[common/client] ivshmem: add portable external frames

client/transports/LGMP/platform/linux.c

@@ -0,0 +1,189 @@
+/**
+ * Looking Glass
+ * Copyright © 2017-2026 The Looking Glass Authors
+ * https://looking-glass.io
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc., 59
+ * Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include "../platform.h"
+
+#include "common/debug.h"
+#include "common/ivshmem_dmabuf.h"
+#include "common/option.h"
+#include "common/stringutils.h"
+
+#include <dirent.h>
+#include <limits.h>
+#include <stdatomic.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+typedef struct LGMPExternalFrame
+{
+  LG_ExternalFrame base;
+  atomic_uint      refs;
+  int              fd;
+}
+LGMPExternalFrame;
+
+static void lgmpExternalFrameRetain(LG_ExternalFrame * frame)
+{
+  LGMPExternalFrame  * this = (LGMPExternalFrame *)frame;
+  const unsigned int   refs = atomic_fetch_add_explicit(
+      &this->refs, 1, memory_order_relaxed);
+  DEBUG_ASSERT(refs > 0 && refs < UINT_MAX);
+}
+
+static void lgmpExternalFrameRelease(LG_ExternalFrame * frame)
+{
+  LGMPExternalFrame  * this = (LGMPExternalFrame *)frame;
+  const unsigned int   refs = atomic_fetch_sub_explicit(
+      &this->refs, 1, memory_order_acq_rel);
+  DEBUG_ASSERT(refs > 0);
+  if (refs != 1)
+    return;
+
+  close(this->fd);
+  free(this);
+}
+
+static bool lgmpExternalFrameQuery(const LG_ExternalFrame * frame,
+    void * result, size_t resultSize)
+{
+  if (!result || resultSize != sizeof(int))
+    return false;
+
+  const LGMPExternalFrame * this = (const LGMPExternalFrame *)frame;
+  *(int *)result = this->fd;
+  return true;
+}
+
+static const LG_ExternalFrameOps lgmpExternalFrameOps =
+{
+  .type    = LG_EXTERNAL_FRAME_DMABUF,
+  .retain  = lgmpExternalFrameRetain,
+  .release = lgmpExternalFrameRelease,
+  .query   = lgmpExternalFrameQuery,
+};
+
+static bool lgmpDeviceValidator(struct Option * opt, const char ** error)
+{
+  const char * transport = option_get_string("app", "transport");
+  if (!transport || strcmp(transport, "lgmp") != 0)
+    return true;
+
+  if (strlen(opt->value.x_string) > 3 &&
+      strncmp(opt->value.x_string, "kvmfr", 5) != 0)
+  {
+    struct stat st;
+    if (stat(opt->value.x_string, &st) != 0)
+    {
+      *error = "Invalid path to the shared memory file";
+      return false;
+    }
+  }
+  return true;
+}
+
+static StringList lgmpDeviceValues(struct Option * option)
+{
+  StringList values = stringlist_new(true);
+  DIR      * dir    = opendir("/sys/class/kvmfr");
+  if (!dir)
+    return values;
+
+  struct dirent * entry;
+  while ((entry = readdir(dir)))
+  {
+    if (entry->d_name[0] == '.')
+      continue;
+
+    char * name;
+    alloc_sprintf(&name, "/dev/%s", entry->d_name);
+    stringlist_push(values, name);
+  }
+
+  closedir(dir);
+  return values;
+}
+
+void lgmpPlatformOptionsInit(void)
+{
+  struct stat  st;
+  const char * defaultDevice = stat("/dev/kvmfr0", &st) == 0 ?
+    "/dev/kvmfr0" : "/dev/shm/looking-glass";
+
+  static struct Option options[] =
+  {
+    {
+      .module         = "lgmp",
+      .name           = "shmDevice",
+      .old_module     = "app",
+      .old_name       = "shmFile",
+      .shortopt       = 'f',
+      .description    = "Shared memory file or KVMFR device path",
+      .type           = OPTION_TYPE_STRING,
+      .value.x_string = NULL,
+      .validator      = lgmpDeviceValidator,
+      .getValues      = lgmpDeviceValues,
+    },
+    {0}
+  };
+
+  options[0].value.x_string = (char *)defaultDevice;
+  option_register(options);
+}
+
+bool lgmpPlatformOpenIVSHMEM(struct IVSHMEM * shm)
+{
+  if (!ivshmemInit(shm))
+    return false;
+
+  if (ivshmemOpenDev(shm, option_get_string("lgmp", "shmDevice"),
+        IVSHMEM_CACHE_MODE_CACHED))
+    return true;
+
+  ivshmemFree(shm);
+  return false;
+}
+
+bool lgmpPlatformSupportsExternalFrame(struct IVSHMEM * shm)
+{
+  return ivshmemHasDMA(shm);
+}
+
+LG_ExternalFrame * lgmpPlatformCreateExternalFrame(struct IVSHMEM * shm,
+    size_t offset, size_t size)
+{
+  const int fd = ivshmemGetDMABuf(shm, offset, size);
+  if (fd < 0)
+    return NULL;
+
+  LGMPExternalFrame * frame = malloc(sizeof(*frame));
+  if (!frame)
+  {
+    close(fd);
+    return NULL;
+  }
+
+  frame->base.ops = &lgmpExternalFrameOps;
+  frame->fd       = fd;
+  atomic_init(&frame->refs, 1);
+  return &frame->base;
+}