sfeed

commit 426fa33dd276fbe662b3794c41db1ab6d59b3c2a
parent 19a4c010f95ad17e02ca59e9949524e801ad22f2
Author: Hiltjo Posthuma <[email protected]>
Date:   Tue,  7 Mar 2023 21:04:36  0100

sfeed_curses: fix (very hard to trigger) memleak when getline() returns EOF for lazyloaded items

Fix the code pattern of freeing the line when getline returns -1 but no error
flag is set on the stream (such as EOF).

Note that on errors (even ENOMEM: out-of-memory) an error flag is set on the
stream and the process would exit and clean up all it's resources.

This would be very hard to trigger. The following conditions would have to be
true:

* Lazyloading of items is enabled: SFEED_LAZYLOAD=1 is set.
* Items of the feed are read and their offsets stored.
* The line is read/lazy-loaded again by it's offset but returns EOF (not a read
  error) this time.
  This could maybe happen if the feed file was changed and made smaller while
  sfeed_curses is running and the remembered offset is now beyond the file.

  Note that the sfeed_curses(1) man page describes a workaround for a similar
  condition by sending SIGHUP if the sfeed(5) data was changed to reload the feed
  file.

References:
* https://man.openbsd.org/getline
  "It is the responsibility of the caller to free(3) *lineptr when it is no
  longer needed. Even when it fails, getdelim() may update *lineptr."
* https://pubs.opengroup.org/onlinepubs/9699919799/functions/getline.html

Diffstat:
M
sfeed_curses.c
 | 
1
 

1 file changed, 1 insertion( ), 0 deletions(-)
diff --git a/sfeed_curses.c b/sfeed_curses.c
@@ -1791,6  1791,7 @@ item_row_get(struct pane *p, off_t pos)
 		if ((linelen = getline(&line, &linesize, f->fp)) <= 0) {
 			if (ferror(f->fp))
 				die("getline: %s", f->path);
 			free(line);
 			return NULL;
 		}