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Date: Thu, 21 Dec 2000 19:16:38 -0600
From: "G. Adam Stanislav" <adam@whizkidtech.net>
To: hackers@FreeBSD.org
Subject: Trouble with lseek
Message-ID: <20001221191638.A284@whizkidtech.net>
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I am trying to determine the size of a file passed as a command line
argument. I am using SYS_lseek. Here is the code up to that point:

_start:
	pop	eax		; argc
	pop	eax		; program name
	pop	ecx		; file to convert
	jecxz	usage

	pop	eax
	or	eax, eax	; Too many arguments?
	jne	usage

	; Open the file
	push	dword O_RDWR
	push	ecx
	sys.open
	jc	cantopen

	mov	ebp, eax	; Save fd

	; Find file size
	sub	eax, eax
	push	dword SEEK_END
	push	eax
	push	eax		; 0 bytes from eof
	push	ebp		; fd
	sys.lseek
	jc	facerr

Unfortunately, the SYS_lseek returns an error (carry is set, EAX=0x16=ESPIPE).
Why? I am not creating any pipes there. The fd returned by the SYS_open
is 3, as expected, so why does SYS_lseek fail?

The sys.lseek macro does a mov eax, 199 / call kernel.function, where
kernel.function is int 80h / ret.

Adam

-- 
Can you imagine the silence if everyone said only what he knows!
		-- Karel Čapek


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