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Re: C99 compliance for src/port/snprintf.c

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Haas <robertmhaas@gmail.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2018-08-16T00:15:58Z
Lists: pgsql-hackers

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I wrote:
> BTW, independently of whether to back-patch, it strikes me that what
> we ought to do in HEAD (after applying this) is to just assume we have
> C99-compliant behavior, and rip out the baroque logic in psnprintf
> and appendPQExpBufferVA that tries to deal with pre-C99 snprintf.

Here's a proposed patch for that.  It also gets rid of some ancient
code that tried to deal with snprintfs that were outright broken,
such as writing past the end of the specified buffer.  Even if anyone
is still using platforms where that's a problem, I'd expect that we'd
have rejected the system snprintf thanks to configure's feature checks.

			regards, tom lane

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Remove test for VA_ARGS, implied by C99.

  2. Introduce minimal C99 usage to verify compiler support.

  3. Require C99 (and thus MSCV 2013 upwards).

  4. Require a C99-compliant snprintf(), and remove related workarounds.

  5. Try to enable C99 in configure, but do not rely on it (yet).

  6. Make snprintf.c follow the C99 standard for snprintf's result value.

  7. Clean up assorted misuses of snprintf()'s result value.