diff options
| -rw-r--r-- | NEWS | 15 | ||||
| m--------- | gnulib | 0 | ||||
| -rw-r--r-- | src/tail.c | 85 |
3 files changed, 61 insertions, 39 deletions
@@ -8,15 +8,22 @@ GNU coreutils NEWS -*- outline -*- Even then, chcon may still be useful. [bug introduced in coreutils-8.0] - stat -f recognizes more file system types: afs, cifs, anon-inode FS, - btrfs, cgroupfs, cramfs-wend, debugfs, futexfs, hfs, inotifyfs, minux3, - nilfs, securityfs, selinux, xenfs - md5sum now prints checksums atomically so that concurrent processes will not intersperse their output. This also affected sum, sha1sum, sha224sum, sha384sum and sha512sum. [the bug dates back to the initial implementation] + stat -f recognizes more file system types: afs, cifs, anon-inode FS, + btrfs, cgroupfs, cramfs-wend, debugfs, futexfs, hfs, inotifyfs, minux3, + nilfs, securityfs, selinux, xenfs + + tail -f (inotify-enabled) now avoids a race condition. + Before, any data appended in the tiny interval between the initial + read-to-EOF and the inotify watch initialization would be ignored + initially (until more data was appended), or forever, if the file + were first renamed or unlinked or never modified. + [The race was introduced in coreutils-7.5] + ** New features md5sum --check now also accepts openssl-style checksums. diff --git a/gnulib b/gnulib -Subproject 447ce7436647899cfe03ee154bb2b2789d3a8ea +Subproject f7f4cd99ff9ce8efee94aafdd5980cb4bb1d139 diff --git a/src/tail.c b/src/tail.c index 97aa8d496..09afeec99 100644 --- a/src/tail.c +++ b/src/tail.c @@ -1168,6 +1168,47 @@ wd_comparator (const void *e1, const void *e2) return spec1->wd == spec2->wd; } +/* Helper function used by `tail_forever_inotify'. */ + +static void +check_fspec (struct File_spec *fspec, int wd, int *prev_wd) +{ + struct stat stats; + char const *name = pretty_name (fspec); + + if (fstat (fspec->fd, &stats) != 0) + { + close_fd (fspec->fd, name); + fspec->fd = -1; + fspec->errnum = errno; + return; + } + + if (S_ISREG (fspec->mode) && stats.st_size < fspec->size) + { + error (0, 0, _("%s: file truncated"), name); + *prev_wd = wd; + xlseek (fspec->fd, stats.st_size, SEEK_SET, name); + fspec->size = stats.st_size; + } + else if (S_ISREG (fspec->mode) && stats.st_size == fspec->size + && timespec_cmp (fspec->mtime, get_stat_mtime (&stats)) == 0) + return; + + if (wd != *prev_wd) + { + if (print_headers) + write_header (name); + *prev_wd = wd; + } + + uintmax_t bytes_read = dump_remainder (name, fspec->fd, COPY_TO_EOF); + fspec->size += bytes_read; + + if (fflush (stdout) != 0) + error (EXIT_FAILURE, errno, _("write error")); +} + /* Tail N_FILES files forever, or until killed. Check modifications using the inotify events system. */ @@ -1249,6 +1290,14 @@ 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. */ + for (i = 0; i < n_files; i++) + { + if (!f[i].ignore) + check_fspec (&f[i], f[i].wd, &prev_wd); + } + evlen += sizeof (struct inotify_event) + 1; evbuf = xmalloc (evlen); @@ -1257,11 +1306,7 @@ tail_forever_inotify (int wd, struct File_spec *f, size_t n_files, This loop sleeps on the `safe_read' call until a new event is notified. */ while (1) { - char const *name; struct File_spec *fspec; - uintmax_t bytes_read; - struct stat stats; - struct inotify_event *ev; /* When watching a PID, ensure that a read from WD will not block @@ -1369,37 +1414,7 @@ tail_forever_inotify (int wd, struct File_spec *f, size_t n_files, continue; } - - name = pretty_name (fspec); - - if (fstat (fspec->fd, &stats) != 0) - { - close_fd (fspec->fd, name); - fspec->fd = -1; - fspec->errnum = errno; - continue; - } - - if (S_ISREG (fspec->mode) && stats.st_size < fspec->size) - { - error (0, 0, _("%s: file truncated"), name); - prev_wd = ev->wd; - xlseek (fspec->fd, stats.st_size, SEEK_SET, name); - fspec->size = stats.st_size; - } - - if (ev->wd != prev_wd) - { - if (print_headers) - write_header (name); - prev_wd = ev->wd; - } - - bytes_read = dump_remainder (name, fspec->fd, COPY_TO_EOF); - fspec->size += bytes_read; - - if (fflush (stdout) != 0) - error (EXIT_FAILURE, errno, _("write error")); + check_fspec (fspec, ev->wd, &prev_wd); } } #endif |