Initialization sections not being run in Linux so.

[technomage]

OK, I compiled the following code into a shared object

void __attribute__ ((constructor)) lib_init(void)
{
  printf("lib_init called");
}

void __attribute__ ((destructor)) lib_quit(void)
{
  printf("lib_quit called");
}

void printUPPERCASE( inLine )
char inLine[];
{
  char Upstring[256];
  char *inptr, *outptr;

  inptr = inLine;
  outptr = Upstring;
  while (*inptr != '\0')
   *outptr++ = toupper(*inptr++);
  *outptr++ = '\0';
  printf(Upstring);
  return;
}

I used

gcc -c -fpic test.c

then

gcc -shared -lc -o test.so test.o

and ran

objdump -t -x test.so

Here are the results. after doing a bit of reading it seems the ((constructor)) style stuff ends up in the .ctors section and the ((destructor)) ends up in the .dtors

test.so:     file format elf32-i386
test.so
architecture: i386, flags 0x00000150:
HAS_SYMS, DYNAMIC, D_PAGED
start address 0x000004f0

Program Header:
    LOAD off    0x00000000 vaddr 0x00000000 paddr 0x00000000 align 2**12
         filesz 0x00000710 memsz 0x00000710 flags r-x
    LOAD off    0x00000710 vaddr 0x00001710 paddr 0x00001710 align 2**12
         filesz 0x0000010c memsz 0x00000110 flags rw-
 DYNAMIC off    0x0000072c vaddr 0x0000172c paddr 0x0000172c align 2**2
         filesz 0x000000c0 memsz 0x000000c0 flags rw-
   STACK off    0x00000000 vaddr 0x00000000 paddr 0x00000000 align 2**2
         filesz 0x00000000 memsz 0x00000000 flags rw-
PAX_FLAGS off    0x00000000 vaddr 0x00000000 paddr 0x00000000 align 2**2
         filesz 0x00000000 memsz 0x00000000 flags --- 2800

Dynamic Section:
  NEEDED      libc.so.6
  INIT        0x480
  FINI        0x6d0
  HASH        0xd4
  STRTAB      0x314
  SYMTAB      0x184
  STRSZ       0xaa
  SYMENT      0x10
  PLTGOT      0x17f8
  PLTRELSZ    0x20
  PLTREL      0x11
  JMPREL      0x458
  REL         0x420
  RELSZ       0x38
  RELENT      0x8
  VERNEED     0x3f0
  VERNEEDNUM  0x1
  VERSYM      0x3be
  RELCOUNT    0x2

Version References:
  required from libc.so.6:
    0x09691f73 0x00 03 GLIBC_2.1.3
    0x0d696910 0x00 02 GLIBC_2.0

Sections:
Idx Name          Size      VMA       LMA       File off  Algn
  0 .hash         000000b0  000000d4  000000d4  000000d4  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  1 .dynsym       00000190  00000184  00000184  00000184  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  2 .dynstr       000000aa  00000314  00000314  00000314  2**0
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  3 .gnu.version  00000032  000003be  000003be  000003be  2**1
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  4 .gnu.version_r 00000030  000003f0  000003f0  000003f0  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  5 .rel.dyn      00000038  00000420  00000420  00000420  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  6 .rel.plt      00000020  00000458  00000458  00000458  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  7 .init         00000017  00000480  00000480  00000480  2**4
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
  8 .plt          00000050  00000498  00000498  00000498  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
  9 .text         000001dc  000004f0  000004f0  000004f0  2**4
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
 10 .fini         0000001b  000006d0  000006d0  000006d0  2**4
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
 11 .rodata       00000020  000006eb  000006eb  000006eb  2**0
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
 12 .eh_frame     00000004  0000070c  0000070c  0000070c  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
 13 .ctors        0000000c  00001710  00001710  00000710  2**2
                  CONTENTS, ALLOC, LOAD, DATA
 14 .dtors        0000000c  0000171c  0000171c  0000071c  2**2
                  CONTENTS, ALLOC, LOAD, DATA
 15 .jcr          00000004  00001728  00001728  00000728  2**2
                  CONTENTS, ALLOC, LOAD, DATA
 16 .dynamic      000000c0  0000172c  0000172c  0000072c  2**2
                  CONTENTS, ALLOC, LOAD, DATA
 17 .got          0000000c  000017ec  000017ec  000007ec  2**2
                  CONTENTS, ALLOC, LOAD, DATA
 18 .got.plt      0000001c  000017f8  000017f8  000007f8  2**2
                  CONTENTS, ALLOC, LOAD, DATA
 19 .data         00000008  00001814  00001814  00000814  2**2
                  CONTENTS, ALLOC, LOAD, DATA
 20 .bss          00000004  0000181c  0000181c  0000081c  2**2
                  ALLOC
 21 .comment      00000136  00000000  00000000  0000081c  2**0
                  CONTENTS, READONLY
 22 .debug_aranges 00000068  00000000  00000000  00000958  2**3
                  CONTENTS, READONLY, DEBUGGING
 23 .debug_info   00000164  00000000  00000000  000009c0  2**0
                  CONTENTS, READONLY, DEBUGGING
 24 .debug_abbrev 00000020  00000000  00000000  00000b24  2**0
                  CONTENTS, READONLY, DEBUGGING
 25 .debug_line   00000179  00000000  00000000  00000b44  2**0
                  CONTENTS, READONLY, DEBUGGING
SYMBOL TABLE:
000000d4 l    d  .hash	00000000              .hash
00000184 l    d  .dynsym	00000000              .dynsym
00000314 l    d  .dynstr	00000000              .dynstr
000003be l    d  .gnu.version	00000000              .gnu.version
000003f0 l    d  .gnu.version_r	00000000              .gnu.version_r
00000420 l    d  .rel.dyn	00000000              .rel.dyn
00000458 l    d  .rel.plt	00000000              .rel.plt
00000480 l    d  .init	00000000              .init
00000498 l    d  .plt	00000000              .plt
000004f0 l    d  .text	00000000              .text
000006d0 l    d  .fini	00000000              .fini
000006eb l    d  .rodata	00000000              .rodata
0000070c l    d  .eh_frame	00000000              .eh_frame
00001710 l    d  .ctors	00000000              .ctors
0000171c l    d  .dtors	00000000              .dtors
00001728 l    d  .jcr	00000000              .jcr
0000172c l    d  .dynamic	00000000              .dynamic
000017ec l    d  .got	00000000              .got
000017f8 l    d  .got.plt	00000000              .got.plt
00001814 l    d  .data	00000000              .data
0000181c l    d  .bss	00000000              .bss
00000000 l    d  .comment	00000000              .comment
00000000 l    d  .debug_aranges	00000000              .debug_aranges
00000000 l    d  .debug_info	00000000              .debug_info
00000000 l    d  .debug_abbrev	00000000              .debug_abbrev
00000000 l    d  .debug_line	00000000              .debug_line
00000000 l    d  *ABS*	00000000              .shstrtab
00000000 l    d  *ABS*	00000000              .symtab
00000000 l    d  *ABS*	00000000              .strtab
00000000 l    df *ABS*	00000000              initfini.c
00000000 l    df *ABS*	00000000              /var/tmp/portage/glibc-2.3.6-r3/work/build-default-i386-pc-linux-gnu-linuxthreads/csu/crti.S
000004f0 l     F .text	00000000              call_gmon_start
00000000 l    df *ABS*	00000000              crtstuff.c
00001710 l     O .ctors	00000000              __CTOR_LIST__
0000171c l     O .dtors	00000000              __DTOR_LIST__
00001728 l     O .jcr	00000000              __JCR_LIST__
00001818 l     O .data	00000000              p.0
0000181c l     O .bss	00000001              completed.1
00000518 l     F .text	00000000              __do_global_dtors_aux
00000574 l     F .text	00000000              frame_dummy
00000000 l    df *ABS*	00000000              crtstuff.c
00001718 l     O .ctors	00000000              __CTOR_END__
00001724 l     O .dtors	00000000              __DTOR_END__
0000070c l     O .eh_frame	00000000              __FRAME_END__
00001728 l     O .jcr	00000000              __JCR_END__
0000069c l     F .text	00000000              __do_global_ctors_aux
00000000 l    df *ABS*	00000000              initfini.c
00000000 l    df *ABS*	00000000              /var/tmp/portage/glibc-2.3.6-r3/work/build-default-i386-pc-linux-gnu-linuxthreads/csu/crtn.S
00000000 l    df *ABS*	00000000              test.c
00001814 l     O .data	00000000              .hidden __dso_handle
00000512 l     F .text	00000000              .hidden __i686.get_pc_thunk.bx
000017f8 l     O *ABS*	00000000              .hidden _GLOBAL_OFFSET_TABLE_
0000172c g     O *ABS*	00000000              _DYNAMIC
00000608 g     F .text	00000092              printUPPERCASE
00000480 g     F .init	00000000              _init
000005de g     F .text	0000002a              lib_quit
0000181c g       *ABS*	00000000              __bss_start
00000000       F *UND*	00000062              toupper@@GLIBC_2.0
00000000       F *UND*	00000036              printf@@GLIBC_2.0
000006d0 g     F .fini	00000000              _fini
00000000  w    F *UND*	0000008c              __cxa_finalize@@GLIBC_2.1.3
0000181c g       *ABS*	00000000              _edata
00001820 g       *ABS*	00000000              _end
000005b4 g     F .text	0000002a              lib_init
00000000  w      *UND*	00000000              _Jv_RegisterClasses
00000000  w      *UND*	00000000              __gmon_start__