Disable sandbox when detecting WSL (fixes pwmt/zathura#50)

doc/man/zathurarc.5.rst

@@ -1055,7 +1055,7 @@ sandbox
 Defines the sandbox mode to use for the seccomp syscall filter. Possible
 values are "none", "normal" and "strict". If "none" is used, the sandbox
 will be disabled. The use of "normal" will provide minimal protection and
-allow normal use of seccomp with support for all features. The "strict" mode
+allow normal use of zathura with support for all features. The "strict" mode
 is a read only sandbox that is intended for viewing documents only.
 
 * Value type: String
@@ -1070,6 +1070,9 @@ Some features are disabled when using strict sandbox mode:
 
 No feature regressions are expected when using normal sandbox mode.
 
+When running under WSL, the default is "none" since seccomp is not supported in
+that environment.
+
 window-icon-document
 ^^^^^^^^^^^^^^^^^^^^
 Defines whether the window document should be updated based on the first page of

zathura/config.c

@@ -292,7 +292,9 @@ config_load_default(zathura_t* zathura)
   girara_setting_add(gsession, "selection-clipboard",    string_value, STRING,  false, _("The clipboard into which mouse-selected data will be written"), NULL, NULL);
   bool_value = true;
   girara_setting_add(gsession, "selection-notification", &bool_value,  BOOLEAN, false, _("Enable notification after selecting text"), NULL, NULL);
-  girara_setting_add(gsession, "sandbox",                "normal",     STRING, true,   _("Sandbox level"), cb_sandbox_changed, NULL);
+  /* default to no sandbox when running in WSL */
+  string_value = running_under_wsl() ? "none" : "normal";
+  girara_setting_add(gsession, "sandbox",                string_value, STRING, true,   _("Sandbox level"), cb_sandbox_changed, NULL);
 
 #define DEFAULT_SHORTCUTS(mode) \
   girara_shortcut_add(gsession, 0,                GDK_KEY_a,          NULL, sc_adjust_window,           (mode),     ZATHURA_ADJUST_BESTFIT, NULL); \

zathura/utils.c

@@ -298,3 +298,15 @@ parse_color(GdkRGBA* color, const char* str)
   }
   return true;
 }
+
+bool
+running_under_wsl(void)
+{
+  bool result = false;
+  char* content = girara_file_read("/proc/version");
+  if (content != NULL && g_strstr_len(content, -1, "Microsoft")) {
+    result = true;
+  }
+  free(content);
+  return result;
+}

zathura/utils.h

@@ -130,4 +130,11 @@ unsigned int find_first_page_column(const char* first_page_column_list,
  */
 bool parse_color(GdkRGBA* color, const char* str);
 
+/**
+ * Check if zathura is running under the Linux subsystem on Windows.
+ *
+ * @return true if running under WSL, false otherwise
+ */
+bool running_under_wsl(void);
+
 #endif // UTILS_H