logcat: clear when specifying file output

If -c and -f are both specified, clear the files rather
than notifying the logger to clear its data. The -f then
acts like a switch between clearing the in-memory log
data, or the on-disk logrotate data.

Bug: 28936216
Change-Id: Ib1d1fb46ea09f81a2fd9bebb6c8f0f9f2355f6e8

logcat/logcat.cpp

@@ -290,6 +290,7 @@ static void show_help(const char *cmd)
                     "                    tag thread threadtime time uid usec UTC year zone\n"
                     "  -D, --dividers  Print dividers between each log buffer\n"
                     "  -c, --clear     Clear (flush) the entire log and exit\n"
+                    "                  if Log to File specified, clear fileset instead\n"
                     "  -d              Dump the log and then exit (don't block)\n"
                     "  -e <expr>, --regex=<expr>\n"
                     "                  Only print lines where the log message matches <expr>\n"
@@ -1033,7 +1034,35 @@ int main(int argc, char **argv)
         }
 
         if (clearLog) {
-            if (android_logger_clear(dev->logger)) {
+            if (g_outputFileName) {
+                int maxRotationCountDigits =
+                    (g_maxRotatedLogs > 0) ? (int) (floor(log10(g_maxRotatedLogs) + 1)) : 0;
+
+                for (int i = g_maxRotatedLogs ; i >= 0 ; --i) {
+                    char *file;
+
+                    if (i == 0) {
+                        asprintf(&file, "%s", g_outputFileName);
+                    } else {
+                        asprintf(&file, "%s.%.*d", g_outputFileName, maxRotationCountDigits, i);
+                    }
+
+                    if (!file) {
+                        perror("while clearing log files");
+                        clearFail = clearFail ?: dev->device;
+                        break;
+                    }
+
+                    err = unlink(file);
+
+                    if (err < 0 && errno != ENOENT && clearFail == NULL) {
+                        perror("while clearing log files");
+                        clearFail = dev->device;
+                    }
+
+                    free(file);
+                }
+            } else if (android_logger_clear(dev->logger)) {
                 clearFail = clearFail ?: dev->device;
             }
         }

logcat/tests/logcat_test.cpp

@@ -772,6 +772,82 @@ TEST(logcat, logrotate_continue) {
     EXPECT_FALSE(system(command));
 }
 
+TEST(logcat, logrotate_clear) {
+    static const char tmp_out_dir_form[] = "/data/local/tmp/logcat.logrotate.XXXXXX";
+    char tmp_out_dir[sizeof(tmp_out_dir_form)];
+    ASSERT_TRUE(NULL != mkdtemp(strcpy(tmp_out_dir, tmp_out_dir_form)));
+
+    static const char log_filename[] = "log.txt";
+    static const unsigned num_val = 32;
+    static const char logcat_cmd[] = "logcat -b all -d -f %s/%s -n %d -r 1";
+    static const char clear_cmd[] = " -c";
+    static const char cleanup_cmd[] = "rm -rf %s";
+    char command[sizeof(tmp_out_dir) + sizeof(logcat_cmd) + sizeof(log_filename) + sizeof(clear_cmd) + 32];
+
+    // Run command with all data
+    {
+        snprintf(command, sizeof(command) - sizeof(clear_cmd),
+                 logcat_cmd, tmp_out_dir, log_filename, num_val);
+
+        int ret;
+        EXPECT_FALSE((ret = system(command)));
+        if (ret) {
+            snprintf(command, sizeof(command), cleanup_cmd, tmp_out_dir);
+            EXPECT_FALSE(system(command));
+            return;
+        }
+        std::unique_ptr<DIR, decltype(&closedir)> dir(opendir(tmp_out_dir), closedir);
+        EXPECT_NE(nullptr, dir);
+        if (!dir) {
+            snprintf(command, sizeof(command), cleanup_cmd, tmp_out_dir);
+            EXPECT_FALSE(system(command));
+            return;
+        }
+        struct dirent *entry;
+        unsigned count = 0;
+        while ((entry = readdir(dir.get()))) {
+            if (strncmp(entry->d_name, log_filename, sizeof(log_filename) - 1)) {
+                continue;
+            }
+            ++count;
+        }
+        EXPECT_EQ(count, num_val + 1);
+    }
+
+    {
+        // Now with -c option tacked onto the end
+        strcat(command, clear_cmd);
+
+        int ret;
+        EXPECT_FALSE((ret = system(command)));
+        if (ret) {
+            snprintf(command, sizeof(command), cleanup_cmd, tmp_out_dir);
+            EXPECT_FALSE(system(command));
+            return;
+        }
+        std::unique_ptr<DIR, decltype(&closedir)> dir(opendir(tmp_out_dir), closedir);
+        EXPECT_NE(nullptr, dir);
+        if (!dir) {
+            snprintf(command, sizeof(command), cleanup_cmd, tmp_out_dir);
+            EXPECT_FALSE(system(command));
+            return;
+        }
+        struct dirent *entry;
+        unsigned count = 0;
+        while ((entry = readdir(dir.get()))) {
+            if (strncmp(entry->d_name, log_filename, sizeof(log_filename) - 1)) {
+                continue;
+            }
+            fprintf(stderr, "Found %s/%s!!!\n", tmp_out_dir, entry->d_name);
+            ++count;
+        }
+        EXPECT_EQ(count, 0U);
+    }
+
+    snprintf(command, sizeof(command), cleanup_cmd, tmp_out_dir);
+    EXPECT_FALSE(system(command));
+}
+
 TEST(logcat, logrotate_nodir) {
     // expect logcat to error out on writing content and exit(1) for nodir
     EXPECT_EQ(W_EXITCODE(1, 0),