printf-like output for gnunet-search

Hi GNUnet folks!

I have edited the gnunet-search utility to accept a --format and a --dir-format parameters and produce a printf-like output. It was pretty easy to do, I only had to edit gnunet/src/fs/gnunet-search.c. The new text printed by gnunet-search --help can explain the two new arguments in detail:

$ gnunet-search --help

gnunet-search [OPTIONS] KEYWORD
Search GNUnet for files that were published on GNUnet
Arguments mandatory for long options are also mandatory for short options.
  -a, --anonymity=LEVEL      set the desired LEVEL of receiver-anonymity
  -c, --config=FILENAME      use configuration file FILENAME
  -F, --dir-format=DIRFORMAT write search results for directories according to
                               DIRFORMAT, where %n is the result number, %f is
                               the file's name and %u is the file's URI; if
                               missing defaults to FORMAT; if the latter is
                               missing too defaults to '#%n:\ngnunet-download
                               -o "%f" -R %u\n\n'
  -f, --format=FORMAT        write search results according to FORMAT, where
                               %n is the result number, %f is the file's name
                               and %u is the file's URI; if missing defaults
                               to '#%n:\ngnunet-download -o "%f" %u\n\n')
  -h, --help                 print this help
  -L, --log=LOGLEVEL         configure logging to use LOGLEVEL
  -l, --logfile=FILENAME     configure logging to write logs to FILENAME
  -N, --results=VALUE        automatically terminate search after VALUE
                               results are found
  -n, --no-network           only search the local peer (no P2P network
                               search)
  -o, --output=PREFIX        write search results to file starting with PREFIX
  -t, --timeout=DELAY        automatically terminate search after DELAY
  -V, --verbose              be verbose
  -v, --version              print the version number
Report bugs to gnunet-developers@gnu.org.
Home page: http://www.gnu.org/s/gnunet/
General help using GNU software: http://www.gnu.org/gethelp/

Basically with this new patch launching

gnunet-search commons

and launching

gnunet-search --format='#%n:\ngnunet-download -o "%f" %u\n\n' \
	--dir-format='#%n:\ngnunet-download -o "%f" -R %u\n\n' \
	commons

are equivalent.

What do you think? I hope you like the idea.

I have done my best to stick to the coding style of the rest of the program. But a good code review is more than welcomed.

Please find attached a patch, or alternatively the single file I have edited.

--madmurphy

From:	madmurphy
Subject:	printf-like output for gnunet-search
Date:	Fri, 4 Feb 2022 18:21:57 +0000