0.3.0: converge relibc to upstream 0.6.0 + Red Bear patches

tests/error.c

@@ -1,10 +1,15 @@
-#include <unistd.h>
-#include <stdio.h>
-#include <string.h>
+#include <err.h>
 #include <errno.h>
+#include <limits.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
 
 #include "test_helpers.h"
 
+// does not compile with glibc
+#ifndef __GLIBC__
 int main(void) {
     chdir("nonexistent");
     int err = errno;
@@ -12,15 +17,44 @@ int main(void) {
     printf("errno: %d = %s\n", err, strerror(errno));
     perror("perror");
 
-    char buf1[256];
+    char buf1[256] = {0};
     int ret1 = strerror_r(err, buf1, 256);
     printf("errno: %d = %s, return: %d\n", err, buf1, ret1);
 
-    char buf2[3];
+    char buf2[3] = {0};
     int ret2 = strerror_r(err, buf2, 3);
     printf("errno: %d = %s, return: %d\n", err, buf2, ret2);
 
     char buf3[256] = {0};
     int ret3 = strerror_r(err, buf3, 0);
     printf("errno: %d = %s, return: %d\n", err, buf3, ret3);
+
+    // Test that the statically allocated buffer doesn't overflow
+    for (int code = EPERM; code < ENOTRECOVERABLE; ++code) {
+        const char* message = strerror(code);
+        if (!message) {
+            errx(EXIT_FAILURE,
+                 "Expected message for error code: %d",
+                 code
+            );
+        }
+    }
+
+    const char* actual_error = strerror(INT_MAX);
+    char expected_error[256] = {0};
+    sprintf(expected_error, "Unknown error %d", INT_MAX);
+    if (strncmp(expected_error, actual_error, 25) != 0) {
+        errx(EXIT_FAILURE,
+             "Expected: %s\nGot: %s",
+             expected_error, actual_error
+        );
+    }
+
+    return EXIT_SUCCESS;
 }
+
+#else
+int main(void) {
+    exit(0);
+}
+#endif