From: a.imamov@postgrespro.ru
To: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Potential issue in ecpg-informix decimal converting functions
Date: Thu, 22 Feb 2024 19:54:37 +0300
Message-ID: <54d2b53327516d9454daa5fb2f893bdc@postgrespro.ru> (raw)
Hi, everyone!
I found a potential bug in dectoint() and dectolong() functions from
informix.c. "Informix Compatibility Mode" doc chapter says that
ECPG_INFORMIX_NUM_OVERFLOW is returned if an overflow occurred. But
check this line in dectoint() or dectolong() (it is present in both):
if (ret == PGTYPES_NUM_OVERFLOW) - condition is always
false because PGTYPESnumeric_to_int() and PGTYPESnumeric_to_long()
functions return only 0 or -1. So ECPG_INFORMIX_NUM_OVERFLOW can never
be returned.
I think dectoint(), dectolong() and PGTYPESnumeric_to_int() functions
should be a little bit different like in proposing patch.
What do you think?
The flaw was catched with the help of Svace static analyzer.
https://svace.pages.ispras.ru/svace-website/en/
Thank you!
Attachments:informix_convert_from_decimal.patch (text/x-diff, 5.7K) downloaddiff --git a/doc/src/sgml/ecpg.sgml b/doc/src/sgml/ecpg.sgmlindex 73351a9136..8390a61cf4 100644--- a/doc/src/sgml/ecpg.sgml+++ b/doc/src/sgml/ecpg.sgml@@ -8882,7 +8882,7 @@ int dectodbl(decimal *np, double *dblp);
<term><function>dectoint</function></term>
<listitem>
<para>
- Convert a variable to type decimal to an integer.+ Convert a variable of type decimal to an integer.
<synopsis>
int dectoint(decimal *np, int *ip);
</synopsis>
@@ -8892,8 +8892,9 @@ int dectoint(decimal *np, int *ip);
</para>
<para>
On success, 0 is returned and a negative value if the conversion
- failed. If an overflow occurred, <literal>ECPG_INFORMIX_NUM_OVERFLOW</literal>- is returned.+ failed. If overflow or underflow occurred, the function returns+ <literal>ECPG_INFORMIX_NUM_OVERFLOW</literal> or+ <literal>ECPG_INFORMIX_NUM_UNDERFLOW</literal> respectively.
</para>
<para>
Note that the ECPG implementation differs from the <productname>Informix</productname>
@@ -8908,7 +8909,7 @@ int dectoint(decimal *np, int *ip);
<term><function>dectolong</function></term>
<listitem>
<para>
- Convert a variable to type decimal to a long integer.+ Convert a variable of type decimal to a long integer.
<synopsis>
int dectolong(decimal *np, long *lngp);
</synopsis>
@@ -8918,8 +8919,9 @@ int dectolong(decimal *np, long *lngp);
</para>
<para>
On success, 0 is returned and a negative value if the conversion
- failed. If an overflow occurred, <literal>ECPG_INFORMIX_NUM_OVERFLOW</literal>- is returned.+ failed. If overflow or underflow occurred, the function returns+ <literal>ECPG_INFORMIX_NUM_OVERFLOW</literal> or+ <literal>ECPG_INFORMIX_NUM_UNDERFLOW</literal> respectively.
</para>
<para>
Note that the ECPG implementation differs from the <productname>Informix</productname>
diff --git a/src/interfaces/ecpg/compatlib/informix.c b/src/interfaces/ecpg/compatlib/informix.cindex 80d40aa3e0..73e84bc6e3 100644--- a/src/interfaces/ecpg/compatlib/informix.c+++ b/src/interfaces/ecpg/compatlib/informix.c@@ -435,6 +435,7 @@ dectoint(decimal *np, int *ip)
{
int ret;
numeric *nres = PGTYPESnumeric_new();
+ int errnum = 0;
if (nres == NULL)
return ECPG_INFORMIX_OUT_OF_MEMORY;
@@ -445,11 +446,18 @@ dectoint(decimal *np, int *ip)
return ECPG_INFORMIX_OUT_OF_MEMORY;
}
+ errno = 0;
ret = PGTYPESnumeric_to_int(nres, ip);
+ errnum = errno;
PGTYPESnumeric_free(nres);
- if (ret == PGTYPES_NUM_OVERFLOW)- ret = ECPG_INFORMIX_NUM_OVERFLOW;+ if (ret)+ {+ if (errnum == PGTYPES_NUM_UNDERFLOW)+ ret = ECPG_INFORMIX_NUM_UNDERFLOW;+ else if (errnum == PGTYPES_NUM_OVERFLOW)+ ret = ECPG_INFORMIX_NUM_OVERFLOW;+ }
return ret;
}
@@ -459,6 +467,7 @@ dectolong(decimal *np, long *lngp)
{
int ret;
numeric *nres = PGTYPESnumeric_new();
+ int errnum = 0;
if (nres == NULL)
return ECPG_INFORMIX_OUT_OF_MEMORY;
@@ -469,11 +478,18 @@ dectolong(decimal *np, long *lngp)
return ECPG_INFORMIX_OUT_OF_MEMORY;
}
+ errno = 0;
ret = PGTYPESnumeric_to_long(nres, lngp);
+ errnum = errno;
PGTYPESnumeric_free(nres);
- if (ret == PGTYPES_NUM_OVERFLOW)- ret = ECPG_INFORMIX_NUM_OVERFLOW;+ if (ret)+ {+ if (errnum == PGTYPES_NUM_UNDERFLOW)+ ret = ECPG_INFORMIX_NUM_UNDERFLOW;+ else if (errnum == PGTYPES_NUM_OVERFLOW)+ ret = ECPG_INFORMIX_NUM_OVERFLOW;+ }
return ret;
}
diff --git a/src/interfaces/ecpg/pgtypeslib/numeric.c b/src/interfaces/ecpg/pgtypeslib/numeric.cindex 35e7b92da4..52b49e1ce9 100644--- a/src/interfaces/ecpg/pgtypeslib/numeric.c+++ b/src/interfaces/ecpg/pgtypeslib/numeric.c@@ -1502,7 +1502,12 @@ PGTYPESnumeric_to_int(numeric *nv, int *ip)
/* silence compilers that might complain about useless tests */
#if SIZEOF_LONG > SIZEOF_INT
- if (l < INT_MIN || l > INT_MAX)+ if (l < INT_MIN)+ {+ errno = PGTYPES_NUM_UNDERFLOW;+ return -1;+ }+ else if(l > INT_MAX)
{
errno = PGTYPES_NUM_OVERFLOW;
return -1;
diff --git a/src/interfaces/ecpg/test/expected/compat_informix-dec_test.stdout b/src/interfaces/ecpg/test/expected/compat_informix-dec_test.stdoutindex 1f8675b3f3..71a5afa4a7 100644--- a/src/interfaces/ecpg/test/expected/compat_informix-dec_test.stdout+++ b/src/interfaces/ecpg/test/expected/compat_informix-dec_test.stdout@@ -3,8 +3,8 @@
(no errno set) - dec[0,3]: r: -1, *
(no errno set) - dec[0,4]: r: -1, *
dec[0,5]: r: 0, 0.00
-(errno == PGTYPES_NUM_OVERFLOW) - dec[0,6]: 0 (r: -1)-(errno == PGTYPES_NUM_OVERFLOW) - dec[0,8]: 0 (r: -1)+(errno == PGTYPES_NUM_OVERFLOW) - dec[0,6]: 0 (r: -1200)+(errno == PGTYPES_NUM_OVERFLOW) - dec[0,8]: 0 (r: -1200)
(errno == PGTYPES_NUM_OVERFLOW) - dec[0,10]: 0 (r: -1)
dec[1,1]: r: 0, -2
@@ -45,8 +45,8 @@ dec[4,2]: r: 0, 592490000000000000000000
dec[4,3]: r: 0, 592490000000000000000000.0
dec[4,4]: r: 0, 592490000000000000000000.00
dec[4,5]: r: 0, 0.00
-(errno == PGTYPES_NUM_OVERFLOW) - dec[4,6]: 0 (r: -1)-(errno == PGTYPES_NUM_OVERFLOW) - dec[4,8]: 0 (r: -1)+(errno == PGTYPES_NUM_OVERFLOW) - dec[4,6]: 0 (r: -1200)+(errno == PGTYPES_NUM_OVERFLOW) - dec[4,8]: 0 (r: -1200)
dec[4,10]: 5.9249e+23 (r: 0)
dec[5,1]: r: 0, -328400
@@ -141,8 +141,8 @@ dec[13,2]: r: 0, 1234567890123456789012345679
dec[13,3]: r: 0, 1234567890123456789012345678.9
dec[13,4]: r: 0, 1234567890123456789012345678.91
dec[13,5]: r: 0, 0.00
-(errno == PGTYPES_NUM_OVERFLOW) - dec[13,6]: 0 (r: -1)-(errno == PGTYPES_NUM_OVERFLOW) - dec[13,8]: 0 (r: -1)+(errno == PGTYPES_NUM_OVERFLOW) - dec[13,6]: 0 (r: -1200)+(errno == PGTYPES_NUM_OVERFLOW) - dec[13,8]: 0 (r: -1200)
dec[13,10]: 1.23457e+27 (r: 0)
(errno == PGTYPES_NUM_OVERFLOW) - dec[14,0]: r: -1200
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To: pgsql-hackers@postgresql.org
Cc: a.imamov@postgrespro.ru, pgsql-hackers@lists.postgresql.org
Subject: Re: Potential issue in ecpg-informix decimal converting functions
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