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Commitf489b48

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Fix contrib/seg to be more wary of long input numbers.
seg stores the number of significant digits in an input numberin a "char" field. If char is signed, and the input is more than127 digits long, the count can read out as negative causingseg_out() to print garbage (or, if you're really unlucky,even crash).To fix, clamp the digit count to be not more than FLT_DIG.(In theory this loses some information about what the originalinput was, but it doesn't seem like useful information; it wouldnot survive dump/restore in any case.)Also, in case there are stored values of the seg type containingbad data, add a clamp in seg_out's restore() subroutine.Per bug #17725 from Robins Tharakan. It's been like thisforever, so back-patch to all supported branches.Discussion:https://postgr.es/m/17725-0a09313b67fbe86e@postgresql.org
1 parentea5ae4c commitf489b48

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4 files changed

+33
-7
lines changed

4 files changed

+33
-7
lines changed

‎contrib/seg/expected/seg.out‎

Lines changed: 7 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -256,6 +256,13 @@ SELECT '12.34567890123456'::seg AS seg;
256256
12.3457
257257
(1 row)
258258

259+
-- Same, with a very long input
260+
SELECT '12.3456789012345600000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000'::seg AS seg;
261+
seg
262+
---------
263+
12.3457
264+
(1 row)
265+
259266
-- Numbers with certainty indicators
260267
SELECT '~6.5'::seg AS seg;
261268
seg

‎contrib/seg/seg.c‎

Lines changed: 6 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -927,9 +927,13 @@ restore(char *result, float val, int n)
927927

928928
/*
929929
* Put a cap on the number of significant digits to avoid garbage in the
930-
* output and ensure we don't overrun the result buffer.
930+
* output and ensure we don't overrun the result buffer. (n should not be
931+
* negative, but check to protect ourselves against corrupted data.)
931932
*/
932-
n=Min(n,FLT_DIG);
933+
if (n <=0)
934+
n=FLT_DIG;
935+
else
936+
n=Min(n,FLT_DIG);
933937

934938
/* remember the sign */
935939
sign= (val<0 ?1 :0);

‎contrib/seg/segparse.y‎

Lines changed: 17 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -3,6 +3,7 @@
33

44
#include"postgres.h"
55

6+
#include<float.h>
67
#include<math.h>
78

89
#include"fmgr.h"
@@ -23,6 +24,8 @@
2324

2425
staticfloatseg_atof(constchar *value);
2526

27+
staticintsig_digits(constchar *value);
28+
2629
staticchar strbuf[25] = {
2730
'0','0','0','0','0',
2831
'0','0','0','0','0',
@@ -63,9 +66,9 @@ range: boundary PLUMIN deviation
6366
result->lower =$1.val -$3.val;
6467
result->upper =$1.val +$3.val;
6568
sprintf(strbuf,"%g", result->lower);
66-
result->l_sigd = Max(Min(6, significant_digits(strbuf)), Max($1.sigd,$3.sigd));
69+
result->l_sigd = Max(sig_digits(strbuf), Max($1.sigd,$3.sigd));
6770
sprintf(strbuf,"%g", result->upper);
68-
result->u_sigd = Max(Min(6, significant_digits(strbuf)), Max($1.sigd,$3.sigd));
71+
result->u_sigd = Max(sig_digits(strbuf), Max($1.sigd,$3.sigd));
6972
result->l_ext ='\0';
7073
result->u_ext ='\0';
7174
}
@@ -122,7 +125,7 @@ boundary: SEGFLOAT
122125
float val = seg_atof($1);
123126

124127
$$.ext ='\0';
125-
$$.sigd =significant_digits($1);
128+
$$.sigd =sig_digits($1);
126129
$$.val = val;
127130
}
128131
|EXTENSIONSEGFLOAT
@@ -131,7 +134,7 @@ boundary: SEGFLOAT
131134
float val = seg_atof($2);
132135

133136
$$.ext =$1[0];
134-
$$.sigd =significant_digits($2);
137+
$$.sigd =sig_digits($2);
135138
$$.val = val;
136139
}
137140
;
@@ -142,7 +145,7 @@ deviation: SEGFLOAT
142145
float val = seg_atof($1);
143146

144147
$$.ext ='\0';
145-
$$.sigd =significant_digits($1);
148+
$$.sigd =sig_digits($1);
146149
$$.val = val;
147150
}
148151
;
@@ -159,5 +162,14 @@ seg_atof(const char *value)
159162
returnDatumGetFloat4(datum);
160163
}
161164

165+
staticint
166+
sig_digits(constchar *value)
167+
{
168+
intn =significant_digits(value);
169+
170+
/* Clamp, to ensure value will fit in sigd fields*/
171+
returnMin(n, FLT_DIG);
172+
}
173+
162174

163175
#include"segscan.c"

‎contrib/seg/sql/seg.sql‎

Lines changed: 3 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -60,6 +60,9 @@ SELECT '3.400e5'::seg AS seg;
6060
-- Digits truncated
6161
SELECT'12.34567890123456'::segAS seg;
6262

63+
-- Same, with a very long input
64+
SELECT'12.3456789012345600000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000'::segAS seg;
65+
6366
-- Numbers with certainty indicators
6467
SELECT'~6.5'::segAS seg;
6568
SELECT'<6.5'::segAS seg;

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