From 4265167cb6e8c647e3a45439b30009a1df7de8a5 Mon Sep 17 00:00:00 2001
From: Felix Fietkau <nbd@nbd.name>
Date: Tue, 22 Jul 2025 10:48:57 +0200
Subject: [PATCH] ucode: add error reporting to pcap_write

Return null on error, true if packets were written,
false if no data available.

Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
 lib-pcap.c    |  7 +++++--
 lib-ucode.c   | 16 +++++++++++-----
 udebug-pcap.h |  2 +-
 3 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/lib-pcap.c b/lib-pcap.c
index 6340789..3293722 100644
--- a/lib-pcap.c
+++ b/lib-pcap.c
@@ -252,10 +252,13 @@ int pcap_snapshot_packet_init(struct udebug *ctx, struct udebug_iter *it)
 	return 0;
 }
 
-void pcap_block_write_file(FILE *f)
+bool pcap_block_write_file(FILE *f)
 {
-	fwrite(pcap_buf, pcap_hdr->len, 1, f);
+	if (fwrite(pcap_buf, pcap_hdr->len, 1, f) != 1)
+		return false;
+
 	fflush(f);
+	return true;
 }
 
 void *pcap_block_get(size_t *len)
diff --git a/lib-ucode.c b/lib-ucode.c
index 92a7dbb..2b1d57f 100644
--- a/lib-ucode.c
+++ b/lib-ucode.c
@@ -351,6 +351,7 @@ uc_udebug_pcap_write(uc_vm_t *vm, size_t nargs)
 	size_t n = ucv_type(arg) == UC_ARRAY ? ucv_array_length(arg) : 1;
 	struct udebug_snapshot **s;
 	struct udebug_iter it;
+	bool ret = false;
 
 	if (!p)
 		return NULL;
@@ -359,10 +360,10 @@ uc_udebug_pcap_write(uc_vm_t *vm, size_t nargs)
 	if (ucv_type(arg) == UC_ARRAY)
 		for (size_t i = 0; i < n; i++) {
 			if ((s[i] = uc_get_snapshot(ucv_array_get(arg, i))) == NULL)
-				return NULL;
+				goto out;
 	} else {
 		if ((s[0] = uc_get_snapshot(arg)) == NULL)
-			return NULL;
+			goto out;
 	}
 
 	udebug_iter_start(&it, s, n);
@@ -374,16 +375,21 @@ uc_udebug_pcap_write(uc_vm_t *vm, size_t nargs)
 			if (pcap_interface_rbuf_init(&p->pcap, rb))
 				continue;
 
-			pcap_block_write_file(p->f);
+			if (!pcap_block_write_file(p->f))
+				return NULL;
 		}
 
 		if (pcap_snapshot_packet_init(&u, &it))
 			continue;
 
-		pcap_block_write_file(p->f);
+		if (!pcap_block_write_file(p->f))
+			return NULL;
+
+		ret = true;
 	}
 
-	return NULL;
+out:
+	return ucv_boolean_new(ret);
 }
 
 static void
diff --git a/udebug-pcap.h b/udebug-pcap.h
index 7c006b7..2ec8389 100644
--- a/udebug-pcap.h
+++ b/udebug-pcap.h
@@ -43,7 +43,7 @@ void pcap_packet_done(void);
 int pcap_interface_rbuf_init(struct pcap_context *p, struct udebug_remote_buf *rb);
 int pcap_snapshot_packet_init(struct udebug *ctx, struct udebug_iter *it);
 
-void pcap_block_write_file(FILE *f);
+bool pcap_block_write_file(FILE *f);
 void *pcap_block_get(size_t *len);
 
 #endif
-- 
2.30.2