gh-127146: Report uid in Emscripten + node as native uid (GH-136509)

hoodmane · miss-islington · commit 9bab16cb7de2 · 2025-07-16T04:17:23.000Z
Corrects the handling of getuid on emscripten, which was consistently reporting as 0. (cherry picked from commit e81c4e8) Co-authored-by: Hood Chatham <roberthoodchatham@gmail.com>
diff --git a/Python/emscripten_syscalls.c b/Python/emscripten_syscalls.c
@@ -0,0 +1,19 @@
+#include "emscripten.h"
+
+// If we're running in node, report the UID of the user in the native system as
+// the UID of the user. Since the nodefs will report the uid correctly, if we
+// don't make getuid report it correctly too we'll see some permission errors.
+// Normally __syscall_getuid32 is a stub that always returns 0 but it is
+// defined with weak linkage so we can override it.
+EM_JS(int, __syscall_getuid32_js, (void), {
+    // If we're in node and we can, report the native uid
+    if (typeof process !== "undefined" && typeof process.getuid === "function") {
+        return process.getuid();
+    }
+    // Fall back to the stub case of returning 0.
+    return 0;
+})
+
+int __syscall_getuid32(void) {
+    return __syscall_getuid32_js();
+}
diff --git a/Tools/c-analyzer/cpython/_parser.py b/Tools/c-analyzer/cpython/_parser.py
@@ -66,6 +66,7 @@ def clean_lines(text):
 Python/dynload_dl.c             # dl.h
 Python/dynload_hpux.c           # dl.h
 Python/emscripten_signal.c
+Python/emscripten_syscalls.c
 Python/thread_pthread.h
 Python/thread_pthread_stubs.h
 
diff --git a/configure b/configure
diff --git a/configure.ac b/configure.ac
@@ -5131,7 +5131,7 @@ PLATFORM_OBJS=
 
 AS_CASE([$ac_sys_system],
   [Emscripten], [
-    AS_VAR_APPEND([PLATFORM_OBJS], [' Python/emscripten_signal.o Python/emscripten_trampoline.o'])
+    AS_VAR_APPEND([PLATFORM_OBJS], [' Python/emscripten_signal.o Python/emscripten_trampoline.o Python/emscripten_syscalls.o'])
     AS_VAR_APPEND([PLATFORM_HEADERS], [' $(srcdir)/Include/internal/pycore_emscripten_signal.h $(srcdir)/Include/internal/pycore_emscripten_trampoline.h'])
   ],
 )

Original file line number	Diff line number	Diff line change
`@@ -5131,7 +5131,7 @@ PLATFORM_OBJS=`
`5131`	`5131`
`5132`	`5132`	`AS_CASE([$ac_sys_system],`
`5133`	`5133`	`[Emscripten], [`
`5134`		`- AS_VAR_APPEND([PLATFORM_OBJS], [' Python/emscripten_signal.o Python/emscripten_trampoline.o'])`
	`5134`	`+ AS_VAR_APPEND([PLATFORM_OBJS], [' Python/emscripten_signal.o Python/emscripten_trampoline.o Python/emscripten_syscalls.o'])`
`5135`	`5135`	`AS_VAR_APPEND([PLATFORM_HEADERS], [' $(srcdir)/Include/internal/pycore_emscripten_signal.h $(srcdir)/Include/internal/pycore_emscripten_trampoline.h'])`
`5136`	`5136`	`],`
`5137`	`5137`	`)`