logcat: -f flag to continue
On startup, check the current logging content, then grab logs from
that time forward rather than restarting from the beginning. Add
support for reading tail time down to the nano-second.
Bonus, permits us to create a logcatd logpersist daemon
Bug: 19608716
Change-Id: Iaab58de4c02b7f97c69de12cf954fedc2163059e
diff --git a/logcat/logcat.cpp b/logcat/logcat.cpp
index 2c2d785..afcc20a 100644
--- a/logcat/logcat.cpp
+++ b/logcat/logcat.cpp
@@ -2,6 +2,7 @@
#include <assert.h>
#include <ctype.h>
+#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <math.h>
@@ -15,8 +16,14 @@
#include <sys/cdefs.h>
#include <sys/socket.h>
#include <sys/stat.h>
+#include <sys/types.h>
#include <arpa/inet.h>
+#include <memory>
+#include <string>
+
+#include <base/file.h>
+#include <base/strings.h>
#include <cutils/sockets.h>
#include <log/log.h>
#include <log/log_read.h>
@@ -231,7 +238,7 @@
fprintf(stderr, "options include:\n"
" -s Set default filter to silent.\n"
" Like specifying filterspec '*:S'\n"
- " -f <filename> Log to file. Default to stdout\n"
+ " -f <filename> Log to file. Default is stdout\n"
" -r <kbytes> Rotate log every kbytes. Requires -f\n"
" -n <count> Sets max number of rotated logs to <count>, default 4\n"
" -v <format> Sets the log print format, where <format> is:\n\n"
@@ -352,6 +359,86 @@
exit(EXIT_FAILURE);
}
+static const char g_defaultTimeFormat[] = "%m-%d %H:%M:%S.%q";
+
+// Find last logged line in gestalt of all matching existing output files
+static log_time lastLogTime(char *outputFileName) {
+ log_time retval(log_time::EPOCH);
+ if (!outputFileName) {
+ return retval;
+ }
+
+ log_time now(CLOCK_REALTIME);
+
+ std::string directory;
+ char *file = strrchr(outputFileName, '/');
+ if (!file) {
+ directory = ".";
+ file = outputFileName;
+ } else {
+ *file = '\0';
+ directory = outputFileName;
+ *file = '/';
+ ++file;
+ }
+ size_t len = strlen(file);
+ log_time modulo(0, NS_PER_SEC);
+ std::unique_ptr<DIR, int(*)(DIR*)>dir(opendir(directory.c_str()), closedir);
+ struct dirent *dp;
+ while ((dp = readdir(dir.get())) != NULL) {
+ if ((dp->d_type != DT_REG)
+ || strncmp(dp->d_name, file, len)
+ || (dp->d_name[len]
+ && ((dp->d_name[len] != '.')
+ || !isdigit(dp->d_name[len+1])))) {
+ continue;
+ }
+
+ std::string file_name = directory;
+ file_name += "/";
+ file_name += dp->d_name;
+ std::string file;
+ if (!android::base::ReadFileToString(file_name, &file)) {
+ continue;
+ }
+
+ bool found = false;
+ for (const auto& line : android::base::Split(file, "\n")) {
+ log_time t(log_time::EPOCH);
+ char *ep = t.strptime(line.c_str(), g_defaultTimeFormat);
+ if (!ep || (*ep != ' ')) {
+ continue;
+ }
+ // determine the time precision of the logs (eg: msec or usec)
+ for (unsigned long mod = 1UL; mod < modulo.tv_nsec; mod *= 10) {
+ if (t.tv_nsec % (mod * 10)) {
+ modulo.tv_nsec = mod;
+ break;
+ }
+ }
+ // We filter any times later than current as we may not have the
+ // year stored with each log entry. Also, since it is possible for
+ // entries to be recorded out of order (very rare) we select the
+ // maximum we find just in case.
+ if ((t < now) && (t > retval)) {
+ retval = t;
+ found = true;
+ }
+ }
+ // We count on the basename file to be the definitive end, so stop here.
+ if (!dp->d_name[len] && found) {
+ break;
+ }
+ }
+ if (retval == log_time::EPOCH) {
+ return retval;
+ }
+ // tail_time prints matching or higher, round up by the modulo to prevent
+ // a replay of the last entry we have just checked.
+ retval += modulo;
+ return retval;
+}
+
} /* namespace android */
@@ -417,12 +504,11 @@
/* FALLTHRU */
case 'T':
if (strspn(optarg, "0123456789") != strlen(optarg)) {
- char *cp = tail_time.strptime(optarg,
- log_time::default_format);
+ char *cp = tail_time.strptime(optarg, g_defaultTimeFormat);
if (!cp) {
logcat_panic(false,
"-%c \"%s\" not in \"%s\" time format\n",
- ret, optarg, log_time::default_format);
+ ret, optarg, g_defaultTimeFormat);
}
if (*cp) {
char c = *cp;
@@ -545,9 +631,11 @@
break;
case 'f':
+ if ((tail_time == log_time::EPOCH) && (tail_lines != 0)) {
+ tail_time = lastLogTime(optarg);
+ }
// redirect output to a file
g_outputFileName = optarg;
-
break;
case 'r':