Linker&loader

This digest from: self-cultivation of programmers-linking, loading and library

The format of the destination file and the executable file is similar, and the contents of the dynamic-link library and the static-link library are very similar to the executable file. For dynamic-link and static-link libraries, the. dll and. lib files are under Windows, respectively, and. So asking prices and. A files under Linux.

For executables or target files, they all have file headers. The file header describes whether the file is an executable file or a linked file or a library file.

Reasons to fragment executable files:

① Protect code Snippets.

② because the CPU cache is limited, reducing the size of the buffer can increase or decrease the hit ratio.

⑤ can share code snippets.

There are two main types of data in the target file: code and data.

Elf Head	Information in this document
Section Head Table	to describe the information for each segment, such as the name of the segment and the position and offset of the segment
. Init
. text	Code snippet
. rodata	Read-only data area	Read-only data, such as a string or const constant
. Data	Data segment	Global variables and local static variables
. BSS	does not occupy space	Uninitialized global variable and local static variable default value is 0
. symtab	Symbol table
. Debug	Debugging information
. Line
. strtab	String table
Section Header table

You can have custom segments in your executable, for example, you can use the tool objcopy to write binary files (a picture) into an executable file.

Linker&loader