diff options
| 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/backend/lib/stringinfo.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/backend/lib/stringinfo.c')
| -rw-r--r-- | src/backend/lib/stringinfo.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/src/backend/lib/stringinfo.c b/src/backend/lib/stringinfo.c index 798a823ac9f..df7e01f76d9 100644 --- a/src/backend/lib/stringinfo.c +++ b/src/backend/lib/stringinfo.c @@ -77,12 +77,15 @@ resetStringInfo(StringInfo str) void appendStringInfo(StringInfo str, const char *fmt,...) { + int save_errno = errno; + for (;;) { va_list args; int needed; /* Try to format the data. */ + errno = save_errno; va_start(args, fmt); needed = appendStringInfoVA(str, fmt, args); va_end(args); @@ -105,6 +108,9 @@ appendStringInfo(StringInfo str, const char *fmt,...) * pass the return value to enlargeStringInfo() before trying again; see * appendStringInfo for standard usage pattern. * + * Caution: callers must be sure to preserve their entry-time errno + * when looping, in case the fmt contains "%m". + * * XXX This API is ugly, but there seems no alternative given the C spec's * restrictions on what can portably be done with va_list arguments: you have * to redo va_start before you can rescan the argument list, and we can't do |