Return correct disk free/available size when FS is mounted with size = 0

base/sys_info_posix.cc

Index: base/sys_info_posix.cc
diff --git a/base/sys_info_posix.cc b/base/sys_info_posix.cc
index 5d1c450139a575705c3c5046ed32c565e4b5e404..65d050ab12afbba79c8301ebf874af1265a630f4 100644
--- a/base/sys_info_posix.cc
+++ b/base/sys_info_posix.cc
@@ -73,6 +73,10 @@ base::LazyInstance<
     base::internal::LazySysInfoValue<int64_t, AmountOfVirtualMemory>>::Leaky
     g_lazy_virtual_memory = LAZY_INSTANCE_INITIALIZER;
 
+}  // namespace

[Lei Zhang, 2016/07/19 23:45:10]

No, that's not what I meant.

namespace base {

namespace {

// all the existing anonymous bits now no longer needs base::

}  // namespace

// all the existing non-anoynymous bits

}  // namespace base

[Sriram, 2016/07/19 23:58:37]

Done.

+
+namespace base {
+
 bool GetDiskSpaceInfo(const base::FilePath& path,
                       int64_t* available_bytes,
                       int64_t* total_bytes) {
@@ -80,16 +84,31 @@ bool GetDiskSpaceInfo(const base::FilePath& path,
   if (HANDLE_EINTR(statvfs(path.value().c_str(), &stats)) != 0)
     return false;
 
-  if (available_bytes)
-    *available_bytes = static_cast<int64_t>(stats.f_bavail) * stats.f_frsize;
-  if (total_bytes)
-    *total_bytes = static_cast<int64_t>(stats.f_blocks) * stats.f_frsize;
-  return true;
-}
+#if defined(OS_LINUX)
+  // On Linux, stats.f_blocks is 0 when memory based file system like tmpfs,
+  // ramfs, or hugetlbfs (all memory file systems). the is mounted without any

[Lei Zhang, 2016/07/19 23:45:10]

So have you checked the ramfs / hugetlbfs behavior w.r.t. size == 0?

[Lei Zhang, 2016/07/19 23:45:10]

typo: "the is mounted"

[Sriram, 2016/07/19 23:58:37]

Yes, See Linux code for:
hugetlbfs - http://lxr.free-electrons.com/source/fs/hugetlbfs/inode.c#L869
/* If no limits set, just report 0 for max/free/used
 * blocks, like simple_statfs() */

For Ramfs: 
http://lxr.free-electrons.com/source/fs/libfs.c#L33
Which uses simple_statfs().

[Sriram, 2016/07/19 23:58:37]

Done.

+  // size limit (i.e. size set to 0).
+  FileSystemType fs_type;
+  const bool zero_size_means_unlimited = stats.f_blocks == 0 &&
+                                         GetFileSystemType(path, &fs_type) &&
+                                         fs_type == FILE_SYSTEM_MEMORY;
+#else
+  const bool zero_size_means_unlimited = false;
+#endif
 
-}  // namespace
+  if (available_bytes) {
+    *available_bytes = zero_size_means_unlimited ?
+        std::numeric_limits<int64_t>::max() :
+        static_cast<int64_t>(stats.f_bavail) * stats.f_frsize;
+  }
 
-namespace base {
+  if (total_bytes) {
+      *total_bytes = zero_size_means_unlimited ?
+          std::numeric_limits<int64_t>::max() :
+          static_cast<int64_t>(stats.f_blocks) * stats.f_frsize;
+  }
+  return true;
+}
 
 #if !defined(OS_OPENBSD)
 int SysInfo::NumberOfProcessors() {