Node and Electron apps can start their helper processes

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "localdesktop"
-version = "1.2.0"
+version = "1.2.1"
 edition = "2021"
 build = "build.rs"
 default-run = "build_apk"

patches/build-proot-android/README.md

@@ -30,6 +30,11 @@ guest rootfs is still dropped, except on the app's own files (a directory bound
 into the guest, such as `/home`), so a script or binary written there can be
 made executable.
 
+And in `src/extension/fake_id0/fake_id0.c`: `fstat` on a socket, eventfd or other descriptor
+that isn't a file gets the real `fstat`, instead of a `stat` of its `/proc/self/fd` link
+(`socket:[N]`), which fails. Node checks its standard streams with `fstat`, and a child process
+gets sockets for them, so every Node or Electron child process aborted at startup.
+
 The shipped `libproot.so` is built with `./build.sh` (NDK r26d). On macOS, put a
 GNU `install` (or a wrapper that handles `install -D`) first in `PATH`.
 

patches/build-proot-android/build/proot/src/extension/fake_id0/fake_id0.c

@@ -807,7 +807,9 @@ static int handle_sysexit_end(Tracee *tracee, Config *config)
 
 		path[result] = '\0';
 
-		if ((strcmp(path + strlen(path) - strlen(" (deleted)"), " (deleted)") == 0) || (strncmp(path, "pipe", 4) == 0)) {
+		/* Not a file to stat by its path: deleted, or a pipe, socket, eventfd and the like, whose
+		 * link reads "pipe:[N]", "socket:[N]", "anon_inode:[eventfd]".  */
+		if ((strcmp(path + strlen(path) - strlen(" (deleted)"), " (deleted)") == 0) || (path[0] != '/')) {
 			register_chained_syscall(tracee, sysnum, peek_reg(tracee, ORIGINAL, SYSARG_1), peek_reg(tracee, ORIGINAL, SYSARG_2), 0, 0, 0, 0);
 		} else {
 			write_data(tracee, peek_reg(tracee, MODIFIED, SYSARG_3), path, sizeof(path));