tail: -50 text bytes
This commit is contained in:
Denis Vlasenko
parent
f4c52b32db
commit
e31f721e14
130
coreutils/tail.c
130
coreutils/tail.c
@ -29,32 +29,17 @@
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static const struct suffix_mult tail_suffixes[] = {
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{ "b", 512 },
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{ "k", 1024 },
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{ "m", 1048576 },
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{ "m", 1024*1024 },
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{ NULL, 0 }
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};
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static int status;
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static void tail_xbb_full_write(const char *buf, size_t len)
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{
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/* If we get a write error, there is really no sense in continuing. */
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if (full_write(STDOUT_FILENO, buf, len) < 0)
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bb_perror_nomsg_and_die();
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}
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static void tail_xprint_header(const char *fmt, const char *filename)
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{
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#if defined __GLIBC__
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if (dprintf(STDOUT_FILENO, fmt, filename) < 0) {
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if (fdprintf(STDOUT_FILENO, fmt, filename) < 0)
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bb_perror_nomsg_and_die();
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}
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#else
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int hdr_len = strlen(fmt) + strlen(filename);
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char *hdr = xzalloc(hdr_len);
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sprintf(hdr, filename, filename);
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tail_xbb_full_write(hdr, hdr_len);
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#endif
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}
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static ssize_t tail_read(int fd, char *buf, size_t count)
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{
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@ -66,7 +51,8 @@ static ssize_t tail_read(int fd, char *buf, size_t count)
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if (!fstat(fd, &sbuf))
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end = sbuf.st_size;
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lseek(fd, end < current ? 0 : current, SEEK_SET);
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if ((r = safe_read(fd, buf, count)) < 0) {
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r = safe_read(fd, buf, count);
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if (r < 0) {
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bb_perror_msg(bb_msg_read_error);
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status = EXIT_FAILURE;
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}
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@ -74,82 +60,55 @@ static ssize_t tail_read(int fd, char *buf, size_t count)
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return r;
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}
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static const char tail_opts[] =
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"fn:c:"
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#if ENABLE_FEATURE_FANCY_TAIL
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"qs:v"
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#endif
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;
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static const char header_fmt[] = "\n==> %s <==\n";
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int tail_main(int argc, char **argv)
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{
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long count = 10;
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unsigned count = 10;
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unsigned sleep_period = 1;
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int from_top = 0;
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int follow = 0;
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int header_threshhold = 1;
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int count_bytes = 0;
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const char *str_c, *str_n, *str_s;
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char *tailbuf;
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size_t tailbufsize;
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int taillen = 0;
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int newline = 0;
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int nfiles, nread, nwrite, seen, i, opt;
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int *fds, nfiles, nread, nwrite, seen, i, opt;
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int *fds;
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char *s, *buf;
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const char *fmt;
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void eat_num(const char *p) {
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if (*p == '-') p++;
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else if (*p == '+') { p++; from_top = 1; }
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count = xatou_sfx(p, tail_suffixes);
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}
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#if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_TAIL
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/* Allow legacy syntax of an initial numeric option without -n. */
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if (argc >= 2 && (argv[1][0] == '+' || argv[1][0] == '-')
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&& isdigit(argv[1][1])
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) {
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optind = 2;
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optarg = argv[1];
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goto GET_COUNT;
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argv[0] = "-n";
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argv--;
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argc++;
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}
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#endif
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while ((opt = getopt(argc, argv, tail_opts)) > 0) {
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switch (opt) {
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case 'f':
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follow = 1;
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break;
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case 'c':
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count_bytes = 1;
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/* FALLS THROUGH */
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case 'n':
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#if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_TAIL
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GET_COUNT:
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#endif
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from_top = 0;
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if (*optarg == '+') {
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++optarg;
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from_top = 1;
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}
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count = xatol_sfx(optarg, tail_suffixes);
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/* Note: Leading whitespace is an error trapped above. */
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if (count < 0) {
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count = -count;
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}
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break;
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opt = getopt32(argc, argv, "fc:n:" USE_FEATURE_FANCY_TAIL("qs:v"), &str_c, &str_n, &str_s);
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#define FOLLOW (opt & 0x1)
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#define COUNT_BYTES (opt & 0x2)
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//if (opt & 0x1) // -f
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if (opt & 0x2) eat_num(str_c); // -c
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if (opt & 0x4) eat_num(str_n); // -n
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#if ENABLE_FEATURE_FANCY_TAIL
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case 'q':
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header_threshhold = INT_MAX;
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break;
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case 's':
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sleep_period = xatou(optarg);
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break;
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case 'v':
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header_threshhold = 0;
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break;
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if (opt & 0x8) header_threshhold = INT_MAX; // -q
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if (opt & 0x10) sleep_period = xatou(str_s); // -s
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if (opt & 0x20) header_threshhold = 0; // -v
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#endif
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default:
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bb_show_usage();
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}
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}
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argc -= optind;
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argv += optind;
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@ -160,34 +119,35 @@ int tail_main(int argc, char **argv)
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struct stat statbuf;
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if (!fstat(STDIN_FILENO, &statbuf) && S_ISFIFO(statbuf.st_mode)) {
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follow = 0;
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opt &= ~1; /* clear FOLLOW */
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}
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*argv = (char *) bb_msg_standard_input;
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goto DO_STDIN;
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}
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do {
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if (LONE_DASH(argv[i])) {
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DO_STDIN:
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fds[nfiles] = STDIN_FILENO;
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} else if ((fds[nfiles] = open(argv[i], O_RDONLY)) < 0) {
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if (NOT_LONE_DASH(argv[i])) {
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fds[nfiles] = open(argv[i], O_RDONLY);
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if (fds[nfiles] < 0) {
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bb_perror_msg("%s", argv[i]);
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status = EXIT_FAILURE;
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continue;
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}
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} else {
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DO_STDIN: /* "-" */
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fds[nfiles] = STDIN_FILENO;
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}
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argv[nfiles] = argv[i];
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++nfiles;
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} while (++i < argc);
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if (!nfiles) {
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if (!nfiles)
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bb_error_msg_and_die("no files");
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}
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tailbufsize = BUFSIZ;
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/* tail the files */
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if (from_top < count_bytes) { /* Each is 0 or 1, so true iff 0 < 1. */
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/* Hence, !from_top && count_bytes */
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if (!from_top && COUNT_BYTES) {
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if (tailbufsize < count) {
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tailbufsize = count + BUFSIZ;
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}
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@ -203,7 +163,7 @@ int tail_main(int argc, char **argv)
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* starting file position may not be the beginning of the file.
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* Beware of backing up too far. See example in wc.c.
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*/
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if ((!(count|from_top)) && (lseek(fds[i], 0, SEEK_END) >= 0)) {
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if (!(count|from_top) && lseek(fds[i], 0, SEEK_END) >= 0) {
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continue;
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}
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@ -221,22 +181,22 @@ int tail_main(int argc, char **argv)
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if (from_top) {
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nwrite = nread;
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if (seen < count) {
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if (count_bytes) {
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if (COUNT_BYTES) {
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nwrite -= (count - seen);
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seen = count;
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} else {
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s = buf;
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do {
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--nwrite;
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if ((*s++ == '\n') && (++seen == count)) {
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if (*s++ == '\n' && ++seen == count) {
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break;
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}
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} while (nwrite);
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}
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}
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tail_xbb_full_write(buf + nread - nwrite, nwrite);
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xwrite(STDOUT_FILENO, buf + nread - nwrite, nwrite);
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} else if (count) {
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if (count_bytes) {
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if (COUNT_BYTES) {
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taillen += nread;
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if (taillen > count) {
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memmove(tailbuf, tailbuf + taillen - count, count);
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@ -286,7 +246,7 @@ int tail_main(int argc, char **argv)
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}
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if (!from_top) {
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tail_xbb_full_write(tailbuf, taillen);
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xwrite(STDOUT_FILENO, tailbuf, taillen);
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}
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taillen = 0;
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@ -296,7 +256,7 @@ int tail_main(int argc, char **argv)
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fmt = NULL;
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while (follow) {
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if (FOLLOW) while (1) {
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sleep(sleep_period);
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i = 0;
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do {
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@ -308,7 +268,7 @@ int tail_main(int argc, char **argv)
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tail_xprint_header(fmt, argv[i]);
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fmt = NULL;
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}
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tail_xbb_full_write(buf, nread);
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xwrite(STDOUT_FILENO, buf, nread);
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}
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} while (++i < nfiles);
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}
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