colcrt: make seek to \n more robust

Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/text-utils/colcrt.c b/text-utils/colcrt.c
index 798f5bd7b8d9d1fba19c342533cc1dda568ae273..113e3d0b69a705dff9af7c9e4a0c65bb7cf4827b 100644 (file)
--- a/text-utils/colcrt.c
+++ b/text-utils/colcrt.c
@@ -151,7 +151,7 @@ static int rubchars(struct colcrt_control *ctl, int col, int n)
 static void colcrt(struct colcrt_control *ctl)
 {
        int col;
-       wint_t c;
+       wint_t c = 0;
        long old_pos;
 
        ctl->print_nl = 1;
@@ -163,16 +163,18 @@ static void colcrt(struct colcrt_control *ctl)
                        output_lines(ctl, col);
                        errno = 0;
                        old_pos = ftell(ctl->f);
-                       while ((c = getwc(ctl->f)) != L'\n') {
-                               long new_pos = ftell(ctl->f);
-                               if (old_pos == new_pos)
-                                       fseek(ctl->f, 1, SEEK_CUR);
-                               else
-                                       old_pos = new_pos;
-                               if (errno == 0 && c == WEOF)
+
+                       while (getwc(ctl->f) != L'\n') {
+                               long new_pos;
+
+                               if (ferror(ctl->f) || feof(ctl->f))
                                        return;
-                               else
-                                       errno = 0;
+                               new_pos = ftell(ctl->f);
+                               if (old_pos == new_pos) {
+                                       if (fseek(ctl->f, 1, SEEK_CUR) < 1)
+                                               return;
+                               } else
+                                       old_pos = new_pos;
                        }
                        col = -1;
                        continue;