1 /* Copyright (C) 2012-2021 Free Software Foundation, Inc.
2
3 This file is part of GCC.
4
5 GCC is free software; you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation; either version 3, or (at your option)
8 any later version.
9
10 GCC is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
14
15 Under Section 7 of GPL version 3, you are granted additional
16 permissions described in the GCC Runtime Library Exception, version
17 3.1, as published by the Free Software Foundation.
18
19 You should have received a copy of the GNU General Public License and
20 a copy of the GCC Runtime Library Exception along with this program;
21 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
22 <http://www.gnu.org/licenses/>. */
23
24 /* This file is part of the vtable verication runtime library (see
25 comments in vtv_rts.cc for more information about vtable
26 verification). This file contains log file utilities. */
27
28 #include <sys/types.h>
29 #include <sys/stat.h>
30 #include <fcntl.h>
31 #include <stdarg.h>
32 #include <stdio.h>
33 #include <stdlib.h>
34 #include <string.h>
35 #if defined (__CYGWIN__) || defined (__MINGW32__)
36 #include <windows.h>
37 #else
38 #include <execinfo.h>
39 #endif
40
41 #include <unistd.h>
42 #include <errno.h>
43
44 #include "vtv_utils.h"
45
46 #ifndef HAVE_SECURE_GETENV
47 # ifdef HAVE___SECURE_GETENV
48 # define secure_getenv __secure_getenv
49 # else
50 # define secure_getenv getenv
51 # endif
52 #endif
53
54 static int vtv_failures_log_fd = -1;
55
56 /* This function takes the NAME of a log file to open, attempts to
57 open it in the logs_dir directory, and returns the resulting file
58 descriptor.
59
60 This function first checks to see if the user has specifed (via
61 the environment variable VTV_LOGS_DIR) a directory to use for the
62 vtable verification logs. If that fails, the function will open
63 the logs in the current directory.
64 */
65
66 int
__vtv_open_log(const char * name)67 __vtv_open_log (const char *name)
68 {
69 char log_name[1024];
70 char log_dir[512];
71 #if defined (__CYGWIN__) || defined (__MINGW32__)
72 pid_t process_id = GetCurrentProcessId ();
73 #else
74 uid_t user_id = getuid ();
75 pid_t process_id = getpid ();
76 #endif
77 char *logs_prefix;
78 bool logs_dir_specified = false;
79 int fd = -1;
80
81 logs_prefix = secure_getenv ("VTV_LOGS_DIR");
82 if (logs_prefix && strlen (logs_prefix) > 0)
83 {
84 logs_dir_specified = true;
85 #ifdef __MINGW32__
86 mkdir (logs_prefix);
87 #else
88 mkdir (logs_prefix, S_IRWXU);
89 #endif
90
91 snprintf (log_dir, sizeof (log_dir), "%s/vtv_logs", logs_prefix);
92
93 #ifdef __MINGW32__
94 mkdir (log_dir);
95 #else
96 mkdir (log_dir, S_IRWXU);
97 #endif
98 #if defined (__CYGWIN__) || defined (__MINGW32__)
99 snprintf (log_name, sizeof (log_name), "%s_%d_%s", log_dir,
100 (unsigned) process_id, name);
101 fd = open (log_name, O_WRONLY | O_APPEND | O_CREAT, S_IRWXU);
102 #else
103 snprintf (log_name, sizeof (log_name), "%s/%d_%d_%s", log_dir,
104 (unsigned) user_id, (unsigned) process_id, name);
105 fd = open (log_name, O_WRONLY | O_APPEND | O_CREAT | O_NOFOLLOW,
106 S_IRWXU);
107 #endif
108 }
109 else
110 fd = dup (2);
111
112 if (fd == -1)
113 __vtv_add_to_log (2, "Cannot open log file %s %s\n", name,
114 strerror (errno));
115 return fd;
116 }
117
118 /* This function takes a file descriptor (FD) and a string (STR) and
119 tries to write the string to the file. */
120
121 static int
vtv_log_write(int fd,const char * str)122 vtv_log_write (int fd, const char *str)
123 {
124 if (write (fd, str, strlen (str)) != -1)
125 return 0;
126
127 if (fd != 2) /* Make sure we dont get in a loop. */
128 __vtv_add_to_log (2, "Error writing to log: %s\n", strerror (errno));
129 return -1;
130 }
131
132
133 /* This function takes a file decriptor (LOG_FILE) and an output
134 format string (FORMAT), followed by zero or more print format
135 arguments (the same as fprintf, for example). It gets the current
136 process ID and PPID, pre-pends them to the formatted message, and
137 writes write it out to the log file referenced by LOG_FILE via calles
138 to vtv_log_write. */
139
140 int
__vtv_add_to_log(int log_file,const char * format,...)141 __vtv_add_to_log (int log_file, const char * format, ...)
142 {
143 /* We dont want to dynamically allocate this buffer. This should be
144 more than enough in most cases. It if isn't we are careful not to
145 do a buffer overflow. */
146 char output[1024];
147
148 va_list ap;
149 va_start (ap, format);
150
151 #if defined (__CYGWIN__) || defined (__MINGW32__)
152 snprintf (output, sizeof (output), "VTV: PID=%ld ", GetCurrentProcessId ());
153 #else
154 snprintf (output, sizeof (output), "VTV: PID=%d PPID=%d ", getpid (),
155 getppid ());
156 #endif
157 vtv_log_write (log_file, output);
158 vsnprintf (output, sizeof (output), format, ap);
159 vtv_log_write (log_file, output);
160 va_end (ap);
161
162 return 0;
163 }
164
165 /* Open error logging file, if not already open, and write vtable
166 verification failure messages (LOG_MSG) to the log file. Also
167 generate a backtrace in the log file, if GENERATE_BACKTRACE is
168 set. */
169
170 void
__vtv_log_verification_failure(const char * log_msg,bool generate_backtrace)171 __vtv_log_verification_failure (const char *log_msg, bool generate_backtrace)
172 {
173 if (vtv_failures_log_fd == -1)
174 vtv_failures_log_fd = __vtv_open_log ("vtable_verification_failures.log");
175
176 if (vtv_failures_log_fd == -1)
177 return;
178
179 __vtv_add_to_log (vtv_failures_log_fd, "%s", log_msg);
180
181 #if !defined (__CYGWIN__) && !defined (__MINGW32__)
182 if (generate_backtrace)
183 {
184 #define STACK_DEPTH 20
185 void *callers[STACK_DEPTH];
186 int actual_depth = backtrace (callers, STACK_DEPTH);
187 backtrace_symbols_fd (callers, actual_depth, vtv_failures_log_fd);
188 }
189 #endif
190 }
191