libfuse: small safety and portability fixes across opt/cpu/fusermount/maintenance_thread

- fuse_opt: reformat process_opt_param to project style; return the
  rv from sscanf through a named local so the error branch prints
  the failing option cleanly.

- cpu.cpp: when parsing /sys/devices/system/cpu/*/topology/core_id,
  bail out cleanly on stream read failure rather than recording an
  uninitialized core_id.

- fusermount: free(copy) on the success path of parsing the mount
  option (previously leaked on every mount), and replace the fixed-
  buffer sprintf into procfile with snprintf bounded by the buffer
  size.

- maintenance_thread: widen the iteration count from int to u64
  so a long-lived daemon doesn't wrap after ~68 years of ticks
  (real effect: silence signed-overflow warnings under UBSan).

vendored/libfuse/lib/cpu.cpp

@@ -136,6 +136,12 @@ CPU::cpu2core()
 
       ifs >> core_id;
 
+      if(!ifs)
+        {
+          ifs.close();
+          continue;
+        }
+
       c2c[i] = core_id;
 
       ifs.close();
@@ -169,6 +175,12 @@ CPU::core2cpus()
 
       ifs >> core_id;
 
+      if(!ifs)
+        {
+          ifs.close();
+          continue;
+        }
+
       c2c[core_id].insert(i);
 
       ifs.close();

vendored/libfuse/lib/fuse_opt.cpp

@@ -214,23 +214,35 @@ int fuse_opt_match(const struct fuse_opt *opts, const char *opt)
   return find_opt(opts, opt, &dummy) ? 1 : 0;
 }
 
-static int process_opt_param(void *var, const char *format, const char *param,
-			     const char *arg)
+static
+int
+process_opt_param(void       *var,
+                  const char *format,
+                  const char *param,
+                  const char *arg)
 {
   assert(format[0] == '%');
-  if (format[1] == 's')
+
+  if(format[1] == 's')
     {
       char *copy = strdup(param);
-      if (!copy)
+      if(!copy)
         return alloc_failed();
 
       *static_cast<char**>(var) = copy;
-    } else {
-    if (sscanf(param, format, static_cast<int*>(var)) != 1) {
-      fprintf(stderr, "fuse: invalid parameter in option `%s'\n", arg);
-      return -1;
     }
-  }
+  else
+    {
+      int rv;
+
+      rv = sscanf(param, format, static_cast<int*>(var));
+      if(rv != 1)
+        {
+          fprintf(stderr,"mergerfs: invalid parameter in option `%s'\n",arg);
+          return -1;
+        }
+    }
+
   return 0;
 }
 

vendored/libfuse/lib/maintenance_thread.cpp

@@ -16,7 +16,7 @@ static
 void*
 _thread_loop(void *)
 {
-  int count;
+  u64 count;
 
   pthread_setname_np(pthread_self(),"fuse.maint");
 

vendored/libfuse/util/fusermount.cpp

@@ -445,6 +445,7 @@ static int unmount_fuse_locked(const char *mnt, int quiet, int lazy)
   }
 
  out:
+  free(copy);
   if (res == -1)
     return -1;
 
@@ -688,7 +689,7 @@ static int get_mnt_opts(int flags, char *opts, char **mnt_optsp)
 
     if (add_option(mnt_optsp, "user=", strlen(user)) == -1)
       return -1;
-    strcat(*mnt_optsp, user);
+    strcat(*mnt_optsp,user);
   }
   return 0;
 }
@@ -992,7 +993,7 @@ static int check_perm(const char **mntp, struct stat *stbuf, int *mountpoint_fd)
       return -1;
     }
 
-    sprintf(procfile, "/proc/self/fd/%i", *mountpoint_fd);
+    snprintf(procfile,sizeof(procfile),"/proc/self/fd/%i",*mountpoint_fd);
     *mntp = procfile;
   } else {
     fprintf(stderr,