zconfig - Man Page

Class for work with config files written in rfc.zeromq.org/spec:4/ZPL.

Synopsis

//  This is a stable class, and may not change except for emergencies. It
//  is provided in stable builds.
//  This class has draft methods, which may change over time. They are not
//  in stable releases, by default. Use --enable-drafts to enable.
//
typedef int (zconfig_fct) (
    zconfig_t *self, void *arg, int level);

//  Create new config item
CZMQ_EXPORT zconfig_t *
    zconfig_new (const char *name, zconfig_t *parent);

//  Load a config tree from a specified ZPL text file; returns a zconfig_t
//  reference for the root, if the file exists and is readable. Returns NULL
//  if the file does not exist.
CZMQ_EXPORT zconfig_t *
    zconfig_load (const char *filename);

//  Equivalent to zconfig_load, taking a format string instead of a fixed
//  filename.
CZMQ_EXPORT zconfig_t *
    zconfig_loadf (const char *format, ...) CHECK_PRINTF (1);

//  Destroy a config item and all its children
CZMQ_EXPORT void
    zconfig_destroy (zconfig_t **self_p);

//  Return name of config item
CZMQ_EXPORT char *
    zconfig_name (zconfig_t *self);

//  Return value of config item
CZMQ_EXPORT char *
    zconfig_value (zconfig_t *self);

//  Insert or update configuration key with value
CZMQ_EXPORT void
    zconfig_put (zconfig_t *self, const char *path, const char *value);

//  Equivalent to zconfig_put, accepting a format specifier and variable
//  argument list, instead of a single string value.
CZMQ_EXPORT void
    zconfig_putf (zconfig_t *self, const char *path, const char *format, ...) CHECK_PRINTF (3);

//  Get value for config item into a string value; leading slash is optional
//  and ignored.
CZMQ_EXPORT char *
    zconfig_get (zconfig_t *self, const char *path, const char *default_value);

//  Set config item name, name may be NULL
CZMQ_EXPORT void
    zconfig_set_name (zconfig_t *self, const char *name);

//  Set new value for config item. The new value may be a string, a printf
//  format, or NULL. Note that if string may possibly contain '%', or if it
//  comes from an insecure source, you must use '%s' as the format, followed
//  by the string.
CZMQ_EXPORT void
    zconfig_set_value (zconfig_t *self, const char *format, ...) CHECK_PRINTF (2);

//  Find our first child, if any
CZMQ_EXPORT zconfig_t *
    zconfig_child (zconfig_t *self);

//  Find our first sibling, if any
CZMQ_EXPORT zconfig_t *
    zconfig_next (zconfig_t *self);

//  Find a config item along a path; leading slash is optional and ignored.
CZMQ_EXPORT zconfig_t *
    zconfig_locate (zconfig_t *self, const char *path);

//  Locate the last config item at a specified depth
CZMQ_EXPORT zconfig_t *
    zconfig_at_depth (zconfig_t *self, int level);

//  Execute a callback for each config item in the tree; returns zero if
//  successful, else -1.
CZMQ_EXPORT int
    zconfig_execute (zconfig_t *self, zconfig_fct handler, void *arg);

//  Add comment to config item before saving to disk. You can add as many
//  comment lines as you like. If you use a null format, all comments are
//  deleted.
CZMQ_EXPORT void
    zconfig_set_comment (zconfig_t *self, const char *format, ...) CHECK_PRINTF (2);

//  Return comments of config item, as zlist.
CZMQ_EXPORT zlist_t *
    zconfig_comments (zconfig_t *self);

//  Save a config tree to a specified ZPL text file, where a filename
//  "-" means dump to standard output.
CZMQ_EXPORT int
    zconfig_save (zconfig_t *self, const char *filename);

//  Equivalent to zconfig_save, taking a format string instead of a fixed
//  filename.
CZMQ_EXPORT int
    zconfig_savef (zconfig_t *self, const char *format, ...) CHECK_PRINTF (2);

//  Report filename used during zconfig_load, or NULL if none
CZMQ_EXPORT const char *
    zconfig_filename (zconfig_t *self);

//  Reload config tree from same file that it was previously loaded from.
//  Returns 0 if OK, -1 if there was an error (and then does not change
//  existing data).
CZMQ_EXPORT int
    zconfig_reload (zconfig_t **self_p);

//  Load a config tree from a memory chunk
CZMQ_EXPORT zconfig_t *
    zconfig_chunk_load (zchunk_t *chunk);

//  Save a config tree to a new memory chunk
CZMQ_EXPORT zchunk_t *
    zconfig_chunk_save (zconfig_t *self);

//  Load a config tree from a null-terminated string
//  Caller owns return value and must destroy it when done.
CZMQ_EXPORT zconfig_t *
    zconfig_str_load (const char *string);

//  Save a config tree to a new null terminated string
//  Caller owns return value and must destroy it when done.
CZMQ_EXPORT char *
    zconfig_str_save (zconfig_t *self);

//  Return true if a configuration tree was loaded from a file and that
//  file has changed in since the tree was loaded.
CZMQ_EXPORT bool
    zconfig_has_changed (zconfig_t *self);

//  Print the config file to open stream
CZMQ_EXPORT void
    zconfig_fprint (zconfig_t *self, FILE *file);

//  Print properties of object
CZMQ_EXPORT void
    zconfig_print (zconfig_t *self);

//  Self test of this class
CZMQ_EXPORT void
    zconfig_test (bool verbose);

#ifdef CZMQ_BUILD_DRAFT_API
//  *** Draft method, for development use, may change without warning ***
//  Create copy of zconfig, caller MUST free the value
//  Create copy of config, as new zconfig object. Returns a fresh zconfig_t
//  object. If config is null, or memory was exhausted, returns null.
//  Caller owns return value and must destroy it when done.
CZMQ_EXPORT zconfig_t *
    zconfig_dup (zconfig_t *self);

//  *** Draft method, for development use, may change without warning ***
//  Destroy subtree (all children)
CZMQ_EXPORT void
    zconfig_remove_subtree (zconfig_t *self);

//  *** Draft method, for development use, may change without warning ***
//  Destroy node and subtree (all children)
CZMQ_EXPORT void
    zconfig_remove (zconfig_t **self_p);

#endif // CZMQ_BUILD_DRAFT_API
Please add '@interface' section in './../src/zconfig.c'.

Description

Lets applications load, work with, and save configuration files. This implements rfc.zeromq.org/spec:4/ZPL, which is a simple structured text format for configuration files.

Here is an example ZPL stream and corresponding config structure:

context
    iothreads = 1
    verbose = 1      #   Ask for a trace
main
    type = zqueue    #  ZMQ_DEVICE type
    frontend
        option
            hwm = 1000
            swap = 25000000     #  25MB
        bind = 'inproc://addr1'
        bind = 'ipc://addr2'
    backend
        bind = inproc://addr3
root                    Down = child
|                     Across = next
v
context-->main
|         |
|         v
|       type=queue-->frontend-->backend
|                      |          |
|                      |          v
|                      |        bind=inproc://addr3
|                      v
|                    option-->bind=inproc://addr1-->bind=ipc://addr2
|                      |
|                      v
|                    hwm=1000-->swap=25000000
v
iothreads=1-->verbose=false

Example

From zconfig_test method.

const char *SELFTEST_DIR_RW = "src/selftest-rw";

const char *testbasedir  = ".test_zconfig";
const char *testfile = "test.cfg";
char *basedirpath = NULL;   // subdir in a test, under SELFTEST_DIR_RW
char *filepath = NULL;      // pathname to testfile in a test, in dirpath

basedirpath = zsys_sprintf ("%s/%s", SELFTEST_DIR_RW, testbasedir);
assert (basedirpath);
filepath = zsys_sprintf ("%s/%s", basedirpath, testfile);
assert (filepath);

// Make sure old aborted tests do not hinder us
zdir_t *dir = zdir_new (basedirpath, NULL);
if (dir) {
    zdir_remove (dir, true);
    zdir_destroy (&dir);
}
zsys_file_delete (filepath);
zsys_dir_delete  (basedirpath);

//  Create temporary directory for test files
zsys_dir_create (basedirpath);

zconfig_t *root = zconfig_new ("root", NULL);
assert (root);
zconfig_t *section, *item;

section = zconfig_new ("headers", root);
assert (section);
item = zconfig_new ("email", section);
assert (item);
zconfig_set_value (item, "some@random.com");
item = zconfig_new ("name", section);
assert (item);
zconfig_set_value (item, "Justin Kayce");
zconfig_putf (root, "/curve/secret-key", "%s", "Top Secret");
zconfig_set_comment (root, "   CURVE certificate");
zconfig_set_comment (root, "   -----------------");
assert (zconfig_comments (root));
zconfig_save (root, filepath);
zconfig_destroy (&root);
root = zconfig_load (filepath);
if (verbose)
    zconfig_save (root, "-");
assert (streq (zconfig_filename (root), filepath));

char *email = zconfig_get (root, "/headers/email", NULL);
assert (email);
assert (streq (email, "some@random.com"));
char *passwd = zconfig_get (root, "/curve/secret-key", NULL);
assert (passwd);
assert (streq (passwd, "Top Secret"));

zconfig_savef (root, "%s/%s", basedirpath, testfile);
assert (!zconfig_has_changed (root));
int rc = zconfig_reload (&root);
assert (rc == 0);
assert (!zconfig_has_changed (root));
zconfig_destroy (&root);

//  Test chunk load/save
root = zconfig_new ("root", NULL);
assert (root);
section = zconfig_new ("section", root);
assert (section);
item = zconfig_new ("value", section);
assert (item);
zconfig_set_value (item, "somevalue");
zconfig_t *search = zconfig_locate (root, "section/value");
assert (search == item);
zchunk_t *chunk = zconfig_chunk_save (root);
assert (strlen ((char *) zchunk_data (chunk)) == 32);
char *string = zconfig_str_save (root);
assert (string);
assert (streq (string, (char *) zchunk_data (chunk)));
freen (string);
assert (chunk);
zconfig_destroy (&root);

root = zconfig_chunk_load (chunk);
assert (root);
char *value = zconfig_get (root, "/section/value", NULL);
assert (value);
assert (streq (value, "somevalue"));

//  Test config can't be saved to a file in a path that doesn't
//  exist or isn't writable
rc = zconfig_savef (root, "%s/path/that/doesnt/exist/%s", basedirpath, testfile);
assert (rc == -1);

zconfig_destroy (&root);
zchunk_destroy (&chunk);

// Test str_load
zconfig_t *config = zconfig_str_load (
    "malamute\n"
    "    endpoint = ipc://@/malamute\n"
    "    producer = STREAM\n"
    "    consumer\n"
    "        STREAM2 = .*\n"
    "        STREAM3 = HAM\n"
    "server\n"
    "    verbose = true\n"
    );
assert (config);
assert (streq (zconfig_get (config, "malamute/endpoint", NULL), "ipc://@/malamute"));
assert (streq (zconfig_get (config, "malamute/producer", NULL), "STREAM"));
assert (zconfig_locate (config, "malamute/consumer"));

zconfig_t *c = zconfig_child (zconfig_locate (config, "malamute/consumer"));
assert (c);
assert (streq (zconfig_name (c), "STREAM2"));
assert (streq (zconfig_value (c), ".*"));

c = zconfig_next (c);
assert (c);
assert (streq (zconfig_name (c), "STREAM3"));
assert (streq (zconfig_value (c), "HAM"));

c = zconfig_next (c);
assert (!c);

assert (streq (zconfig_get (config, "server/verbose", NULL), "true"));

zconfig_t *dup = zconfig_dup (config);
assert (dup);
assert (streq (zconfig_get (dup, "server/verbose", NULL), "true"));
zconfig_destroy (&dup);

zconfig_destroy (&config);

//  Test subtree removal
        {
                zconfig_t *root = zconfig_str_load (
                        "context\n"
                        "    iothreads = 1\n"
                        "    verbose = 1      #   Ask for a trace\n"
                        "main\n"
                        "    type = zqueue    #  ZMQ_DEVICE type\n"
                        "    frontend\n"
                        "        option\n"
                        "            hwm = 1000\n"
                        "            swap = 25000000     #  25MB\n"
                        "        bind = 'inproc://addr1'\n"
                        "        bind = 'ipc://addr2'\n"
                        "    backend\n"
                        "        bind = inproc://addr3\n"
                );

    //  no subtree
    zconfig_t *to_delete = zconfig_locate (root, "context/iothreads");
    assert (to_delete);

    zconfig_remove_subtree (to_delete);

    zconfig_t *check = zconfig_locate (root, "context/iothreads");
    assert (check);
    assert (streq (zconfig_value (check), "1"));

    check = zconfig_locate (root, "context/verbose");
    assert (check);
    assert (streq (zconfig_value (check), "1"));

    //  existing subtree
    to_delete = zconfig_locate (root, "main/frontend/option");
    assert (to_delete);

    zconfig_remove_subtree (to_delete);

    check = zconfig_locate (root, "main/frontend/option/hwm");
    assert (check == NULL);
    check = zconfig_locate (root, "main/frontend/option/swap");
    assert (check == NULL);
    check = zconfig_locate (root, "main/frontend/option");
    assert (check);
    assert (streq (zconfig_value (check), ""));
    check = zconfig_next (check);
    assert (check);
    assert (streq (zconfig_name (check), "bind"));
    assert (streq (zconfig_value (check), "inproc://addr1"));
    check = zconfig_next (check);
    assert (check);
    assert (streq (zconfig_name (check), "bind"));
    assert (streq (zconfig_value (check), "ipc://addr2"));
    assert (zconfig_next (check) == NULL);

    to_delete = zconfig_locate (root, "main/frontend");
    assert (to_delete);

    zconfig_remove_subtree (to_delete);

    check = zconfig_locate (root, "main/frontend/option/hwm");
    assert (check == NULL);
    check = zconfig_locate (root, "main/frontend/option/swap");
    assert (check == NULL);
    check = zconfig_locate (root, "main/frontend/option");
    assert (check == NULL);
    check = zconfig_locate (root, "main/frontend/bind");
    assert (check == NULL);
    check = zconfig_locate (root, "main/frontend");
    assert (check);
    assert (streq (zconfig_value (check), ""));
    assert (zconfig_child (check) == NULL);
    check = zconfig_next (check);
    assert (check);
    assert (streq (zconfig_name (check), "backend"));
    assert (streq (zconfig_value (check), ""));

    to_delete = zconfig_locate (root, "main");
    assert (to_delete);

    zconfig_remove_subtree (to_delete);

    check = zconfig_locate (root, "main/type");
    assert (check == NULL);
    check = zconfig_locate (root, "main/frontend");
    assert (check == NULL);
    check = zconfig_locate (root, "main/backend");
    assert (check == NULL);
    check = zconfig_locate (root, "main");
    assert (check);

    //  root
    zconfig_remove_subtree (root);

    assert (root);
    assert (zconfig_child (root) == NULL);
    check = zconfig_locate (root, "main");
    assert (check == NULL);
    check = zconfig_locate (root, "context");
    assert (check == NULL);

    zconfig_destroy (&root);
}

//  Test node and subtree removal
        {
                zconfig_t *root = zconfig_str_load (
                        "A1 = abc\n"
                        "    x\n"
                        "        1\n"
                        "        2\n"
                        "    y = 1      #   Ask for a trace\n"
                        "A2\n"
                        "    B1 = zqueue    #  ZMQ_DEVICE type\n"
                        "    B2\n"
                        "        C1\n"
                        "            hwm = 1000\n"
                        "            swap = 25000000     #  25MB\n"
                        "        C2 = 50\n"
                        "        C3\n"
                        "            bind = addr3\n"
                        "    B3\n"
                        "        bind = inproc://addr4\n"
                        "    B4 = Ignac\n"
                        "        z = 5\n"
                        "A3\n"
                        "A4\n"
                );

    zconfig_t *to_delete = zconfig_locate (root, "A2/B2/C3");
    assert (to_delete);

    zconfig_remove (&to_delete);

    zconfig_t *check = zconfig_locate (root, "A2/B2/C2");
    assert (check);
    assert (streq (zconfig_value (check), "50"));
    assert (zconfig_next (check) == NULL);
    assert (zconfig_locate (root, "A2/B2/C3/bind") == NULL);
    assert (zconfig_locate (root, "A2/B2/C3") == NULL);

    to_delete = zconfig_locate (root, "A2/B2");
    assert (to_delete);

    zconfig_remove (&to_delete);

    check = zconfig_locate (root, "A2");
    assert (check);
    check = zconfig_child (check);
    assert (check);
    assert (streq (zconfig_name (check), "B1"));
    assert (streq (zconfig_value (check), "zqueue"));
    check = zconfig_next (check);
    assert (check);
    assert (streq (zconfig_name (check), "B3"));
    assert (streq (zconfig_value (check), ""));
    assert (zconfig_locate (root, "A2/B2/C1") == NULL);
    assert (zconfig_locate (root, "A2/B2/C2") == NULL);
    assert (zconfig_locate (root, "A2/B2") == NULL);
    assert (zconfig_locate (root, "A2/B4"));

    to_delete = zconfig_locate (root, "A2/B1");
    assert (to_delete);

    zconfig_remove (&to_delete);

    check = zconfig_locate (root, "A2");
    assert (check);
    check = zconfig_child (check);
    assert (check);
    assert (streq (zconfig_name (check), "B3"));
    assert (streq (zconfig_value (check), ""));
    check = zconfig_next (check);
    assert (check);
    assert (streq (zconfig_name (check), "B4"));
    assert (streq (zconfig_value (check), "Ignac"));
    assert (zconfig_next (check) == NULL);
    assert (zconfig_locate (root, "A2/B1") == NULL);
    assert (zconfig_locate (root, "A2/B2") == NULL);

    to_delete = zconfig_locate (root, "A2/B3");
    assert (to_delete);

    zconfig_remove (&to_delete);

    check = zconfig_locate (root, "A2");
    assert (check);
    check = zconfig_child (check);
    assert (check);
    assert (streq (zconfig_name (check), "B4"));
    assert (streq (zconfig_value (check), "Ignac"));
    assert (zconfig_next (check) == NULL);

    to_delete = zconfig_locate (root, "A2");
    assert (to_delete);

    zconfig_remove (&to_delete);

    check = zconfig_locate (root, "A1");
    assert (check);
    check = zconfig_next (check);
    assert (check);
    assert (streq (zconfig_name (check), "A3"));
    assert (zconfig_locate (root, "A2/B4") == NULL);
    assert (zconfig_locate (root, "A2") == NULL);

    to_delete = zconfig_locate (root, "A1");
    assert (to_delete);

    zconfig_remove (&to_delete);

    check = zconfig_child (root);
    assert (check);
    assert (streq (zconfig_name (check), "A3"));
    assert (zconfig_locate (root, "A1/x/1") == NULL);
    assert (zconfig_locate (root, "A1/x") == NULL);
    assert (zconfig_locate (root, "A1/y") == NULL);
    assert (zconfig_locate (root, "A3"));
    assert (zconfig_locate (root, "A4"));

    //  called on root should be equivalent to zconfig_destroy (&root)
    zconfig_remove (&root);
}

//  Delete all test files
dir = zdir_new (basedirpath, NULL);
assert (dir);
zdir_remove (dir, true);
zdir_destroy (&dir);

zstr_free (&basedirpath);
zstr_free (&filepath);

#if defined (__WINDOWS__)
zsys_shutdown();
#endif

Authors

The czmq manual was written by the authors in the AUTHORS file.

Resources

Main web site:

Report bugs to the email <zeromq-dev@lists.zeromq.org[1]>

Notes

1.

zeromq-dev@lists.zeromq.org
mailto:zeromq-dev@lists.zeromq.org

Info

10/31/2019 CZMQ 4.2.1 CZMQ Manual