wip: Build with -Wconversionlukeshu/safe-conversion

I think this found a real bug in the dhcp packet parser.

I don't think anything called lib9p_str{,n}() values that could be big
enough, but their bounds-checking was broken.

1 files changed, 7 insertions, 7 deletions

diff --git a/lib9p/srv.c b/lib9p/srv.c
index fc5d0f2..a4ac369 100644
--- a/lib9p/srv.c
+++ b/lib9p/srv.c
@@ -398,7 +398,7 @@ static void srv_respond_error(struct srv_req *req) {
 	/* Truncate the error-string if necessary to avoid needing to
 	 * return LIB9P_ERRNO_L_ERANGE.  */
 	if (((uint32_t)host.errstr.len) + overhead > sess->max_msg_size)
-		host.errstr.len = sess->max_msg_size - overhead;
+		host.errstr.len = (uint16_t)(sess->max_msg_size - overhead);
 
 	struct lib9p_Rmsg_send_buf net;
 
@@ -409,7 +409,7 @@ static void srv_respond_error(struct srv_req *req) {
 	srv_msglog(req, LIB9P_TYP_Rerror, &host);
 	r = srv_write_Rmsg(req, &net);
 	if (r < 0)
-		srv_nonrespond_errorf("write: %s", net_strerror(-r));
+		srv_nonrespond_errorf("write: %s", net_strerror(LM_SAFEDOWNCAST(int, -r)));
 }
 
 /* read coroutine *************************************************************/
@@ -421,14 +421,14 @@ static inline bool srv_read_exactly(lo_interface net_stream_conn fd, uint8_t *bu
 	while (*done < goal) {
 		ssize_t r = io_read(fd, &buf[*done], goal - *done);
 		if (r < 0) {
-			srv_nonrespond_errorf("read: %s", net_strerror(-r));
+			srv_nonrespond_errorf("read: %s", net_strerror(LM_SAFEDOWNCAST(int, -r)));
 			return true;
 		} else if (r == 0) {
 			if (*done != 0)
 				srv_nonrespond_errorf("read: unexpected EOF");
 			return true;
 		}
-		*done += r;
+		*done += LM_SAFEDOWNCAST(size_t, r);
 	}
 	return false;
 }
@@ -623,7 +623,7 @@ void lib9p_srv_worker(struct srv_req *ctx) {
 		srv_respond_error(ctx);
 		goto release;
 	}
-	host_req = calloc(1, host_size);
+	host_req = calloc(1, LM_SAFEDOWNCAST(size_t, host_size));
 	assert(host_req);
 	enum lib9p_msg_type typ;
 	lib9p_Tmsg_unmarshal(&ctx->basectx, ctx->net_bytes,
@@ -1064,7 +1064,7 @@ static void handle_Topen(struct srv_req *ctx,
 	}
 	if (stat.mode & LIB9P_DM_APPEND) {
 		fidflags |= FIDFLAG_APPEND;
-		reqmode = reqmode & ~LIB9P_O_TRUNC;
+		reqmode &= LM_BITFLIP(LIB9P_O_TRUNC);
 	}
 	uint8_t perm_bits = 0;
 	bool rd = false, wr = false;
@@ -1277,7 +1277,7 @@ static void handle_Tread(struct srv_req *ctx,
 		struct iovec iov;
 		LO_CALL(fidinfo->file.io, pread, ctx, req->count, req->offset, &iov);
 		if (!lib9p_ctx_has_error(&ctx->basectx) && !ctx->flush_acknowledged) {
-			resp.count = iov.iov_len;
+			resp.count = LM_SAFEDOWNCAST(iov.iov_len);
 			resp.data = iov.iov_base;
 			if (resp.count > req->count)
 				resp.count = req->count;