[nanopb] Add function to get rest of buffer (#8650)

upstream_utils/nanopb_patches/0001-Marked-imported-files-as-modified-by-WPILib.patch

@@ -1,7 +1,7 @@
 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
 From: Thad House <thadhouse1@gmail.com>
 Date: Mon, 28 Oct 2024 17:38:55 -0700
-Subject: [PATCH 1/4] Marked imported files as modified by WPILib
+Subject: [PATCH 1/5] Marked imported files as modified by WPILib
 
 ---
  generator/nanopb_generator.py |   2 +

upstream_utils/nanopb_patches/0002-Remove-extern-C.patch

@@ -1,7 +1,7 @@
 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
 From: Thad House <thadhouse1@gmail.com>
 Date: Mon, 28 Oct 2024 16:58:15 -0700
-Subject: [PATCH 2/4] Remove extern C
+Subject: [PATCH 2/5] Remove extern C
 
 ---
  generator/nanopb_generator.py |  8 --------

upstream_utils/nanopb_patches/0003-Generate-messages-or-anything-non-static-as-callback.patch

@@ -1,7 +1,7 @@
 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
 From: Thad House <thadhouse1@gmail.com>
 Date: Tue, 29 Oct 2024 20:23:48 -0700
-Subject: [PATCH 3/4] Generate messages or anything non static as callback
+Subject: [PATCH 3/5] Generate messages or anything non static as callback
 
 ---
  generator/nanopb_generator.py | 6 ++++--

upstream_utils/nanopb_patches/0004-Generate-as-cpp-and-add-wpilib-requirements.patch

@@ -1,7 +1,7 @@
 From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
 From: Thad House <thadhouse1@gmail.com>
 Date: Sat, 2 Nov 2024 20:25:45 -0700
-Subject: [PATCH 4/4] Generate as cpp and add wpilib requirements
+Subject: [PATCH 4/5] Generate as cpp and add wpilib requirements
 
 ---
  generator/nanopb_generator.py | 43 +++++++++++++++++++++++++++--------

upstream_utils/nanopb_patches/0005-Add-function-to-get-entire-buffer-during-read.patch

@@ -0,0 +1,55 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Thad House <thadhouse1@gmail.com>
+Date: Sun, 1 Mar 2026 14:33:44 -0800
+Subject: [PATCH 5/5] Add function to get entire buffer during read
+
+---
+ pb_decode.c | 17 +++++++++++++++++
+ pb_decode.h |  6 ++++++
+ 2 files changed, 23 insertions(+)
+
+diff --git a/pb_decode.c b/pb_decode.c
+index 03143e02a596b2f03023437e5f18e5f118580d22..2dc32bd175c38098a9ba57ee274ff909320ffd6f 100644
+--- a/pb_decode.c
++++ b/pb_decode.c
+@@ -81,6 +81,23 @@ static bool checkreturn buf_read(pb_istream_t *stream, pb_byte_t *buf, size_t co
+     return true;
+ }
+ 
++const pb_byte_t* pb_claim_rest_of_buffer(pb_istream_t *stream, size_t *size)
++{
++#ifndef PB_BUFFER_ONLY
++    if (stream->callback != buf_read) {
++        return NULL;
++    }
++#endif
++
++    const pb_byte_t *source = (const pb_byte_t*)stream->state;
++    if (size != NULL) {
++        *size = stream->bytes_left;
++    }
++    stream->state = (pb_byte_t*)stream->state + stream->bytes_left;
++    stream->bytes_left = 0;
++    return source;
++}
++
+ bool checkreturn pb_read(pb_istream_t *stream, pb_byte_t *buf, size_t count)
+ {
+     if (count == 0)
+diff --git a/pb_decode.h b/pb_decode.h
+index a96f18169127c3d2cd80ba89138421f2340b1fe2..58b49e2aa1c08a3909cad75ce43d63758eafeef6 100644
+--- a/pb_decode.h
++++ b/pb_decode.h
+@@ -136,6 +136,12 @@ void pb_release(const pb_msgdesc_t *fields, void *dest_struct);
+  */
+ pb_istream_t pb_istream_from_buffer(const pb_byte_t *buf, size_t msglen);
+ 
++/*
++ * Claim the rest of the istream buffer and return a pointer to it. The size of the
++ * remaining buffer is returned in the size parameter.
++ */
++const pb_byte_t* pb_claim_rest_of_buffer(pb_istream_t *stream, size_t *size);
++
+ /* Function to read from a pb_istream_t. You can use this if you need to
+  * read some custom header data, or to read data in field callbacks.
+  */

wpiutil/src/main/native/thirdparty/nanopb/include/pb_decode.h

@@ -136,6 +136,12 @@ void pb_release(const pb_msgdesc_t *fields, void *dest_struct);
  */
 pb_istream_t pb_istream_from_buffer(const pb_byte_t *buf, size_t msglen);
 
+/*
+ * Claim the rest of the istream buffer and return a pointer to it. The size of the
+ * remaining buffer is returned in the size parameter.
+ */
+const pb_byte_t* pb_claim_rest_of_buffer(pb_istream_t *stream, size_t *size);
+
 /* Function to read from a pb_istream_t. You can use this if you need to
  * read some custom header data, or to read data in field callbacks.
  */

wpiutil/src/main/native/thirdparty/nanopb/src/pb_decode.cpp

@@ -81,6 +81,23 @@ static bool checkreturn buf_read(pb_istream_t *stream, pb_byte_t *buf, size_t co
     return true;
 }
 
+const pb_byte_t* pb_claim_rest_of_buffer(pb_istream_t *stream, size_t *size)
+{
+#ifndef PB_BUFFER_ONLY
+    if (stream->callback != buf_read) {
+        return NULL;
+    }
+#endif
+
+    const pb_byte_t *source = (const pb_byte_t*)stream->state;
+    if (size != NULL) {
+        *size = stream->bytes_left;
+    }
+    stream->state = (pb_byte_t*)stream->state + stream->bytes_left;
+    stream->bytes_left = 0;
+    return source;
+}
+
 bool checkreturn pb_read(pb_istream_t *stream, pb_byte_t *buf, size_t count)
 {
     if (count == 0)