[line_buffer] refactor left a bug with non-blocking files

Fixes #662

src/line_buffer.cc

@@ -495,15 +495,6 @@ Result<line_info, string> line_buffer::load_next_line(file_range prev_line)
 
     auto offset = prev_line.next_offset();
     retval.li_file_range.fr_offset = offset;
-    if (this->lb_last_line_offset != -1 && offset >
-        this->lb_last_line_offset) {
-        /*
-         * Don't return anything past the last known line.  The caller needs
-         * to try reading at the offset of the last line again.
-         */
-        return Ok(retval);
-    }
-
     while (!done) {
         char *line_start, *lf;
 
@@ -544,11 +535,11 @@ Result<line_info, string> line_buffer::load_next_line(file_range prev_line)
             ((request_size > retval.li_file_range.fr_size) &&
              (retval.li_file_range.fr_size > 0) &&
              (!this->is_pipe() || request_size > DEFAULT_INCREMENT))) {
-            if ((lf != NULL) &&
+            if ((lf != nullptr) &&
                 ((size_t) (lf - line_start) >= MAX_LINE_BUFFER_SIZE - 1)) {
-                lf = NULL;
+                lf = nullptr;
             }
-            if (lf != NULL) {
+            if (lf != nullptr) {
                 retval.li_partial = false;
                 retval.li_file_range.fr_size = lf - line_start;
                 // delim
@@ -595,6 +586,9 @@ Result<line_info, string> line_buffer::load_next_line(file_range prev_line)
             done = true;
         }
         else {
+            if (!this->is_pipe() || !this->is_pipe_closed()) {
+                retval.li_partial = true;
+            }
             request_size += DEFAULT_INCREMENT;
         }
 

test/test_line_buffer2.cc

@@ -37,6 +37,8 @@
 #include "auto_fd.hh"
 #include "line_buffer.hh"
 
+using namespace std;
+
 static const char *TEST_DATA =
     "Hello, World!\n"
     "Goodbye, World!\n";
@@ -90,5 +92,66 @@ int main(int argc, char *argv[])
         assert(result.isErr());
     }
 
+    {
+        static string first = "Hello";
+        static string second = ", World!";
+        static string third = "Goodbye, World!";
+        static string last = "\n";
+
+        line_buffer lb;
+        auto_fd pi[2];
+        off_t off = 0;
+
+        assert(auto_fd::pipe(pi) == 0);
+        log_perror(write(pi[1], first.c_str(), first.size()));
+        fcntl(pi[0], F_SETFL, O_NONBLOCK);
+
+        lb.set_fd(pi[0]);
+        auto load_result = lb.load_next_line({off});
+        auto li = load_result.unwrap();
+        assert(li.li_partial);
+        assert(li.li_file_range.fr_size == 5);
+        log_perror(write(pi[1], second.c_str(), second.size()));
+        auto load_result2 = lb.load_next_line({off});
+        li = load_result2.unwrap();
+        assert(li.li_partial);
+        assert(li.li_file_range.fr_size == 13);
+        log_perror(write(pi[1], last.c_str(), last.size()));
+        auto load_result3 = lb.load_next_line({off});
+        li = load_result3.unwrap();
+        assert(!li.li_partial);
+        assert(li.li_file_range.fr_size == 14);
+        auto load_result4 = lb.load_next_line(li.li_file_range);
+        li = load_result4.unwrap();
+        auto last_range = li.li_file_range;
+        assert(li.li_partial);
+        assert(li.li_file_range.empty());
+        log_perror(write(pi[1], third.c_str(), third.size()));
+        auto load_result5 = lb.load_next_line(last_range);
+        li = load_result5.unwrap();
+        assert(li.li_partial);
+        assert(li.li_file_range.fr_size == 15);
+        log_perror(write(pi[1], last.c_str(), last.size()));
+        auto load_result6 = lb.load_next_line(last_range);
+        li = load_result6.unwrap();
+        assert(!li.li_partial);
+        assert(li.li_file_range.fr_size == 16);
+
+        auto load_result7 = lb.load_next_line(li.li_file_range);
+        li = load_result7.unwrap();
+        assert(li.li_partial);
+        assert(li.li_file_range.empty());
+        assert(!lb.is_pipe_closed());
+
+        pi[1].reset();
+
+        auto load_result8 = lb.load_next_line(li.li_file_range);
+        li = load_result8.unwrap();
+        assert(!li.li_partial);
+        assert(li.li_file_range.empty());
+        assert(lb.is_pipe_closed());
+
+    }
+
     return retval;
 }