tree cf408c56c67bbcbb757c3298bb9ce50f4eb44490
parent a2501a20651bad1c1645547c8ad99af4f5c64e2e
author Neels Hofmeyr <neels@hofmeyr.de> 1522246365 +0200
committer Neels Hofmeyr <neels@hofmeyr.de> 1522246740 +0200

vty/command.c: write_config_file(): sanely compose temp path

Fix GCC version 7.3.0 (Debian 7.3.0-12) compiler warning:

../../../../src/libosmocore/src/vty/command.c: In function ‘write_config_file’:
../../../../src/libosmocore/src/vty/command.c:2741:2: error: null destination pointer [-Werror=format-overflow=]
  sprintf(config_file_tmp, "%s.XXXXXX", config_file);
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Check agains NULL after each _talloc_zero() in write_config_file().

While at it, add a comment explaining why we don't use talloc_asprintf() instead.

Change-Id: I7bdc52afe724c1d21f419fe49a6e2ebca9420969