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Fix XPath mod SIGFPE on zero divisor, and xml_diff() with NULL first tree #703

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Fix XPath mod SIGFPE on zero divisor, and xml_diff() with NULL first tree #703

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02e2b1b
fix: XPath mod crashed with SIGFPE on zero divisor
khromenokroman Oct 8, 2026
e6afa3e
fix: xml_diff() returned NULL instead of x1 when x0 is NULL
khromenokroman Oct 8, 2026
663d1b0
test: XPath mod including zero and non-integer divisor
khromenokroman Oct 8, 2026
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2 changes: 1 addition & 1 deletion lib/src/clixon_xml_diff.c
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Original file line number Diff line number Diff line change
Expand Up @@ -539,7 +539,7 @@ xml_diff(cxobj *x0,
goto ok;
}
if (x0 == NULL){
if (cxvec_append(x0, second, secondlen) < 0)
if (cxvec_append(x1, second, secondlen) < 0)
goto done;
goto ok;
}
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4 changes: 3 additions & 1 deletion lib/src/clixon_xpath_eval.c
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Expand Up @@ -763,7 +763,9 @@ xp_numop(xp_ctx *xc1,
xr->xc_number = n1/n2;
break;
case XO_MOD:
xr->xc_number = ((int)n1)%((int)n2);
/* XPath 1.0 3.5: remainder from a truncating division, as fmod().
* Integer % crashes with SIGFPE if n2 truncates to 0 */
xr->xc_number = fmod(n1, n2);
break;
case XO_ADD:
xr->xc_number = n1+n2;
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19 changes: 19 additions & 0 deletions test/test_xpath.sh
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Expand Up @@ -412,6 +412,25 @@ expectpart "$($clixon_util_xpath -D $DBG -f $xml2 -p "string-length(\"12345\")")
new "xpath string-length path"
expectpart "$($clixon_util_xpath -D $DBG -f $xml2 -p "string-length(aaa/name)")" 0 "number:3"

# mod: XPath 1.0 3.5, remainder from a truncating division
new "xpath 5 mod 2"
expectpart "$($clixon_util_xpath -D $DBG -f $xml2 -p "5 mod 2")" 0 "number:1.0"

new "xpath 5 mod -2"
expectpart "$($clixon_util_xpath -D $DBG -f $xml2 -p "5 mod -2")" 0 "number:1.0"

new "xpath -5 mod 2"
expectpart "$($clixon_util_xpath -D $DBG -f $xml2 -p "-5 mod 2")" 0 "number:-1.0"

new "xpath 5.5 mod 2"
expectpart "$($clixon_util_xpath -D $DBG -f $xml2 -p "5.5 mod 2")" 0 "number:1.5"

new "xpath 1 mod 0 is NaN, not crash"
expectpart "$($clixon_util_xpath -D $DBG -f $xml2 -p "1 mod 0")" 0 "number:" "nan"

new "xpath 1 mod 0.5, divisor truncated to int was 0"
expectpart "$($clixon_util_xpath -D $DBG -f $xml2 -p "1 mod 0.5")" 0 "number:0.0"

# translate
new "xpath translate" # modified
expectpart "$($clixon_util_xpath -D $DBG -f $xml2 -p "translate(\"bar\", \"abc\",\"DEF\")")" 0 "string:EDr$"
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