Squash various compiler warnings

Unused-result from sensitive APIs, printf/scanf formatting types, set
but never used variables, and uninitialized variables.

Also there's one select(enum) that doesn't cover all cases.

src/lnav_commands.cc

@@ -156,7 +156,7 @@ static string com_adjust_log_time(exec_context &ec, string cmdline, vector<strin
                 char buffer[1024];
 
                 snprintf(buffer, sizeof(buffer),
-                         "info: log timestamps will be adjusted by %ld.%06d seconds",
+                         "info: log timestamps will be adjusted by %ld.%06ld seconds",
                          time_diff.tv_sec, time_diff.tv_usec);
 
                 retval = buffer;

src/lnav_log.cc

@@ -305,6 +305,8 @@ void log_msg_extra_complete()
     }
 }
 
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wunused-result"
 static void sigabrt(int sig)
 {
     char crash_path[1024], latest_crash_path[1024];
@@ -339,10 +341,10 @@ static void sigabrt(int sig)
         "%s/latest-crash.log", lnav_log_crash_dir);
     if ((fd = open(crash_path, O_CREAT|O_TRUNC|O_WRONLY, 0600)) != -1) {
         if (log_ring.lr_frag_start < (off_t)BUFFER_SIZE) {
-            write(fd, &log_ring.lr_data[log_ring.lr_frag_start],
+            (void)write(fd, &log_ring.lr_data[log_ring.lr_frag_start],
                 log_ring.lr_frag_end - log_ring.lr_frag_start);
         }
-        write(fd, log_ring.lr_data, log_ring.lr_length);
+        (void)write(fd, log_ring.lr_data, log_ring.lr_length);
 #ifdef HAVE_EXECINFO_H
         backtrace_symbols_fd(frames, frame_count, fd);
 #endif
@@ -395,9 +397,7 @@ static void sigabrt(int sig)
         fprintf(stderr, "\nWould you like to attach a debugger? (y/N) ");
         fflush(stderr);
 
-        scanf("%c", &response);
-
-        if (tolower(response) == 'y') {
+        if (scanf("%c", &response) > 0 && tolower(response) == 'y') {
             pid_t lnav_pid = getpid();
             pid_t child_pid;
 
@@ -436,6 +436,7 @@ static void sigabrt(int sig)
 
     _exit(1);
 }
+#pragma GCC diagnostic pop
 
 void log_install_handlers(void)
 {

src/log_vtab_impl.cc

@@ -849,6 +849,7 @@ string log_vtab_manager::unregister_vtab(intern_string_t name)
     }
     else {
         auto_mem<char> sql(sqlite3_free);
+        __attribute((unused))
         int   rc;
 
         sql = sqlite3_mprintf("DROP TABLE %s ", name.get());

src/logfile_sub_source.cc

@@ -324,7 +324,7 @@ void logfile_sub_source::text_attrs_for_line(textview_curses &lv,
         chtype graph = ACS_VLINE;
         if (is_first_for_file) {
             if (is_last_for_file) {
-                graph = ACS_DIAMOND;
+                graph = ACS_HLINE;
             }
             else {
                 graph = ACS_ULCORNER;
@@ -472,6 +472,9 @@ bool logfile_sub_source::rebuild_index(bool force)
             logfile &lf = *ld.get_file();
 
             switch (lf.rebuild_index()) {
+                case logfile::RR_NO_NEW_LINES:
+                    // No changes
+                    break;
                 case logfile::RR_NEW_LINES:
                     retval = true;
                     if (!this->lss_index.empty()) {

src/readline_callbacks.cc

@@ -502,7 +502,9 @@ void rl_display_matches(void *dummy, readline_curses *rc)
 {
     const std::vector<std::string> &matches = rc->get_matches();
     textview_curses &tc = lnav_data.ld_match_view;
-    unsigned long width, height;
+    unsigned long width;
+    __attribute((unused))
+    unsigned long height;
     int max_len, cols, rows;
 
     getmaxyx(lnav_data.ld_window, height, width);

src/string-extension-functions.cc

@@ -103,7 +103,7 @@ regexp_match(const char *re, const char *str)
         }
         else {
             char *cap_copy = (char *)alloca(cap->length() + 1);
-            int64_t i_value;
+            long long int i_value;
             double d_value;
             int end_index;
 
@@ -112,7 +112,7 @@ regexp_match(const char *re, const char *str)
 
             if (sscanf(cap_copy, "%lld%n", &i_value, &end_index) == 1 &&
                 (end_index == cap->length())) {
-                return i_value;
+                return (int64_t)i_value;
             }
             else if (sscanf(cap_copy, "%lf%n", &d_value, &end_index) == 1 &&
                      (end_index == cap->length())) {
@@ -139,7 +139,7 @@ regexp_match(const char *re, const char *str)
             else {
                 const char *cap_start = pi.get_substr_start(cap);
                 char *cap_copy = (char *) alloca(cap->length() + 1);
-                int64_t i_value;
+                long long int i_value;
                 double d_value;
                 int end_index;
 

src/view_curses.cc

@@ -204,10 +204,10 @@ attr_line_t &attr_line_t::with_ansi_string(const char *str, ...)
     va_list args;
 
     va_start(args, str);
-    vasprintf(formatted_str.out(), str, args);
+    auto ret = vasprintf(formatted_str.out(), str, args);
     va_end(args);
 
-    if (formatted_str != NULL) {
+    if (ret >= 0 && formatted_str != NULL) {
         this->al_string = formatted_str;
         scrub_ansi_string(this->al_string, this->al_attrs);
     }

test/scripty.cc

@@ -517,7 +517,7 @@ int main(int argc, char *argv[])
 	else {
 	    int maxfd, out_len = 0;
 	    bool got_expected = true;
-	    bool got_user_step;
+	    bool got_user_step = false;
 	    struct timeval last, now;
 	    char out_buffer[8192];
 	    fd_set read_fds;

test/test_ncurses_unicode.cc

@@ -27,8 +27,9 @@ int main(int argc, char *argv[])
     FILE *file = fopen(argv[1], "r");
     int row = 0;
     while (!feof(file)) {
-        fgets(buf, sizeof(buf), file);
-        mvwaddstr(stdscr, row++, 0, buf);
+        if (0 < fgets(buf, sizeof(buf), file)) {
+            mvwaddstr(stdscr, row++, 0, buf);
+        }
     }
     getch();
     endwin();