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From a2ceb95e2a7d5bf0270f0d342d2edb560f5cfcf4 Mon Sep 17 00:00:00 2001
From: Jim Warner <james.warner@comcast.net>
Date: Thu, 17 Aug 2017 01:11:11 -0500
Subject: [PATCH] top: protect against the anomalous 'Mem' graph display
Until this patch, top falsely assumed that there would
always be some (small) amount of physical memory after
subtracting 'used' and 'available' from the total. But
as the issue referenced below attests, a sum of 'used'
and 'available' might exceed that total memory amount.
I'm not sure if this is a problem with our calculation
of the 'used' amount, a flaw in the kernel 'available'
algorithms or some other reason I cannot even imagine.
Anyway, this patch protects against such a contingency
through the following single line addition of new code
. if (pct_used + pct_misc > 100.0 || pct_misc < 0) ...
The check for less than zero is not actually necessary
as long as the source numbers remain unsigned. However
should they ever become signed, we'll have protection.
[ Most of the changes in this commit simply separate ]
[ a variable's definition from its associated logic. ]
Reference(s):
https://gitlab.com/procps-ng/procps/issues/64
Signed-off-by: Jim Warner <james.warner@comcast.net>
---
top/top.c | 19 ++++++++++++-------
1 files changed, 12 insertions(+), 7 deletions(-)
diff --git a/top/top.c b/top/top.c
index 385df1d..948805e 100644
--- a/top/top.c
+++ b/top/top.c
@@ -5249,21 +5249,26 @@ numa_nope:
{ "%-.*s~4", "%-.*s~6", "%-.*s~6", Graph_blks }
};
char used[SMLBUFSIZ], util[SMLBUFSIZ], dual[MEDBUFSIZ];
- int ix = w->rc.graph_mems - 1;
- float pct_used = (float)kb_main_used * (100.0 / (float)kb_main_total),
+ float pct_used, pct_misc, pct_swap;
+ int ix, num_used, num_misc;
+
+ pct_used = (float)kb_main_used * (100.0 / (float)kb_main_total);
#ifdef MEMGRAPH_OLD
- pct_misc = (float)(kb_main_buffers + kb_main_cached) * (100.0 / (float)kb_main_total),
+ pct_misc = (float)(kb_main_buffers + kb_main_cached) * (100.0 / (float)kb_main_total);
#else
- pct_misc = (float)(kb_main_total - kb_main_available - kb_main_used) * (100.0 / (float)kb_main_total),
+ pct_misc = (float)(kb_main_total - kb_main_available - kb_main_used) * (100.0 / (float)kb_main_total);
#endif
- pct_swap = kb_swap_total ? (float)kb_swap_used * (100.0 / (float)kb_swap_total) : 0;
+ if (pct_used + pct_misc > 100.0 || pct_misc < 0) pct_misc = 0;
+ pct_swap = kb_swap_total ? (float)kb_swap_used * (100.0 / (float)kb_swap_total) : 0;
+ ix = w->rc.graph_mems - 1;
#ifndef QUICK_GRAPHS
- int num_used = (int)((pct_used * Graph_adj) + .5),
- num_misc = (int)((pct_misc * Graph_adj) + .5);
+ num_used = (int)((pct_used * Graph_adj) + .5),
+ num_misc = (int)((pct_misc * Graph_adj) + .5);
if (num_used + num_misc > Graph_len) --num_misc;
snprintf(used, sizeof(used), gtab[ix].used, num_used, gtab[ix].type);
snprintf(util, sizeof(util), gtab[ix].misc, num_misc, gtab[ix].type);
#else
+ (void)num_used; (void)num_misc;
snprintf(used, sizeof(used), gtab[ix].used, (int)((pct_used * Graph_adj) + .5), gtab[ix].type);
snprintf(util, sizeof(util), gtab[ix].misc, (int)((pct_misc * Graph_adj) + .4), gtab[ix].type);
#endif
--
libgit2 0.26.0
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