Add a few consts where appropriate

qrexec-lib/copy-file.c

@@ -37,7 +37,7 @@ int copy_file(int outfd, int infd, long long size, unsigned long *crc32)
 	return COPY_FILE_OK;
 }
 
-char * copy_file_status_to_str(int status)
+const char * copy_file_status_to_str(int status)
 {
 	switch (status) {
 		case COPY_FILE_OK: return "OK";

qrexec-lib/libqrexec-utils.h

@@ -47,7 +47,7 @@ int read_ready_vchan_ext(void);
 int read_all(int fd, void *buf, int size);
 int read_all_vchan_ext(void *buf, int size);
 int write_all(int fd, const void *buf, int size);
-int write_all_vchan_ext(void *buf, int size);
+int write_all_vchan_ext(const void *buf, int size);
 int buffer_space_vchan_ext(void);
 void fix_fds(int fdin, int fdout, int fderr);
 void set_nonblock(int fd);

qrexec-lib/libqubes-rpc-filecopy.h

@@ -63,7 +63,7 @@ enum {
 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);
+const char *copy_file_status_to_str(int status);
 void set_size_limit(long long new_bytes_limit, long long new_files_limit);
 void set_verbose(int value);
 int write_all(int fd, const void *buf, int size);

qrexec-lib/txrx-vchan.c

@@ -36,7 +36,7 @@ int write_all_vchan_ext(const void *buf, int size)
 
 	while (written < size) {
 		ret =
-		    libvchan_write(ctrl, (char *) buf + written,
+		    libvchan_write(ctrl, (const char *) buf + written,
 				   size - written);
 		if (ret <= 0) {
 			perror("write");