glibc/wasmtime - libc fatal debug workaround

src/glibc/assert/__libc_assert_fail.c

@@ -20,14 +20,30 @@
 #include <array_length.h>
 #include <intprops.h>
 #include <stdio.h>
+#include <stdlib.h>
+
+#ifdef WASM_DEBUG_LIBC_FATAL
+// TODO: For some reason, glibc's libc_assert_fail is not printing the error message when a fatal error is triggered.
+// As a temporary workaround, we manually forward the message to Wasmtime and let Wasmtime handle the printing.
+// Ideally, we should fix the issue and restore proper handling via glibc's native libc_assert_fail in the future.
+void __imported__libc_assert_fail(const char *assertion, const char *file, unsigned int line, const char *function) __attribute__((
+   __import_module__("debug"),
+   __import_name__("libc_assert_fail")
+));
+#endif
 
 void
 __libc_assert_fail (const char *assertion, const char *file, unsigned int line,
                     const char *function)
 {
-  char linebuf[INT_BUFSIZE_BOUND (unsigned int)];
-  array_end (linebuf)[-1] = '\0';
-  char *linestr = _itoa_word (line, array_end (linebuf) - 1, 10, 0);
-  __libc_message ("Fatal glibc error: %s:%s (%s): assertion failed: %s\n",
-                  file, linestr, function, assertion);
-}
+#ifdef WASM_DEBUG_LIBC_FATAL
+   __imported__libc_assert_fail(assertion, file, line, function);
+   abort();
+#else
+   char linebuf[INT_BUFSIZE_BOUND (unsigned int)];
+   array_end (linebuf)[-1] = '\0';
+   char *linestr = _itoa_word (line, array_end (linebuf) - 1, 10, 0);
+   __libc_message ("Fatal glibc error: %s:%s (%s): assertion failed: %s\n",
+                   file, linestr, function, assertion);
+#endif
+}

src/glibc/malloc/malloc.c

@@ -5766,15 +5766,28 @@ libc_hidden_def (__libc_mallopt)
 
 extern char **__libc_argv attribute_hidden;
 
+#ifdef WASM_DEBUG_MALLOC_ERR
+// TODO: malloc_printerr is currently unable to print messages to the console correctly.
+// This is a temporary workaround to ensure that error messages are printed.
+void __imported__malloc_printerr(const char *str) __attribute__((
+  __import_module__("debug"),
+  __import_name__("malloc_printerr")
+));
+#endif
+
 static void
 malloc_printerr (const char *str)
 {
+#ifdef WASM_DEBUG_MALLOC_ERR
+  __imported__malloc_printerr(str);
+  __builtin_unreachable ();
+#else
 #if IS_IN (libc)
   __libc_message ("%s\n", str);
 #else
   __libc_fatal (str);
 #endif
-  __builtin_unreachable ();
+#endif
 }
 
 #if IS_IN (libc)
@@ -6047,4 +6060,4 @@ compat_symbol (libc, __libc_free, cfree, GLIBC_2_0);
  * Local variables:
  * c-basic-offset: 2
  * End:
- */
+ */

src/wasmtime/crates/lind-common/src/lib.rs

@@ -218,6 +218,33 @@ pub fn add_to_linker<
             wasmtime_lind_multi_process::signal::signal_handler(&mut caller);
         },
     )?;
+
+    // a temporary solution to have libc_assert_fail correctly working
+    linker.func_wrap(
+        "debug",
+        "libc_assert_fail",
+        move |mut caller: Caller<'_, T>, assertion: i32, file: i32, line: i32, function: i32| {
+            let mem_base = get_memory_base(&caller);
+            let assertion = rawposix::interface::get_cstr(mem_base + assertion as u64).unwrap();
+            let file = rawposix::interface::get_cstr(mem_base + file as u64).unwrap();
+            let function = rawposix::interface::get_cstr(mem_base + function as u64).unwrap();
+            eprintln!(
+                "Fatal glibc error: {}:{} ({}): assertion failed: {}\n",
+                assertion, file, line, function
+            );
+        },
+    )?;
+
+    // a temporary solution to have malloc_printerr correctly working
+    linker.func_wrap(
+        "debug",
+        "malloc_printerr",
+        move |mut caller: Caller<'_, T>, msg: i32| {
+            let mem_base = get_memory_base(&caller);
+            let msg = rawposix::interface::get_cstr(mem_base + msg as u64).unwrap();
+            eprintln!("malloc_printerr: {}", msg);
+        },
+    )?;
 
     Ok(())
 }