obs-ffmpeg: add NVENC blacklist check for Linux

Similar to the Windows counter part. Check the PCI bus for
installed cards. When found at least one VGA compatible adapter
from NVIDIA that is not in the blacklist we pass the check.

plugins/obs-ffmpeg/obs-ffmpeg.c

@@ -43,7 +43,7 @@ extern struct obs_encoder_info vaapi_encoder_info;
 
 static const char *nvenc_check_name = "nvenc_check";
 
-#ifdef _WIN32
+#if defined(_WIN32) || defined(__linux__)
 static const int blacklisted_adapters[] = {
 	0x1298, // GK208M [GeForce GT 720M]
 	0x1140, // GF117M [GeForce 610M/710M/810M/820M / GT 620M/625M/630M/720M]
@@ -105,7 +105,9 @@ static bool is_blacklisted(const int device_id)
 
 	return false;
 }
+#endif
 
+#if defined(_WIN32)
 typedef HRESULT(WINAPI *create_dxgi_proc)(const IID *, IDXGIFactory1 **);
 
 static bool nvenc_device_available(void)
@@ -164,6 +166,59 @@ finish:
 }
 #endif
 
+#if defined(__linux__)
+static int get_id_from_sys(char *d_name, char *type)
+{
+	char file_name[1024];
+	char *c;
+	int id;
+
+	snprintf(file_name, sizeof(file_name), "/sys/bus/pci/devices/%s/%s",
+		 d_name, type);
+	if ((c = os_quick_read_utf8_file(file_name)) == NULL) {
+		return -1;
+	}
+	id = strtol(c, NULL, 16);
+	bfree(c);
+
+	return id;
+}
+
+static bool nvenc_device_available(void)
+{
+	os_dir_t *dir;
+	struct os_dirent *dirent;
+	bool available = false;
+
+	if ((dir = os_opendir("/sys/bus/pci/devices")) == NULL) {
+		return true;
+	}
+
+	while ((dirent = os_readdir(dir)) != NULL) {
+		int id;
+
+		if (get_id_from_sys(dirent->d_name, "class") !=
+		    0x030000) { // 0x030000 = VGA compatible controller
+			continue;
+		}
+
+		if (get_id_from_sys(dirent->d_name, "vendor") !=
+		    0x10de) { // 0x10de = NVIDIA Corporation
+			continue;
+		}
+
+		if ((id = get_id_from_sys(dirent->d_name, "device")) > 0 &&
+		    !is_blacklisted(id)) {
+			available = true;
+			break;
+		}
+	}
+
+	os_closedir(dir);
+	return available;
+}
+#endif
+
 #ifdef _WIN32
 extern bool load_nvenc_lib(void);
 #endif
@@ -194,6 +249,11 @@ static bool nvenc_supported(void)
 		success = true;
 		goto finish;
 	}
+#elif defined(__linux__)
+	if (!nvenc_device_available()) {
+		goto cleanup;
+	}
+	lib = os_dlopen("libnvidia-encode.so.1");
 #else
 	lib = os_dlopen("libnvidia-encode.so.1");
 #endif