From 0e4c64698f3e203e6ce9b78874499b4f5196a138 Mon Sep 17 00:00:00 2001
From: Kwarde <kevin@kwarde.com>
Date: Mon, 28 Jul 2025 10:16:00 +0200
Subject: [PATCH] Adds ftell(), removed reading from file in fseek/ftell tests
 (since that modifies pointer location)

---
 src/file.asm  | 23 +++++++++++++++++++++++
 src/tests.asm | 42 ++++++++++++++++--------------------------
 2 files changed, 39 insertions(+), 26 deletions(-)

diff --git a/src/file.asm b/src/file.asm
index 5190cad..5943ea5 100644
--- a/src/file.asm
+++ b/src/file.asm
@@ -16,6 +16,7 @@ section .text
 	global	fwrite
 	global	fread
 	global	fseek
+	global	ftell
 
 ;----- stat(*file[], *statBuffer[]) -----;
 ; Gets information from a file, stores it into statBuffer[]
@@ -297,3 +298,25 @@ fseek:
 	syscall
 	add	rsp, SIZE_QWORD
 	ret
+
+;--- ftell(*filePointer) ---;
+; Gets pointer location in file.
+; Return value: Pointer location or -errno on error
+; Used registers:
+;	rax*	(ret)
+;	rdi	(arg) Pointer to file
+;	rsi	syscall arg
+;	rdx	syscall arg
+ftell:
+	cmp	rdi, 2
+	jg	.cnt
+	mov	rax, -EBADF
+	ret
+	.cnt:
+	sub	rsp, SIZE_QWORD
+	mov	rax, NR_lseek
+	xor	rsi, rsi
+	mov	rdx, SEEK_CUR
+	syscall
+	add	rsp, SIZE_QWORD
+	ret
diff --git a/src/tests.asm b/src/tests.asm
index 47c90e7..7414275 100644
--- a/src/tests.asm
+++ b/src/tests.asm
@@ -98,6 +98,7 @@ extern	fgettype
 extern	fgetmod
 extern	fread
 extern	fseek
+extern	ftell
 
 section .rodata
 	;;;
@@ -139,7 +140,7 @@ section .rodata
 	TEST_fopen		equ	1 ;Includes fclose
 	TEST_fwrite		equ	1
 	TEST_fread		equ	1
-	TEST_fseek		equ	1
+	TEST_fseek		equ	1 ;Includes ftell
 	TEST_stat		equ	1
 	TEST_lstat		equ	1
 	TEST_fgettype		equ	1
@@ -356,9 +357,10 @@ section .rodata
 	;fread()
 	addTestHeader(_fread, "fread")
 	addTest(fread1, "fread(fp1, strBuff1, 64)")
-	;fseek()
+	;fseek() / ftell()
 	addTestHeader(_fseek, "fseek")
 	addTest(fseek1, "fseek(fp1, SEEK_SET, 5)")
+	addTest(ftell1, "ftell(fp1)")
 	addTest(fseek2, "fseek(fp1, SEEK_CUR, -1)")
 	addTest(fseek3, "fseek(fp1, SEEK_SET, 0)")
 	;stat()
@@ -1326,16 +1328,6 @@ _start:
 
 ;--- fseek()
 %if TEST_fseek
-	%macro fseek_relptr 1
-	%endmacro
-	%macro fseek_readput 0
-	mov	rdi, [fp1]
-	lea	rsi, [rel strBuff1]
-	mov	rdx, 64
-	call	fread
-	lea	rdi, [rel strBuff1]
-	call	puts
-	%endmacro
 	printTestHeader(_fseek)
 
 	lea	rdi, [rel file1]
@@ -1350,27 +1342,22 @@ _start:
 	mov	rdx, 5
 	call	fseek
 	assert_eq(5)
-	fseek_readput
+	printTest(ftell1)
+	mov	rdi, [fp1]
+	call	ftell
+	assert_eq(5)
 
 	; TEST 2: fseek(fp1, SEEK_CUR, -1)
 	printTest(fseek2)
 	mov	rdi, [fp1]
-	mov	rsi, SEEK_SET
-	mov	rdx, 5
-	call	fseek
-	;^ fseek_readput (fread) modified pointer, so restore it to result of test 1
-	mov	rdi, [fp1]
 	mov	rsi, SEEK_CUR
 	mov	rdx, -1
 	call	fseek
 	assert_eq(4)
-	fseek_readput
-	; FAIL. Returned is 26 (which is length of the file)
-	; My best guess is -1 is treated as unsigned. However, according to man 2 lseek:
-	;	The off_t data type is a signed integer data type
-	; ( offset in rdx is supposed to be (off_t) offset )
-	; If it turns out unsigned after all, I'll have to manually get current location of pointer (call NR_lseek with SEEK_CUR and offset 0; returned value is current location)
-	; ... and then substract given argument from that
+	printTest(ftell1)
+	mov	rdi, [fp1]
+	call	ftell
+	assert_eq(4)
 
 	; TEST 3: fseek(fp1, SEEK_SET, 0)
 	printTest(fseek3)
@@ -1379,7 +1366,10 @@ _start:
 	xor	rdx, rdx
 	call	fseek
 	assert_eq(0)
-	fseek_readput
+	printTest(ftell1)
+	mov	rdi, [fp1]
+	call	ftell
+	assert_eq(0)
 
 	mov	rdi, [fp1]
 	call	fclose