feat(headers): stddef/stdint/stdbool/limits/float/assert + features wiring

src/internal/assert_fail.c

@@ -0,0 +1,80 @@
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include "syscall.h"
+
+/*
+ * The failing-assertion sink behind <assert.h>.
+ *
+ * Writes the standard-shaped diagnostic to fd 2 through the raw syscall
+ * layer, then traps. No abort(), exit() or stdio: those land in later todos
+ * and an assertion failure must be able to fire from a half-initialized
+ * runtime. __builtin_trap() terminates with SIGILL, which the assert QA
+ * harness expects (the standard only requires abnormal termination).
+ *
+ * Not declared hidden, unlike the other src/internal helpers: <assert.h>
+ * declares this symbol to consumers, so it is part of the public ABI surface
+ * and must resolve across the shared-library boundary.
+ */
+
+/* Convert v to decimal digits at p; returns the next free position. */
+static char *
+append_dec(char *p, int v)
+{
+    char tmp[12];
+    int i = 0;
+
+    if (v == 0)
+    {
+        *p++ = '0';
+        return p;
+    }
+    while (v > 0)
+    {
+        tmp[i++] = (char)('0' + v % 10);
+        v /= 10;
+    }
+    while (i > 0)
+    {
+        *p++ = tmp[--i];
+    }
+    return p;
+}
+
+/* Append the string s at p; returns the next free position. */
+static char *
+append_str(char *p, const char *s)
+{
+    while (*s != '\0')
+    {
+        *p++ = *s++;
+    }
+    return p;
+}
+
+/*
+ * The __vlibc_assert_fail name sits in the implementation-reserved namespace
+ * by design (it is the libc's private assert plumbing), so the
+ * reserved-identifier check is waived.
+ */
+__attribute__((noreturn)) void
+__vlibc_assert_fail(const char *expr, const char *file, int line,
+                    const char *func) // NOLINT(bugprone-reserved-identifier)
+{
+    char msg[384];
+    char *p = msg;
+
+    p = append_str(p, "Assertion failed: ");
+    p = append_str(p, expr);
+    p = append_str(p, " (file ");
+    p = append_str(p, file);
+    p = append_str(p, ": line ");
+    p = append_dec(p, line);
+    p = append_str(p, ", func ");
+    p = append_str(p, func);
+    p = append_str(p, ")\n");
+
+    (void)__syscall3(SYS_write, 2, (long)msg, (long)(p - msg));
+    __builtin_trap();
+}