clixon/doc/DEVELOP.md

README for Clixon developers

• Code documentation
• C style
• How to work in git (how-to-work-in-git)
• How the meta-configure stuff works
• How to debug
• New release

Documentation

How to document the code

/*! This is a small comment on one line
 *
 * This is a detailed description
 * spanning several lines.
 *
 * Example usage:
 * @code
 *   fn(a, &b);
 * @endcode
 *
 * @param[in] src         This is a description of the first parameter
 * @param[in,out] dest    This is a description of the second parameter
 * @retval TRUE           This is a description of the return value
 * @retval FALSE          This is a description of another return value
 * @see                   See also this function
 */

C style

Clixon uses 4-char indentation, a la emacs "cc-mode".

Function declarations

Functions in C code are written as follows:

static int
myfn(int           par1,
     my_structure *par2)
{
    int           retval = -1;
    my_structure *ms;

    ms = NULL;

Notes:

1. The return type of the function and all qualifers on first line (static int)
2. Function name and first parameter on second line, thereafter each parameter on own line
3. Each parameter indented to match the "longest" (my_structure)
4. Pointer declarations written: type *p, not: type* p.
5. All local variables in a function declared at top of function, not inline with C-statements.
6. Local variables can be initialized with scalars or constants, not eg malloc or functions with return values that need to be checked for errors
7. There is a single empty line between local variable declarations and the first function statement.

Function signatures are declared in include files or in forward declaration using "one-line" syntax, unless very long:

static int myfn(int par1, my_structure *par2);

Errors

Errors are typically declared as follows:

    if (myfn(0) < 0){
       clicon_err(OE_UNIX, EINVAL, "myfn");
       goto done;
    }

All function returns that have return values must be checked

Default return values form a function are:

• 0 OK
• -1 Fatal Error

In some cases, Clixon uses three-value returns as follows:

• 1 OK
• 0 Invalid
• -1 Fatal error

Return values

Clixon uses goto:s only to get a single point of exit functions as follows:

{
    int retval = -1;

    ...
    retval = 0;
  done:
    return retval
}

Notes:

1. Use only a single return statement in a function
2. Do not use of goto:s in other ways

Comments

Use /* */. Use // only for temporal comments.

Do not use "======", ">>>>>" or "<<<<<<" in comments since git merge conflict uses that.

Format ints

Use:

• %zu for size_t
• PRIu64 for uint64
• %p for pointers

Include files

Avoid include statements in .h files, place them in .c files whenever possible.

The reason is to avoid deep include chains where file dependencies are difficult to analyze and understand. If include statements are only placed in .c files, there is only a single level of include file dependencies.

The drawback is that the same include file may need to be repeated in many .c files.

Structs

Struct fields should have a prefix to distinguish them from other struct fields. The prefix should use an abbreviation of the struct name.

Example:

struct my_struct{
  int   ms_foo;
  char *ms_string[42];
}

where ms_ is the prefix and is an abbreviation of my_struct.

Global variables

Try to avoid global variables.

If you absolutely need one, try to contain it as static within a single C-file, ie do not declare it extern and use it elsewhere.

Also, always prepend a global variable with _, underscore.

How to work in git

Clixon uses semantic versioning (https://semver.org).

Try to keep a single master branch always working. Currently testing is made using Travis CI.

However, releases are made periodically (ca every 1 month) which is more tested.

A release branch can be made, eg release-4.0 where 4.0.0, 4.0.1 are tagged

Commit messages: https://chris.beams.io/posts/git-commit/

How the autotools stuff works

configure.ac --.
                    |   .------> autoconf* -----> configure
     [aclocal.m4] --+---+
                    |   `-----> [autoheader*] --> [config.h.in]
     [acsite.m4] ---'

                           .-------------> [config.cache]
     configure* ------------+-------------> config.log
                            |
     [config.h.in] -.       v            .-> [config.h] -.
                    +--> config.status* -+               +--> make*
     Makefile.in ---'                    `-> Makefile ---'

Note: remember to run autoheader sometimes (when?) And when you do note (https://github.com/clicon/cligen/issues/17) which states that cligen_custom.h should be in quote.

Get config.sub and config.guess:

$ wget -O config.guess 'https://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.guess;hb=HEAD'
$ wget -O config.sub 'https://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.sub;hb=HEAD'

Or generate:

libtoolize --force
aclocal
autoheader
automake --force-missing --add-missing

Debug

How to debug

Configure in debug mode

   ./configure --enable-debug

Send debug level in run-time to backend:

  echo "<rpc username=\"root\" xmlns=\"urn:ietf:params:xml:ns:netconf:base:1.0\"><debug xmlns=\"http://clicon.org/lib\"><level>1</level></debug></rpc>]]>]]>" | clixon_netconf -q -o CLICON_NETCONF_HELLO_OPTIONAL=true

Set backend debug

Using netconf:

<rpc xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"><debug xmlns="http://clicon.org/lib"><level>1</level></debug></rpc>

Using curl:

curl -Ssik -X POST -H "Content-Type: application/yang-data+json" http://localhost/restconf/operations/clixon-lib:debug -d '{"clixon-lib:input":{"level":1}}'

Set restconf debug

All three must be true:

1. clixon-restconf.yang is used (so that debug config can be set)
2. AND the XML is in running db not in clixon-config (so that restconf reads the new config from backend) 3 CLICON_BACKEND_RESTCONF_PROCESS is true (so that backend restarts restconf)

Otherwise you need to restart clixon_restconf manually

Using netconf:

clixon_netconf -q -o CLICON_NETCONF_HELLO_OPTIONAL=true <<EOF
<rpc xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"><edit-config><target><candidate/></target><config><restconf xmlns="http://clicon.org/restconf"><debug>1</debug></restconf></config></edit-config></rpc>]]>]]>
<rpc xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"><commit/></rpc>]]>]]>
EOF

Using restconf/curl

curl -Ssik -X PUT -H "Content-Type: application/yang-data+json" http://localhost/restconf/data/clixon-restconf:restconf/debug -d '{"clixon-restconf:debug":1}' 

Get restconf daemon status:

curl -Ssik -X POST -H "Content-Type: application/yang-data+json" http://localhost/restconf/operations/clixon-lib:process-control -d '{"clixon-lib:input":{"name":"restconf","operation":"status"}}'

Make your own simplified yang and configuration file.

cat <<EOF > /tmp/my.yang
module mymodule{
   container x {
    list y {
      key "a";
      leaf a {
        type string;
      }
    }
  }
}
EOF
cat <<EOF > /tmp/myconf.xml
<config>
  <CLICON_CONFIGFILE>/tmp/myconf.xml</CLICON_CONFIGFILE>
  <CLICON_YANG_DIR>/usr/local/share/example/yang</CLICON_YANG_DIR>
  <CLICON_YANG_MODULE_MAIN>example</CLICON_YANG_MODULE_MAIN>
  <CLICON_SOCK>/usr/local/var/example/example.sock</CLICON_SOCK>
  <CLICON_BACKEND_PIDFILE>/usr/local/var/example/example.pidfile</CLICON_BACKEND_PIDFILE>
  <CLICON_XMLDB_DIR>/usr/local/var/example</CLICON_XMLDB_DIR>
</config>
EOF
 sudo clixon_backend -F -s init -f /tmp/myconf.xml -y /tmp/my.yang

Run valgrind and callgrind

 valgrind --leak-check=full --show-leak-kinds=all clixon_netconf -qf /tmp/myconf.xml -y /tmp/my.yang
 LD_BIND_NOW=y valgrind --tool=callgrind clixon_netconf -qf /tmp/myconf.xml -y /tmp/my.yang
 sudo kcachegrind
 valgrind --tool=massif clixon_netconf -qf /tmp/myconf.xml -y /tmp/my.yang
 massif-visualizer

To turn callgrind off/on:

 valgrind --tool=callgrind --instr-atstart=no clixon_netconf -qf /tmp/myconf.xml -y /tmp/my.yang
 ...
 callgrind_control -i on

valgrind and gdb

valgrind --vgdb=yes --vgdb-error=0 clixon_cli

gdb clixon_cli
(gdb) target remote | /usr/lib/valgrind/../../bin/vgdb --pid=1311 # see output from valgrind
(gdb) cont

New release

What to think about when doing a new release.

• Ensure all tests run OK
• review CHANGELOG, write one-liner
• review README.md wording about latest release
• New yang/clicon/clixon-config@XXX.yang revision?
• In configure.ac, for minor releases change CLIXON_VERSION in configure.ac to eg: (minor should have been bumped):

  CLIXON_VERSION="\"${CLIXON_VERSION_MAJOR}.${CLIXON_VERSION_MINOR}.${CLIXON_VERSION_PATCH}\""

• For patch releases change CLIXON_VERSION_PATCH
• Run autoconf
• Git stuff:

  git tag -a <version>
  git push origin <version>

• Add a github "release" and copy release info from CHANGELOG

After release:

• Bump minor version and add a "PRE":

  CLIXON_VERSION_MINOR="10" ++
  CLIXON_VERSION="\"${CLIXON_VERSION_MAJOR}.${CLIXON_VERSION_MINOR}.${CLIXON_VERSION_PATCH}.PRE\""

• Run autoconf

Create release branch:

  git checkout -b release-4.2 4.2.0
  git push origin release-4.2

Merge a branch back:

  git merge --no-ff release-4.2

Use of constants etc

Use MAXPATHLEN (not PATH_MAX) in sys/param.h

Emulating a serial console

socat PTY,link=/tmp/clixon-tty,rawer EXEC:"/usr/local/bin/clixon_cli -f /usr/local/etc/example.xml",pty,stderr & screen /tmp/clixon-tty

Coverage

LDFLAGS=-coverage LINKAGE=static CFLAGS="-O2 -Wall -coverage" ./configure
bash <(curl -s https://codecov.io/bash) -t <token>

Static analysis

sudo apt install clang-tools # on ubuntu
scan-build ./configure --enable-debug
scan-build make
scan-view /tmp/scan-build-2022-02-03-100113-27646-1 # example