1/* Copyright (C) 2012-2013
2   Free Software Foundation
3
4   This file is part of GCC.
5
6   GCC is free software; you can redistribute it and/or modify
7   it under the terms of the GNU General Public License as published by
8   the Free Software Foundation; either version 3, or (at your option)
9   any later version.
10
11   GCC is distributed in the hope that it will be useful,
12   but WITHOUT ANY WARRANTY; without even the implied warranty of
13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14   GNU General Public License for more details.
15
16   Under Section 7 of GPL version 3, you are granted additional
17   permissions described in the GCC Runtime Library Exception, version
18   3.1, as published by the Free Software Foundation.
19
20   You should have received a copy of the GNU General Public License and
21   a copy of the GCC Runtime Library Exception along with this program;
22   see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
23   <http://www.gnu.org/licenses/>.  */
24
25/* This file is part of the vtable verication runtime library (see
26   comments in vtv_rts.cc for more information about vtable
27   verification).  This file contains log file utilities.  */
28
29#include <sys/types.h>
30#include <sys/stat.h>
31#include <fcntl.h>
32#include <stdarg.h>
33#include <stdio.h>
34#include <stdlib.h>
35#include <string.h>
36#if defined (__CYGWIN__) || defined (__MINGW32__)
37#include <windows.h>
38#else
39#include <execinfo.h>
40#endif
41
42#include <unistd.h>
43#include <errno.h>
44
45#include "vtv_utils.h"
46
47#ifndef HAVE_SECURE_GETENV
48#  ifdef HAVE___SECURE_GETENV
49#    define secure_getenv __secure_getenv
50#  else
51#    define secure_getenv getenv
52#  endif
53#endif
54
55static int vtv_failures_log_fd = -1;
56
57/* This function takes the NAME of a log file to open, attempts to
58   open it in the logs_dir directory, and returns the resulting file
59   descriptor.
60
61   This function first checks to see if the user has specifed (via
62   the environment variable VTV_LOGS_DIR) a directory to use for the
63   vtable verification logs.  If that fails, the function will open
64   the logs in the current directory.
65*/
66
67int
68__vtv_open_log (const char *name)
69{
70  char log_name[1024];
71  char log_dir[512];
72#if defined (__CYGWIN__) || defined (__MINGW32__)
73  pid_t process_id = GetCurrentProcessId ();
74#else
75  uid_t user_id = getuid ();
76  pid_t process_id = getpid ();
77#endif
78  char *logs_prefix;
79  bool logs_dir_specified = false;
80  int fd = -1;
81
82  logs_prefix = secure_getenv ("VTV_LOGS_DIR");
83  if (logs_prefix && strlen (logs_prefix) > 0)
84    {
85      logs_dir_specified = true;
86#ifdef __MINGW32__
87      mkdir (logs_prefix);
88#else
89      mkdir (logs_prefix, S_IRWXU);
90#endif
91
92      snprintf (log_dir, sizeof (log_dir), "%s/vtv_logs", logs_prefix);
93
94#ifdef __MINGW32__
95      mkdir (log_dir);
96#else
97      mkdir (log_dir, S_IRWXU);
98#endif
99#if defined (__CYGWIN__) || defined (__MINGW32__)
100      snprintf (log_name, sizeof (log_name), "%s_%d_%s", log_dir,
101		(unsigned) process_id, name);
102      fd = open (log_name, O_WRONLY | O_APPEND | O_CREAT, S_IRWXU);
103#else
104      snprintf (log_name, sizeof (log_name), "%s/%d_%d_%s", log_dir,
105		(unsigned) user_id, (unsigned) process_id, name);
106      fd = open (log_name, O_WRONLY | O_APPEND | O_CREAT | O_NOFOLLOW,
107		 S_IRWXU);
108#endif
109    }
110  else
111    fd = dup (2);
112
113  if (fd == -1)
114    __vtv_add_to_log (2, "Cannot open log file %s %s\n", name,
115                    strerror (errno));
116  return fd;
117}
118
119/* This function takes a file descriptor (FD) and a string (STR) and
120   tries to write the string to the file.  */
121
122static int
123vtv_log_write (int fd, const char *str)
124{
125  if (write (fd, str, strlen (str)) != -1)
126    return 0;
127
128  if (fd != 2) /* Make sure we dont get in a loop.  */
129    __vtv_add_to_log (2, "Error writing to log: %s\n", strerror (errno));
130  return -1;
131}
132
133
134/* This function takes a file decriptor (LOG_FILE) and an output
135 format string (FORMAT), followed by zero or more print format
136 arguments (the same as fprintf, for example).  It gets the current
137 process ID and PPID, pre-pends them to the formatted message, and
138 writes write it out to the log file referenced by LOG_FILE via calles
139 to vtv_log_write.  */
140
141int
142__vtv_add_to_log (int log_file, const char * format, ...)
143{
144  /* We dont want to dynamically allocate this buffer. This should be
145     more than enough in most cases. It if isn't we are careful not to
146     do a buffer overflow.  */
147  char output[1024];
148
149  va_list ap;
150  va_start (ap, format);
151
152#if defined (__CYGWIN__) || defined (__MINGW32__)
153  snprintf (output, sizeof (output), "VTV: PID=%ld ", GetCurrentProcessId ());
154#else
155  snprintf (output, sizeof (output), "VTV: PID=%d PPID=%d ", getpid (),
156            getppid ());
157#endif
158  vtv_log_write (log_file, output);
159  vsnprintf (output, sizeof (output), format, ap);
160  vtv_log_write (log_file, output);
161  va_end (ap);
162
163  return 0;
164}
165
166/* Open error logging file, if not already open, and write vtable
167   verification failure messages (LOG_MSG) to the log file.  Also
168   generate a backtrace in the log file, if GENERATE_BACKTRACE is
169   set.  */
170
171void
172__vtv_log_verification_failure (const char *log_msg, bool generate_backtrace)
173{
174  if (vtv_failures_log_fd == -1)
175    vtv_failures_log_fd = __vtv_open_log ("vtable_verification_failures.log");
176
177  if (vtv_failures_log_fd == -1)
178    return;
179
180  __vtv_add_to_log (vtv_failures_log_fd, "%s", log_msg);
181
182#if !defined (__CYGWIN__) && !defined (__MINGW32__)
183  if (generate_backtrace)
184    {
185#define STACK_DEPTH 20
186      void *callers[STACK_DEPTH];
187      int actual_depth = backtrace (callers, STACK_DEPTH);
188      backtrace_symbols_fd (callers, actual_depth, vtv_failures_log_fd);
189    }
190#endif
191}
192