df: Set negative free space values to zero.

Some file systems (eg. UFS) may report negative free spave values.
Previously this caused underflow, but now it is prevented by setting
negative values to zero.

Change-Id: I821adb8a6d7a40dcbd6c65ab3541fbcd714f8aba

Conflicts:

	src/df.c

diff --git a/src/df.c b/src/df.c
index 2e9b2ae8288dd64f1a75d30b51d83593a8fd4ef8..9d53b0b67eb7c326d3b1811682144d2a7cb6b14b 100644 (file)
--- a/src/df.c
+++ b/src/df.c
@@ -280,7 +280,22 @@ static int df_read (void)
                        uint64_t blk_reserved;
                        uint64_t blk_used;
 
-                       /* Sanity-check for the values in the struct */
+                       /*
+                        * Sanity-check for the values in the struct
+                        */
+                       /* Check for negative "available" byes. For example UFS can
+                        * report negative free space for user. Notice. blk_reserved
+                        * will start to diminish after this. */
+#if HAVE_STATVFS
+                       /* Cast is needed to avoid compiler warnings.
+                        * ((struct statvfs).f_bavail is unsigned (POSIX)) */
+                       if (((int64_t) statbuf.f_bavail) < 0)
+                               statbuf.f_bavail = 0;
+#elif HAVE_STATFS
+                       if (statbuf.f_bavail < 0)
+                               statbuf.f_bavail = 0;
+#endif
+                       /* Make sure that f_blocks >= f_bfree >= f_bavail */
                        if (statbuf.f_bfree < statbuf.f_bavail)
                                statbuf.f_bfree = statbuf.f_bavail;
                        if (statbuf.f_blocks < statbuf.f_bfree)