Create LinuxAPI_16_limits.asm

Author: XlogicX

ASM_x86/LinuxAPI_16_limits.asm

@@ -0,0 +1,73 @@
+; Mess with a resource limit of process and fail resource usages using get and setlimit API Calls
+; API calls found in this example program:
+; 	getpriority, setpriority, write, exit
+; High level description of what theis example program does:
+;	Get current open file handle limit values using getlimit()
+;	Set the value to 0 (even 2 would be too low to open a new handle; because STDIN/OUT/ERR)
+;	Try to open a new file handle (get error)
+
+section .text
+global _start
+
+_start:
+
+; How many file handles can we have open? (I got 1024 when I ran this)
+;------------------------------------------------------------------------------
+	mov 	eax, 76			; getlimit()
+	mov		ebx, 7
+	mov		ecx, rlimit		; data structure for rusage
+    int    	0x80
+
+; Set the limit to none #lol
+;------------------------------------------------------------------------------
+	mov 	eax, 75			; setlimit()
+	mov		ebx, 7
+	mov		ecx, cpusoft	; data structure for rusage
+    int    	0x80
+
+; Try opening a file
+;------------------------------------------------------------------------------
+	mov		eax, 5				;open
+	mov		ebx, newfile		;pointer to the filename
+	mov		ecx, 0				;Flags, for Read Only
+	int		0x80
+	; If the file exists, the return value should be error code ...ffffffe8
+	; which is: EMFILE (Too many open files)
+
+; Exit
+;------------------------------------------------------------------------------
+	mov 	eax, 1
+	int 	0x80
+
+section .data
+	cpusoft	dd 0
+	cpuhard dd 0
+	newfile db 'LinuxAPI_16_limits.asm', 0x00
+
+section .bss
+	rlimit resb 8
+	filehandle resb 4
+
+; rlimit data structure
+;------------------------------------------------------------------------------
+; soft limit
+; hard limit
+
+; Resource Codes
+;------------------------------------------------------------------------------
+; 0 - CPU			CPU time (seconds)
+; 1 - FSIZE			File size (bytes)
+; 2 - DATA			Process data segment (bytes)
+; 3 - STACK			Size of stack segment (bytes)
+; 4 - CORE			Core file size (bytes)
+; 5 - RSS			Resident set size (bytes; not implemented)
+; 6 - NPROC			Number of processes for real user ID
+; 7 - NOFILE		Maximum file descriptor number plus one
+; 8 - MEMLOCK		Locked memory (bytes)
+; 9 - AS			Process virtual memory size (bytes)
+; 10 - LOCKS		Number of locks
+; 11 - SIGPENDING	Number of queued signals for real user ID
+; 12 - MSGQUEUE		Bytes allocated for POSIX message queues for real user ID
+; 13 - NICE			Nice value
+; 14 - RTPRIO		Realtime scheduling priority
+; 15 - RTTIME		Realtime CPU time (microseconds)