Re: Persist injection points across server restarts

Hi,

> This is v19 work, so I am adding that to the next commit fest.
>
> Rebased, to fix a conflict I've introduced with a different commit.
>
>
Thank you for the rebased patches.  I reviewed the code and have a few
comments for
your consideration.

It appears that Github CI is reporting failures with
injection_points/002_data_persist
failing across all OSes.

Following are comments on
v2-0002-injection_points-Add-function-to-flush-injection-.patch
1.
 /*
+        * Rename file into place, so we atomically replace any old one.
+        */
+       (void) durable_rename(INJ_DUMP_FILE_TMP, INJ_DUMP_FILE, LOG);

I wonder if it would be better to include a check for the return value of
`durable_rename` to
manage potential failure scenarios.

2. +
+       file = AllocateFile(INJ_DUMP_FILE ".tmp", PG_BINARY_W);

Could we perhaps add a brief comment clarifying the rationale behind the
use of a
temporary file in this context?

3.   +               if (fread(buf, 1, len + 1, file) != len + 1)
+                       goto error;
+               library = pstrdup(buf);

It seems that `buf` should be null-terminated before being passed to
`pstrdup(buf)`.
Otherwise, `strlen` might not accurately determine the length. This seems
to be
consistent with the handling of `fread` calls in `snapmgr.c`.

Thank you,
Rahila Syed