path: root/src/audit-error.c

#include <stdio.h>
#include <search.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <strings.h>
#include <string.h>
#include <signal.h>

#include "config.h"
#include "backtrace.h"

int lt_audit_parse_init(struct lt_config_shared *cfg);
int lt_audit_parse();
extern FILE *lt_audit_in;

#define SYMBOL_TAB_SIZE 100
static struct hsearch_data symbol_tab;
static int symbol_tab_init = 0;

struct lt_error_sym* lt_error_sym_get(struct lt_config_audit *cfg,
				      const char *name)
{
	struct lt_error_sym *sym;
	ENTRY e, *ep;

	if (!symbol_tab_init)
		return NULL;

	PRINT_VERBOSE(cfg, 1, "request for <%s>\n", name);

	e.key = (char*) name;
	hsearch_r(e, FIND, &ep, &symbol_tab);

	if (!ep) {
		PRINT_VERBOSE(cfg, 1, "failed to find <%s>\n", name);
		return NULL;
	}

	sym = (struct lt_error_sym*) ep->data;

	PRINT_VERBOSE(cfg, 1, "found %p <%s>\n", sym, sym->name);
	return sym;
}

extern __thread int pipe_fd;

static void share_info(struct lt_config_audit *cfg,
		       long ret, int keep,
		       struct timeval *tv,
		       struct link_map *lr,
		       const La_regs *inregs)
{
	void *ret_addr;
#define LT_MAXMSG 100
	char text[LT_MAXMSG];

	lt_error_get_retaddr(cfg, &ret_addr, inregs);
	ret_addr -= lr->l_addr;

	if (keep)
		snprintf(text, LT_MAXMSG, "ERROR SIMULATION no change, ret %p",
			 ret_addr);
	else
		snprintf(text, LT_MAXMSG, "ERROR SIMULATION inserted %ld, ret %p",
			 ret, ret_addr);

	if (lt_sh(cfg, pipe)) {
		char buf[LT_FIFO_MSG_MAXLEN];
		int len;

		len = lt_fifo_mtext_get(cfg->sh, buf, tv, text);
		/* TODO erro handling */
		lt_fifo_send(cfg->sh, pipe_fd, buf, len);
	} else
		lt_out_text(cfg->sh, tv, syscall(SYS_gettid), text);

	dump_backtrace(cfg->sh, 0);
}

static struct lt_config_shared *ss_cfg;

static void sig_segv_handler(int sig)
{
	char text[LT_MAXMSG];
	struct timeval tv;

	gettimeofday(&tv, NULL);

	snprintf(text, LT_MAXMSG, "ERROR SIMULATION got SIGSEGV");

	if (lt_sh(ss_cfg, pipe)) {
		char buf[LT_FIFO_MSG_MAXLEN];
		int len;

		len = lt_fifo_mtext_get(ss_cfg, buf, &tv, text);
		/* TODO erro handling */
		lt_fifo_send(ss_cfg, pipe_fd, buf, len);
	} else
		lt_out_text(ss_cfg->sh, &tv, syscall(SYS_gettid), text);

	dump_backtrace(ss_cfg, 0);
	exit(-1);
}

static int install_sigsegv(struct lt_config_shared *cfg)
{
	struct sigaction act;

	bzero(&act, sizeof(act));
	act.sa_handler = sig_segv_handler;

	ss_cfg = cfg;

	return sigaction(SIGSEGV, &act, NULL);
}

static __thread unsigned long automated_sym_cnt = 0;


/* TODO make type agnostics... now only AFTER type */
static void update_start_info(struct lt_config_audit *cfg,
			     const char *symname, int is_entry)
{
	if (cfg->error_allowed)
		return;

	if (is_entry && cfg->error_start_after_entries) {
		if (strcmp(symname, cfg->error_start_after_sym))
			return;

		cfg->error_start_after_current++;

		if (cfg->error_start_after_current != cfg->error_start_after_entries)
			return;

		cfg->error_allowed = 1;
	}
}

int lt_error_sym_entry(struct lt_config_audit *cfg,
		       const char *symname)
{
	update_start_info(cfg, symname, 1);
	return 0;
}

int lt_error_sym_exit(struct lt_config_audit *cfg,
		      const char *symname,
		      struct lt_symbol *sym,
		      struct timeval *tv,
		      struct link_map *lr,
		      const La_regs *inregs,
		      La_retval *outregs,
		      long *info)
{
	struct lt_error_sym *esym;
	struct lt_error_config *cfg_err = cfg->error_config;
	int keep = 0;
	int handle_sigsegv;
	long ret;

	/* we're not interested in this symbol */
	if (!sym || !sym->error)
		return -1;

	update_start_info(cfg, symname, 0);

	if (!cfg->error_allowed)
		return -1;

	if (cfg_err->type == LT_ERROR_RUN_TYPE_AUTO) {
		struct lt_error_sym *esym;

		PRINT_VERBOSE(cfg, 1, "automated_sym_cnt %d,  cfg_err->sym_cnt %d\n",
			      automated_sym_cnt, cfg_err->sym_cnt);

		if (automated_sym_cnt >= cfg_err->sym_cnt)
			return -1;

		esym = &cfg_err->sym[automated_sym_cnt];
		ret = esym->ret;
		keep = esym->keep;
		handle_sigsegv = esym->handle_sigsegv;

		*info = automated_sym_cnt++;
	} else {

		esym = sym->error;

		PRINT_VERBOSE(cfg, 1, "symbol %s, call %lu, n %ld\n",
			      sym->name, esym->call_configured, cfg_err->n);

		/* we are not interested in this call number  */
		if (esym->call_current++ != esym->call_configured)
			return -1;

		ret = esym->ret;
		handle_sigsegv = esym->handle_sigsegv;
	}

	if (keep)
		PRINT_VERBOSE(cfg, 1, "keeping the return value\n",
			      ret);
	else
		PRINT_VERBOSE(cfg, 1, "changing retval to %lu\n",
			      ret);

	/* The fun begins right now.. let's change the return
	 * value for the symbol ... */
	if (!keep)
		lt_error_set_retval(cfg, ret, outregs);

	/* and share some info about the sinner */
	share_info(cfg, ret, keep, tv, lr, inregs);

	if (handle_sigsegv && install_sigsegv(cfg->sh))
		PRINT_VERBOSE(cfg, 1, "failed to install SIGSEGV handler\n");

	return 0;
}

static int symbol_add(struct lt_config_audit *cfg,
		      struct lt_error_config *cfg_err,
		      struct lt_error_sym *sym)
{
	ENTRY e, *ep;

	PRINT_VERBOSE(cfg, 1, "symbol %s, ret %ld\n",
			sym->name.symbol, sym->ret);

	/* should be safe, since only one thread
	 * is doing the initialization */
	if (!symbol_tab_init) {
		if (!hcreate_r(SYMBOL_TAB_SIZE, &symbol_tab)) {
			perror("failed to create hash table");
			return -1;
		}
		symbol_tab_init = 1;
		PRINT_VERBOSE(cfg, 1, "symbol table initialized\n");
	}

	e.key = sym->name.symbol;
	if (hsearch_r(e, FIND, &ep, &symbol_tab)) {
		PRINT_VERBOSE(cfg, 1, "symbol %s already in the table\n",
			      sym->name.symbol);
		/* This is a bug in normal processing,
		 * but completelly ok in automated mode. */
		return cfg_err->type == LT_ERROR_RUN_TYPE_AUTO? 0 : -1;
	}

	e.key = sym->name.symbol;
	e.data = sym;

	if (!hsearch_r(e, ENTER, &ep, &symbol_tab)) {
		perror("hsearch_r failed");
		free(sym);

		PRINT_VERBOSE(cfg, 3,
			"reached the error symbol limit %d\n",
			SYMBOL_TAB_SIZE);
		return -1;
	}

	PRINT_VERBOSE(cfg, 1, "ok\n");
	return 0;
}

static void display_error_symbols(struct lt_config_audit *cfg,
				  char *names, int size)
{
	char *p;

	PRINT_VERBOSE(cfg, 1, "START size %d\n", size);

	while(size) {
		PRINT_VERBOSE(cfg, 1, "name %s\n", names);
		p = memchr(names, 0, size);
		size -= ++p - names;
		names = p;
	}

	PRINT_VERBOSE(cfg, 1, "END\n");
}


static int init_start_info(struct lt_config_audit *cfg,
			   struct lt_error_config *cfg_err,
			   char *names)
{
	struct lt_error_start *start = &cfg_err->start;

	if (start->type == LT_ERROR_START_TYPE_AFTER) {
		if (start->after.name.index != -1)
			cfg->error_start_after_sym = names + start->after.name.index;

		cfg->error_start_after_entries = start->after.entries;
		cfg->error_start_after_exits   = start->after.exits;

		PRINT_VERBOSE(cfg, 1, "START AFTER entries %ld, exits %ld, sym %s\n",
			cfg->error_start_after_entries,
			cfg->error_start_after_exits,
			cfg->error_start_after_sym);
	}

	return 0;
}

int lt_error_init(struct lt_config_audit *cfg)
{
	struct lt_error_config *cfg_err = cfg->error_config;
	int sym_cnt = cfg_err->sym_cnt, i, ok = 1;
	char *names;

	lt_sh(cfg, error_sim) = 0;

	names = (char*) (((void*) &cfg_err->sym) +
		(sym_cnt * sizeof(struct lt_error_sym)));

	display_error_symbols(cfg, names, cfg_err->names_size);

	for(i = 0; i < sym_cnt; i++) {
		struct lt_error_sym *sym;

		sym = &cfg_err->sym[i];

		PRINT_VERBOSE(cfg, 1, "symbol index %d, name %s\n",
			      sym->name.index, names + sym->name.index);

		sym->name.symbol = names + sym->name.index;

		if (symbol_add(cfg, cfg_err, sym)) {
			ok = 0;
			break;
		}
	}

	if (!ok) {
		if (symbol_tab_init)
			hdestroy_r(&symbol_tab);
		return -1;
	}

	if (init_start_info(cfg, cfg_err, names))
		return -1;

	lt_sh(cfg, error_sim) = 1;
	return 0;
}

int lt_error_config_read(struct lt_config_audit *cfg, int fd)
{
	int size;
	struct lt_error_config *cfg_err, cfg_err_st;
	ssize_t n;

	n = read(fd, &cfg_err_st, sizeof(cfg_err_st));
	if (n != sizeof(cfg_err_st)) {
		perror("read failed");
		return -1;
	}

	size = cfg_err_st.sym_cnt * sizeof(struct lt_error_sym);
	size += cfg_err_st.names_size;

	PRINT_VERBOSE(cfg, 1, "symbols count %d, names_size %d, total size %d\n",
		      cfg_err_st.sym_cnt, cfg_err_st.names_size, size);

	cfg_err = malloc(sizeof(*cfg_err) + size);
	if (!cfg_err) {
		perror("malloc failed");
		return -1;
	}

	*cfg_err = cfg_err_st;

	if (size != read(fd, &cfg_err->sym, size)) {
		PRINT_VERBOSE(cfg, 1, "failed: no error symbols defined\n");
		return -1;
	}

	cfg->error_config = cfg_err;
	return 0;
}