`jq_reset` calls `jv_free` on the `exit_code` and the `error_message` stored on the jq state.
However, it doesn't replace the actual instance of those members. This means that subsequent
calls to `jq_reset` will call `jv_free` again on those members, which in turn may call `free`
on the same pointer multiple times. Freeing the same pointer multiple times is undefined
behavior and can cause heap corruption, which is how I spotted this issue.
In practice, this issue only occurs when using a program that may `halt_error`, because that
is when the `exit_code` and `error_message` are set to values other than `jv_invalid`.
Subsequent attempts to call `jq_start` (which calls `jq_reset` internally) after hitting a
`halt_error` can cause you to run into this issue.
The changes simply reset the `exit_code` and the `error_message` to `jv_invalid` (the initial
value set in `jq_init`) after they are freed.
tests/mantest were failing on Raspberry Pi OS 11:
==10205== Conditional jump or move depends on uninitialised value(s)
==10205== at 0x48806F8: checkfail (jq_test.c:58)
==10205== by 0x48806F8: run_jq_tests (jq_test.c:99)
==10205== by 0x4880FCB: jq_testsuite (jq_test.c:39)
==10205== by 0x10B37F: main (main.c:576)
==10205==
==10205== Conditional jump or move depends on uninitialised value(s)
==10205== at 0x4880714: checkfail (jq_test.c:58)
==10205== by 0x4880714: run_jq_tests (jq_test.c:99)
==10205== by 0x4880FCB: jq_testsuite (jq_test.c:39)
==10205== by 0x10B37F: main (main.c:576)
valgrind (3.19.0) locally on macOS docker container seems to detect this leak but not CI.
$ cat modulemeta.test
modulemeta | .deps |= length
"c"
{"whatever":null,"deps":6}
$ valgrind --error-exitcode=1 --leak-check=full -q ./jq --run-tests < modulemeta.test
Test #1: 'modulemeta | .deps |= length' at line number 1
*** Insufficient results for test at line number 3: modulemeta | .deps |= length
0 of 1 tests passed (0 malformed, 0 skipped)
==14129== 482 (392 direct, 90 indirect) bytes in 1 blocks are definitely lost in loss record 7 of 8
==14129== at 0x48407B4: malloc (vg_replace_malloc.c:381)
==14129== by 0x13BC78: jv_mem_alloc (jv_alloc.c:122)
==14129== by 0x1371C6: jvp_object_new (jv.c:1521)
==14129== by 0x145840: parse_token (jv_parse.c:167)
==14129== by 0x145840: scan (jv_parse.c:684)
==14129== by 0x145840: jv_parser_next (jv_parse.c:793)
==14129== by 0x1463CB: jv_parse_sized (jv_parse.c:865)
==14129== by 0x136BD9: run_jq_tests (jq_test.c:183)
==14129== by 0x1370FA: jq_testsuite (jq_test.c:34)
==14129== by 0x13135C: main (main.c:582)
==14129==
Extend jv_number to use decNumber for storing number literals. Any math
operations on the numbers will truncate them to double precision.
Comparisons when both numbers are literal numbers will compare them
without truncation.
Delay conversion of numbers to doubles until a math operation is performed,
to preserve precision. A literal jv_number will only need conversion to
double once, and will reuse the resultant double on subsequent
conversions.
Outputting literal jv_numbers preserves the original precision.
Add strong pthread requirement to manage contexts/allocations for
converting numbers between their decNumber, string, and double formats.
Samar Sunkaria