qrexec-lib: use registered callbacks

...instead of exported symbols of certain name. This is first step to
use change it to shared libraries.

qrexec-lib/copy-file.c

@@ -3,7 +3,11 @@
 #include "libqubes-rpc-filecopy.h"
 #include "crc32.h"
 
-extern void notify_progress(int, int);
+notify_progress_t *notify_progress_func = NULL;
+void register_notify_progress(notify_progress_t *func)
+{
+	notify_progress_func = func;
+}
 
 int copy_file(int outfd, int infd, long long size, unsigned long *crc32)
 {
@@ -26,7 +30,8 @@ int copy_file(int outfd, int infd, long long size, unsigned long *crc32)
 			*crc32 = Crc32_ComputeBuf(*crc32, buf, ret);
 		if (!write_all(outfd, buf, ret))
 			return COPY_FILE_WRITE_ERROR;
-		notify_progress(ret, 0);
+		if (notify_progress_func != NULL)
+			notify_progress_func(ret, 0);
 		written += ret;
 	}
 	return COPY_FILE_OK;

qrexec-lib/exec.c

@@ -22,8 +22,12 @@
 #include <stdlib.h>
 #include <unistd.h>
 #include <stdio.h>
+#include "libqrexec-utils.h"
 
-extern void do_exec(const char *);
+static do_exec_t *exec_func = NULL;
+void register_exec_func(do_exec_t *func) {
+	exec_func = func;
+}
 
 void fix_fds(int fdin, int fdout, int fderr)
 {
@@ -59,7 +63,8 @@ void do_fork_exec(const char *cmdline, int *pid, int *stdin_fd, int *stdout_fd,
 		} else
 			fix_fds(inpipe[0], outpipe[1], 2);
 
-		do_exec(cmdline);
+		if (exec_func != NULL)
+			exec_func(cmdline);
 		exit(-1);
 	default:;
 	}

qrexec-lib/libqrexec-utils.h

@@ -27,6 +27,9 @@ struct buffer {
 	int buflen;
 };
 
+typedef void (do_exec_t)(const char *);
+void register_exec_func(do_exec_t *func);
+
 void buffer_init(struct buffer *b);
 void buffer_free(struct buffer *b);
 void buffer_append(struct buffer *b, const char *data, int len);

qrexec-lib/libqubes-rpc-filecopy.h

@@ -60,6 +60,8 @@ enum {
 	COPY_FILE_WRITE_ERROR
 };
 
+typedef void (notify_progress_t)(int, int);
+void register_notify_progress(notify_progress_t *func);
 int copy_file(int outfd, int infd, long long size, unsigned long *crc32);
 char *copy_file_status_to_str(int status);
 void set_size_limit(long long new_bytes_limit, long long new_files_limit);