蓝色的笔记本

//main.c                    //x.c

extern void foo(void);      |   #include <stdio.h>
                            |
int main(void)              |   void foo()
{                           |   {
    foo();                  |       printf("foo\n");
    return 0;               |   }
}                           |

> objdump -d main.o
00000000 <main>:
   0:	55                   	push   %ebp
   1:	89 e5                	mov    %esp,%ebp
   3:	83 e4 f0             	and    $0xfffffff0,%esp
   6:	e8 fc ff ff ff       	call   7 <main+0x7>
   b:	b8 00 00 00 00       	mov    $0x0,%eax
  10:	c9                   	leave
  11:	c3                   	ret

typedef struct {
        Elf32_Addr r_offset;
        uint32_t   r_info;
        int32_t    r_addend;
} Elf32_Rela;

#define EI_NIDENT 16
typedef struct {
    unsigned char e_ident[EI_NIDENT];
    Elf32_Half e_type;               /* 此elf文件的类型见下表  */
    Elf32_Half e_machine;            /* CPU平台架构  */
    Elf32_Word e_version;            /* 此文件的版本  */
    Elf32_Addr e_entry;              /* 加载完该程序后的执行入口  */
    Elf32_Off e_phoff;               /* program header table在文件中的偏移量  */
    Elf32_Off e_shoff;               /* section header table在此文件中的偏移量 */
    Elf32_Word e_flags;              /* processor-specific flags associated with the file */
    Elf32_Half e_ehsize;             /* the ELF header's size in bytes. */
    Elf32_Half e_phentsize;          /* program-header-table数组中一个元素的大小 */
    Elf32_Half e_phnum;              /* program-header-table数组元素的个数 */
    Elf32_Half e_shentsize;          /* section header table数组中一个元素的大小 */
    Elf32_Half e_shnum;              /* section header table包含的元素个数 */
    Elf32_Half e_shstrndx;           /* the section header table index of the entry associated with the section name string table. */
 } Elf32_Ehdr;

typedef struct {
   uint32_t   p_type;   /* 此元素描述的是哪种segment，以及如何解析  */
   Elf32_Off  p_offset; /* segment首字节在文件中的偏移值  */
   Elf32_Addr p_vaddr;  /* 应该加载到内存中的哪个虚拟地址中  */
   Elf32_Addr p_paddr;  /* 相关的物理地址，BSD中为0  */
   uint32_t   p_filesz; /* 文件的字节数  */
   uint32_t   p_memsz;  /* 加载到内存中的字节数  */
   uint32_t   p_flags;  /* segment类型标志位  */
   uint32_t   p_align;  /* 内存对齐  */
} Elf32_Phdr;

typedef struct
{
	Elf32_Word sh_name;      /* Section name (string tbl index)   */
	Elf32_Word sh_type;      /* Section type                      */
	Elf32_Word sh_flags;     /* Section flags                     */
	Elf32_Addr sh_addr;      /* Section virtual addr at execution */
	Elf32_Off sh_offset;     /* Section file offset               */
	Elf32_Word sh_size;      /* Section size in bytes             */
	Elf32_Word sh_link;      /* Link to another section           */
	Elf32_Word sh_info;      /* Additional section information    */
	Elf32_Word sh_addralign; /* Section alignment                 */
	Elf32_Word sh_entsize;   /* Entry size if section holds table */
} Elf32_Shdr;

typedef struct {
       uint32_t      st_name;
       Elf32_Addr    st_value;
       uint32_t      st_size;
       unsigned char st_info;
       unsigned char st_other;
       uint16_t      st_shndx;
} Elf32_Sym;

typedef struct {
        Elf32_Addr      r_offset;
        Elf32_Word      r_info;
} Elf32_Rel;
 
typedef struct {
        Elf32_Addr      r_offset;
        Elf32_Word      r_info;
        Elf32_Sword     r_addend;
} Elf32_Rela;

typedef struct {
        Elf32_Sword    d_tag;
        union {
            Elf32_Word d_val;
            Elf32_Addr d_ptr;
        } d_un;
 } Elf32_Dyn;
           
extern Elf64_Dyn _DYNAMIC[];

Last modified 2017-11-10; size 644 bytes
  MD5 checksum ac6d7477d45479490e4ea3f660b1dcdd
  Compiled from "BMWCar.java"
public class BMWCar implements Car
  minor version: 0
  major version: 52
  flags: ACC_PUBLIC, ACC_SUPER
Constant pool:
   #1 = Methodref          #12.#23        // java/lang/Object."<init>":()V
   #2 = String             #24            // 宝马
   #3 = Fieldref           #11.#25        // BMWCar.name:Ljava/lang/String;
   #4 = Fieldref           #26.#27        // java/lang/System.out:Ljava/io/PrintStream;
   #5 = Class              #28            // java/lang/StringBuilder
   #6 = Methodref          #5.#23         // java/lang/StringBuilder."<init>":()V
   #7 = String             #29            // BMW car drive.
   #8 = Methodref          #5.#30         // java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
   #9 = Methodref          #5.#31         // java/lang/StringBuilder.toString:()Ljava/lang/String;
  #10 = Methodref          #32.#33        // java/io/PrintStream.println:(Ljava/lang/String;)V
  #11 = Class              #34            // BMWCar
  #12 = Class              #35            // java/lang/Object
  #13 = Class              #36            // Car
  #14 = Utf8               name
  #15 = Utf8               Ljava/lang/String;
  #16 = Utf8               <init>
  #17 = Utf8               ()V
  #18 = Utf8               Code
  #19 = Utf8               LineNumberTable
  #20 = Utf8               drive
  #21 = Utf8               SourceFile
  #22 = Utf8               BMWCar.java
  #23 = NameAndType        #16:#17        // "<init>":()V
  #24 = Utf8               宝马
  #25 = NameAndType        #14:#15        // name:Ljava/lang/String;
  #26 = Class              #37            // java/lang/System
  #27 = NameAndType        #38:#39        // out:Ljava/io/PrintStream;
  #28 = Utf8               java/lang/StringBuilder
  #29 = Utf8               BMW car drive.
  #30 = NameAndType        #40:#41        // append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
  #31 = NameAndType        #42:#43        // toString:()Ljava/lang/String;
  #32 = Class              #44            // java/io/PrintStream
  #33 = NameAndType        #45:#46        // println:(Ljava/lang/String;)V
  #34 = Utf8               BMWCar
  #35 = Utf8               java/lang/Object
  #36 = Utf8               Car
  #37 = Utf8               java/lang/System
  #38 = Utf8               out
  #39 = Utf8               Ljava/io/PrintStream;
  #40 = Utf8               append
  #41 = Utf8               (Ljava/lang/String;)Ljava/lang/StringBuilder;
  #42 = Utf8               toString
  #43 = Utf8               ()Ljava/lang/String;
  #44 = Utf8               java/io/PrintStream
  #45 = Utf8               println
  #46 = Utf8               (Ljava/lang/String;)V
{
  public BMWCar();
    descriptor: ()V
    flags: ACC_PUBLIC
    Code:
      stack=2, locals=1, args_size=1
         0: aload_0
         1: invokespecial #1                  // Method java/lang/Object."<init>":()V
         4: aload_0
         5: ldc           #2                  // String 宝马
         7: putfield      #3                  // Field name:Ljava/lang/String;
        10: return
      LineNumberTable:
        line 6: 0
        line 7: 4
        line 8: 10

  public void drive();
    descriptor: ()V
    flags: ACC_PUBLIC
    Code:
      stack=3, locals=1, args_size=1
         0: getstatic     #4                  // Field java/lang/System.out:Ljava/io/PrintStream;
         3: new           #5                  // class java/lang/StringBuilder
         6: dup
         7: invokespecial #6                  // Method java/lang/StringBuilder."<init>":()V
        10: ldc           #7                  // String BMW car drive.
        12: invokevirtual #8                  // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
        15: aload_0
        16: getfield      #3                  // Field name:Ljava/lang/String;
        19: invokevirtual #8                  // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
        22: invokevirtual #9                  // Method java/lang/StringBuilder.toString:()Ljava/lang/String;
        25: invokevirtual #10                 // Method java/io/PrintStream.println:(Ljava/lang/String;)V
        28: return
      LineNumberTable:
        line 12: 0
        line 13: 28
}
SourceFile: "BMWCar.java"

cp_info {
    u1 tag; //cp-info的类型
    u1 info[];//类型对应的数组
}

field_info {
    u2             access_flags;
    u2             name_index;//指向常量池的index，表示字段名
    u2             descriptor_index;//指向常量池的inde，字段的描述符
    u2             attributes_count;
    attribute_info attributes[attributes_count];
}

method_info {
    u2             access_flags;
    u2             name_index;
    u2             descriptor_index;
    u2             attributes_count;
    attribute_info attributes[attributes_count];//Code字节码信息
}

attribute_info {
    u2 attribute_name_index;
    u4 attribute_length;
    u1 info[attribute_length];
}