pgsql: port/snprintf(): fix overflow and do padding

port/snprintf():  fix overflow and do padding

Prevent port/snprintf() from overflowing its local fixed-size
buffer and pad to the desired number of digits with zeros, even
if the precision is beyond the ability of the native sprintf().
port/snprintf() is only used on systems that lack a native
snprintf().

Reported by Bruce Momjian. Patch by Tom Lane.    Backpatch to all
supported versions.

Security: CVE-2015-0242

Branch
------
master

Details
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http://git.postgresql.org/pg/commitdiff/29725b3db67ad3f09da1a7fb6690737d2f8d6c0a

Modified Files
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src/port/snprintf.c |   69 +++++++++++++++++++++++++++++++++++++++++++++------
1 file changed, 62 insertions(+), 7 deletions(-)