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Fix contrib/seg to be more wary of long input numbers.

2022年12月21日 22:51:50 +0000 (17:51 -0500)

seg stores the number of significant digits in an input number
in a "char" field. If char is signed, and the input is more than
127 digits long, the count can read out as negative causing
seg_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 original
input was, but it doesn't seem like useful information; it would
not survive dump/restore in any case.)

Also, in case there are stored values of the seg type containing
bad data, add a clamp in seg_out's restore() subroutine.

Per bug #17725 from Robins Tharakan. It's been like this
forever, so back-patch to all supported branches.

Discussion: https://postgr.es/m/17725-0a09313b67fbe86e@postgresql.org

contrib/seg/expected/seg.out patch | blob | blame | history

contrib/seg/seg.c patch | blob | blame | history

contrib/seg/segparse.y patch | blob | blame | history

contrib/seg/sql/seg.sql patch | blob | blame | history

diff --git a/contrib/seg/expected/seg.out b/contrib/seg/expected/seg.out

index e617dd7e29965f1d3eb85845c70a80d8f2ebc26d..2320464dd4712555d6971355e9a3d7e264e4cc0a 100644 (file)

--- a/contrib/seg/expected/seg.out

+++ b/contrib/seg/expected/seg.out

@@ -256,6 +256,13 @@ SELECT '12.34567890123456'::seg AS seg;

12.3457

(1 row)

+-- Same, with a very long input

+SELECT '12.3456789012345600000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000'::seg AS seg;

+ seg

+---------

+ 12.3457

+(1 row)

-- Numbers with certainty indicators

SELECT '~6.5'::seg AS seg;

seg

diff --git a/contrib/seg/seg.c b/contrib/seg/seg.c

index e964560053d1b1669951bc61744fac19f38dbe07..a7effc1b190c44eca50a1a7a1baba1516dbe9ff7 100644 (file)

--- a/contrib/seg/seg.c

+++ b/contrib/seg/seg.c

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

* Put a cap on the number of significant digits to avoid garbage in the

- * output and ensure we don't overrun the result buffer.

+ * output and ensure we don't overrun the result buffer. (n should not be

+ * negative, but check to protect ourselves against corrupted data.)

- n = Min(n, FLT_DIG);

+ if (n <= 0)

+ n = FLT_DIG;

+ else

+ n = Min(n, FLT_DIG);

/* remember the sign */

sign = (val < 0 ? 1 : 0);

diff --git a/contrib/seg/segparse.y b/contrib/seg/segparse.y

index 1d2adbbec893f018ddc440fa1a289f8c23b001ad..0156c3e02748bddf847ce1203afa0c336a48fc51 100644 (file)

--- a/contrib/seg/segparse.y

+++ b/contrib/seg/segparse.y

@@ -3,6 +3,7 @@

#include "postgres.h"

+#include <float.h>

#include <math.h>

#include "fmgr.h"

@@ -20,6 +21,8 @@

static float seg_atof(const char *value);

+static int sig_digits(const char *value);

static char strbuf[25] = {

'0', '0', '0', '0', '0',

@@ -62,9 +65,9 @@ range: boundary PLUMIN deviation

result->lower = 1ドル.val - 3ドル.val;

result->upper = 1ドル.val + 3ドル.val;

sprintf(strbuf, "%g", result->lower);

- result->l_sigd = Max(Min(6, significant_digits(strbuf)), Max(1ドル.sigd, 3ドル.sigd));

+ result->l_sigd = Max(sig_digits(strbuf), Max(1ドル.sigd, 3ドル.sigd));

sprintf(strbuf, "%g", result->upper);

- result->u_sigd = Max(Min(6, significant_digits(strbuf)), Max(1ドル.sigd, 3ドル.sigd));

+ result->u_sigd = Max(sig_digits(strbuf), Max(1ドル.sigd, 3ドル.sigd));

result->l_ext = '0円';

result->u_ext = '0円';

}

@@ -121,7 +124,7 @@ boundary: SEGFLOAT

float val = seg_atof(1ドル);

$$.ext = '0円';

- $$.sigd = significant_digits(1ドル);

+ $$.sigd = sig_digits(1ドル);

$$.val = val;

}

| EXTENSION SEGFLOAT

@@ -130,7 +133,7 @@ boundary: SEGFLOAT

float val = seg_atof(2ドル);

$$.ext = 1ドル[0];

- $$.sigd = significant_digits(2ドル);

+ $$.sigd = sig_digits(2ドル);

$$.val = val;

}

;

@@ -141,7 +144,7 @@ deviation: SEGFLOAT

float val = seg_atof(1ドル);

$$.ext = '0円';

- $$.sigd = significant_digits(1ドル);

+ $$.sigd = sig_digits(1ドル);

$$.val = val;

}

;

@@ -157,3 +160,12 @@ seg_atof(const char *value)

datum = DirectFunctionCall1(float4in, CStringGetDatum(value));

return DatumGetFloat4(datum);

}

+static int

+sig_digits(const char *value)

+ int n = significant_digits(value);

+ /* Clamp, to ensure value will fit in sigd fields */

+ return Min(n, FLT_DIG);

diff --git a/contrib/seg/sql/seg.sql b/contrib/seg/sql/seg.sql

index 6fe33e90e4e5abbb65a0900eb0e86faaf8c7fbb9..a027d4de97ed7613c3935c56ba9f5dae70f41b79 100644 (file)

--- a/contrib/seg/sql/seg.sql

+++ b/contrib/seg/sql/seg.sql

@@ -60,6 +60,9 @@ SELECT '3.400e5'::seg AS seg;

-- Digits truncated

SELECT '12.34567890123456'::seg AS seg;

+-- Same, with a very long input

+SELECT '12.3456789012345600000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000'::seg AS seg;

-- Numbers with certainty indicators

SELECT '~6.5'::seg AS seg;

SELECT '<6.5'::seg AS seg;

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