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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2018-09-26 13:31:56 -0400 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2018-09-26 13:31:56 -0400 |
| commit | d6c55de1f99a9028540516316b95321a7b12a540 (patch) | |
| tree | 7c95ff050f56bcf20648e3d7a8a7fbb2ddbc7293 /src/common/psprintf.c | |
| parent | 96bf88d52711ad3a0a4cc2d1d9cb0e2acab85e63 (diff) | |
| download | postgresql-d6c55de1f99a9028540516316b95321a7b12a540.tar.gz postgresql-d6c55de1f99a9028540516316b95321a7b12a540.zip | |
Implement %m in src/port/snprintf.c, and teach elog.c to rely on that.
I started out with the idea that we needed to detect use of %m format specs
in contexts other than elog/ereport calls, because we couldn't rely on that
working in *printf calls. But a better answer is to fix things so that it
does work. Now that we're using snprintf.c all the time, we can implement
%m in that and we've fixed the problem.
This requires also adjusting our various printf-wrapping functions so that
they ensure "errno" is preserved when they call snprintf.c.
Remove elog.c's handmade implementation of %m, and let it rely on
snprintf to support the feature. That should provide some performance
gain, though I've not attempted to measure it.
There are a lot of places where we could now simplify 'printf("%s",
strerror(errno))' into 'printf("%m")', but I'm not in any big hurry
to make that happen.
Patch by me, reviewed by Michael Paquier
Discussion: https://postgr.es/m/2975.1526862605@sss.pgh.pa.us
Diffstat (limited to 'src/common/psprintf.c')
| -rw-r--r-- | src/common/psprintf.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/src/common/psprintf.c b/src/common/psprintf.c index 04465a18e69..2cf100f0954 100644 --- a/src/common/psprintf.c +++ b/src/common/psprintf.c @@ -45,6 +45,7 @@ char * psprintf(const char *fmt,...) { + int save_errno = errno; size_t len = 128; /* initial assumption about buffer size */ for (;;) @@ -60,6 +61,7 @@ psprintf(const char *fmt,...) result = (char *) palloc(len); /* Try to format the data. */ + errno = save_errno; va_start(args, fmt); newlen = pvsnprintf(result, len, fmt, args); va_end(args); @@ -89,6 +91,9 @@ psprintf(const char *fmt,...) * Other error cases do not return, but exit via elog(ERROR) or exit(). * Hence, this shouldn't be used inside libpq. * + * Caution: callers must be sure to preserve their entry-time errno + * when looping, in case the fmt contains "%m". + * * Note that the semantics of the return value are not exactly C99's. * First, we don't promise that the estimated buffer size is exactly right; * callers must be prepared to loop multiple times to get the right size. |