char *s, *buf;
const char *fmt;
#if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_TAIL
/* Allow legacy syntax of an initial numeric option without -n. */
if (argv[1] && (argv[1][0] == '+' || argv[1][0] == '-')
&& isdigit(argv[1][1])
) {
count = eat_num(&argv[1][1]);
argv++;
argc--;
}
#endif
USE_FEATURE_FANCY_TAIL(opt_complementary = "s+";) /* -s N */
opt = getopt32(argv, "fc:n:" USE_FEATURE_FANCY_TAIL("qs:v"),
&str_c, &str_n USE_FEATURE_FANCY_TAIL(,&sleep_period));
#define FOLLOW (opt & 0x1)
#define COUNT_BYTES (opt & 0x2)
//if (opt & 0x1) // -f
if (opt & 0x2) count = eat_num(str_c); // -c
if (opt & 0x4) count = eat_num(str_n); // -n
#if ENABLE_FEATURE_FANCY_TAIL
if (opt & 0x8) header_threshhold = INT_MAX; // -q
if (opt & 0x20) header_threshhold = 0; // -v
#endif
argc -= optind;
argv += optind;
from_top = G.status; /* 1 if there was "-c +N" or "-n +N" */
G.status = EXIT_SUCCESS;
int tail_main(int argc, char **argv)
{
unsigned count = 10;
unsigned sleep_period = 1;
bool from_top;
int header_threshhold = 1;
const char *str_c, *str_n, *str_s;
char *tailbuf;
size_t tailbufsize;
int taillen = 0;
int newline = 0;
int nfiles, nread, nwrite, seen, i, opt;
int *fds;
char *s, *buf;
const char *fmt;
#if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_TAIL
/* Allow legacy syntax of an initial numeric option without -n. */
if (argc >= 2 && (argv[1][0] == '+' || argv[1][0] == '-')
&& isdigit(argv[1][1])
) {
argv[0] = (char*)"-n";
argv--;
argc++;
}
#endif
opt = getopt32(argc, argv, "fc:n:" USE_FEATURE_FANCY_TAIL("qs:v"), &str_c, &str_n, &str_s);
#define FOLLOW (opt & 0x1)
#define COUNT_BYTES (opt & 0x2)
//if (opt & 0x1) // -f
if (opt & 0x2) count = eat_num(str_c); // -c
if (opt & 0x4) count = eat_num(str_n); // -n
#if ENABLE_FEATURE_FANCY_TAIL
if (opt & 0x8) header_threshhold = INT_MAX; // -q
if (opt & 0x10) sleep_period = xatou(str_s); // -s
if (opt & 0x20) header_threshhold = 0; // -v
#endif
argc -= optind;
argv += optind;
from_top = status;
/* open all the files */
fds = xmalloc(sizeof(int) * (argc + 1));
status = nfiles = i = 0;
if (argc == 0) {
struct stat statbuf;
if (!fstat(STDIN_FILENO, &statbuf) && S_ISFIFO(statbuf.st_mode)) {
opt &= ~1; /* clear FOLLOW */
}
*argv = (char *) bb_msg_standard_input;
goto DO_STDIN;
}
do {
if (NOT_LONE_DASH(argv[i])) {
fds[nfiles] = open(argv[i], O_RDONLY);
if (fds[nfiles] < 0) {
bb_perror_msg("%s", argv[i]);
status = EXIT_FAILURE;
continue;
}
} else {
DO_STDIN: /* "-" */
fds[nfiles] = STDIN_FILENO;
}
argv[nfiles] = argv[i];
++nfiles;
} while (++i < argc);
if (!nfiles)
bb_error_msg_and_die("no files");
tailbufsize = BUFSIZ;
/* tail the files */
if (!from_top && COUNT_BYTES) {
if (tailbufsize < count) {
tailbufsize = count + BUFSIZ;
}
}
buf = tailbuf = xmalloc(tailbufsize);
fmt = header_fmt + 1; /* Skip header leading newline on first output. */
i = 0;
do {
/* Be careful. It would be possible to optimize the count-bytes
* case if the file is seekable. If you do though, remember that
* starting file position may not be the beginning of the file.
* Beware of backing up too far. See example in wc.c.
*/
if (!(count | from_top) && lseek(fds[i], 0, SEEK_END) >= 0) {
continue;
}
if (nfiles > header_threshhold) {
tail_xprint_header(fmt, argv[i]);
fmt = header_fmt;
}
buf = tailbuf;
taillen = 0;
seen = 1;
newline = 0;
while ((nread = tail_read(fds[i], buf, tailbufsize-taillen)) > 0) {
if (from_top) {
nwrite = nread;
if (seen < count) {
if (COUNT_BYTES) {
nwrite -= (count - seen);
seen = count;
} else {
s = buf;
do {
--nwrite;
if (*s++ == '\n' && ++seen == count) {
break;
}
} while (nwrite);
}
}
xwrite(STDOUT_FILENO, buf + nread - nwrite, nwrite);
} else if (count) {
if (COUNT_BYTES) {
taillen += nread;
if (taillen > count) {
memmove(tailbuf, tailbuf + taillen - count, count);
taillen = count;
}
} else {
int k = nread;
int nbuf = 0;
while (k) {
--k;
if (buf[k] == '\n') {
++nbuf;
}
}
if (newline + nbuf < count) {
newline += nbuf;
taillen += nread;
} else {
int extra = 0;
if (buf[nread-1] != '\n') {
extra = 1;
}
k = newline + nbuf + extra - count;
s = tailbuf;
while (k) {
if (*s == '\n') {
--k;
}
++s;
}
taillen += nread - (s - tailbuf);
memmove(tailbuf, s, taillen);
newline = count - extra;
}
if (tailbufsize < taillen + BUFSIZ) {
tailbufsize = taillen + BUFSIZ;
tailbuf = xrealloc(tailbuf, tailbufsize);
}
}
buf = tailbuf + taillen;
}
}
if (!from_top) {
xwrite(STDOUT_FILENO, tailbuf, taillen);
}
taillen = 0;
} while (++i < nfiles);
buf = xrealloc(tailbuf, BUFSIZ);
fmt = NULL;
if (FOLLOW) while (1) {
sleep(sleep_period);
i = 0;
do {
if (nfiles > header_threshhold) {
fmt = header_fmt;
}
while ((nread = tail_read(fds[i], buf, sizeof(buf))) > 0) {
if (fmt) {
tail_xprint_header(fmt, argv[i]);
fmt = NULL;
}
xwrite(STDOUT_FILENO, buf, nread);
}
} while (++i < nfiles);
}
return status;
}
