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/*
* Low-level C file interface via JNI
*
* Adrian Bowyer
* 2 October 2005
*
*/
// Teeny class to hold the JNI calls to some C functions that access
// low-level file setup, reading and writing
class c_c_file
{
public native int c_open(String file_name); // Open file, returning a descriptor
public native void c_fcntl(int fd, int wait); // Wait (or not) for input
public native int c_write(int fd, String str, int len); // Write len bytes of str (number actually sent is returned)
public native String c_read(int fd); // Read into string
public native int c_n_read(); // Number of bytes read by c_read()
static
{
System.loadLibrary("c_c_file"); // load the .so file with the native fns.
}
}
// Wrapper class for c_c_file; this retains the static instance
// of it and the file descriptor, so the rest of the software doesn't
// need to care about them.
class c_file
{
private static int fd; // C file descriptor of the file
private static c_c_file ccf; // Instance of the C JNI calls.
// The constructor opens the file
public c_file(String file_name)
{
ccf = new c_c_file();
fd = ccf.c_open(file_name);
if(fd == -1)
System.err.println("Unable to open file:" + file_name);
}
// Wait 1 (or not 0) for input
public void fcntl(int wait)
{
ccf.c_fcntl(fd, wait);
}
// Write len bytes of str (number actually sent is returned)
public int write(String str, int len)
{
return ccf.c_write(fd, str, len);
}
// Read into string
public String read()
{
return ccf.c_read(fd);
}
// Number of bytes read by last call to c_read()
// (Nasty. But simple...)
public int n_read()
{
return ccf.c_n_read();
}
}
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