Include VARHDRSZ when allocating return value#20
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iCyberon merged 1 commit intoiCyberon:masterfrom Sep 6, 2019
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According to the PostgreSQL documentation, the VARHDRSZ header needs to be included in the allocation for the return value. Without this, the allocations are 4 bytes short (which explains the results describe in issue iCyberon#19), writing the data flies off the end of the allocated space (by 4 bytes), and is then overwritten by subsequent allocations. From the docs: ``` char buffer[40]; /* our source data */ ... text *destination = (text *) palloc(VARHDRSZ + 40); SET_VARSIZE(destination, VARHDRSZ + 40); memcpy(destination->data, buffer, 40); ``` (Notice the `VARHDRSZ + 40` in *both* the `palloc()` and the `SET_VARSIZE()` calls. While the existing code had `+ VARHDRSZ` in the `VARSIZE()` call, it was missing from `palloc()`. Fixes iCyberon#19, and probably iCyberon#15. Signed-off-by: Jared Reisinger <jaredreisinger@hotmail.com>
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Awesome! thanks for the work @JaredReisinger. |
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According to the PostgreSQL documentation, the VARHDRSZ header needs to be included in the allocation for the return value. Without this, the allocations are 4 bytes short (which explains the results described in issue #19), writing the data flies off the end of the allocated space (by 4 bytes), and is then overwritten by subsequent allocations.
From the docs:
(Notice the
VARHDRSZ + 40in both thepalloc()and theSET_VARSIZE()calls. While the existing code had+ VARHDRSZin theVARSIZE()call, it was missing frompalloc().Fixes #19, and probably #15.
Signed-off-by: Jared Reisinger jaredreisinger@hotmail.com