execvpe: Execute a shell if errno == ENOEXEC

libc/src/unistd.cpp

@@ -68,9 +68,21 @@ extern "C"
             int err = errno;
             execve(file.chars(), argv, envp);
 
-            if (errno != ENOENT && errno != EACCES) return -1;
+            if (errno != ENOENT && errno != EACCES && errno != ENOEXEC) return -1;
 
-            // FIXME: POSIX says that if errno == ENOEXEC, we should run /bin/sh <path>.
+            if (errno == ENOEXEC)
+            {
+                Vector<char*> shell_argv;
+                shell_argv.try_append(const_cast<char*>("sh"));
+                char* const* arg = argv;
+                do {
+                    shell_argv.try_append(*arg);
+                } while (*(arg++));
+
+                execve("/bin/sh", shell_argv.data(), envp);
+                errno = ENOEXEC;
+                return -1;
+            }
 
             if (err == EACCES) errno = err;
         }