#include "argmatch.h"
#include "c-strtod.h"
#include "error.h"
+#include "fcntl-safer.h"
#include "inttostr.h"
#include "posixver.h"
#include "quote.h"
/* Number of items to tail. */
#define DEFAULT_N_LINES 10
-/* A special value for dump_remainder's N_BYTES parameter. */
-#define COPY_TO_EOF OFF_T_MAX
+/* Special values for dump_remainder's N_BYTES parameter. */
+#define COPY_TO_EOF UINTMAX_MAX
+#define COPY_A_BUFFER (UINTMAX_MAX - 1)
/* FIXME: make Follow_name the default? */
#define DEFAULT_FOLLOW_MODE Follow_descriptor
/* File descriptor on which the file is open; -1 if it's not open. */
int fd;
- /* The size of the file the last time we checked. */
+ /* Attributes of the file the last time we checked. */
off_t size;
-
- /* The device and inode of the file the last time we checked. */
+ struct timespec mtime;
dev_t dev;
ino_t ino;
+ mode_t mode;
+
+ /* 1 if O_NONBLOCK is clear, 0 if set, -1 if not known. */
+ int blocking;
/* The specified name initially referred to a directory or some other
type for which tail isn't meaningful. Unlike for a permission problem
/* See description of DEFAULT_MAX_N_... below. */
unsigned int n_unchanged_stats;
- /* See description of DEFAULT_MAX_N_... below. */
- unsigned int n_consecutive_size_changes;
-
/* A file is tailable if it exists, is readable, and is of type
IS_TAILABLE_FILE_TYPE. */
int tailable;
};
/* When tailing a file by name, if there have been this many consecutive
- iterations for which the size has remained the same, then open/fstat
+ iterations for which the file has not changed, then open/fstat
the file to determine if that file name is still associated with the
same device/inode-number pair as before. This option is meaningful only
when following by name. --max-unchanged-stats=N */
static unsigned long max_n_unchanged_stats_between_opens =
DEFAULT_MAX_N_UNCHANGED_STATS_BETWEEN_OPENS;
-/* This variable is used to ensure that a file that is unlinked or moved
- aside, yet always growing will be recognized as having been renamed.
- After detecting this many consecutive size changes for a file, open/fstat
- the file to determine if that file name is still associated with the
- same device/inode-number pair as before. This option is meaningful only
- when following by name. --max-consecutive-size-changes=N */
-#define DEFAULT_MAX_N_CONSECUTIVE_SIZE_CHANGES 200
-static unsigned long max_n_consecutive_size_changes_between_opens =
- DEFAULT_MAX_N_CONSECUTIVE_SIZE_CHANGES;
-
/* The name this program was run with. */
char *program_name;
RETRY_OPTION = CHAR_MAX + 1,
ALLOW_MISSING_OPTION, /* deprecated, FIXME: remove in late 2004 */
MAX_UNCHANGED_STATS_OPTION,
-
- /* FIXME: remove this in 2001, unless someone can show a good
- reason to keep it. */
- MAX_CONSECUTIVE_SIZE_CHANGES_OPTION,
-
PID_OPTION,
PRESUME_INPUT_PIPE_OPTION,
LONG_FOLLOW_OPTION
{"follow", optional_argument, NULL, LONG_FOLLOW_OPTION},
{"lines", required_argument, NULL, 'n'},
{"max-unchanged-stats", required_argument, NULL, MAX_UNCHANGED_STATS_OPTION},
- {"max-consecutive-size-changes", required_argument, NULL,
- MAX_CONSECUTIVE_SIZE_CHANGES_OPTION},
{"pid", required_argument, NULL, PID_OPTION},
{"presume-input-pipe", no_argument, NULL,
PRESUME_INPUT_PIPE_OPTION}, /* do not document */
error (EXIT_FAILURE, errno, _("write error"));
}
+/* Record a file F with descriptor FD, size SIZE, status ST, and
+ blocking status BLOCKING. */
+
+static void
+record_open_fd (struct File_spec *f, int fd,
+ off_t size, struct stat const *st,
+ int blocking)
+{
+ f->fd = fd;
+ f->size = size;
+ f->mtime.tv_sec = st->st_mtime;
+ f->mtime.tv_nsec = TIMESPEC_NS (st->st_mtim);
+ f->dev = st->st_dev;
+ f->ino = st->st_ino;
+ f->mode = st->st_mode;
+ f->blocking = blocking;
+ f->n_unchanged_stats = 0;
+ f->ignore = 0;
+}
+
+/* Close the file with descriptor FD and name FILENAME. */
+
static void
close_fd (int fd, const char *filename)
{
/* Read and output N_BYTES of file PRETTY_FILENAME starting at the current
position in FD. If N_BYTES is COPY_TO_EOF, then copy until end of file.
+ If N_BYTES is COPY_A_BUFFER, then copy at most one buffer's worth.
Return the number of bytes read from the file. */
static uintmax_t
size_t n = MIN (n_remaining, BUFSIZ);
size_t bytes_read = safe_read (fd, buffer, n);
if (bytes_read == SAFE_READ_ERROR)
- error (EXIT_FAILURE, errno, _("error reading %s"),
- quote (pretty_filename));
+ {
+ if (errno != EAGAIN)
+ error (EXIT_FAILURE, errno, _("error reading %s"),
+ quote (pretty_filename));
+ break;
+ }
if (bytes_read == 0)
break;
xwrite (STDOUT_FILENO, buffer, bytes_read);
- n_remaining -= bytes_read;
n_written += bytes_read;
+ if (n_bytes != COPY_TO_EOF)
+ {
+ n_remaining -= bytes_read;
+ if (n_remaining == 0 || n_bytes == COPY_A_BUFFER)
+ break;
+ }
}
return n_written;
/* FIXME: describe */
static void
-recheck (struct File_spec *f)
+recheck (struct File_spec *f, bool blocking)
{
/* open/fstat the file and announce if dev/ino have changed */
struct stat new_stats;
- int fd;
int fail = 0;
int is_stdin = (STREQ (f->name, "-"));
int was_tailable = f->tailable;
int prev_errnum = f->errnum;
int new_file;
+ int fd = (is_stdin
+ ? STDIN_FILENO
+ : open_safer (f->name, O_RDONLY | (blocking ? 0 : O_NONBLOCK)));
assert (valid_file_spec (f));
- fd = (is_stdin ? STDIN_FILENO : open (f->name, O_RDONLY));
-
/* If the open fails because the file doesn't exist,
then mark the file as not tailable. */
f->tailable = !(reopen_inaccessible_files && fd == -1);
if (new_file)
{
- /* Record new file info in f. */
- f->fd = fd;
- f->size = 0; /* Start at the beginning of the file... */
- f->dev = new_stats.st_dev;
- f->ino = new_stats.st_ino;
- f->n_unchanged_stats = 0;
- f->n_consecutive_size_changes = 0;
- f->ignore = 0;
- xlseek (f->fd, f->size, SEEK_SET, pretty_name (f));
+ /* Start at the beginning of the file. */
+ record_open_fd (f, fd, 0, &new_stats, (is_stdin ? -1 : blocking));
+ xlseek (fd, 0, SEEK_SET, pretty_name (f));
}
}
-/* FIXME: describe */
+/* Return true if any of the N_FILES files in F are live, i.e., have
+ open file descriptors. */
-static unsigned int
-n_live_files (const struct File_spec *f, int n_files)
+static bool
+any_live_files (const struct File_spec *f, int n_files)
{
int i;
- unsigned int n_live = 0;
for (i = 0; i < n_files; i++)
- {
- if (f[i].fd >= 0)
- ++n_live;
- }
- return n_live;
+ if (0 <= f[i].fd)
+ return true;
+ return false;
}
/* Tail NFILES files forever, or until killed.
static void
tail_forever (struct File_spec *f, int nfiles, double sleep_interval)
{
+ /* Use blocking I/O as an optimization, when it's easy. */
+ bool blocking = (pid == 0 && follow_mode == Follow_descriptor
+ && nfiles == 1 && ! S_ISREG (f[0].mode));
int last;
int writer_is_dead = 0;
while (1)
{
int i;
- int any_changed;
+ bool any_input = false;
- any_changed = 0;
for (i = 0; i < nfiles; i++)
{
+ int fd;
+ char const *name;
+ mode_t mode;
struct stat stats;
+ uintmax_t bytes_read;
if (f[i].ignore)
continue;
if (f[i].fd < 0)
{
- recheck (&f[i]);
+ recheck (&f[i], blocking);
continue;
}
- if (fstat (f[i].fd, &stats) < 0)
+ fd = f[i].fd;
+ name = pretty_name (&f[i]);
+ mode = f[i].mode;
+
+ if (f[i].blocking != blocking)
{
- f[i].fd = -1;
- f[i].errnum = errno;
- error (0, errno, "%s", pretty_name (&f[i]));
- continue;
+ int old_flags = fcntl (fd, F_GETFL);
+ int new_flags = old_flags | (blocking ? 0 : O_NONBLOCK);
+ if (old_flags < 0
+ || (new_flags != old_flags
+ && fcntl (fd, F_SETFL, new_flags) == -1))
+ error (EXIT_FAILURE, errno,
+ _("%s: cannot change nonblocking mode"), name);
+ f[i].blocking = blocking;
}
- if (stats.st_size == f[i].size)
+ if (!blocking)
{
- f[i].n_consecutive_size_changes = 0;
- if ((max_n_unchanged_stats_between_opens
- <= f[i].n_unchanged_stats++)
- && follow_mode == Follow_name)
+ if (fstat (fd, &stats) != 0)
{
- recheck (&f[i]);
- f[i].n_unchanged_stats = 0;
+ f[i].fd = -1;
+ f[i].errnum = errno;
+ error (0, errno, "%s", name);
+ continue;
}
- continue;
- }
- /* Ensure that a file that's unlinked or moved aside, yet always
- growing will be recognized as having been renamed. */
- if ((max_n_consecutive_size_changes_between_opens
- <= f[i].n_consecutive_size_changes++)
- && follow_mode == Follow_name)
- {
- f[i].n_consecutive_size_changes = 0;
- recheck (&f[i]);
- continue;
- }
+ if ((! S_ISREG (stats.st_mode) || f[i].size == stats.st_size)
+ && f[i].mtime.tv_sec == stats.st_mtime
+ && f[i].mtime.tv_nsec == TIMESPEC_NS (stats.st_mtim)
+ && f[i].mode == stats.st_mode)
+ {
+ if ((max_n_unchanged_stats_between_opens
+ <= f[i].n_unchanged_stats++)
+ && follow_mode == Follow_name)
+ {
+ recheck (&f[i], blocking);
+ f[i].n_unchanged_stats = 0;
+ }
+ continue;
+ }
- /* This file has changed size. Print out what we can, and
- then keep looping. */
+ /* This file has changed. Print out what we can, and
+ then keep looping. */
- any_changed = 1;
+ f[i].mtime.tv_sec = stats.st_mtime;
+ f[i].mtime.tv_nsec = TIMESPEC_NS (stats.st_mtim);
+ f[i].mode = stats.st_mode;
- /* reset counter */
- f[i].n_unchanged_stats = 0;
+ /* reset counter */
+ f[i].n_unchanged_stats = 0;
- if (stats.st_size < f[i].size)
- {
- error (0, 0, _("%s: file truncated"), pretty_name (&f[i]));
- last = i;
- xlseek (f[i].fd, (off_t) stats.st_size, SEEK_SET,
- pretty_name (&f[i]));
- f[i].size = stats.st_size;
- continue;
- }
+ if (S_ISREG (mode) && stats.st_size < f[i].size)
+ {
+ error (0, 0, _("%s: file truncated"), name);
+ last = i;
+ xlseek (fd, stats.st_size, SEEK_SET, name);
+ f[i].size = stats.st_size;
+ continue;
+ }
- if (i != last)
- {
- if (print_headers)
- write_header (pretty_name (&f[i]));
- last = i;
+ if (i != last)
+ {
+ if (print_headers)
+ write_header (name);
+ last = i;
+ }
}
- f[i].size += dump_remainder (pretty_name (&f[i]), f[i].fd,
- COPY_TO_EOF);
+
+ bytes_read = dump_remainder (name, fd,
+ blocking ? COPY_A_BUFFER : COPY_TO_EOF);
+ any_input |= (bytes_read != 0);
+ f[i].size += bytes_read;
}
- if (n_live_files (f, nfiles) == 0 && ! reopen_inaccessible_files)
+ if (! any_live_files (f, nfiles) && ! reopen_inaccessible_files)
{
error (0, 0, _("no files remaining"));
break;
}
- /* If none of the files changed size, sleep. */
- if (!any_changed)
+ if ((!any_input | blocking) && fflush (stdout) != 0)
+ error (EXIT_FAILURE, errno, _("write error"));
+
+ /* If nothing was read, sleep and/or check for dead writers. */
+ if (!any_input)
{
if (writer_is_dead)
break;
which lseek (... SEEK_END) works. */
if ( ! presume_input_pipe
&& S_ISREG (stats.st_mode)
- && (start_pos = lseek (fd, (off_t) 0, SEEK_CUR)) != -1
- && start_pos < (end_pos = lseek (fd, (off_t) 0, SEEK_END)))
+ && (start_pos = lseek (fd, 0, SEEK_CUR)) != -1
+ && start_pos < (end_pos = lseek (fd, 0, SEEK_END)))
{
*read_pos = end_pos;
if (end_pos != 0 && file_lines (pretty_filename, fd, n_lines,
}
else
{
- fd = open (f->name, O_RDONLY);
+ fd = open_safer (f->name, O_RDONLY);
}
f->tailable = !(reopen_inaccessible_files && fd == -1);
}
else
{
- f->fd = fd;
-
/* Note: we must use read_pos here, not stats.st_size,
to avoid a race condition described by Ken Raeburn:
http://mail.gnu.org/archive/html/bug-textutils/2003-05/msg00007.html */
- f->size = read_pos;
- f->dev = stats.st_dev;
- f->ino = stats.st_ino;
- f->n_unchanged_stats = 0;
- f->n_consecutive_size_changes = 0;
- f->ignore = 0;
+ record_open_fd (f, fd, read_pos, &stats, (is_stdin ? -1 : 1));
}
}
else
}
break;
- case MAX_CONSECUTIVE_SIZE_CHANGES_OPTION:
- /* --max-consecutive-size-changes=N */
- if (xstrtoul (optarg, NULL, 10,
- &max_n_consecutive_size_changes_between_opens, "")
- != LONGINT_OK)
- {
- error (EXIT_FAILURE, 0,
- _("%s: invalid maximum number of consecutive size changes"),
- optarg);
- }
- break;
-
case PID_OPTION:
{
strtol_error s_err;
exit_status |= tail_file (&F[i], n_units);
if (forever)
- {
- /* This fflush appears to be required only on Solaris 5.7. */
- if (fflush (stdout) < 0)
- error (EXIT_FAILURE, errno, _("write error"));
-
- SETVBUF (stdout, NULL, _IONBF, 0);
- tail_forever (F, n_files, sleep_interval);
- }
+ tail_forever (F, n_files, sleep_interval);
if (have_read_stdin && close (STDIN_FILENO) < 0)
error (EXIT_FAILURE, errno, "-");
projects / platform / upstream / coreutils.git / commitdiff