[stdin] fix handling of stdin piper

Fixes #1011

src/lnav.cc

@@ -3069,7 +3069,7 @@ SELECT tbl_name FROM sqlite_master WHERE sql LIKE 'CREATE VIRTUAL TABLE%'
             if (e.code().value() != EPIPE) {
                 fprintf(stderr, "error: %s\n", e.what());
             }
-        } catch (line_buffer::error& e) {
+        } catch (const line_buffer::error& e) {
             fprintf(stderr, "error: %s\n", strerror(e.e_err));
         }
 
@@ -3078,15 +3078,25 @@ SELECT tbl_name FROM sqlite_master WHERE sql LIKE 'CREATE VIRTUAL TABLE%'
         if (stdin_captured && stdin_opts.so_out.empty()
             && !(lnav_data.ld_flags & LNF_HEADLESS))
         {
-            ghc::filesystem::permissions(stdin_tmp_path,
-                                         ghc::filesystem::perms::owner_read);
-            auto stdin_size = ghc::filesystem::file_size(stdin_tmp_path);
-            if (verbosity == verbosity_t::quiet
-                || stdin_size > MAX_STDIN_CAPTURE_SIZE)
+            auto stdin_fd = stdin_reader->get_fd();
+            struct stat stdin_stat;
+            nonstd::optional<file_ssize_t> stdin_size;
+
+            // NB: the file can be deleted by the time we get here
+            fchmod(stdin_fd.get(), S_IRUSR);
+            if (fstat(stdin_fd.get(), &stdin_stat) != -1) {
+                stdin_size = stdin_stat.st_size;
+            }
+            if (!ghc::filesystem::exists(stdin_tmp_path)
+                || verbosity == verbosity_t::quiet || !stdin_size
+                || stdin_size.value() > MAX_STDIN_CAPTURE_SIZE)
             {
-                log_info("not saving large stdin capture -- %s",
-                         stdin_tmp_path.c_str());
-                ghc::filesystem::remove(stdin_tmp_path);
+                std::error_code rm_err_code;
+
+                log_info("not saving stdin capture -- %s (size=%d)",
+                         stdin_tmp_path.c_str(),
+                         stdin_size.value_or(-1));
+                ghc::filesystem::remove(stdin_tmp_path, rm_err_code);
             } else {
                 auto home = getenv_opt("HOME");
                 auto path_str = stdin_tmp_path.string();
@@ -3104,7 +3114,7 @@ SELECT tbl_name FROM sqlite_master WHERE sql LIKE 'CREATE VIRTUAL TABLE%'
                     lnav::console::user_message::info(
                         attr_line_t()
                             .append(lnav::roles::number(humanize::file_size(
-                                stdin_size, humanize::alignment::none)))
+                                stdin_size.value(), humanize::alignment::none)))
                             .append(" of data from stdin was captured and "
                                     "will be saved for one day.  You can "
                                     "reopen it by running:\n")

src/piper_proc.cc

@@ -46,6 +46,8 @@
 #include "config.h"
 #include "line_buffer.hh"
 
+using namespace std::chrono_literals;
+
 static const char* STDIN_EOF_MSG = "---- END-OF-STDIN ----";
 
 static ssize_t
@@ -109,9 +111,18 @@ piper_proc::piper_proc(auto_fd pipefd, bool timestamp, auto_fd filefd)
             log_perror(fcntl(pipefd.get(), F_SETFL, O_NONBLOCK));
             lb.set_fd(pipefd);
             do {
+                static const auto TIMEOUT
+                    = std::chrono::duration_cast<std::chrono::milliseconds>(1s)
+                          .count();
                 struct pollfd pfd = {lb.get_fd(), POLLIN, 0};
 
-                poll(&pfd, 1, -1);
+                auto poll_rc = poll(&pfd, 1, TIMEOUT);
+                if (poll_rc == 0) {
+                    // update the timestamp to keep the file alive from any
+                    // cleanup processes
+                    log_perror(futimes(this->pp_fd.get(), nullptr));
+                    continue;
+                }
                 while (true) {
                     auto load_result = lb.load_next_line(last_range);