X-Authentication-Warning:	sirppi.helsinki.fi: peuha owned process doing -bs
Date:	Wed, 26 Jan 2000 09:00:24 +0200 (EET)
From:	Esa A E Peuha <peuha AT cc DOT helsinki DOT fi>
Sender:	peuha AT cc DOT helsinki DOT fi
To:	djgpp-workers AT delorie DOT com
Subject:	Patch for crt0.S
Message-ID:	<Pine.OSF.4.20.0001260859090.17239-100000@sirppi.helsinki.fi>
MIME-Version:	1.0
Reply-To:	djgpp-workers AT delorie DOT com

Here's a patch to crt0.S.  This prevents the program from crashing in the
rare case when the very first call to ___sbrk fails.

*** src/libc/crt0/crt0.S	Wed Aug 11 02:24:38 1999
--- src/libc/crt0/crt0~.S	Sun Jan 23 21:19:34 2000
***************
*** 42,47 ****
--- 42,51 ----
  	.long	0
  sbrk16_api_seg:
  	.word	0
+ stubinfo_ds_selector:
+ 	.word	0
+ stubinfo_cs_selector:
+ 	.word	0
  zero:
  	.long	0
          
***************
*** 99,104 ****
--- 103,116 ----
  	stosl
  #endif
  
+ /* These are for the exit code, to allow it to be called before stubinfo is moved */
+ 	.byte 0x64 /* fs: */
+ 	pushw	STUBINFO_DS_SELECTOR
+ 	popw	stubinfo_ds_selector
+ 	.byte 0x64 /* fs: */
+ 	pushw	STUBINFO_CS_SELECTOR
+ 	popw	stubinfo_cs_selector
+ 
  /* Enable NULL pointer protection if DPMI supports it */
  	testb	$0x1, __crt0_startup_flags+1		/* include/crt0.h */
  	jnz	1f
***************
*** 238,243 ****
--- 250,257 ----
  	movl	STUBINFO_SIZE, %eax
  	pushl	%eax
  	call	___sbrk
+ 	cmpl	$-1, %eax
+ 	je	no_memory
  	movl	%eax, __stubinfo
  	movl	%eax, %edi
  	.byte 0x64 /* fs: */
***************
*** 329,341 ****
  	movw	$0x101, %ax
  	int	$0x31			/* Free block and selector */
  9:
! 	movl	__stubinfo, %edx
! 	movl	STUBINFO_CS_SELECTOR(%edx), %eax
  	movw	%ax, sbrk16_api_seg
  	xorl	%edi, %edi
  	movl	%edi, sbrk16_api_ofs	/* Offset is zero */
  
! 	movw	STUBINFO_DS_SELECTOR(%edx), %es
  	movb	%cl, %dl		/* Exit status */
  	movl	$exit16_first_byte, %esi
  	movl	$(exit16_last_byte - exit16_first_byte), %ecx
--- 343,354 ----
  	movw	$0x101, %ax
  	int	$0x31			/* Free block and selector */
  9:
! 	movw	stubinfo_cs_selector, %ax
  	movw	%ax, sbrk16_api_seg
  	xorl	%edi, %edi
  	movl	%edi, sbrk16_api_ofs	/* Offset is zero */
  
! 	movw	stubinfo_ds_selector, %es
  	movb	%cl, %dl		/* Exit status */
  	movl	$exit16_first_byte, %esi
  	movl	$(exit16_last_byte - exit16_first_byte), %ecx

-- 
Esa Peuha
student of mathematics at the University of Helsinki
http://www.helsinki.fi/~peuha/

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