[core] compare entire "/bin/sh" "-c" after execve

compare entire "/bin/sh" "-c" strings after execve if execve fails

src/fdevent.c

@@ -786,11 +786,11 @@ pid_t fdevent_fork_execve(const char *name, char *argv[], char *envp[], int fdin
     execve(name, argv, envp ? envp : environ);
 
     int errnum = errno;
-    if (0 == memcmp(argv[0], "/bin/sh", sizeof("/bin/sh")-1)
-        && argv[1] && 0 == memcmp(argv[1], "-c", sizeof("-c")-1))
-        perror(argv[2]);
-    else
-        perror(argv[0]);
+    int argnum =
+      (0 == strcmp(argv[0], "/bin/sh") && argv[1] && 0 == strcmp(argv[1], "-c"))
+      ? 2
+      : 0;
+    perror(argv[argnum]);
     _exit(errnum);
 
  #else