#18098: snprintf: different results on 32 and 64 bits.
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Reporter: bipolar | Owner: nobody
Type: bug | Status: new
Priority: normal | Milestone: Unscheduled
Component: - General | Version: R1/beta4
Resolution: | Keywords:
Blocked By: | Blocking:
Platform: All |
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Description changed by bipolar:
Old description:
While running the wget2 test-suite, Begasus found some failing tests (see
https://github.com/haikuports/haikuports/pull/7484).
I've managed to distill/recreate the failing test cases with the
following `test_snprintf` small program:
{{{
#include <stdio.h>
int main(void)
{
char* fmts[]={"%0lld","%0lli","%0llu","%00lld","%00lli",
"%00llu"};
char result[32];
int i;
for (i=0; i < 6; i++) {
// Without using "(long long int)0" here, the 32 bits
versions output a different
// big number (like "141014943242649600") on each run,
instead of "".
// On 64 bits, using just 0, works ok (output is "0").
snprintf(result, sizeof(result), fmts[i], (long long
int)0);
printf("(%s, 0) - Expected: '0' got: '%s'\n", fmts[i],
result);
}
return 0;
}
}}}
Output on 32 bits (on both gcc2 and gcc11):
{{{
test_snprintf(%0lld, 0) - Expected: '0' got: ''
(%0lli, 0) - Expected: '0' got: ''
(%0llu, 0) - Expected: '0' got: ''
(%00lld, 0) - Expected: '0' got: ''
(%00lli, 0) - Expected: '0' got: ''
(%00llu, 0) - Expected: '0' got: ''
}}}
Output on 64 bits:
{{{
test_snprintf(%0lld, 0) - Expected: '0' got: '0'
(%0lli, 0) - Expected: '0' got: '0'
(%0llu, 0) - Expected: '0' got: '0'
(%00lld, 0) - Expected: '0' got: '0'
(%00lli, 0) - Expected: '0' got: '0'
(%00llu, 0) - Expected: '0' got: '0'
}}}
Not sure about how important this difference in behavior might be (or if
I'm also messing things up in that test), but...
At least this is easy to reproduce.
(just to be clear, the wget2 test-suite expects the behavior seen on the
64 bits version, thus my use of "Expected: '0'").
test_snprintf(%0lld, 0) - Expected: '0' got: ''
test_snprintf(%0lld, 0) - Expected: '0' got: '0'
