diff options
Diffstat (limited to 'src/tail.c')
| -rw-r--r-- | src/tail.c | 58 |
1 files changed, 46 insertions, 12 deletions
diff --git a/src/tail.c b/src/tail.c index 19e658b32..bc1d04a8f 100644 --- a/src/tail.c +++ b/src/tail.c @@ -925,12 +925,10 @@ fremote (int fd, const char *name) # define fremote(fd, name) false #endif -/* FIXME: describe */ - +/* open/fstat F->name and handle changes. */ static void recheck (struct File_spec *f, bool blocking) { - /* open/fstat the file and announce if dev/ino have changed */ struct stat new_stats; bool ok = true; bool is_stdin = (STREQ (f->name, "-")); @@ -1312,7 +1310,7 @@ wd_comparator (const void *e1, const void *e2) return spec1->wd == spec2->wd; } -/* Helper function used by 'tail_forever_inotify'. */ +/* Output (new) data for FSPEC->fd. */ static void check_fspec (struct File_spec *fspec, int wd, int *prev_wd) { @@ -1364,12 +1362,18 @@ static bool tail_forever_inotify (int wd, struct File_spec *f, size_t n_files, double sleep_interval) { +# if TAIL_TEST_SLEEP + /* Delay between open() and inotify_add_watch() + to help trigger different cases. */ + xnanosleep (1000000); +# endif unsigned int max_realloc = 3; /* Map an inotify watch descriptor to the name of the file it's watching. */ Hash_table *wd_to_name; bool found_watchable_file = false; + bool tailed_but_unwatchable = false; bool found_unwatchable_dir = false; bool no_inotify_resources = false; bool writer_is_dead = false; @@ -1438,6 +1442,8 @@ tail_forever_inotify (int wd, struct File_spec *f, size_t n_files, if (f[i].wd < 0) { + if (f[i].fd != -1) /* already tailed. */ + tailed_but_unwatchable = true; if (errno == ENOSPC || errno == ENOMEM) { no_inotify_resources = true; @@ -1459,8 +1465,10 @@ tail_forever_inotify (int wd, struct File_spec *f, size_t n_files, /* Linux kernel 2.6.24 at least has a bug where eventually, ENOSPC is always returned by inotify_add_watch. In any case we should revert to polling when there are no inotify resources. Also a specified directory may not - be currently present or accessible, so revert to polling. */ - if (no_inotify_resources || found_unwatchable_dir) + be currently present or accessible, so revert to polling. Also an already + tailed but unwatchable due rename/unlink race, should also revert. */ + if (no_inotify_resources || found_unwatchable_dir + || (follow_mode == Follow_descriptor && tailed_but_unwatchable)) { hash_free (wd_to_name); @@ -1472,12 +1480,38 @@ tail_forever_inotify (int wd, struct File_spec *f, size_t n_files, prev_wd = f[n_files - 1].wd; - /* Check files again. New data can be available since last time we checked - and before they are watched by inotify. */ + /* Check files again. New files or data can be available since last time we + checked and before they are watched by inotify. */ for (i = 0; i < n_files; i++) { - if (!f[i].ignore) - check_fspec (&f[i], f[i].wd, &prev_wd); + if (! f[i].ignore) + { + /* check for new files. */ + if (follow_mode == Follow_name) + recheck (&(f[i]), false); + else if (f[i].fd != -1) + { + /* If the file was replaced in the small window since we tailed, + then assume the watch is on the wrong item (different to + that we've already produced output for), and so revert to + polling the original descriptor. */ + struct stat stats; + + if (stat (f[i].name, &stats) == 0 + && (f[i].dev != stats.st_dev || f[i].ino != stats.st_ino)) + { + error (0, errno, _("%s was replaced"), + quote (pretty_name (&(f[i])))); + hash_free (wd_to_name); + + errno = 0; + return true; + } + } + + /* check for new data. */ + check_fspec (&f[i], f[i].wd, &prev_wd); + } } evlen += sizeof (struct inotify_event) + 1; @@ -1840,7 +1874,7 @@ tail_file (struct File_spec *f, uintmax_t n_units) { struct stat stats; -#if TEST_RACE_BETWEEN_FINAL_READ_AND_INITIAL_FSTAT +#if TAIL_TEST_SLEEP /* Before the tail function provided 'read_pos', there was a race condition described in the URL below. This sleep call made the window big enough to exercise the problem. */ @@ -2286,7 +2320,7 @@ main (int argc, char **argv) if (fflush (stdout) != 0) error (EXIT_FAILURE, errno, _("write error")); - if (!tail_forever_inotify (wd, F, n_files, sleep_interval)) + if (! tail_forever_inotify (wd, F, n_files, sleep_interval)) return EXIT_FAILURE; } error (0, errno, _("inotify cannot be used, reverting to polling")); |