000 00 0 0 0
[ 1] .interp PROGBITS 0000000000400238 000238 00001c 00 A 0 0 1
[ 2] .note.ABI-tag NOTE 0000000000400254 000254 000020 00 A 0 0 4
[ 3] .note.gnu.build-id NOTE 0000000000400274 000274 000024 00 A 0 0 4
[ 4] .gnu.hash GNU_HASH 0000000000400298 000298 00001c 00 A 5 0 8
[ 5] .dynsym DYNSYM 00000000004002b8 0002b8 000078 18 A 6 1 8
[ 6] .dynstr STRTAB 0000000000400330 000330 000060 00 A 0 0 1
[ 7] .gnu.version VERSYM 0000000000400390 000390 00000a 02 A 5 0 2
[ 8] .gnu.version_r VERNEED 00000000004003a0 0003a0 000040 00 A 6 2 8
[ 9] .rela.dyn RELA 00000000004003e0 0003e0 000030 18 A 5 0 8
[10] .rela.plt RELA 0000000000400410 000410 000030 18 AI 5 26 8
[11] .init PROGBITS 0000000000400440 000440 000017 00 AX 0 0 4
[12] .rela.init RELA 0000000000000000 001880 000018 18 I 31 11 8
[13] .plt PROGBITS 0000000000400460 000460 000030 10 AX 0 0 16
[14] .text PROGBITS 0000000000400490 000490 0002c2 00 AX 0 0 16
[15] .rela.text RELA 0000000000000000 001898 0001c8 18 I 31 14 8
[16] .fini PROGBITS 0000000000400754 000754 000009 00 AX 0 0 4
[17] .rodata PROGBITS 0000000000400760 000760 000004 04 AM 0 0 4
[18] .eh_frame PROGBITS 00000000004007a0 0007a0 000100 00 A 0 0 8
[19] .rela.eh_frame RELA 0000000000000000 001a60 000078 18 I 31 18 8
[20] .init_array INIT_ARRAY 0000000000600e00 000e00 000008 08 WA 0 0 8
[21] .rela.init_array RELA 0000000000000000 001ad8 000018 18 I 31 20 8
[22] .fini_array FINI_ARRAY 0000000000600e08 000e08 000008 08 WA 0 0 8
[23] .rela.fini_array RELA 0000000000000000 001af0 000018 18 I 31 22 8
[24] .dynamic DYNAMIC 0000000000600e10 000e10 0001e0 10 WA 6 0 8
[25] .got PROGBITS 0000000000600ff0 000ff0 000010 08 WA 0 0 8
[26] .got.plt PROGBITS 0000000000601000 001000 000028 08 WA 0 0 8
[27] .data PROGBITS 0000000000601028 001028 000010 00 WA 0 0 8
[28] .tm_clone_table PROGBITS 0000000000601038 001038 000000 00 WA 0 0 8
[29] .bss NOBITS 0000000000601038 001038 000008 00 WA 0 0 1
[30] .comment PROGBITS 0000000000000000 001038 000029 01 MS 0 0 1
[31] .symtab SYMTAB 0000000000000000 001068 000600 18 32 43 8
[32] .strtab STRTAB 0000000000000000 001668 000214 00 0 0 1
[33] .shstrtab STRTAB 0000000000000000 001b08 00011e 00 0 0 1
Key to Flags:
W (write), A (alloc), X (execute), M (merge), S (strings), I (info),
L (link order), O (extra OS processing required), G (group), T (TLS),
C (compressed), x (unknown), o (OS specific), E (exclude),
l (large), p (processor specific)
链接是一个有损过程。 .o 中的重定位可以在链接图像中解决。 objcopy 不知道是否隐藏了引用。因此，它只是试图非常保守：在 --remove-section.
之后不更改地址如果你想避免.eh_frame_hdr和.eh_frame，最好是使用-fno-exceptions -fno-asynchronous-unwind-tables.