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..f480055cc4b472304b51e1c8f5c9d6246b81cbce 100644
--- a/base/sys_info_posix.cc
+++ b/base/sys_info_posix.cc
@@ -28,6 +28,11 @@
 #include <sys/statvfs.h>
 #endif
 
+#if defined(OS_LINUX)
+#include <linux/magic.h>
+#include <sys/vfs.h>
+#endif
+
 namespace {
 
 #if !defined(OS_OPENBSD)
@@ -73,6 +78,23 @@ base::LazyInstance<
     base::internal::LazySysInfoValue<int64_t, AmountOfVirtualMemory>>::Leaky
     g_lazy_virtual_memory = LAZY_INSTANCE_INITIALIZER;
 
+#if defined(OS_LINUX)
+bool IsStatsZeroIfUnlimited(const base::FilePath& path) {
+  struct statfs stats;
+
+  if (HANDLE_EINTR(statfs(path.value().c_str(), &stats)) != 0)
+    return false;
+
+  switch (stats.f_type) {
+    case TMPFS_MAGIC:
+    case HUGETLBFS_MAGIC:
+    case RAMFS_MAGIC:
+      return true;
+  }
+  return false;
+}
+#endif
+
 bool GetDiskSpaceInfo(const base::FilePath& path,
                       int64_t* available_bytes,
                       int64_t* total_bytes) {
@@ -80,10 +102,25 @@ 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;
+#if defined(OS_LINUX)
+  const bool zero_size_means_unlimited =
+      stats.f_blocks == 0 && IsStatsZeroIfUnlimited(path);
+#else
+  const bool zero_size_means_unlimited = false;
+#endif
+
+  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;
+  }
+
+  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;
 }