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Интерактивная система просмотра системных руководств (man-ов)

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etext (3)
  • etext (3) ( FreeBSD man: Библиотечные вызовы )
  • >> etext (3) ( Linux man: Библиотечные вызовы )
  •  

    NAME

    etext, edata, end - end of program segments
     
    

    SYNOPSIS

    extern etext;
    extern edata;
    extern end;
    
     

    DESCRIPTION

    The addresses of these symbols indicate the end of various program segments:
    etext
    This is the first address past the end of the text segment (the program code).
    edata
    This is the first address past the end of the initialized data segment.
    end
    This is the first address past the end of the uninitialized data segment (also known as the BSS segment).
     

    CONFORMING TO

    Although these symbols have long been provided on most Unix systems, they are not standardized; use with caution.  

    NOTES

    The program must explicitly declare these symbols; they are not defined in any header file.

    On some systems the names of these symbols are preceded by underscores, thus: _etext, _edata, and _end. These symbols are also defined for programs compiled on Linux.

    At the start of program execution, the program break will be somewhere near &end (perhaps at the start of the following page). However, the break will change as memory is allocated via brk(2) or malloc(3). Use sbrk(2) with an argument of zero to find the current value of the program break.  

    EXAMPLE

    When run, the program below produces output such as the following:
    
    $ ./a.out
    First address past:
        program text (etext)       0x8048568
        initialized data (edata)   0x804a01c
        uninitialized data (end)   0x804a024
    
     

    Program source

    #include <stdio.h>
    #include <stdlib.h>
    
    extern char etext, edata, end; /* The symbols must have some type,
                                       or "gcc -Wall" complains */
    
    int
    main(int argc, char *argv[])
    {
        printf("First address past:\n");
        printf("    program text (etext)      %10p\n", &etext);
        printf("    initialized data (edata)  %10p\n", &edata);
        printf("    uninitialized data (end)  %10p\n", &end);
    
        exit(EXIT_SUCCESS);
    }
    
     

    SEE ALSO

    objdump(1), readelf(1), sbrk(2), elf(5)  

    COLOPHON

    This page is part of release 3.14 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.


     

    Index

    NAME
    SYNOPSIS
    DESCRIPTION
    CONFORMING TO
    NOTES
    EXAMPLE
    Program source
    SEE ALSO
    COLOPHON


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