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/* Copyright (C) 2012-2013
Free Software Foundation
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.
GCC is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.
You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
<http://www.gnu.org/licenses/>. */
/* This file is part of the vtable verication runtime library (see
comments in vtv_rts.cc for more information about vtable
verification). This file contains log file utilities. */
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <execinfo.h>
#include <unistd.h>
#include <errno.h>
#include "vtv_utils.h"
#ifndef HAVE_SECURE_GETENV
# ifdef HAVE___SECURE_GETENV
# define secure_getenv __secure_getenv
# else
# define secure_getenv getenv
# endif
#endif
static int vtv_failures_log_fd = -1;
/* This function takes the NAME of a log file to open, attempts to
open it in the logs_dir directory, and returns the resulting file
descriptor.
This function first checks to see if the user has specifed (via
the environment variable VTV_LOGS_DIR) a directory to use for the
vtable verification logs. If that fails, the function will open
the logs in the current directory.
*/
int
__vtv_open_log (const char *name)
{
char log_name[1024];
char log_dir[512];
uid_t user_id = getuid ();
pid_t process_id = getpid ();
char *logs_prefix;
bool logs_dir_specified = false;
int fd = -1;
logs_prefix = secure_getenv ("VTV_LOGS_DIR");
if (logs_prefix && strlen (logs_prefix) > 0)
{
logs_dir_specified = true;
mkdir (logs_prefix, S_IRWXU);
snprintf (log_dir, sizeof (log_dir), "%s/vtv_logs", logs_prefix);
mkdir (log_dir, S_IRWXU);
snprintf (log_name, sizeof (log_name), "%s/%d_%d_%s", log_dir,
(unsigned) user_id, (unsigned) process_id, name);
fd = open (log_name, O_WRONLY | O_APPEND | O_CREAT | O_NOFOLLOW,
S_IRWXU);
}
else
fd = dup (2);
if (fd == -1)
__vtv_add_to_log (2, "Cannot open log file %s %s\n", name,
strerror (errno));
return fd;
}
/* This function takes a file descriptor (FD) and a string (STR) and
tries to write the string to the file. */
static int
vtv_log_write (int fd, const char *str)
{
if (write (fd, str, strlen (str)) != -1)
return 0;
if (fd != 2) /* Make sure we dont get in a loop. */
__vtv_add_to_log (2, "Error writing to log: %s\n", strerror (errno));
return -1;
}
/* This function takes a file decriptor (LOG_FILE) and an output
format string (FORMAT), followed by zero or more print format
arguments (the same as fprintf, for example). It gets the current
process ID and PPID, pre-pends them to the formatted message, and
writes write it out to the log file referenced by LOG_FILE via calles
to vtv_log_write. */
int
__vtv_add_to_log (int log_file, const char * format, ...)
{
/* We dont want to dynamically allocate this buffer. This should be
more than enough in most cases. It if isn't we are careful not to
do a buffer overflow. */
char output[1024];
va_list ap;
va_start (ap, format);
snprintf (output, sizeof (output), "VTV: PID=%d PPID=%d ", getpid (),
getppid ());
vtv_log_write (log_file, output);
vsnprintf (output, sizeof (output), format, ap);
vtv_log_write (log_file, output);
va_end (ap);
return 0;
}
/* Open error logging file, if not already open, and write vtable
verification failure messages (LOG_MSG) to the log file. Also
generate a backtrace in the log file, if GENERATE_BACKTRACE is
set. */
void
__vtv_log_verification_failure (const char *log_msg, bool generate_backtrace)
{
if (vtv_failures_log_fd == -1)
vtv_failures_log_fd = __vtv_open_log ("vtable_verification_failures.log");
if (vtv_failures_log_fd == -1)
return;
__vtv_add_to_log (vtv_failures_log_fd, "%s", log_msg);
if (generate_backtrace)
{
#define STACK_DEPTH 20
void *callers[STACK_DEPTH];
int actual_depth = backtrace (callers, STACK_DEPTH);
backtrace_symbols_fd (callers, actual_depth, vtv_failures_log_fd);
}
}
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