devman and vfs: check if a function is not implemented before calling

src/sys/devman.c

@@ -31,6 +31,10 @@ int devman_write(int *error, int dev, void* buff, size_t count, size_t offset){
 	if(major(dev) > highestmajor)
 		return ENODEV;
 
+
+	if(!majorcalls[major(dev)]->write)
+                return ENOTTY;
+
 	return majorcalls[major(dev)]->write(error, minor(dev), buff, count, offset);
 	
 	
@@ -40,6 +44,9 @@ int devman_read(int *error, int dev, void* buff, size_t count, size_t offset){
 	
 	if(major(dev) > highestmajor)
 		return ENODEV;
+
+	if(!majorcalls[major(dev)]->read)
+                return ENOTTY;
 	
 
 	return majorcalls[major(dev)]->read(error, minor(dev), buff, count, offset);
@@ -51,6 +58,9 @@ int devman_isatty(int dev){
 	
 	if(major(dev) > highestmajor)
 		return ENOTTY;
+
+	if(!majorcalls[major(dev)]->isatty)
+                return ENOTTY;
 	
 	return majorcalls[major(dev)]->isatty(minor(dev));
 	
@@ -61,6 +71,10 @@ int devman_isseekable(int dev, size_t* max){
         if(major(dev) > highestmajor)
                 return ENOTTY;
 
+	if(!majorcalls[major(dev)]->isseekable)
+                return 0;
+
+
         return majorcalls[major(dev)]->isseekable(minor(dev), max);
 
 }

src/sys/keyboard.c

@@ -127,7 +127,6 @@ int keyboard_getnew(){
 
 }
 
-static int write(int *error, int minor, void* buff, size_t count){*error = EINVAL; return -1;}
 static int read(int *error, int minor, void* buff, size_t count, size_t offset){
 	count /= sizeof(kbpacket_t);
 	if(count == 0){
@@ -146,16 +145,8 @@ static int read(int *error, int minor, void* buff, size_t count, size_t offset){
 
 }
 
-static int isatty(){
-	return ENOTTY;
-}
-
-static int seekable(){
-	return 0;
-}
-
 static devcalls calls = {
-	read, write, isatty, seekable
+	read
 };
 
 void keyboard_init(){

src/sys/pseudodevs/full.c

@@ -13,17 +13,13 @@ static int write(int* error, int minor, void* buff, size_t count, size_t offset)
 	return -1;
 }
 
-static int isatty(int minor){
-	return ENOTTY;
-}
-
 static int isseekable(int minor, size_t* max){
         *max = ~(size_t)0;
         return 0;
 }
 
 static devcalls calls = {
-	read, write, isatty, isseekable
+	read, write, NULL, isseekable
 };
 
 void fulldev_init(){

src/sys/pseudodevs/null.c

@@ -12,17 +12,13 @@ static int write(int* error, int minor, void* buff, size_t count, size_t offset)
 	return count;
 }
 
-static int isatty(int minor){
-	return ENOTTY;
-}
-
 static int isseekable(int minor, size_t* max){
         *max = ~(size_t)0;
         return 0;
 }
 
 static devcalls calls = {
-	read, write, isatty, isseekable
+	read, write, NULL, isseekable
 };
 
 void nulldev_init(){

src/sys/pseudodevs/zero.c

@@ -13,17 +13,13 @@ static int write(int* error, int minor, void* buff, size_t count, size_t offset)
 	return count;
 }
 
-static int isatty(int minor){
-	return ENOTTY;
-}
-
 static int isseekable(int minor, size_t* max){
 	*max = ~(size_t)0;
 	return 0;
 }
 
 static devcalls calls = {
-	read, write, isatty, isseekable
+	read, write, NULL, isseekable
 };
 
 void zerodev_init(){