Partially Linked to Dynamic Linking in C











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I'm still struggling to understand the core difference between dynamic linking and static linking, below is a picture and sample code from my textbook:



/* main2.c */
#include <stdio.h>
#include "vector.h"

int x[2] = {1, 2};
int y[2] = {3, 4};
int z[2];

int main()
{
addvec(x, y, z, 2);
printf("z = [%d %d]n", z[0], z[1]);
return 0;
}


and libvector.so just a DLL that provides definition needed by main2.c



enter image description here



So my questions are:



Why p2 is a 'partially linked executable object file'? Since it is called 'partially linked', so it must have done some static linking. But since none of the code or data sections from libvector.so or libc.so are actually copied into the executable p2 at this point. So why p2 is still 'partially linked'? Isn't the static linking is about copying code and data sections from objects files, if there is no copy, then there is no static linking involved?










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  • 1




    The two object files have been incorporated into the executable, along with information about the functions that they call that are, presumably, supplied by the shared objects. Most people would call p2 and executable, and leave the 'partially linked' out of the equation. I suppose it is only partially linked by comparison with what runs after the dynamic loader (linker) has finished, but that's not relevant to most people.
    – Jonathan Leffler
    Nov 8 at 6:49










  • There is only one object file in the partially linked executable itself (main.o)
    – Antti Haapala
    Nov 8 at 7:02










  • @AnttiHaapala: OK — that should have started "The object file has"… Many (most?) programs have more than one object file (though "more than one" often means "more than two", too).
    – Jonathan Leffler
    Nov 8 at 7:20

















up vote
2
down vote

favorite












I'm still struggling to understand the core difference between dynamic linking and static linking, below is a picture and sample code from my textbook:



/* main2.c */
#include <stdio.h>
#include "vector.h"

int x[2] = {1, 2};
int y[2] = {3, 4};
int z[2];

int main()
{
addvec(x, y, z, 2);
printf("z = [%d %d]n", z[0], z[1]);
return 0;
}


and libvector.so just a DLL that provides definition needed by main2.c



enter image description here



So my questions are:



Why p2 is a 'partially linked executable object file'? Since it is called 'partially linked', so it must have done some static linking. But since none of the code or data sections from libvector.so or libc.so are actually copied into the executable p2 at this point. So why p2 is still 'partially linked'? Isn't the static linking is about copying code and data sections from objects files, if there is no copy, then there is no static linking involved?










share|improve this question




















  • 1




    The two object files have been incorporated into the executable, along with information about the functions that they call that are, presumably, supplied by the shared objects. Most people would call p2 and executable, and leave the 'partially linked' out of the equation. I suppose it is only partially linked by comparison with what runs after the dynamic loader (linker) has finished, but that's not relevant to most people.
    – Jonathan Leffler
    Nov 8 at 6:49










  • There is only one object file in the partially linked executable itself (main.o)
    – Antti Haapala
    Nov 8 at 7:02










  • @AnttiHaapala: OK — that should have started "The object file has"… Many (most?) programs have more than one object file (though "more than one" often means "more than two", too).
    – Jonathan Leffler
    Nov 8 at 7:20















up vote
2
down vote

favorite









up vote
2
down vote

favorite











I'm still struggling to understand the core difference between dynamic linking and static linking, below is a picture and sample code from my textbook:



/* main2.c */
#include <stdio.h>
#include "vector.h"

int x[2] = {1, 2};
int y[2] = {3, 4};
int z[2];

int main()
{
addvec(x, y, z, 2);
printf("z = [%d %d]n", z[0], z[1]);
return 0;
}


and libvector.so just a DLL that provides definition needed by main2.c



enter image description here



So my questions are:



Why p2 is a 'partially linked executable object file'? Since it is called 'partially linked', so it must have done some static linking. But since none of the code or data sections from libvector.so or libc.so are actually copied into the executable p2 at this point. So why p2 is still 'partially linked'? Isn't the static linking is about copying code and data sections from objects files, if there is no copy, then there is no static linking involved?










share|improve this question















I'm still struggling to understand the core difference between dynamic linking and static linking, below is a picture and sample code from my textbook:



/* main2.c */
#include <stdio.h>
#include "vector.h"

int x[2] = {1, 2};
int y[2] = {3, 4};
int z[2];

int main()
{
addvec(x, y, z, 2);
printf("z = [%d %d]n", z[0], z[1]);
return 0;
}


and libvector.so just a DLL that provides definition needed by main2.c



enter image description here



So my questions are:



Why p2 is a 'partially linked executable object file'? Since it is called 'partially linked', so it must have done some static linking. But since none of the code or data sections from libvector.so or libc.so are actually copied into the executable p2 at this point. So why p2 is still 'partially linked'? Isn't the static linking is about copying code and data sections from objects files, if there is no copy, then there is no static linking involved?







c linker dynamic-linking






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edited Nov 8 at 7:26









Antti Haapala

79k16148191




79k16148191










asked Nov 8 at 6:37









amjad

3047




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  • 1




    The two object files have been incorporated into the executable, along with information about the functions that they call that are, presumably, supplied by the shared objects. Most people would call p2 and executable, and leave the 'partially linked' out of the equation. I suppose it is only partially linked by comparison with what runs after the dynamic loader (linker) has finished, but that's not relevant to most people.
    – Jonathan Leffler
    Nov 8 at 6:49










  • There is only one object file in the partially linked executable itself (main.o)
    – Antti Haapala
    Nov 8 at 7:02










  • @AnttiHaapala: OK — that should have started "The object file has"… Many (most?) programs have more than one object file (though "more than one" often means "more than two", too).
    – Jonathan Leffler
    Nov 8 at 7:20
















  • 1




    The two object files have been incorporated into the executable, along with information about the functions that they call that are, presumably, supplied by the shared objects. Most people would call p2 and executable, and leave the 'partially linked' out of the equation. I suppose it is only partially linked by comparison with what runs after the dynamic loader (linker) has finished, but that's not relevant to most people.
    – Jonathan Leffler
    Nov 8 at 6:49










  • There is only one object file in the partially linked executable itself (main.o)
    – Antti Haapala
    Nov 8 at 7:02










  • @AnttiHaapala: OK — that should have started "The object file has"… Many (most?) programs have more than one object file (though "more than one" often means "more than two", too).
    – Jonathan Leffler
    Nov 8 at 7:20










1




1




The two object files have been incorporated into the executable, along with information about the functions that they call that are, presumably, supplied by the shared objects. Most people would call p2 and executable, and leave the 'partially linked' out of the equation. I suppose it is only partially linked by comparison with what runs after the dynamic loader (linker) has finished, but that's not relevant to most people.
– Jonathan Leffler
Nov 8 at 6:49




The two object files have been incorporated into the executable, along with information about the functions that they call that are, presumably, supplied by the shared objects. Most people would call p2 and executable, and leave the 'partially linked' out of the equation. I suppose it is only partially linked by comparison with what runs after the dynamic loader (linker) has finished, but that's not relevant to most people.
– Jonathan Leffler
Nov 8 at 6:49












There is only one object file in the partially linked executable itself (main.o)
– Antti Haapala
Nov 8 at 7:02




There is only one object file in the partially linked executable itself (main.o)
– Antti Haapala
Nov 8 at 7:02












@AnttiHaapala: OK — that should have started "The object file has"… Many (most?) programs have more than one object file (though "more than one" often means "more than two", too).
– Jonathan Leffler
Nov 8 at 7:20






@AnttiHaapala: OK — that should have started "The object file has"… Many (most?) programs have more than one object file (though "more than one" often means "more than two", too).
– Jonathan Leffler
Nov 8 at 7:20














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The partially linked executable would have all of the .o object files (here only main.o) linked together, and possibly linking stubs, relocation tables and such to facilitate dynamic linking. The dynamic linker does just the remaining "n %" just before running the program.






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    The partially linked executable would have all of the .o object files (here only main.o) linked together, and possibly linking stubs, relocation tables and such to facilitate dynamic linking. The dynamic linker does just the remaining "n %" just before running the program.






    share|improve this answer

























      up vote
      1
      down vote













      The partially linked executable would have all of the .o object files (here only main.o) linked together, and possibly linking stubs, relocation tables and such to facilitate dynamic linking. The dynamic linker does just the remaining "n %" just before running the program.






      share|improve this answer























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        up vote
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        down vote









        The partially linked executable would have all of the .o object files (here only main.o) linked together, and possibly linking stubs, relocation tables and such to facilitate dynamic linking. The dynamic linker does just the remaining "n %" just before running the program.






        share|improve this answer












        The partially linked executable would have all of the .o object files (here only main.o) linked together, and possibly linking stubs, relocation tables and such to facilitate dynamic linking. The dynamic linker does just the remaining "n %" just before running the program.







        share|improve this answer












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        answered Nov 8 at 7:07









        Antti Haapala

        79k16148191




        79k16148191






























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