From c8f814519573b226f0dbee3389a3a9fc70cce27d Mon Sep 17 00:00:00 2001
From: Michael Scire <SciresM@gmail.com>
Date: Tue, 23 Feb 2021 21:28:32 -0800
Subject: [PATCH] bsd: allow user-specified tmem backing buffer

---
 nx/include/switch/services/bsd.h |  3 +++
 nx/source/services/bsd.c         | 13 +++++++++++--
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/nx/include/switch/services/bsd.h b/nx/include/switch/services/bsd.h
index 08b1ae43..80958a99 100644
--- a/nx/include/switch/services/bsd.h
+++ b/nx/include/switch/services/bsd.h
@@ -18,6 +18,9 @@
 typedef struct  {
     u32 version;                ///< Observed 1 on [2.0.0+] LibAppletWeb, 2 on [3.0.0+].
 
+    void *tmem_buffer;          ///< User-provided buffer to use as backing for transfer memory. If NULL, a buffer will be allocated automatically. Must be large enough and page-aligned.
+    size_t tmem_buffer_size;    ///< Size of the user-provided transfer memory backing buffer. Must be large enough and page-aligned.
+
     u32 tcp_tx_buf_size;        ///< Size of the TCP transfer (send) buffer (initial or fixed).
     u32 tcp_rx_buf_size;        ///< Size of the TCP receive buffer (initial or fixed).
     u32 tcp_tx_buf_max_size;    ///< Maximum size of the TCP transfer (send) buffer. If it is 0, the size of the buffer is fixed to its initial value.
diff --git a/nx/source/services/bsd.c b/nx/source/services/bsd.c
index 8c0d68c5..0e3002be 100644
--- a/nx/source/services/bsd.c
+++ b/nx/source/services/bsd.c
@@ -37,6 +37,9 @@ static TransferMemory g_bsdTmem;
 static const BsdInitConfig g_defaultBsdInitConfig = {
     .version = 1,
 
+    .tmem_buffer            = NULL,
+    .tmem_buffer_size       = 0,
+
     .tcp_tx_buf_size        = 0x8000,
     .tcp_rx_buf_size        = 0x10000,
     .tcp_tx_buf_max_size    = 0x40000,
@@ -213,8 +216,14 @@ Result _bsdInitialize(const BsdInitConfig *config, u32 num_sessions, u32 service
     if (R_SUCCEEDED(rc))
         rc = smGetServiceWrapper(&g_bsdMonitor, bsd_srv);
 
-    if (R_SUCCEEDED(rc))
-        rc = tmemCreate(&g_bsdTmem, _bsdGetTransferMemSizeForConfig(config), 0);
+    if (R_SUCCEEDED(rc)) {
+        const size_t min_tmem_size = _bsdGetTransferMemSizeForConfig(config);
+
+        if (config->tmem_buffer != NULL && config->tmem_buffer_size >= min_tmem_size)
+            rc = tmemCreateFromMemory(&g_bsdTmem, config->tmem_buffer, config->tmem_buffer_size, 0);
+        else
+            rc = tmemCreate(&g_bsdTmem, min_tmem_size, 0);
+    }
 
     if (R_SUCCEEDED(rc))
         rc = _bsdRegisterClient(&g_bsdTmem, config, &g_bsdClientPid);