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Commit701c881

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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 parent33dd895 commit701c881

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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
@@ -928,9 +928,13 @@ restore(char *result, float val, int n)
928928

929929
/*
930930
* Put a cap on the number of significant digits to avoid garbage in the
931-
* output and ensure we don't overrun the result buffer.
931+
* output and ensure we don't overrun the result buffer. (n should not be
932+
* negative, but check to protect ourselves against corrupted data.)
932933
*/
933-
n=Min(n,FLT_DIG);
934+
if (n <=0)
935+
n=FLT_DIG;
936+
else
937+
n=Min(n,FLT_DIG);
934938

935939
/* remember the sign */
936940
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"
@@ -20,6 +21,8 @@
2021

2122
staticfloatseg_atof(constchar *value);
2223

24+
staticintsig_digits(constchar *value);
25+
2326
staticchar strbuf[25] = {
2427
'0','0','0','0','0',
2528
'0','0','0','0','0',
@@ -62,9 +65,9 @@ range: boundary PLUMIN deviation
6265
result->lower =$1.val -$3.val;
6366
result->upper =$1.val +$3.val;
6467
sprintf(strbuf,"%g", result->lower);
65-
result->l_sigd = Max(Min(6, significant_digits(strbuf)), Max($1.sigd,$3.sigd));
68+
result->l_sigd = Max(sig_digits(strbuf), Max($1.sigd,$3.sigd));
6669
sprintf(strbuf,"%g", result->upper);
67-
result->u_sigd = Max(Min(6, significant_digits(strbuf)), Max($1.sigd,$3.sigd));
70+
result->u_sigd = Max(sig_digits(strbuf), Max($1.sigd,$3.sigd));
6871
result->l_ext ='\0';
6972
result->u_ext ='\0';
7073
}
@@ -121,7 +124,7 @@ boundary: SEGFLOAT
121124
floatval = seg_atof($1);
122125

123126
$$.ext ='\0';
124-
$$.sigd =significant_digits($1);
127+
$$.sigd =sig_digits($1);
125128
$$.val = val;
126129
}
127130
|EXTENSIONSEGFLOAT
@@ -130,7 +133,7 @@ boundary: SEGFLOAT
130133
floatval = seg_atof($2);
131134

132135
$$.ext =$1[0];
133-
$$.sigd =significant_digits($2);
136+
$$.sigd =sig_digits($2);
134137
$$.val = val;
135138
}
136139
;
@@ -141,7 +144,7 @@ deviation: SEGFLOAT
141144
floatval = seg_atof($1);
142145

143146
$$.ext ='\0';
144-
$$.sigd =significant_digits($1);
147+
$$.sigd =sig_digits($1);
145148
$$.val = val;
146149
}
147150
;
@@ -157,3 +160,12 @@ seg_atof(const char *value)
157160
datum =DirectFunctionCall1(float4in,CStringGetDatum(value));
158161
returnDatumGetFloat4(datum);
159162
}
163+
164+
staticint
165+
sig_digits(constchar *value)
166+
{
167+
intn =significant_digits(value);
168+
169+
/* Clamp, to ensure value will fit in sigd fields*/
170+
returnMin(n, FLT_DIG);
171+
}

‎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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