Wes Hardaker wrote:
"NC" == Nicklas Chien <[EMAIL PROTECTED]> writes:
NC> The "Tutorial Sections" talk how to compile a module in unix-like
NC> system. Can the net-snmp support dlmod in windows?If yes,how to compile
NC> the module? I had readed the readme.win32,it just says that add the .c
NC> & .h files and rebuild the snmpd not the dynamical load.Thanks
I believe it has been done and is possible. But I don't know who does
know how. If you do figure it out, please help us by documenting what
you find!
Net-SNMP doesn't currently support DLMOD for Windows. Last December I
spent some time trying to implement it. I modified dlmod.c to support
DLLs, and I compiled a module as a DLL. I was able to load the module,
but it didn't work because there was a problem with global variables.
I can't go into much detail because it's been a while since I looked at
it, but there are issues with global variables and DLLs. For a DLL to
access global variables from the application that loaded the DLL (the
agent), the global variable may need to be 'shared' using #pragma in
MSVC or they have to be imported / exported. The module would also have
to import the global variables used in the library (netsnmp.dll).
At the time, I didn't want to try to change all the global variable
definitions in the agent as seemed like too much work and I figured it
wouldn't be an easy task.
The library has already been put in to a DLL (netsnmp.dll) which was
originally done to support the Perl module. Maybe most of the work is
already done and it's not as hard as I originally thought.
I lost the notes I wrote while working on this, but I do have a copy of
dlmod.c that contains the code to load DLLs. Hopefully it's the latest
working version. I have attached a patch.
Hopefully someone can make this work. Once it is figured out it may
allow us to easily separate the library DLL in to the multiple libraries
used on other systems (libnetsnmp, agent, helpers, mibs, trapd).
Alex
--- dlmod.c 2007-06-21 08:33:56.000000000 -0400
+++ dlmod-win32.c 2007-08-24 12:11:19.000000000 -0400
@@ -28,9 +28,12 @@
#include "struct.h"
#include "util_funcs.h"
-#if defined(HAVE_DLFCN_H) && ( defined(HAVE_DLOPEN) || defined(HAVE_LIBDL) )
+#if (defined(HAVE_DLFCN_H) && ( defined(HAVE_DLOPEN) || defined(HAVE_LIBDL) ) || defined(WIN32))
+#ifndef WIN32
#include <dlfcn.h>
+#endif
+
#include "dlmod.h"
static struct dlmod *dlmods = NULL;
@@ -77,10 +80,10 @@
strncpy(dlmod_path, SNMPDLMODPATH, sizeof(dlmod_path));
dlmod_path[ sizeof(dlmod_path)-1 ] = 0;
if (p) {
- if (p[0] == ':') {
+ if (p[0] == ENV_SEPARATOR_CHAR) {
len = strlen(dlmod_path);
- if (dlmod_path[len - 1] != ':') {
- strncat(dlmod_path, ":", sizeof(dlmod_path) - len -1);
+ if (dlmod_path[len - 1] != ENV_SEPARATOR_CHAR) {
+ strncat(dlmod_path, ENV_SEPARATOR, sizeof(dlmod_path) - len -1);
len++;
}
strncat(dlmod_path, p + 1, sizeof(dlmod_path) - len);
@@ -139,7 +142,13 @@
{
char sym_init[64];
char *p, tmp_path[255];
+#ifdef WIN32
+ void (WINAPI *dl_init)(void);
+ char *tmp_path2 = NULL;
+ HANDLE hInst = NULL;
+#else
int (*dl_init) (void);
+#endif
char *st;
DEBUGMSGTL(("dlmod", "dlmod_load_module %s: %s\n", dlm->name,
@@ -149,6 +158,65 @@
(dlm->status != DLMOD_UNLOADED && dlm->status != DLMOD_ERROR))
return;
+#ifdef WIN32
+ if (dlm->path[1] == ':') { /* driveletter:path */
+ hInst = LoadLibrary(dlm->path);
+
+ if (hInst == NULL)
+ {
+ DEBUGMSGTL(("dlmod","Could not load DLL %s.\n", dlm->path));
+ dlm->status = DLMOD_ERROR;
+ return;
+ }
+ else {
+ DEBUGMSGTL(("dlmod","DLL %s loaded.\n", dlm->path));
+ }
+ } else {
+ tmp_path[0] = '\0';
+ for (p = strtok_r(dlmod_path, ENV_SEPARATOR, &st); p; p = strtok_r(NULL, ENV_SEPARATOR, &st)) {
+ DEBUGMSGTL(("dlmod", "1: %s 2: %s\n", p, tmp_path));
+
+ tmp_path2 = _strlwr( _strdup( dlm->path ) );
+ if (strstr(tmp_path2,".dll"))
+ snprintf(tmp_path, sizeof(tmp_path), "%s\\%s", p, dlm->path);
+ else
+ snprintf(tmp_path, sizeof(tmp_path), "%s\\%s.dll", p, dlm->path);
+ if (tmp_path2)
+ free (tmp_path2);
+ DEBUGMSGTL(("dlmod", "p: %s tmp_path: %s\n", p, tmp_path));
+ hInst = LoadLibrary(tmp_path);
+
+ if (hInst == NULL)
+ {
+ DEBUGMSGTL(("dlmod","Could not load DLL %s.\n", tmp_path));
+ dlm->status = DLMOD_ERROR;
+ }
+ else {
+ DEBUGMSGTL(("dlmod","DLL %s loaded.\n", tmp_path));
+ }
+ }
+ strncpy(dlm->path, tmp_path, sizeof(dlm->path));
+ if (dlm->status == DLMOD_ERROR)
+ return;
+ }
+
+ snprintf(sym_init, sizeof(sym_init), "init_%s", dlm->name);
+
+ dl_init = (void (WINAPI *)(void)) GetProcAddress ((HMODULE) hInst, sym_init);
+
+ if (dl_init == NULL) {
+ FreeLibrary(hInst);
+ snprintf(dlm->error, sizeof(dlm->error),
+ "dlsym failed: can't find \'%s\'", sym_init);
+ dlm->status = DLMOD_ERROR;
+ return;
+ }
+
+ dl_init();
+ dlm->error[0] = '\0';
+ dlm->status = DLMOD_LOADED;
+
+#else /* WIN32 */
if (dlm->path[0] == '/') {
#ifdef RTLD_NOW
dlm->handle = dlopen(dlm->path, RTLD_NOW);
@@ -162,7 +230,8 @@
return;
}
} else {
- for (p = strtok_r(dlmod_path, ":", &st); p; p = strtok_r(NULL, ":", &st)) {
+ tmp_path[0] = '\0';
+ for (p = strtok_r(dlmod_path, ENV_SEPARATOR, &st); p; p = strtok_r(NULL, ENV_SEPARATOR, &st)) {
snprintf(tmp_path, sizeof(tmp_path), "%s/%s.so", p, dlm->path);
DEBUGMSGTL(("dlmod", "p: %s tmp_path: %s\n", p, tmp_path));
#ifdef RTLD_NOW
@@ -193,18 +262,34 @@
dl_init();
dlm->error[0] = '\0';
dlm->status = DLMOD_LOADED;
+#endif /* WIN32 */
}
void
dlmod_unload_module(struct dlmod *dlm)
{
char sym_deinit[64];
+#ifdef WIN32
+ void (WINAPI *dl_deinit)(void);
+ HANDLE hInst = NULL;
+#else
int (*dl_deinit) (void);
+#endif
if (!dlm || dlm->status != DLMOD_LOADED)
return;
snprintf(sym_deinit, sizeof(sym_deinit), "deinit_%s", dlm->name);
+#ifdef WIN32
+ dl_deinit = (void (WINAPI *)(void)) GetProcAddress ((HMODULE) hInst, sym_deinit);
+ if (dl_deinit == NULL) {
+ snprintf(dlm->error, sizeof(dlm->error),
+ "dlsym failed: can't find \'%s\'", sym_deinit);
+ } else {
+ dl_deinit();
+ }
+ FreeLibrary(hInst);
+#else /* WIN32 */
dl_deinit = dlsym(dlm->handle, sym_deinit);
if (dl_deinit == NULL) {
snprintf(dlm->error, sizeof(dlm->error),
@@ -213,6 +298,7 @@
dl_deinit();
}
dlclose(dlm->handle);
+#endif /* WIN32 */
dlm->status = DLMOD_UNLOADED;
DEBUGMSGTL(("dlmod", "Module %s unloaded\n", dlm->name));
}
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