commit xpath
This commit is contained in:
Olof hagsand
parent
554c1cb9de
commit
9bd941ab76
14 changed files with 306 additions and 130 deletions
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@ -32,7 +32,7 @@ DOXYFILE_ENCODING = UTF-8
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# title of most generated pages and in a few other places.
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# The default value is: My Project.
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PROJECT_NAME = "CLICON"
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PROJECT_NAME = "CliXoN"
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# The PROJECT_NUMBER tag can be used to enter a project or revision number. This
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# could be handy for archiving the generated documentation or if some version
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154
doc/FAQ.txt
154
doc/FAQ.txt
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@ -1,86 +1,140 @@
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Frequently Asked Questions - Clixon
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Frequently Asked Questions - CliXon
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===================================
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Q: What is the best way of understanding Clixon?
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A: Run the ietf yang routing example.
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Q: What is CliXon?
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------------------
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CliXon is a configuration management tool including CLI generation,
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Yang parser, netconf interface and an embedded databases.
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Q: How do you build and install Clixon (and the example)?
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A: Clixon: ./configure; make; sudo make install; sudo make install-include
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Example: cd example; make; sudo make install
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Q: Why should you use CliXon?
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-----------------------------
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If you want an easy-to-use config frontend based on yang with an open-source license.
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Typically for embedded devices requiring a config interface such as routers and switches.
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Q: Is there any reference documentation?
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A: Clixon uses Doxygen for reference documentation.
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Q: What license is available?
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-----------------------------
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The basic license is open-source, GPLv3. Contact authors for commercial license.
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Q: Is CliXon extendible?
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------------------------
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Yes. All application semantics is defined in plugins with well-defined APIs. There are currently three types of plugins: for CLI, for Netconf and for the backend.
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Q: Which language is CliXon implemented in?
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-------------------------------------------
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CliXon is written in C. The plugins are written in C. The CLI
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specification uses cligen.
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There is a project for writing plugins in Python. It is reasonable
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simple to spawn an external script from a backend.
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Q: Is CliXon different from Clicon?
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-----------------------------------
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Yes, but CliXon is a fork of Clicon focussing on Yang specification and XML
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database. The yang support in clicon was grown out of a key-based
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scheme that became more and more complex since it had to translate
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between many different formats. CliXon uses only XML internally.
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The commit transaction mechanism has been simplified too. But CliXon
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is not backward compliant with key-based Clicon applications, such as
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Rost.
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Q: How to best understand CliXon?
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---------------------------------
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Run the ietf yang routing example. It is used in many of the answers below.
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Q: How do you build and install CliXon (and the example)?
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---------------------------------------------------------
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CliXon:
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./configure;
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make;
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sudo make install;
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sudo make install-include
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The example:
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cd example;
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make;
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sudo make install
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Q: What about reference documentation?
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--------------------------------------
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CliXon uses Doxygen for reference documentation.
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Build using 'make doc' and aim your browser at doc/html/index.html
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Q: How do you run the example?
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A: Start a backend server: 'clicon_backend -Ff /usr/local/etc/routing.conf'
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Start a cli session: clicon_cli -f /usr/local/etc/routing.conf
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Start a netconf session: clicon_netconf -f /usr/local/etc/routing.conf
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------------------------------
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- Start a backend server: 'clicon_backend -Ff /usr/local/etc/routing.conf'
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- Start a cli session: clicon_cli -f /usr/local/etc/routing.conf
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- Start a netconf session: clicon_netconf -f /usr/local/etc/routing.conf
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Q: How does Clixon differ from Clicon?
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A: Clixon is a fork of Clicon focussing on Yang specification and XML
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database. The yang support in clicon was grown out of a key-based
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scheme that was complex since it had to translate between
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formats. Clixon uses only XML. A simplified commit transaction
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mechanism has been added to. But Clixon is not backward compliant with
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key-based Clicon applications, such as ROST.
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Q: In the example, how can you alter its semantics?
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Q: How do you change the example?
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---------------------------------
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- routing.conf.local - Override default settings
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- The yang specifications - Alter accepted XML, database format and the configuration part of the CLI commands that are generated.
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- The yang specifications - This is the central part. It changes the XML, database and the config cli.
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- routing_cli.cli - Change the fixed part of the CLI commands
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- routing_cli.c - New cli commands may need to write a new C-funtion.
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- routing_backend.c - What happens at commit.
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- routing_cli.c - Cli C-commands are placed here.
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- routing_backend.c - Commit and validate functions.
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- routing_netconf.c - Modify semantics of netconf commands.
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Q: How do you check what is in a database?
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clicon_dbctrl -d <database> -p
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The name of the running or candidate databases are found in the
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configuration file, eg /usr/local/var/routing/candidate_db
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------------------------------------------
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Use clicon_dbctrl. The name of the running or candidate databases are found in the
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configuration file.
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Example:
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/interfaces/interface/eth0/ipv4
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/interfaces/interface/eth0/type bgp
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/interfaces/interface/eth0
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/interfaces/interface/eth0/name eth0
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Each line corresponds to a database entry (node in an XML tree). If
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the node is a leaf, the value appears as the second entry.
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> clicon_dbctrl -d /usr/local/var/routing/candidate_db / -p
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/interfaces/interface/eth0/ipv4
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/interfaces/interface/eth0/type bgp
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/interfaces/interface/eth0
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/interfaces/interface/eth0/name eth0
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Each line corresponds to a database entry (node in an XML tree).
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If the node is a leaf, the value appears as the second entry ('bgp' and 'eth0').
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Q: How do you write a commit rule in the example?
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A: You write a commit function in routing_backend.c.
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Q: How do you write a commit function?
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--------------------------------------
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You write a commit function in routing_backend.c.
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Every time a commit is made, transaction_commit() is called in the
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backend. It has a 'transaction_data td' argument which is used to fetch
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information on added, deleted and changed entries. You access this
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information using access functions as defined in clicon_backend_transaction.h
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Q: How do you check what has changed on commit?
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A: You use XPATHs on the XML trees in the transaction commit callback.
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-----------------------------------------------
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You use XPATHs on the XML trees in the transaction commit callback.
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Suppose you want to print all added interfaces:
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cxobj *target = transaction_target(td); # wanted XML tree
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# Get all added i/fs
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cxobj **vec = xpath_vec_flag(target, "//interface", &len, XML_FLAG_ADD);
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for (i=0; i<len; i++) # Loop over added i/fs
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clicon_xml2file(stdout, vec[i]) # Print the added interface
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The flags you can check for are: XML_FLAG_ADD, _DEL and _CHANGE, and their combinations.
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cxobj *target = transaction_target(td); # wanted XML tree
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vec = xpath_vec_flag(target, "//interface", &len, XML_FLAG_ADD); /* Get added i/fs */
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for (i=0; i<len; i++) /* Loop over added i/fs */
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clicon_xml2file(stdout, vec[i], 0, 1); /* Print the added interface */
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You can look for added, deleted and changed entries in this way.
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Q How do I access the XML tree?
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A: Using XPATH, find and iteration functions defined in the XML library. Example
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Q: How do I access the XML tree?
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--------------------------------
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Using XPATH, find and iteration functions defined in the XML library. Example library functions:
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xml_child_each(),
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xml_find(),
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xml_body(),
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clicon_xml2file(),
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xml_apply()
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More are found in the doxygen reference.
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Q: How do you write a CLI callback function?
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You add an entry in routing_cli.cli
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--------------------------------------------
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(1) You add an entry in routing_cli.cli
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example("This is a comment") <var:int32>("This is a variable"), mycallback("myarg");
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Then define a function in routing_cli.c
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(2) Then define a function in routing_cli.c
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mycallback(clicon_handle h, cvec *cvv, cg_var *arg)
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where 'cvv' contains the value of the variable and 'arg' contains the
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function parameter 'myarg'.
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Q: What are cg_var and cvec used in CLI callbacks?
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Those are 'CLIgen variables' and vector of CLOgen
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variables. Documented in CLIgen documentation. Some examples on usage is found in the
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--------------------------------------------------
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Those are 'CLIgen variables' and vector of CLIgen variables.
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They are documented in CLIgen documentation. Some examples on usage is found in the
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routing_cli.c
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Q: How do you write a validation rule?
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Similar to a commit rule, but instead write the transaction_validate() function.
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Check for consitencies in the XML trees and if they fail, make an clicon_err() call.
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Q: How do you write a validation function?
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------------------------------------------
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Similar to a commit function, but instead write the transaction_validate() function.
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Check for inconsistencies in the XML trees and if they fail, make an clicon_err() call.
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clicon_err(OE_PLUGIN, 0, "Route %s lacks ipv4 addr", name);
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return -1;
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The validation or commit will then be aborted.
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@ -30,13 +30,13 @@ pdflatex = @PDFLATEX@
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SUBDIRS =
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.PHONY: clean all $(SUBDIRS)
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.PHONY: clean all doc $(SUBDIRS)
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all: $(SUBDIRS) doc
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echo "Build doxygen doc and graphs: make graphs"
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echo "Build doxygen doc: make doc"
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# Regular doxygen documentation
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doc:
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doc:
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doxygen Doxyfile # generates html dir
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echo "Build doxygen graphs: make graphs"
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