在 dl_iterate_phdr 的帮助下，我可以通过 dlpi_addr 加载主可执行文件和所有二进制文件的
start地址，它与我可以通过 printf 打印的函数指针地址相关，但是其他字段，例如
p_offsetp_vaddrp_paddr p_memszp_filesz作为参考，这是当我使用 dlpi_addr dlpi_name dlpi_phdr.p_offset dlpi_phdr.p_vaddr dlpi_phdr.p_paddr dlpi_phdr.p_memsz dlpi_phdr.p_filesz 的 64 位 PIE 可执行文件打印以下字符串时得到的输出类型。
“秒 0x%lx %s %ld %ld %ld %ld %ld ”
sec 0x55bf2722f000 64 64 64 784 784
sec 0x7fff8a3ea000 linux-vdso.so.1 0 0 0 4079 4079
sec 0x7f03ce15d000 /lib/x86_64-linux-gnu/libgstplayer-1.0.so.0 0 0 0 21128 21128
sec 0x7f03ce08b000 /lib/x86_64-linux-gnu/libgstvideo-1.0.so.0 0 0 0 108632 108632
sec 0x7f03ce004000 /lib/x86_64-linux-gnu/libgstbase-1.0.so.0 0 0 0 57520 57520
sec 0x7f03cdeae000 /lib/x86_64-linux-gnu/libgstreamer-1.0.so.0 0 0 0 192512 192512
sec 0x7f03cde4d000 /lib/x86_64-linux-gnu/libgobject-2.0.so.0 0 0 0 59216 59216
sec 0x7f03cdd05000 /lib/x86_64-linux-gnu/libglib-2.0.so.0 0 0 0 119968 119968
sec 0x7f03cdcf2000 /lib/x86_64-linux-gnu/libgstwebrtc-1.0.so.0 0 0 0 16776 16776
sec 0x7f03cdcd7000 /lib/x86_64-linux-gnu/libgstsdp-1.0.so.0 0 0 0 20248 20248
sec 0x7f03cdc54000 /lib/x86_64-linux-gnu/libgstaudio-1.0.so.0 0 0 0 64008 64008
sec 0x7f03cdc3e000 /lib/x86_64-linux-gnu/libgstapp-1.0.so.0 0 0 0 15208 15208
sec 0x7f03cdbb6000 /lib/x86_64-linux-gnu/libgstgl-1.0.so.0 0 0 0 92984 92984
sec 0x7f03cd9c7000 /lib/x86_64-linux-gnu/libgio-2.0.so.0 0 0 0 236080 236080
sec 0x7f03cd600000 /lib/x86_64-linux-gnu/libstdc++.so.6 0 0 0 637488 637488
sec 0x7f03cd9a8000 /lib/x86_64-linux-gnu/libz.so.1 0 0 0 8832 8832
...and more
这是 elf 可执行 objdump 部分列表
Sections:
Idx Name Size VMA LMA File off Algn
0 .interp 0000001c 0000000000000350 0000000000000350 00000350 2**0
CONTENTS, ALLOC, LOAD, READONLY, DATA
1 .note.gnu.property 00000020 0000000000000370 0000000000000370 00000370 2**3
CONTENTS, ALLOC, LOAD, READONLY, DATA
2 .note.gnu.build-id 00000024 0000000000000390 0000000000000390 00000390 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
3 .note.ABI-tag 00000020 00000000000003b4 00000000000003b4 000003b4 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
4 .gnu.hash 00000624 00000000000003d8 00000000000003d8 000003d8 2**3
CONTENTS, ALLOC, LOAD, READONLY, DATA
5 .dynsym 000059a0 0000000000000a00 0000000000000a00 00000a00 2**3
CONTENTS, ALLOC, LOAD, READONLY, DATA
6 .dynstr 00004e8a 00000000000063a0 00000000000063a0 000063a0 2**0
CONTENTS, ALLOC, LOAD, READONLY, DATA
7 .gnu.version 00000778 000000000000b22a 000000000000b22a 0000b22a 2**1
CONTENTS, ALLOC, LOAD, READONLY, DATA
8 .gnu.version_r 000002c0 000000000000b9a8 000000000000b9a8 0000b9a8 2**3
CONTENTS, ALLOC, LOAD, READONLY, DATA
9 .rela.dyn 00552480 000000000000bc68 000000000000bc68 0000bc68 2**3
CONTENTS, ALLOC, LOAD, READONLY, DATA
10 .rela.plt 00001290 000000000055e0e8 000000000055e0e8 0055e0e8 2**3
CONTENTS, ALLOC, LOAD, READONLY, DATA
11 .init 00000017 0000000000560000 0000000000560000 00560000 2**2
CONTENTS, ALLOC, LOAD, READONLY, CODE
12 .plt 00000c70 0000000000560020 0000000000560020 00560020 2**4
CONTENTS, ALLOC, LOAD, READONLY, CODE
13 .plt.got 00000288 0000000000560c90 0000000000560c90 00560c90 2**3
CONTENTS, ALLOC, LOAD, READONLY, CODE
14 .text 03693fac 0000000000560f40 0000000000560f40 00560f40 2**6
CONTENTS, ALLOC, LOAD, READONLY, CODE
15 .fini 00000009 0000000003bf4eec 0000000003bf4eec 03bf4eec 2**2
CONTENTS, ALLOC, LOAD, READONLY, CODE
16 .rodata 01f5cd20 0000000003bf5000 0000000003bf5000 03bf5000 2**12
CONTENTS, ALLOC, LOAD, READONLY, DATA
17 .debug_gdb_scripts 00000022 0000000005b51d20 0000000005b51d20 05b51d20 2**0
CONTENTS, ALLOC, LOAD, READONLY, DATA
18 .eh_frame_hdr 0012f7a4 0000000005b51d44 0000000005b51d44 05b51d44 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
19 .eh_frame 00755710 0000000005c814e8 0000000005c814e8 05c814e8 2**3
CONTENTS, ALLOC, LOAD, READONLY, DATA
20 .gcc_except_table 002634a8 00000000063d6bf8 00000000063d6bf8 063d6bf8 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
21 .tdata 00005398 000000000663b740 000000000663b740 0663a740 2**3
CONTENTS, ALLOC, LOAD, DATA, THREAD_LOCAL
22 .tbss 00000a00 0000000006640ad8 0000000006640ad8 0663fad8 2**3
ALLOC, THREAD_LOCAL
23 .init_array 00000090 0000000006640ad8 0000000006640ad8 0663fad8 2**3
CONTENTS, ALLOC, LOAD, DATA
24 .fini_array 00000008 0000000006640b68 0000000006640b68 0663fb68 2**3
CONTENTS, ALLOC, LOAD, DATA
25 .data.rel.ro 00367708 0000000006640b70 0000000006640b70 0663fb70 2**4
CONTENTS, ALLOC, LOAD, DATA
26 .dynamic 00000360 00000000069a8278 00000000069a8278 069a7278 2**3
CONTENTS, ALLOC, LOAD, DATA
27 .got 0001ba20 00000000069a85d8 00000000069a85d8 069a75d8 2**3
CONTENTS, ALLOC, LOAD, DATA
28 .data 00037c58 00000000069c4000 00000000069c4000 069c3000 2**4
CONTENTS, ALLOC, LOAD, DATA
29 .bss 026a5348 00000000069fbc80 00000000069fbc80 069fac58 2**7
ALLOC
30 .comment 0000006b 0000000000000000 0000000000000000 069fac58 2**0
CONTENTS, READONLY
31 .debug_aranges 00420190 0000000000000000 0000000000000000 069facc3 2**0
CONTENTS, READONLY, DEBUGGING, OCTETS
32 .debug_pubnames 08936c54 0000000000000000 0000000000000000 06e1ae53 2**0
CONTENTS, READONLY, DEBUGGING, OCTETS
33 .debug_info 1df05433 0000000000000000 0000000000000000 0f751aa7 2**0
CONTENTS, READONLY, DEBUGGING, OCTETS
34 .debug_abbrev 00442a52 0000000000000000 0000000000000000 2d656eda 2**0
CONTENTS, READONLY, DEBUGGING, OCTETS
35 .debug_line 0423eb3e 0000000000000000 0000000000000000 2da9992c 2**0
CONTENTS, READONLY, DEBUGGING, OCTETS
36 .debug_str 0b447666 0000000000000000 0000000000000000 31cd846a 2**0
CONTENTS, READONLY, DEBUGGING, OCTETS
37 .debug_loc 123b4882 0000000000000000 0000000000000000 3d11fad0 2**0
CONTENTS, READONLY, DEBUGGING, OCTETS
38 .debug_pubtypes 0cce2c03 0000000000000000 0000000000000000 4f4d4352 2**0
CONTENTS, READONLY, DEBUGGING, OCTETS
39 .debug_ranges 07b1f340 0000000000000000 0000000000000000 5c1b6f55 2**0
CONTENTS, READONLY, DEBUGGING, OCTETS
40 .debug_addr 0000d840 0000000000000000 0000000000000000 63cd6295 2**0
CONTENTS, READONLY, DEBUGGING, OCTETS
41 .debug_line_str 00001f90 0000000000000000 0000000000000000 63ce3ad5 2**0
CONTENTS, READONLY, DEBUGGING, OCTETS
42 .debug_loclists 00039d5e 0000000000000000 0000000000000000 63ce5a65 2**0
CONTENTS, READONLY, DEBUGGING, OCTETS
43 .debug_rnglists 00009afd 0000000000000000 0000000000000000 63d1f7c3 2**0
CONTENTS, READONLY, DEBUGGING, OCTETS
44 .debug_str_offsets 0001c6c0 0000000000000000 0000000000000000 63d292c0 2**0
CONTENTS, READONLY, DEBUGGING, OCTETS
那么，这些小数字是怎么回事？我该如何正确使用 Linux api？参考现有答案
如何检测当前进程中动态库（共享对象）的大小？建议解析 /proc/self/maps，这有点愚蠢，这个获取 ELF 标头主要可执行文件仅显示我已经拥有的起始地址
我尝试了 dladdr 以及 dladdr1 来加载一些信息，我以各种方式加载了 /proc/self/exe 的文件部分，但我不知道 dl_iterate_phdr 的输出如何让我将其信息与第三方库相关联
更新： 这是 readelf 实用程序的输出
Elf file type is DYN (Position-Independent Executable file)
Entry point 0x6cfe20
There are 14 program headers, starting at offset 64
Program Headers:
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
PHDR 0x000040 0x0000000000000040 0x0000000000000040 0x000310 0x000310 R 0x8
INTERP 0x000350 0x0000000000000350 0x0000000000000350 0x00001c 0x00001c R 0x1
[Requesting program interpreter: /lib64/ld-linux-x86-64.so.2]
LOAD 0x000000 0x0000000000000000 0x0000000000000000 0x55f378 0x55f378 R 0x1000
LOAD 0x560000 0x0000000000560000 0x0000000000560000 0x3694ef5 0x3694ef5 R E 0x1000
LOAD 0x3bf5000 0x0000000003bf5000 0x0000000003bf5000 0x2a450a0 0x2a450a0 R 0x1000
LOAD 0x663a740 0x000000000663b740 0x000000000663b740 0x3c0518 0x2a65888 RW 0x1000
DYNAMIC 0x69a7278 0x00000000069a8278 0x00000000069a8278 0x000360 0x000360 RW 0x8
NOTE 0x000370 0x0000000000000370 0x0000000000000370 0x000020 0x000020 R 0x8
NOTE 0x000390 0x0000000000000390 0x0000000000000390 0x000044 0x000044 R 0x4
TLS 0x663a740 0x000000000663b740 0x000000000663b740 0x005398 0x005d98 R 0x8
GNU_PROPERTY 0x000370 0x0000000000000370 0x0000000000000370 0x000020 0x000020 R 0x8
GNU_EH_FRAME 0x5b51d44 0x0000000005b51d44 0x0000000005b51d44 0x12f7a4 0x12f7a4 R 0x4
GNU_STACK 0x000000 0x0000000000000000 0x0000000000000000 0x000000 0x000000 RW 0x10
GNU_RELRO 0x663a740 0x000000000663b740 0x000000000663b740 0x3888c0 0x3888c0 R 0x1
Section to Segment mapping:
Segment Sections...
00
01 .interp
02 .interp .note.gnu.property .note.gnu.build-id .note.ABI-tag .gnu.hash .dynsym .dynstr .gnu.version .gnu.version_r .rela.dyn .rela.plt
03 .init .plt .plt.got .text .fini
04 .rodata .debug_gdb_scripts .eh_frame_hdr .eh_frame .gcc_except_table
05 .tdata .init_array .fini_array .data.rel.ro .dynamic .got .data .bss
06 .dynamic
07 .note.gnu.property
08 .note.gnu.build-id .note.ABI-tag
09 .tdata .tbss
10 .note.gnu.property
11 .eh_frame_hdr
12
13 .tdata .init_array .fini_array .data.rel.ro .dynamic .got
我正在使用 rust 绑定，但欢迎使用 c/c++/whatever-calling-libc 回答
libc::dl_iterate_phdr(Some(collect_objs), std::ptr::null_mut());
unsafe extern "C" fn collect_objs(
info: *mut dl_phdr_info,
_sz: usize,
data: *mut c_void,
) -> c_int {
libc::printf("sec 0x%lx %s %ld %ld %ld %ld %ld \n\0".as_bytes().as_ptr() as *const i8,
(*info).dlpi_addr,
(*info).dlpi_name,
(*(*info).dlpi_phdr).p_offset,
(*(*info).dlpi_phdr).p_vaddr,
(*(*info).dlpi_phdr).p_paddr,
(*(*info).dlpi_phdr).p_memsz,
(*(*info).dlpi_phdr).p_filesz);
0
}
.debug_*
部分。如果将 MemSiz 字段加起来，我会得到 156 618 913 字节（约 156 MB）。程序运行时，仅加载具有非零 MemSiz 的条目（并保存在内存中）。这些都不是调试信息。
如果我将 FileSiz 字段加起来，我会得到 116 093 745 字节（大约 116 MB，比 MemSiz 小大约 40 MB）。造成这种差异的原因是某些内存区域（例如
.bss
和
.tbss部分）是用 0 (NUL) 字节初始化的，而这些 0 (NUL) 字节在程序文件中被省略。
.debug_*
部分的总大小（在 objdump(1) 的输出中）为 1 563 733 215 字节 (1563 MB)。它们仅由 gdb(1) 等调试器在调试程序时使用。这些部分包含行号信息（哪个汇编指令位于哪个 (C) 源文件的哪一行）、函数信息（哪个汇编指令位于哪个函数中）、类型信息（哪个结构体具有哪些字段名称和类型）、堆栈布局信息（在堆栈上存储局部变量和函数参数的任何汇编指令中）等。当我们将其加起来时：FileSiz 为 116 MB +
.debug_*
部分为 1563 MB，我们得到 1679 MB，我们可以将其四舍五入为 1.7 GB，与问题中报告的文件大小相匹配。要缩小程序文件，请运行
strip filename
。这将删除
.debug_*部分，并使文件大小约为 116 MB。仍然可以在调试器中调试程序，但调试器显示的信息将不那么详细，而且用处也更少。即使没有
.debug_*部分，常规执行（包括 C++ 中的异常处理）也不会发生变化。
not描述了它返回的内容，实际上，而不是dl_iterate_phdr
应该被称为
dl_iterate_objects，因为在回调中，如文档所述，它返回给你（惊喜）共享对象，它们是可执行文件/lib，而不是节头本身。它返回的变量名称
p_memsz实际上并不是指向某个内存对象的指针/指针偏移量，正如您可能从其名称中想到的那样，而是一个节的大小，而是一个实际大小，无论结构的其他字段是否是实际指针如手册中所述，
dlpi_phnum不是当前节的编号，而是节数组的长度。文档的名称和实际情况之间存在矛盾，这导致我加载对象的第一部分（这是标头部分），并惊讶为什么它相对于可执行文件大小如此之小，我应该查看示例在手册的底部了解它实际返回的内容，而不是拼凑出这个 api 实际是什么的谜题
这是手册中示例程序的代码输出
#define _GNU_SOURCE
#include <link.h>
#include <stdlib.h>
#include <stdio.h>
static int
callback(struct dl_phdr_info *info, size_t size, void *data)
{
char *type;
int p_type, j;
printf("Name: \"%s\" (%d segments)\n", info->dlpi_name,
info->dlpi_phnum);
for (j = 0; j < info->dlpi_phnum; j++) {
p_type = info->dlpi_phdr[j].p_type;
type = (p_type == PT_LOAD) ? "PT_LOAD" :
(p_type == PT_DYNAMIC) ? "PT_DYNAMIC" :
(p_type == PT_INTERP) ? "PT_INTERP" :
(p_type == PT_NOTE) ? "PT_NOTE" :
(p_type == PT_INTERP) ? "PT_INTERP" :
(p_type == PT_PHDR) ? "PT_PHDR" :
(p_type == PT_TLS) ? "PT_TLS" :
(p_type == PT_GNU_EH_FRAME) ? "PT_GNU_EH_FRAME" :
(p_type == PT_GNU_STACK) ? "PT_GNU_STACK" :
(p_type == PT_GNU_RELRO) ? "PT_GNU_RELRO" : NULL;
printf(" %2d: [%14p; memsz:%7lx] flags: 0x%x; ", j,
(void *) (info->dlpi_addr + info->dlpi_phdr[j].p_vaddr),
info->dlpi_phdr[j].p_memsz,
info->dlpi_phdr[j].p_flags);
if (type != NULL)
printf("%s\n", type);
else
printf("[other (0x%x)]\n", p_type);
}
return 0;
}
int
main(int argc, char *argv[])
{
dl_iterate_phdr(callback, NULL);
exit(EXIT_SUCCESS);
}
并为其输出巨大的可执行文件正在运行
Name: "" (14 segments)
0: [0x563b1048e040; memsz: 310] flags: 0x4; PT_PHDR
1: [0x563b1048e350; memsz: 1c] flags: 0x4; PT_INTERP
2: [0x563b1048e000; memsz: 55f180] flags: 0x4; PT_LOAD
3: [0x563b109ee000; memsz:36936b5] flags: 0x5; PT_LOAD
4: [0x563b14082000; memsz:2a44490] flags: 0x4; PT_LOAD
5: [0x563b16ac78e0; memsz:2a656e8] flags: 0x6; PT_LOAD
6: [0x563b16e342a8; memsz: 360] flags: 0x6; PT_DYNAMIC
7: [0x563b1048e370; memsz: 20] flags: 0x4; PT_NOTE
8: [0x563b1048e390; memsz: 44] flags: 0x4; PT_NOTE
9: [0x563b16ac78e0; memsz: 5d98] flags: 0x4; PT_TLS
10: [0x563b1048e370; memsz: 20] flags: 0x4; [other (0x6474e553)]
11: [0x563b15fded44; memsz: 12f6c4] flags: 0x4; PT_GNU_EH_FRAME
12: [0x563b1048e000; memsz: 0] flags: 0x6; PT_GNU_STACK
13: [0x563b16ac78e0; memsz: 388720] flags: 0x4; PT_GNU_RELRO
Name: "linux-vdso.so.1" (4 segments)
0: [0x7ffe23dbc000; memsz: fef] flags: 0x5; PT_LOAD
1: [0x7ffe23dbc3e0; memsz: 120] flags: 0x4; PT_DYNAMIC
2: [0x7ffe23dbc500; memsz: 60] flags: 0x4; PT_NOTE
3: [0x7ffe23dbc560; memsz: 4c] flags: 0x4; PT_GNU_EH_FRAME
Name: "/lib/x86_64-linux-gnu/libgstplayer-1.0.so.0" (9 segments)
0: [0x7ff5f2572000; memsz: 5288] flags: 0x4; PT_LOAD
1: [0x7ff5f2578000; memsz: 6261] flags: 0x5; PT_LOAD
2: [0x7ff5f257f000; memsz: 443c] flags: 0x4; PT_LOAD
3: [0x7ff5f2584750; memsz: b60] flags: 0x6; PT_LOAD
4: [0x7ff5f25848e0; memsz: 250] flags: 0x6; PT_DYNAMIC
5: [0x7ff5f2572238; memsz: 24] flags: 0x4; PT_NOTE
6: [0x7ff5f2580fc0; memsz: 64c] flags: 0x4; PT_GNU_EH_FRAME
7: [0x7ff5f2572000; memsz: 0] flags: 0x6; PT_GNU_STACK
8: [0x7ff5f2584750; memsz: 8b0] flags: 0x4; PT_GNU_RELRO
Name: "/lib/x86_64-linux-gnu/libgstvideo-1.0.so.0" (9 segments)
0: [0x7ff5f24a0000; memsz: 1a858] flags: 0x4; PT_LOAD
1: [0x7ff5f24bb000; memsz: 73271] flags: 0x5; PT_LOAD
2: [0x7ff5f252f000; memsz: 2f4f4] flags: 0x4; PT_LOAD
3: [0x7ff5f255f870; memsz: 118e8] flags: 0x6; PT_LOAD
4: [0x7ff5f256ee20; memsz: 250] flags: 0x6; PT_DYNAMIC
5: [0x7ff5f24a0238; memsz: 24] flags: 0x4; PT_NOTE
6: [0x7ff5f2545d08; memsz: 2e14] flags: 0x4; PT_GNU_EH_FRAME
7: [0x7ff5f24a0000; memsz: 0] flags: 0x6; PT_GNU_STACK
8: [0x7ff5f255f870; memsz: 10790] flags: 0x4; PT_GNU_RELRO
Name: "/lib/x86_64-linux-gnu/libgstbase-1.0.so.0" (9 segments)
0: [0x7ff5f2419000; memsz: e0b0] flags: 0x4; PT_LOAD
1: [0x7ff5f2428000; memsz: 54c5d] flags: 0x5; PT_LOAD
2: [0x7ff5f247d000; memsz: 20650] flags: 0x4; PT_LOAD
3: [0x7ff5f249e9f0; memsz: 1450] flags: 0x6; PT_LOAD
4: [0x7ff5f249ece8; memsz: 220] flags: 0x6; PT_DYNAMIC
5: [0x7ff5f2419238; memsz: 24] flags: 0x4; PT_NOTE
6: [0x7ff5f248d9c4; memsz: 153c] flags: 0x4; PT_GNU_EH_FRAME
7: [0x7ff5f2419000; memsz: 0] flags: 0x6; PT_GNU_STACK
8: [0x7ff5f249e9f0; memsz: 610] flags: 0x4; PT_GNU_RELRO
...and more