From 42982b5a5d461530a792e69b3e8abdd9d6d67052 Mon Sep 17 00:00:00 2001
From: Frank Plowman <post@frankplowman.com>
Date: Fri, 22 Dec 2023 12:00:01 +0000
Subject: [PATCH] avformat/ffrtmpcrypt: Fix int-conversion warning
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The gcrypt definition of `bn_new` used to use the return statement
on errors, with an AVERROR return value, regardless of the signature
of the function where the macro is used - it is called in
`dh_generate_key` and `ff_dh_init` which return pointers. As a result,
compiling with gcrypt and the ffrtmpcrypt protocol resulted in an
int-conversion warning. GCC 14 may upgrade these to errors [1].

This patch fixes the problem by changing the macro to remove `AVERROR`
and instead set `bn` to null if the allocation fails. This is the
behaviour of all the other `bn_new` implementations and so the result is
already checked at all the callsites. AFAICT, this should be the only
change needed to get ffmpeg off Fedora's naughty list of projects with
warnings which may be upgraded to errors in GCC 14 [2].

[1]: https://gcc.gnu.org/pipermail/gcc/2023-May/241264.html
[2]: https://www.mail-archive.com/devel@lists.fedoraproject.org/msg196024.html

Signed-off-by: Frank Plowman <post@frankplowman.com>
Signed-off-by: Martin Storsjö <martin@martin.st>
---
 libavformat/rtmpdh.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/libavformat/rtmpdh.c b/libavformat/rtmpdh.c
index 5ddae537a1..6a6c2ccd87 100644
--- a/libavformat/rtmpdh.c
+++ b/libavformat/rtmpdh.c
@@ -113,15 +113,18 @@ static int bn_modexp(FFBigNum bn, FFBigNum y, FFBigNum q, FFBigNum p)
     return 0;
 }
 #elif CONFIG_GCRYPT
-#define bn_new(bn)                                              \
-    do {                                                        \
-        if (!gcry_control(GCRYCTL_INITIALIZATION_FINISHED_P)) { \
-            if (!gcry_check_version("1.5.4"))                   \
-                return AVERROR(EINVAL);                         \
-            gcry_control(GCRYCTL_DISABLE_SECMEM, 0);            \
-            gcry_control(GCRYCTL_INITIALIZATION_FINISHED, 0);   \
-        }                                                       \
-        bn = gcry_mpi_new(1);                                   \
+#define bn_new(bn)                                                \
+    do {                                                          \
+        if (!gcry_control(GCRYCTL_INITIALIZATION_FINISHED_P)) {   \
+            if (gcry_check_version("1.5.4")) {                    \
+                gcry_control(GCRYCTL_DISABLE_SECMEM, 0);          \
+                gcry_control(GCRYCTL_INITIALIZATION_FINISHED, 0); \
+            }                                                     \
+        }                                                         \
+        if (gcry_control(GCRYCTL_INITIALIZATION_FINISHED_P))      \
+            bn = gcry_mpi_new(1);                                 \
+        else                                                      \
+            bn = NULL;                                            \
     } while (0)
 #define bn_free(bn)                 gcry_mpi_release(bn)
 #define bn_set_word(bn, w)          gcry_mpi_set_ui(bn, w)
-- 
2.43.0

