NAME¶
smiInit, smiExit, smiSetErrorLevel, smiGetFlags, smiSetFlags, smiLoadModule,
smiGetPath, smiSetPath, smiReadConfig - SMI library configuration routines
SYNOPSIS¶
#include <smi.h>
int smiInit(const char *tag);
int smiExit();
void smiSetErrorLevel(int level);
int smiGetFlags();
void smiSetFlags(int userflags);
char *smiLoadModule(char *module);
int smiIsLoaded(char *module);
char *smiGetPath();
int smiSetPath(char *path);
int smiSetSeverity(char *pattern, int severity);
int smiReadConfig(char *filename, const char *tag);
void smiSetErrorHandler(SmiErrorHandler *smiErrorHandler);
typedef void (SmiErrorHandler) (char *path, int line,
int severity, char *msg, char *tag);
DESCRIPTION¶
These functions provide some initialization and adjustment operations for the
SMI library.
The
smiInit() function should be the first SMI function called in an
application. It initializes its internal structures. If
tag is not
NULL, the global configuration file and (on UNIX systems) a user configuration
file are read implicitly, if existent. All global statements and those
statements with a tag (a ``tag: '' prefix) that matches the
tag
argument are executed. (see also CONFIGURATION FILES below).
smiInit()
returns zero on success, or otherwise a negative value.
The
smiInit() function can also be used to support multiple sets of MIB
data. In this case, the
tag argument may be prepended by a colon and a
name to differentiate the data sets. Any library function call subsequent to
an
smiInit("tag:dataset") call is using the specified data
set.
The
smiExit() function should be called when the application no longer
needs any SMI information to release any allocated SMI resources.
The
smiSetErrorLevel() function sets the pedantic level (0-9) of the SMI
parsers of the SMI library, currently SMIv1/v2 and SMIng. The higher the
level, the louder it complains. Values up to 3 should be regarded as errors,
higher level could be interpreted as warnings. But note that this
classification is some kind of personal taste. The default level is 0, since
usually only MIB checkers want to tune a higher level.
The
smiGetFlags() and
smiSetFlags() functions allow to fetch,
modify, and set some
userflags that control the SMI library's
behaviour. If
SMI_FLAG_ERRORS is not set, no error messages are printed
at all to keep the SMI library totally quiet, which might be mandatory for
some applications. If
SMI_FLAG_STATS is set, the library prints some
module statistics. If
SMI_FLAG_RECURSIVE is set, the library also
complains about errors in modules that are read due to import statements. If
SMI_FLAG_NODESCR is set, no description and references strings are
stored in memory. This may save a huge amount of memory in case of
applications that do not need this information.
The
smiSetSeverity() function allows to set the severity of all error
that have name prefixed by
pattern to the value
severity.
The
smiLoadModule() function specifies an additional MIB
module
that the application claims to know or an additional file path to read. Only
after a module is made known through this function, iterating retrieval
functions and retrieval functions without fully qualified identifiers will
return results from this module.
smiLoadModule() returns the name of
the loaded module, of NULL if it could not be loaded.
The
smiIsLoaded() function returns a positive value if the module named
module is already loaded, or zero otherwise.
The
smiGetPath() and
smiSetPath() functions allow to fetch,
modify, and set the path that is used to search MIB modules.
smiGetPath() returns a copy of the current search path in the form
"DIR1:DIR2:...", or NULL if no path is set. The application should
free this string if it is no longer needed.
smiSetPath() sets the
search path to
path.
The
smiReadConfig() function reads the configuration file
filename. All global statements in the configuration file and those
statements with a tag (a ``tag: '' prefix) that matches the
tag
argument, if present, are executed.
The
smiSetErrorHandler() function allows to set a callback function that
is called by the MIB parsers deviating from the builtin default error handler,
that prints error messages to stderr. The error handler has to comply with the
SmiErrorHandler function type. The
path,
line,
severity,
msg, and
tag arguements carry the module's
pathname, the line number within the module, the error severity level, a
textual error message, and a short error name of the error being reported.
MODULE LOCATIONS¶
The SMI library may retrieve MIB modules from different kinds of resources.
Currently, SMIv1/v2 and SMIng module files are supported. If in an
smiLoadModule() function call a module is specified by a path name
(identified by containing at least one dot or slash character), this is
assumed to be the exact file to read. Otherwise, if a module is identified by
its plain module name, the correspondant file (either SMIv1/2 or SMIng) is
searched along a path. This path is initialized with
/usr/share/mibs/ietf:/usr/share/mibs/iana:/usr/share/mibs/irtf:/usr/share/mibs/site:/usr/share/mibs/tubs:/usr/share/pibs/ietf:/usr/share/pibs/site:/usr/share/pibs/tubs.
Afterwards the optional global and user configuration files are parsed for
`path' commands, and finally the optional
SMIPATH environment variable
is evaluated. The `path' command argument and the environment variable either
start with a path separator character (`:' on UNIX-like systems, `;' on
MS-Windows systems) to append to the path, or end with a path separator
character to prepend to the path, or otherwise completely replace the path.
The path can also be controlled by the
smiGetPath() and
smiSetPath() functions (see above).
When files are searched by a given module name, they might have no extension or
one of the extensions `.my', `.smiv2', `.sming', `.mib', or `.txt'. However,
the MIB module language is identified by the file's content, not by its file
name extension.
CONFIGURATION FILES¶
SMI library configuration files read at initialization and on demand by
smiReadConfig() have a simple line oriented syntax. Empty lines and
those starting with `#' are ignored. Other lines start with an optional tag
(prepended by a colon), followed by a command and options dependent on the
command. Tags are used to limit the scope of a command to those applications
that are using this tag.
The
load command is used to preload a given MIB module. If multiple
modules shall be preloaded, multiple
load commands must be used.
The
path command allows to prepend or append components to the MIB module
search path or to modify it completely (see also MODULE LOCATIONS above).
The
cache command allows to add an additional directory for MIB module
lookup as a last resort. The first argument specifies the directory and the
rest of the line starting from the second argument specifies the caching
method, which is invoked with the MIB module name appended if the module is
found neither in one of the regular directories nor in the cache directory
beforehand.
The
level command sets the error level.
The
hide command allows to tune the list of errors that are reported. It
raises all errors with names prefixed by the given pattern to severity level
9. [Currently, there is no way to list the error names. RTFS: error.c.]
Example configuration:
#
# $HOME/.smirc
#
# add a private directory
path :/usr/home/strauss/lib/mibs
# don't show any errors by default
level 0
# preload some basic modules
load SNMPv2-SMI
load SNMPv2-TC
load SNMPv2-CONF
# want to make smilint shout
smilint: level 8
# but please don't claim about
# any names longer than 32 chars
smilint: hide namelength-32
tcpdump: load DISMAN-SCRIPT-MIB
smiquery: load IF-MIB
smiquery: load DISMAN-SCRIPT-MIB
FILES¶
/etc/smi.conf global configuration file
$HOME/.smirc user configuration file
${prefix}/include/smi.h SMI library header file
/usr/share/mibs/ SMI module repository directory
SEE ALSO¶
libsmi(3),
smi.h
AUTHOR¶
(C) 1999-2001 Frank Strauss, TU Braunschweig, Germany
<strauss@ibr.cs.tu-bs.de>