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gcc: fix comparing floating point warning

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Since we enabled some more gcc warnings - let's adapt for
it and check for double equals with DBL_EPSILON.

Current close_enough() is far from perfect
for more details see i.e. here:
http://randomascii.wordpress.com/2012/01/11/tricks-with-the-floating-point-format/
but fairly enough for lvm2 use-case.
This commit is contained in:
Zdenek Kabelac 2013-10-25 10:38:09 +02:00
parent d4e5140b52
commit 8e1f2e733e
3 changed files with 23 additions and 5 deletions
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1
WHATS_NEW
View File

@ -1,5 +1,6 @@
Version 2.02.104 -
===================================
Compare equality of double values with DBL_EPSILON predefined constant.
Use additional gcc warning flags by default.
Add ignore_lvm_mirrors to config file to read/ignore labels on mirrors.
Add internal flag for temporary LVs to properly direct udev to not interfere.

11
daemons/lvmetad/lvmetad-core.c
View File

@ -26,6 +26,9 @@
#include <stdint.h>
#include <unistd.h>
#include <math.h> /* fabs() */
#include <float.h> /* DBL_EPSILON */
typedef struct {
log_state *log; /* convenience */
const char *log_config;
@ -503,6 +506,12 @@ bad:
return reply_fail("out of memory");
}
/* Test if the doubles are close enough to be considered equal */
static int close_enough(double d1, double d2)
{
return fabs(d1 - d2) < DBL_EPSILON;
}
static int compare_value(struct dm_config_value *a, struct dm_config_value *b)
{
int r = 0;
@ -514,7 +523,7 @@ static int compare_value(struct dm_config_value *a, struct dm_config_value *b)
switch (a->type) {
case DM_CFG_STRING: r = strcmp(a->v.str, b->v.str); break;
case DM_CFG_FLOAT: r = (a->v.f == b->v.f) ? 0 : (a->v.f > b->v.f) ? 1 : -1; break;
case DM_CFG_FLOAT: r = close_enough(a->v.f, b->v.f) ? 0 : (a->v.f > b->v.f) ? 1 : -1; break;
case DM_CFG_INT: r = (a->v.i == b->v.i) ? 0 : (a->v.i > b->v.i) ? 1 : -1; break;
case DM_CFG_EMPTY_ARRAY: return 0;
}

16
lib/display/display.c
View File

@ -20,6 +20,8 @@
#include "toolcontext.h"
#include "segtype.h"
#include "defaults.h"
#include <math.h> /* fabs() */
#include <float.h> /* DBL_EPSILON */
#define SIZE_BUF 128
@ -41,6 +43,12 @@ static const struct {
static const int _num_policies = sizeof(_policies) / sizeof(*_policies);
/* Test if the doubles are close enough to be considered equal */
static int _close_enough(double d1, double d2)
{
return fabs(d1 - d2) < DBL_EPSILON;
}
uint64_t units_to_bytes(const char *units, char *unit_type)
{
char *ptr = NULL;
@ -53,7 +61,7 @@ uint64_t units_to_bytes(const char *units, char *unit_type)
if (ptr == units)
return 0;
v = (uint64_t) strtoull(units, NULL, 10);
if ((double) v == custom_value)
if (_close_enough((double) v, custom_value))
custom_value = 0; /* Use integer arithmetic */
units = ptr;
} else
@ -126,10 +134,10 @@ uint64_t units_to_bytes(const char *units, char *unit_type)
return 0;
}
if (custom_value)
return (uint64_t) (custom_value * multiplier);
if (_close_enough(custom_value, 0.))
return v * multiplier; /* Use integer arithmetic */
else
return v * multiplier;
return (uint64_t) (custom_value * multiplier);
}
char alloc_policy_char(alloc_policy_t alloc)