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/* Copyright (C) 2012
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 <string.h>
#include <unistd.h>
#include <errno.h>
#include "vtv_utils.h"
/* This is the directory into which all vtable verication log files
get written, if possible. */
static const char * const logs_dir = "/var/log/chrome/vtv_logs";
/* This is the directory into which the vtable verification log files
will get written if they can't be written to the directory
above. */
static const char * const alt_logs_dir = "/tmp/vtv_logs";
/* 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
decriptor. */
int
vtv_open_log (const char *name)
{
/* Try to create the logs under /var/log/chrome first, which is
persistent across reboots. This location only exists on
ChromeOS. This code should not be commited upstream GCC. */
char log_name[256];
snprintf (log_name, sizeof (log_name), "%s/%s", logs_dir, name);
mkdir (logs_dir, S_IRWXU);
int fd = open (log_name, O_WRONLY | O_APPEND | O_CREAT, S_IRWXU);
if (fd != -1)
return fd;
/* Otherwise, try to open in /tmp. */
snprintf(log_name, sizeof(log_name), "%s/%s", alt_logs_dir, name);
mkdir(alt_logs_dir, S_IRWXU);
fd = open(log_name, O_WRONLY | O_APPEND | O_CREAT, S_IRWXU);
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);
/* fdatasync is quite expensive. Only enable if you suspect you are
loosing log data in in a program crash? */
/* fdatasync(log_file); */
return 0;
}
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