From 5ddff681670a0090cab6486d467399d92dffbef6 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sigrid=20Solveig=20Hafl=C3=ADnud=C3=B3ttir?=
 <ftrvxmtrx@gmail.com>
Date: Wed, 30 Mar 2022 20:55:33 +0000
Subject: [PATCH] libtags: m4a: do not div by zero

---
 sys/src/cmd/audio/libtags/m4a.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/sys/src/cmd/audio/libtags/m4a.c b/sys/src/cmd/audio/libtags/m4a.c
index b1e0fda30..924ba51a2 100644
--- a/sys/src/cmd/audio/libtags/m4a.c
+++ b/sys/src/cmd/audio/libtags/m4a.c
@@ -8,6 +8,7 @@ int
 tagm4a(Tagctx *ctx)
 {
 	uvlong duration;
+	uint x;
 	uchar *d;
 	int sz, type, dtype, i, skip, n;
 
@@ -101,12 +102,14 @@ tagm4a(Tagctx *ctx)
 				if(ctx->read(ctx, d, 16) != 16)
 					return -1;
 				sz -= 16;
-				duration = beuint(&d[12]) / beuint(&d[8]);
+				if((x = beuint(&d[8])) > 0)
+					duration = beuint(&d[12]) / x;
 			}else if(d[1] == 1){ /* version 1 */
 				if(ctx->read(ctx, d, 28) != 28)
 					return -1;
 				sz -= 28;
-				duration = ((uvlong)beuint(&d[20])<<32 | beuint(&d[24])) / (uvlong)beuint(&d[16]);
+				if((x = beuint(&d[16])) > 0)
+					duration = ((uvlong)beuint(&d[20])<<32 | beuint(&d[24])) / (uvlong)x;
 			}
 			ctx->duration = duration * 1000;
 			continue;