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<H2><A NAME="SECTION00041000000000000000">
API</A>
</H2>
Each program using libclamav must include <I>clamav.h</I> header file:
<PRE>
#include <clamav.h>
</PRE>
The first step is an engine initialization. There are three functions
available:
<PRE>
int cl_loaddb(const char *filename, struct cl_node **root,
int *virnum);
int cl_loaddbdir(const char *dirname, struct cl_node **root,
int *virnum);
char *cl_retdbdir(void);
</PRE>
<I>cl_loaddb()</I> loads one database per time, <I>cl_loaddbdir()</I>
loads all <I>.db</I> and .db2 files from the directory <I>dirname</I>.
<I>cl_retdbdir()</I> returns hardcoded database directory path.
The database will be saved under <I>root</I> and the number of the loaded
signatures will be <B>added</B> to <I>virnum</I>. Pointer to the tree
structure (trie, see <A HREF="node28.html#engine">6.2</A>) must initially point to the NULL. If you
don't want to save the number of signatures loaded pass the NULL as the
third argument. <I>cl_loaddb</I> functions return 0 on success and
other value on failure.
<PRE>
struct cl_node *root = NULL;
int ret;
ret = cl_loaddbdir(cl_retdbdir(), &root, NULL);
</PRE>
There's elegant way to print libclamav's error codes:
<PRE>
char *cl_perror(int clerror);
</PRE>
<I>cl_perror()</I> returns a (statically allocated) string describing
<I>clerror</I> code:
<PRE>
if(ret) {
printf("cl_loaddbdir() error: %s\n", cl_perror(ret));
exit(1);
}
</PRE>
When database is loaded, you must create the proper trie with:
<PRE>
void cl_buildtrie(struct cl_node *root);
</PRE>
In our example:
<PRE>
cl_buildtrie(root);
</PRE>
OK, now you can scan a buffer, descriptor or file with:
<PRE>
int cl_scanbuff(const char *buffer, unsigned int length,
char **virname, const struct cl_node *root);
int cl_scandesc(int desc, char **virname, unsigned long int
*scanned, const struct cl_node *root, const struct cl_limits
*limits, int options);
int cl_scanfile(const char *filename, char **virname,
unsigned long int *scanned, const struct cl_node *root,
const struct cl_limits *limits, int options);
</PRE>
All the functions save a virus name address under <I>virname</I> pointer.
<I>virname</I> points to the name in the trie structure, thus it can't be
released directly. <I>cl_scandesc()</I> and <I>cl_scanfile()</I> can
increase <I>scanned</I> value in CL_COUNT_PRECISION units. They also
support archive limits:
<PRE>
struct cl_limits {
int maxreclevel;
int maxfiles;
long int maxfilesize;
};
</PRE>
The last argument configures scan engine. Currently it supports
<B>CL_ARCHIVE</B> (enables archive scanning) and <B>CL_RAW</B>
(disables archive scanning).
The functions return 0 (<B>CL_CLEAN</B>) when no virus is found,
<B>CL_VIRUS</B> when virus is found and other value on failure.
<PRE>
struct cl_limits limits;
char *virname;
/* maximal number of files in archive */;
limits.maxfiles = 100
/* maximal archived file size == 10 Mb */
limits.maxfilesize = 10 * 1048576;
/* maximal recursion level */
limits.maxreclevel = 8;
if((ret = cl_scanfile("/home/zolw/test", &virname, NULL, root,
&limits, CL_ARCHIVE)) == CL_VIRUS) {
printf("Detected %s virus.\n", virname);
} else {
printf("No virus detected.\n");
if(ret != CL_CLEAN)
printf("Error: %s\n", cl_perror(ret));
}
</PRE>
When you don't need to scan more files, the trie should be released
with:
<PRE>
void cl_freetrie(struct cl_node *root);
</PRE>
You will find some examples in clamav sources. Each program using
libclamav must be linked against it:
<PRE>
gcc -Wall ex1.c -o ex1 -lclamav
</PRE>
Enjoy !
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<ADDRESS>
Tomasz Kojm
2002-11-21
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