[fpc-devel]Library linking with C explanation

[Sergey Korshunoff]

 >> >> Reply-To: core at freepascal.org
 >> >> Date: Sun, 3 Jun 2001 15:12:42 +0200 (CEST)
 >> >> From: Peter Vreman <pfv at cooldown.demon.nl>
 >> >> X-Sender: pfv at dell
 >> >> To: core at freepascal.org
 >> >> Subject: Library linking with C working !
 >> >>
 >> >>
 >> >> It was more easy than i first thought. No need for .ctor and
 >> >> .dtor stuff. Just pass "-init <Symbolname>" to the linker and the
 >> >> symbol to run at load of the library is set. The same for -fini.
 >> >>
 >> >> The 1.0.5 compiler works correctly.
 >>
 >> Congratulation!
 >> We speak about last variant of 1.0.5 -- that is right?
 >> FPC 1.0.5 from 14 march 2001 do not works correctly.

As I see from compiler source LOG, changes are made at 6 june 2001.
And "-init SYMBOL" key is quite new for ld. My old ld do not have it.
It upgraded to GNU ld 2.10.90 (Copyright 2000 Free Software Foundation).
I use glibc v2.1.1. Result:
    In my configuration 1.0.5 _do not_ work correctly.
There is problem with argc, argv, envp.

Are You shure, that INIT function for *.so can get this args?
I look sources from ld-linux.so. As I understand, this args are
send to global constructors and not to *.so INIT function.

I examine DCC behavior.
There is no ParamCount and ParamStr avaible for library functions
( ParamCount result in DCC compiled example is 0).
And GetEnvironmentVariable() in DCC use function from libc

There is error in FPC 1.0.5 ParamCount:
  it result is -1 when argc is 0

My patches:
=========================================
diff -urN 1.0.5-010619/rtl/linux/i386/dllprt0.as rtl/linux/i386/dllprt0.as
-+- 1.0.5-010619/rtl/linux/i386/dllprt0.as Wed Jun 13 03:39:42 2001
+++ rtl/linux/i386/dllprt0.as   Tue Jun 19 18:27:48 2001
@@ -26,12 +26,16 @@
         pushl   %ebp
         movl    %esp,%ebp

-        movl    8(%ebp),%eax
-        movl    12(%ebp),%ecx
-        movl    16(%ebp),%edx
-
+#        movl    8(%ebp),%eax
+        movl    $0,%eax
         movl    %eax,U_SYSLINUX_ARGC  /* Move the argument counter    */
+
+#        movl    12(%ebp),%ecx
+        movl    $0,%ecx
         movl    %ecx,U_SYSLINUX_ARGV  /* Move the argument pointer    */
+
+#        movl    16(%ebp),%edx
+        movl    $0,%edx
         movl    %edx,U_SYSLINUX_ENVP  /* Move the environment pointer */

         movb $1,U_SYSLINUX_ISLIBRARY
diff -urN 1.0.5-010619/rtl/objpas/syspch.inc rtl/objpas/syspch.inc
-+- 1.0.5-010619/rtl/objpas/syspch.inc  Wed Jan 31 05:15:26 2001
+++ rtl/objpas/syspch.inc       Tue Jun 19 19:17:21 2001
@@ -37,8 +37,11 @@

 function StrPas(Str: PChar): string;
 begin
-  SetLength(result, StrLen(Str));
-  Move(Str^, result[1], Length(result));
+  if Str = nil then StrPas:=''
+  else begin
+    SetLength(result, StrLen(Str));
+    Move(Str^, result[1], Length(result));
+  end;
 end ;

 {  StrAlloc allocates a buffer of Size + 4
diff -urN 1.0.5-010619/rtl/unix/sysunix.inc rtl/unix/sysunix.inc
-+- 1.0.5-010619/rtl/unix/sysunix.inc   Wed Jun 13 03:40:26 2001
+++ rtl/unix/sysunix.inc        Wed Jun 20 03:01:48 2001
@@ -55,7 +55,9 @@

 Function ParamCount: Longint;
 Begin
-  Paramcount:=argc-1
+  if argc = 0 then
+    Paramcount:=argc else
+    Paramcount:=argc-1;
 End;

=========================================

Regards,
    Sergey Korshunoff