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Creating a C Library: Difference between revisions
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Link to the global constructors article, fix symbol sizes
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(Link to the global constructors article, fix symbol sizes) |
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= Program Initialization =
:''See also: [[Calling Global Constructors]]''
The first and most important thing to implement in a C library is the _start function, to which control is passed from your program loader. It's task is to initialize and run the process. Normally this is done by initializing the C library (if needed), then calling the global constructors, and finally calling exit(main(argc, argv)). You can change the name of the default program entry point by adding ENTRY=_my_start_name in your OS-specific binutils emulparams script (binutils/ld/emulparams). You can change which start files are used by modifying gcc/gcc/config/myos.h in your OS-specific GCC. The macros STARTFILE_SPEC and ENDFILE_SPEC define the object files to use in the GCC spec language. See gcc/gcc/config/gnu-user.h for examples on how to use this. If you decide to use the conventional (GNU-like) names and semantics for these initialization files, the following information applies:
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popq %rbp
ret
.size _init, . - _init
.section .fini
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popq %rbp
ret
.size _fini, . - _fini
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