additional readdir refactor cleanup

Differences between readdir and getdents is minimal at best. Leaving code
for now to allow for possible expansion later.

src/fuse_readdir_linux.cpp

@@ -0,0 +1,129 @@
+/*
+  Copyright (c) 2019, Antonio SJ Musumeci <trapexit@spawn.link>
+
+  Permission to use, copy, modify, and/or distribute this software for any
+  purpose with or without fee is hereby granted, provided that the above
+  copyright notice and this permission notice appear in all copies.
+
+  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+#include "branch.hpp"
+#include "errno.hpp"
+#include "fs_base_close.hpp"
+#include "fs_base_getdents.hpp"
+#include "fs_base_open.hpp"
+#include "fs_base_stat.hpp"
+#include "fs_devid.hpp"
+#include "fs_inode.hpp"
+#include "fs_path.hpp"
+#include "hashset.hpp"
+#include "linux_dirent.h"
+#include "mempools.hpp"
+
+#include <fuse.h>
+#include <fuse_dirents.h>
+
+#include <string>
+#include <vector>
+
+#include <stddef.h>
+
+using std::string;
+using std::vector;
+
+namespace l
+{
+  static
+  int
+  close_free_ret_enomem(int   fd_,
+                        void *buf_)
+  {
+    fs::close(fd_);
+    g_DENTS_BUF_POOL.free(buf_);
+    return -ENOMEM;
+  }
+
+  static
+  int
+  readdir(const Branches &branches_,
+          const char     *dirname_,
+          fuse_dirents_t *buf_)
+  {
+    int rv;
+    dev_t dev;
+    char *buf;
+    HashSet names;
+    string basepath;
+    uint64_t namelen;
+    struct linux_dirent *d;
+
+    buf = (char*)g_DENTS_BUF_POOL.alloc();
+    if(buf == NULL)
+      return -ENOMEM;
+
+    for(size_t i = 0, ei = branches_.size(); i != ei; i++)
+      {
+        int dirfd;
+        int64_t nread;
+
+        basepath = fs::path::make(&branches_[i].path,dirname_);
+
+        dirfd = fs::open_dir_ro(basepath);
+        if(dirfd == -1)
+          continue;
+
+        dev = fs::devid(dirfd);
+        if(dev == (dev_t)-1)
+          dev = i;
+
+        for(;;)
+          {
+            nread = fs::getdents(dirfd,buf,g_DENTS_BUF_POOL.size());
+            if(nread == -1)
+              break;
+            if(nread == 0)
+              break;
+
+            for(int64_t pos = 0; pos < nread; pos += d->reclen)
+              {
+                d = (struct linux_dirent*)(buf + pos);
+                namelen = strlen(d->name);
+
+                rv = names.put(d->name,namelen);
+                if(rv == 0)
+                  continue;
+
+                d->ino = fs::inode::recompute(d->ino,dev);
+
+                rv = fuse_dirents_add_linux(buf_,d,namelen);
+                if(rv)
+                  return close_free_ret_enomem(dirfd,buf);
+              }
+          }
+
+        fs::close(dirfd);
+      }
+
+    g_DENTS_BUF_POOL.free(buf);
+
+    return 0;
+  }
+}
+
+namespace FUSE
+{
+  int
+  readdir_linux(const Branches &branches_,
+                const char     *dirname_,
+                fuse_dirents_t *buf_)
+  {
+    return l::readdir(branches_,dirname_,buf_);
+  }
+}