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- #include "libbb.h"
- #include "common_bufsiz.h"
- struct globals {
- bool from_top;
- bool exitcode;
- } FIX_ALIASING;
- #define G (*(struct globals*)bb_common_bufsiz1)
- #define INIT_G() do { setup_common_bufsiz(); } while (0)
- static void tail_xprint_header(const char *fmt, const char *filename)
- {
- if (fdprintf(STDOUT_FILENO, fmt, filename) < 0)
- bb_perror_nomsg_and_die();
- }
- static ssize_t tail_read(int fd, char *buf, size_t count)
- {
- ssize_t r;
- r = full_read(fd, buf, count);
- if (r < 0) {
- bb_perror_msg(bb_msg_read_error);
- G.exitcode = EXIT_FAILURE;
- }
- return r;
- }
- #define header_fmt_str "\n==> %s <==\n"
- static unsigned eat_num(const char *p)
- {
- if (*p == '-')
- p++;
- else if (*p == '+') {
- p++;
- G.from_top = 1;
- }
- return xatou_sfx(p, bkm_suffixes);
- }
- int tail_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
- int tail_main(int argc, char **argv)
- {
- unsigned count = 10;
- unsigned sleep_period = 1;
- const char *str_c, *str_n;
- char *tailbuf;
- size_t tailbufsize;
- unsigned header_threshhold = 1;
- unsigned nfiles;
- int i, opt;
- int *fds;
- const char *fmt;
- int prev_fd;
- INIT_G();
- #if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_TAIL
-
- if (argv[1] && (argv[1][0] == '+' || argv[1][0] == '-')
- && isdigit(argv[1][1])
- ) {
- count = eat_num(argv[1]);
- argv++;
- argc--;
- }
- #endif
-
- opt = getopt32(argv, IF_FEATURE_FANCY_TAIL("^")
- "fc:n:"IF_FEATURE_FANCY_TAIL("qs:+vF")
- IF_FEATURE_FANCY_TAIL("\0" "Ff"),
- &str_c, &str_n IF_FEATURE_FANCY_TAIL(,&sleep_period)
- );
- #define FOLLOW (opt & 0x1)
- #define COUNT_BYTES (opt & 0x2)
-
- if (opt & 0x2) count = eat_num(str_c);
- if (opt & 0x4) count = eat_num(str_n);
- #if ENABLE_FEATURE_FANCY_TAIL
-
- if (opt & 0x8) header_threshhold = UINT_MAX;
-
- if (opt & 0x20) header_threshhold = 0;
- # define FOLLOW_RETRY (opt & 0x40)
- #else
- # define FOLLOW_RETRY 0
- #endif
- argc -= optind;
- argv += optind;
-
- fds = xmalloc(sizeof(fds[0]) * (argc + 1));
- if (!argv[0]) {
- struct stat statbuf;
- if (fstat(STDIN_FILENO, &statbuf) == 0
- && S_ISFIFO(statbuf.st_mode)
- ) {
- opt &= ~1;
- }
- argv[0] = (char *) bb_msg_standard_input;
- }
- nfiles = i = 0;
- do {
- int fd = open_or_warn_stdin(argv[i]);
- if (fd < 0 && !FOLLOW_RETRY) {
- G.exitcode = EXIT_FAILURE;
- continue;
- }
- fds[nfiles] = fd;
- argv[nfiles++] = argv[i];
- } while (++i < argc);
- if (!nfiles)
- bb_error_msg_and_die("no files");
-
- tailbufsize = BUFSIZ;
- if (!G.from_top && COUNT_BYTES) {
- if (tailbufsize < count + BUFSIZ) {
- tailbufsize = count + BUFSIZ;
- }
- }
-
- tailbuf = NULL;
-
- fmt = header_fmt_str + 1;
- i = 0;
- do {
- char *buf;
- int taillen;
- int newlines_seen;
- unsigned seen;
- int nread;
- int fd = fds[i];
- if (ENABLE_FEATURE_FANCY_TAIL && fd < 0)
- continue;
- if (nfiles > header_threshhold) {
- tail_xprint_header(fmt, argv[i]);
- fmt = header_fmt_str;
- }
- if (!G.from_top) {
- off_t current = lseek(fd, 0, SEEK_END);
- if (current > 0) {
- unsigned off;
- if (COUNT_BYTES) {
-
- if (count == 0)
- continue;
- current -= count;
- if (current < 0)
- current = 0;
- xlseek(fd, current, SEEK_SET);
- bb_copyfd_size(fd, STDOUT_FILENO, count);
- continue;
- }
- #if 1
-
- off = (count | 0xf);
- if (off > (INT_MAX / (64*1024)))
- off = (INT_MAX / (64*1024));
- current -= off * (64*1024);
- if (current < 0)
- current = 0;
- xlseek(fd, current, SEEK_SET);
- #endif
- }
- }
- if (!tailbuf)
- tailbuf = xmalloc(tailbufsize);
- buf = tailbuf;
- taillen = 0;
-
- seen = 1;
- newlines_seen = 0;
- while ((nread = tail_read(fd, buf, tailbufsize - taillen)) > 0) {
- if (G.from_top) {
- int nwrite = nread;
- if (seen < count) {
-
- if (COUNT_BYTES) {
- nwrite -= (count - seen);
- seen += nread;
- } else {
- char *s = buf;
- do {
- --nwrite;
- if (*s++ == '\n' && ++seen == count) {
- break;
- }
- } while (nwrite);
- }
- }
- if (nwrite > 0)
- xwrite(STDOUT_FILENO, buf + nread - nwrite, nwrite);
- } else if (count) {
- if (COUNT_BYTES) {
- taillen += nread;
- if (taillen > (int)count) {
- memmove(tailbuf, tailbuf + taillen - count, count);
- taillen = count;
- }
- } else {
- int k = nread;
- int newlines_in_buf = 0;
- do {
- k--;
- if (buf[k] == '\n') {
- newlines_in_buf++;
- }
- } while (k);
- if (newlines_seen + newlines_in_buf < (int)count) {
- newlines_seen += newlines_in_buf;
- taillen += nread;
- } else {
- int extra = (buf[nread-1] != '\n');
- char *s;
- k = newlines_seen + newlines_in_buf + extra - count;
- s = tailbuf;
- while (k) {
- if (*s == '\n') {
- k--;
- }
- s++;
- }
- taillen += nread - (s - tailbuf);
- memmove(tailbuf, s, taillen);
- newlines_seen = count - extra;
- }
- if (tailbufsize < (size_t)taillen + BUFSIZ) {
- tailbufsize = taillen + BUFSIZ;
- tailbuf = xrealloc(tailbuf, tailbufsize);
- }
- }
- buf = tailbuf + taillen;
- }
- }
- if (!G.from_top) {
- xwrite(STDOUT_FILENO, tailbuf, taillen);
- }
- } while (++i < nfiles);
- prev_fd = fds[i-1];
- tailbuf = xrealloc(tailbuf, BUFSIZ);
- fmt = NULL;
- if (FOLLOW) while (1) {
- sleep(sleep_period);
- i = 0;
- do {
- int nread;
- const char *filename = argv[i];
- int fd = fds[i];
- if (FOLLOW_RETRY) {
- struct stat sbuf, fsbuf;
- if (fd < 0
- || fstat(fd, &fsbuf) < 0
- || stat(filename, &sbuf) < 0
- || fsbuf.st_dev != sbuf.st_dev
- || fsbuf.st_ino != sbuf.st_ino
- ) {
- int new_fd;
- if (fd >= 0)
- close(fd);
- new_fd = open(filename, O_RDONLY);
- if (new_fd >= 0) {
- bb_error_msg("%s has %s; following end of new file",
- filename, (fd < 0) ? "appeared" : "been replaced"
- );
- } else if (fd >= 0) {
- bb_perror_msg("%s has become inaccessible", filename);
- }
- fds[i] = fd = new_fd;
- }
- }
- if (ENABLE_FEATURE_FANCY_TAIL && fd < 0)
- continue;
- if (nfiles > header_threshhold) {
- fmt = header_fmt_str;
- }
- for (;;) {
-
- struct stat sbuf;
-
- if (fstat(fd, &sbuf) == 0 && sbuf.st_size > 0) {
- off_t current = lseek(fd, 0, SEEK_CUR);
- if (sbuf.st_size < current)
- xlseek(fd, 0, SEEK_SET);
- }
- nread = tail_read(fd, tailbuf, BUFSIZ);
- if (nread <= 0)
- break;
- if (fmt && (fd != prev_fd)) {
- tail_xprint_header(fmt, filename);
- fmt = NULL;
- prev_fd = fd;
- }
- xwrite(STDOUT_FILENO, tailbuf, nread);
- }
- } while (++i < nfiles);
- }
- if (ENABLE_FEATURE_CLEAN_UP) {
- free(fds);
- free(tailbuf);
- }
- return G.exitcode;
- }
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