Implement a crash handler to ease debugging
git-svn-id: file:///home/svn/framework3/trunk@10416 4d416f70-5f16-0410-b530-b9f4589650daunstable
pks
parent
3c99897115
commit
89b33c2cc7
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@ -17,6 +17,10 @@
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#include <sys/socket.h>
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#include <endian.h>
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#include <asm/sigcontext.h>
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#include <asm/ucontext.h>
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#include "linker.h"
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#include "linker_debug.h"
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#include "linker_format.h"
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@ -133,23 +137,210 @@ int dlsocket(void *libc)
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}
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/*
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* If we are compiled into an executable, we'll start here. I can't be
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* bothered adding socketcall() wrappers for bind / accept / connect / crap, so
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* use bash / nc / whatever to put a socket on fd 5 for now.
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*
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extern soinfo *solist;
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/*
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* This can't handle PROT_WRITE only memory :-)
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*/
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void dump_memory(char **ptr, int *len, char *prefix, long unsigned int location, size_t count)
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{
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unsigned char discard[count];
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int fds[2];
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int rc;
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size_t n;
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if(pipe(fds) == -1) return;
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if(write(fds[1], location, count) == count) {
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if(read(fds[0], discard, count) == count) {
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n = 0;
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while(n < count) {
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rc = format_buffer(*ptr, *len, "%s+%4d: %02x%02x%02x%02x %02x%02x%02x%02x %02x%02x%02x%02x %02x%02x%02x%02x\n",
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prefix, n, discard[n + 0], discard[n + 1], discard[n + 2], discard[n + 3],
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discard[n + 4], discard[n + 5], discard[n + 6], discard[n + 7],
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discard[n + 8], discard[n + 9], discard[n + 10], discard[n + 11],
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discard[n + 12], discard[n + 13], discard[n + 14], discard[n + 15]
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);
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*ptr += rc;
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*len -= rc;
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n += 16;
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}
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rc = format_buffer(*ptr, *len, "\n");
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*ptr += rc;
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*len -= rc;
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}
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}
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close(fds[0]);
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close(fds[1]);
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}
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void *special_sig_stack;
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void sigcrash(int signo, siginfo_t *info, void *context)
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{
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struct ucontext *uc = (struct ucontext *)(context);
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struct sigcontext *sg = (struct sigcontext *)(& uc->uc_mcontext);
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char buf[8192], *p;
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int len, rc;
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int fd;
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soinfo *si;
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char filename[64];
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// reset signal handler, in case of another crash
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signal(signo, SIG_DFL);
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memset(buf, 0, sizeof(buf));
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p = buf;
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len = sizeof(buf);
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rc = format_buffer(p, len, "\n[ meterpreter crash -- caught signal %d ]\n\n", signo);
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p += rc;
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len -= rc;
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rc = format_buffer(p, len, "Special registers:\nEIP: 0x%08x ESP: 0x%08x EBP: 0x%08x\n\n",
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sg->eip, sg->esp, sg->ebp);
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p += rc;
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len -= rc;
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rc = format_buffer(p, len, "General registers:\nEAX: 0x%08x EBX: 0x%08x ECX: 0x%08x" \
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" EDX: 0x%08x ESI: 0x%08x EDI: 0x%08x\n\n",
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sg->eax, sg->ebx, sg->ecx, sg->edx, sg->esi, sg->edi);
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p += rc;
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len -= rc;
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rc = format_buffer(p, len, "Loaded libraries:\n");
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p += rc;
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len -= rc;
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for(si = solist; si; si = si->next) {
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rc = format_buffer(p, len, "%s %08x - %08x", si->name, si->base, si->base + si->size);
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p += rc;
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len -= rc;
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if(sg->eip >= si->base && sg->eip <= (si->base + si->size)) {
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rc = format_buffer(p, len, " [eip offset: %08x]", sg->eip - si->base);
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p += rc;
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len -= rc;
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}
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rc = format_buffer(p, len, "\n");
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p += rc;
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len -= rc;
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}
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rc = format_buffer(p, len, "\nRegister pointer contents:\n");
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p += rc;
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len -= rc;
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dump_memory(&p, &len, "EAX", sg->eax, 32);
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dump_memory(&p, &len, "EBX", sg->ebx, 32);
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dump_memory(&p, &len, "ECX", sg->ecx, 32);
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dump_memory(&p, &len, "EDX", sg->edx, 32);
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dump_memory(&p, &len, "ESI", sg->esi, 32);
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dump_memory(&p, &len, "EDI", sg->edi, 32);
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dump_memory(&p, &len, "EBP", sg->ebp, 64);
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dump_memory(&p, &len, "ESP", sg->esp, 64);
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dump_memory(&p, &len, "EIP", sg->eip, 16);
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fd = open("/proc/self/maps", O_RDONLY);
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if(fd != -1) {
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rc = read(fd, p, len);
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if(rc != -1) {
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p += rc;
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len -= rc;
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}
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close(fd);
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}
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memset(filename, 0, sizeof(filename));
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format_buffer(filename, sizeof(filename) - 1, "/tmp/meterpreter.crash.%d", getpid());
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fd = open(filename, O_WRONLY|O_TRUNC|O_CREAT, 0644);
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if(fd) {
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write(fd, buf, 8192 - len);
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close(fd);
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}
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write(2, buf, 8192 - len);
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}
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void sigchld(int signo)
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{
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waitpid(-1, NULL, WNOHANG);
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}
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#define NEWSTKSIZE (4096 * 32)
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void handle_crashes()
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{
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struct sigaction sa;
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memset(&sa, 0, sizeof(struct sigaction));
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sa.sa_sigaction = sigcrash;
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sa.sa_flags = SA_SIGINFO | SA_ONSTACK;
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/*
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* We set up a special signal handler stack on the chance that
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* if our thread's esp is corrupt / too long, we can still execute
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* the crash handler.
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*/
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special_sig_stack = mmap(NULL, NEWSTKSIZE, PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
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if(special_sig_stack == MAP_FAILED) {
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TRACE("[ (%s) unable to mmap for special stack. ]", __FUNCTION__);
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sa.sa_flags &= ~SA_ONSTACK;
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special_sig_stack = NULL;
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} else {
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stack_t newstk;
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newstk.ss_sp = special_sig_stack;
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newstk.ss_flags = 0;
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newstk.ss_size = NEWSTKSIZE;
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if(sigaltstack(&newstk, NULL) == -1) {
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TRACE("[ (%s) unable to sigaltstack. errno = %d ]", __FUNCTION__, errno);
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munmap(special_sig_stack, NEWSTKSIZE);
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special_sig_stack = NULL;
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sa.sa_flags &= ~SA_ONSTACK;
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}
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}
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sigaction(SIGSEGV, &sa, NULL); sigaction(SIGILL, &sa, NULL);
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sigaction(SIGFPE, &sa, NULL); sigaction(SIGSYS, &sa, NULL);
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sigaction(SIGABRT, &sa, NULL);
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}
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/*
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* This is the entry point for the meterpreter payload, either as a stand alone executable, or a
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* payload executing on the remote machine.
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*
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* If executed as a stand alone, int fd will be invalid. Later on, once libc has been loaded,
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* it will connect to the metasploit meterpreter server.
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*/
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void _start(int fd)
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{
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signal(SIGCHLD, sigchld);
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signal(SIGPIPE, SIG_IGN);
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alarm(0); // clear out any pending alarms.
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// we can't run ./msflinker directly. Use rtldtest to test the code
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metsrv_rtld(fd);
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signal(SIGCHLD, sigchld); // reap pids
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signal(SIGPIPE, SIG_IGN); // ignore read/write pipe errors, make them return -1.
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handle_crashes(); // try to make debugging a little easier.
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metsrv_rtld(fd);
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}
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@ -105,7 +105,7 @@ static int link_image(soinfo *si, unsigned wr_offset);
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static int socount = 0;
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static soinfo sopool[SO_MAX];
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static soinfo *freelist = NULL;
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static soinfo *solist = &libdl_info;
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soinfo *solist = &libdl_info;
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static soinfo *sonext = &libdl_info;
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#if ALLOW_SYMBOLS_FROM_MAIN
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static soinfo *somain; /* main process, always the one after libdl_info */
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