Add perror() (currently only errors 1-34 from asm-generic/errno-base.h)

console.asm

@@ -8,6 +8,46 @@ section .rodata
 	bufferLength	equ	4096
 	ERR_buffLen	db	"<!> ERROR: Failed to complete printf(), reached buffer length!",0xA,0x0
 	lERR_buffLen	equ	$-ERR_buffLen-1
+
+	; Errors (perror)
+	perrorMsg	db	"%s: %s",10,0
+	errorMsgs	dq	em0,em1,em2,em3,em4,em5,em6,em7,em8,em9,em10,em11,em12,em13,em14,em15,em16,em17,em18,em19,em20,em21,em22,em23,em24,em25,em26,em27,em28,em29,em30,em31,em32,em33,em34
+	em0		db	"No error",0
+	em1		db	"Operation not permitted",0
+	em2		db	"No such file or directory",0
+	em3		db	"No such process",0
+	em4		db	"Interrupted system call",0
+	em5		db	"I/O error",0
+	em6		db	"No such device or address",0
+	em7		db	"Argument list too long",0
+	em8		db	"Exec format error",0
+	em9		db	"Bad file number",0
+	em10		db	"No child processes",0
+	em11		db	"Try again",0
+	em12		db	"Out of memory",0
+	em13		db	"Permission denied",0
+	em14		db	"Bad address",0
+	em15		db	"Block device required",0
+	em16		db	"Device or resource busy",0
+	em17		db	"File exists",0
+	em18		db	"Cross-device link",0
+	em19		db	"No such device",0
+	em20		db	"Not a directory",0
+	em21		db	"Is a directory",0
+	em22		db	"Invalid argument",0
+	em23		db	"File table overflow",0
+	em24		db	"Too many open files",0
+	em25		db	"Not a typewriter",0
+	em26		db	"Text file busy",0
+	em27		db	"File too large",0
+	em28		db	"No space left on device",0
+	em29		db	"Illegal seek",0
+	em30		db	"Read-only file system",0
+	em31		db	"Too many links",0
+	em32		db	"Broken pipe",0
+	em33		db	"Math argument out of domain of func",0
+	em34		db	"Math result not representable",0
+
 section .bss
 	printfBuff	resb	bufferLength
 	printfNBuff	resb	32
@@ -15,6 +55,7 @@ section .text
 	global	print
 	global	puts
 	global	printf
+	global	perror
 
 ;----- print (char* string) -----;
 ; return value: N/A
@@ -212,3 +253,22 @@ printf:
 
 	leave
 	ret
+;----- perror(const char *str) -----;
+; retrieves last returned error. Uses rax to fetch errno.
+; errno must be negative
+; Returns nothing (rax restored to original value)
+perror:
+	push	rax
+	cmp	rax, 0
+	jge	.quit
+	neg	rax
+	cmp	rax, 34
+	jg	.quit
+	mov	rsi, rdi
+	lea	rdi, [rel perrorMsg]
+	lea	rdx, [errorMsgs + rax*8]
+	mov	rdx, [rdx]
+	call	printf
+	.quit:
+	pop	rax
+	ret