os_{read,write}_file now make sure their buffers are present before calling

{read,write} on the host.

1 files changed, 36 insertions, 28 deletions

diff --git a/arch/um/os-Linux/file.c b/arch/um/os-Linux/file.c
index eabdf9a..1b9924e 100644
--- a/arch/um/os-Linux/file.c
+++ b/arch/um/os-Linux/file.c
@@ -312,20 +312,37 @@ int os_seek_file(int fd, __u64 offset)
 	return(0);
 }
 
-int os_read_file(int fd, void *buf, int len)
+static int fault_buffer(void *start, int len, 
+			int (*copy_proc)(void *addr, void *buf, int len))
 {
-	int n;
+	int page = getpagesize(), i;
+	char c;
 
-	/* Force buf into memory if it's not already. */
+	for(i = 0; i < len; i += page){
+		if((*copy_proc)(start + i, &c, sizeof(c)))
+			return(-EFAULT);
+	}
+	if((len % page) != 0){
+		if((*copy_proc)(start + len - 1, &c, sizeof(c)))
+			return(-EFAULT);
+	}
+	return(0);
+}
 
-	/* XXX This fails if buf is kernel memory */
-#ifdef notdef
-	if(copy_to_user_proc(buf, &c, sizeof(c)))
-		return(-EFAULT);
-#endif
+static int file_io(int fd, void *buf, int len,
+		   int (*io_proc)(int fd, void *buf, int len),
+		   int (*copy_user_proc)(void *addr, void *buf, int len))
+{
+	int n, err;
 
 	do {
-		n = read(fd, buf, len);
+		n = (*io_proc)(fd, buf, len);
+		if((n < 0) && (errno == EFAULT)){
+			err = fault_buffer(buf, len, copy_user_proc);
+			if(err)
+				return(err);
+			n = (*io_proc)(fd, buf, len);
+		}
 	} while((n < 0) && (errno == EINTR));
 
 	if(n < 0)
@@ -333,25 +350,16 @@ int os_read_file(int fd, void *buf, int len)
 	return(n);
 }
 
-int os_write_file(int fd, const void *buf, int count)
+int os_read_file(int fd, void *buf, int len)
 {
-	int n;
-
-	/* Force buf into memory if it's not already. */
-	
-	/* XXX This fails if buf is kernel memory */
-#ifdef notdef
-	if(copy_to_user_proc(buf, buf, buf[0]))
-		return(-EFAULT);
-#endif
-
-	do {
-		n = write(fd, buf, count);
-	} while((n < 0) && (errno == EINTR));
+	return(file_io(fd, buf, len, (int (*)(int, void *, int)) read, 
+		       copy_from_user_proc));
+}
 
-	if(n < 0)
-		return(-errno);
-	return(n);
+int os_write_file(int fd, const void *buf, int len)
+{
+	return(file_io(fd, (void *) buf, len, 
+		       (int (*)(int, void *, int)) write, copy_to_user_proc));
 }
 
 int os_file_size(char *file, long long *size_out)
@@ -610,8 +618,8 @@ int os_create_unix_socket(char *file, int len, int close_on_exec)
 
 	err = bind(sock, (struct sockaddr *) &addr, sizeof(addr));
 	if (err < 0){
-		printk("create_listening_socket - bind failed, errno = %d\n",
-		       errno);
+		printk("create_listening_socket at '%s' - bind failed, "
+		       "errno = %d\n", file, errno);
 		return(-errno);
 	}