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/** @file
* @brief Debug logging macros.
*/
/* Copyright (C) 2008,2011,2012,2014,2015,2019 Olly Betts
*
* This program 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 2 of the License, or
* (at your option) any later version.
*
* This program 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <config.h>
#ifdef XAPIAN_DEBUG_LOG
#include "debuglog.h"
#include "errno_to_string.h"
#include "str.h"
#include <sys/types.h>
#include "safefcntl.h"
#include "safesysstat.h"
#include "safeunistd.h"
#include <cerrno>
#include <cstdlib> // For getenv().
#include <string>
using namespace std;
DebugLogger xapian_debuglogger_;
DebugLogger::~DebugLogger()
{
LOGLINE(ALWAYS, PACKAGE_STRING": debug log ended");
}
void
DebugLogger::initialise_categories_mask()
{
fd = -2;
const char* f = getenv("XAPIAN_DEBUG_LOG");
int flags = 0;
if (f && *f) {
if (f[0] == '-' && f[1] == '\0') {
// Filename "-" means "log to stderr".
fd = 2;
} else {
string fnm, pid;
while (*f) {
if (*f == '%') {
if (f[1] == 'p') {
// Replace %p in the filename with the process id.
if (pid.empty()) pid = str(getpid());
fnm += pid;
f += 2;
continue;
} else if (f[1] == '!') {
// %! in the filename means we should attempt to ensure
// that debug output is written to disk so that none is
// lost if we crash.
//
// We use O_DSYNC in preference if available - updating
// the log file's mtime isn't important.
#if O_DSYNC - 0 != 0
flags = O_DSYNC;
#elif O_SYNC - 0 != 0
flags = O_SYNC;
#endif
f += 2;
continue;
}
}
fnm += *f++;
}
flags |= O_CREAT|O_WRONLY|O_APPEND|O_CLOEXEC;
fd = open(fnm.c_str(), flags, 0644);
if (fd == -1) {
// If we failed to open the log file, report to stderr, but
// don't spew all the log output to stderr too or else the
// user will probably miss the message about the debug log
// failing to open!
fd = 2;
LOGLINE(ALWAYS, PACKAGE_STRING": Failed to open debug log '"
<< fnm << "' (" << errno_to_string(errno) << ')');
fd = -2;
}
}
if (fd >= 0) {
const char* v = getenv("XAPIAN_DEBUG_FLAGS");
if (v) {
bool toggle = (*v == '-');
if (toggle) ++v;
categories_mask = 0;
while (*v) {
int ch = *v++ - '@';
if (ch > 0 && ch <= 26) categories_mask |= 1ul << ch;
}
if (toggle) categories_mask ^= 0xffffffff;
}
}
}
LOGLINE(ALWAYS, PACKAGE_STRING": debug log started");
}
void
DebugLogger::log_line(debuglog_categories category, const string& msg)
{
if (fd < 0) return;
// Preserve errno over logging calls, so they can safely be added to code
// which expects errno not to change.
int saved_errno = errno;
string line;
line.reserve(9 + indent_level + msg.size());
line = char(category) + '@';
line += ' ';
line += str(getpid());
line.append(indent_level + 1, ' ');
line += msg;
line += '\n';
const char* p = line.data();
size_t to_do = line.size();
while (to_do) {
ssize_t n = write(fd, p, to_do);
if (n < 0) {
// Retry if interrupted by a signal.
if (errno == EINTR) continue;
// Upon other errors, close the log file, moan to stderr, and stop
// logging.
(void)close(fd);
fd = 2;
LOGLINE(ALWAYS, PACKAGE_STRING": Failed to write log output ("
<< errno_to_string(errno) << ')');
fd = -2;
break;
}
p += n;
to_do -= n;
}
errno = saved_errno;
}
#endif // XAPIAN_DEBUG_LOG
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