X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=coreutils%2Ftail.c;h=e7a24a7a8be276d17c83b0812151242d681a3b54;hb=f560422fa079b07a761a572ca4f9cf287c2cc47e;hp=48abc4b847c7460b278fc5b0ae89a34c2a6f9118;hpb=f8fd4db92f5626ef0065f5838fad42ad0fd0b362;p=oweals%2Fbusybox.git diff --git a/coreutils/tail.c b/coreutils/tail.c index 48abc4b84..e7a24a7a8 100644 --- a/coreutils/tail.c +++ b/coreutils/tail.c @@ -4,13 +4,8 @@ * * Copyright (C) 2001 by Matt Kraai * - * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. + * Licensed under GPLv2 or later, see file LICENSE in this source tree. */ - -/* BB_AUDIT SUSv3 compliant (need fancy for -c) */ -/* BB_AUDIT GNU compatible -c, -q, and -v options in 'fancy' configuration. */ -/* http://www.opengroup.org/onlinepubs/007904975/utilities/tail.html */ - /* Mar 16, 2003 Manuel Novoa III (mjn3@codepoet.org) * * Pretty much rewritten to fix numerous bugs and reduce realloc() calls. @@ -23,301 +18,387 @@ * 6) no check for lseek error * 7) lseek attempted when count==0 even if arg was +0 (from top) */ +//config:config TAIL +//config: bool "tail" +//config: default y +//config: help +//config: tail is used to print the last specified number of lines +//config: from files. +//config: +//config:config FEATURE_FANCY_TAIL +//config: bool "Enable -q, -s, -v, and -F options" +//config: default y +//config: depends on TAIL +//config: help +//config: These options are provided by GNU tail, but +//config: are not specific in the SUSv3 standard: +//config: -q Never output headers giving file names +//config: -s SEC Wait SEC seconds between reads with -f +//config: -v Always output headers giving file names +//config: -F Same as -f, but keep retrying + +//applet:IF_TAIL(APPLET(tail, BB_DIR_USR_BIN, BB_SUID_DROP)) + +//kbuild:lib-$(CONFIG_TAIL) += tail.o -#include -#include -#include -#include -#include -#include -#include -#include "busybox.h" - -static const struct suffix_mult tail_suffixes[] = { - { "b", 512 }, - { "k", 1024 }, - { "m", 1048576 }, - { NULL, 0 } -}; +/* BB_AUDIT SUSv3 compliant (need fancy for -c) */ +/* BB_AUDIT GNU compatible -c, -q, and -v options in 'fancy' configuration. */ +/* http://www.opengroup.org/onlinepubs/007904975/utilities/tail.html */ -static int status; +//usage:#define tail_trivial_usage +//usage: "[OPTIONS] [FILE]..." +//usage:#define tail_full_usage "\n\n" +//usage: "Print last 10 lines of each FILE (or stdin) to stdout.\n" +//usage: "With more than one FILE, precede each with a filename header.\n" +//usage: "\n -f Print data as file grows" +//usage: "\n -c [+]N[kbm] Print last N bytes" +//usage: "\n -n N[kbm] Print last N lines" +//usage: "\n -n +N[kbm] Start on Nth line and print the rest" +//usage: IF_FEATURE_FANCY_TAIL( +//usage: "\n -q Never print headers" +//usage: "\n -s SECONDS Wait SECONDS between reads with -f" +//usage: "\n -v Always print headers" +//usage: "\n -F Same as -f, but keep retrying" +//usage: "\n" +//usage: "\nN may be suffixed by k (x1024), b (x512), or m (x1024^2)." +//usage: ) +//usage: +//usage:#define tail_example_usage +//usage: "$ tail -n 1 /etc/resolv.conf\n" +//usage: "nameserver 10.0.0.1\n" + +#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 we get an output error, there is really no sense in continuing. */ - if (dprintf(STDOUT_FILENO, fmt, filename) < 0) { + if (fdprintf(STDOUT_FILENO, fmt, filename) < 0) bb_perror_nomsg_and_die(); - } -} - -/* len should probably be size_t */ -static void tail_xbb_full_write(const char *buf, size_t len) -{ - /* If we get a write error, there is really no sense in continuing. */ - if (bb_full_write(STDOUT_FILENO, buf, len) < 0) { - bb_perror_nomsg_and_die(); - } } static ssize_t tail_read(int fd, char *buf, size_t count) { ssize_t r; - off_t current,end; - struct stat sbuf; - - end = current = lseek(fd, 0, SEEK_CUR); - if (!fstat(fd, &sbuf)) - end = sbuf.st_size; - lseek(fd, end < current ? 0 : current, SEEK_SET); - if ((r = safe_read(fd, buf, count)) < 0) { - bb_perror_msg("read"); - status = EXIT_FAILURE; + + r = full_read(fd, buf, count); + if (r < 0) { + bb_perror_msg(bb_msg_read_error); + G.exitcode = EXIT_FAILURE; } return r; } -static const char tail_opts[] = - "fn:c:" -#if ENABLE_FEATURE_FANCY_TAIL - "qs:v" -#endif - ; +#define header_fmt_str "\n==> %s <==\n" -static const char header_fmt[] = "\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) { - long count = 10; - unsigned int sleep_period = 1; - int from_top = 0; - int follow = 0; - int header_threshhold = 1; - int count_bytes = 0; + unsigned count = 10; + unsigned sleep_period = 1; + const char *str_c, *str_n; char *tailbuf; size_t tailbufsize; - int taillen = 0; - int newline = 0; + unsigned header_threshhold = 1; + unsigned nfiles; + int i, opt; - int *fds, nfiles, nread, nwrite, seen, i, opt; - char *s, *buf; + int *fds; const char *fmt; + int prev_fd; -#if !ENABLE_DEBUG_YANK_SUSv2 || ENABLE_FEATURE_FANCY_TAIL + INIT_G(); + +#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]) */ - && (((unsigned int)(argv[1][1] - '0')) <= 9)))) - { - optind = 2; - optarg = argv[1]; - goto GET_COUNT; + if (argv[1] && (argv[1][0] == '+' || argv[1][0] == '-') + && isdigit(argv[1][1]) + ) { + count = eat_num(argv[1]); + argv++; + argc--; } #endif - while ((opt = getopt(argc, argv, tail_opts)) > 0) { - switch (opt) { - case 'f': - follow = 1; - break; - case 'c': - count_bytes = 1; - /* FALLS THROUGH */ - case 'n': -#if !ENABLE_DEBUG_YANK_SUSv2 || ENABLE_FEATURE_FANCY_TAIL - GET_COUNT: -#endif - count = bb_xgetlarg10_sfx(optarg, tail_suffixes); - /* Note: Leading whitespace is an error trapped above. */ - if (*optarg == '+') { - from_top = 1; - } else { - from_top = 0; - } - if (count < 0) { - count = -count; - } - break; + /* -s NUM, -F imlies -f */ + IF_FEATURE_FANCY_TAIL(opt_complementary = "Ff";) + opt = getopt32(argv, "fc:n:" IF_FEATURE_FANCY_TAIL("qs:+vF"), + &str_c, &str_n IF_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 - case 'q': - header_threshhold = INT_MAX; - break; - case 's': - sleep_period =bb_xgetularg10_bnd(optarg, 0, UINT_MAX); - break; - case 'v': - header_threshhold = 0; - break; + /* q: make it impossible for nfiles to be > header_threshhold */ + if (opt & 0x8) header_threshhold = UINT_MAX; // -q + //if (opt & 0x10) // -s + if (opt & 0x20) header_threshhold = 0; // -v +# define FOLLOW_RETRY (opt & 0x40) +#else +# define FOLLOW_RETRY 0 #endif - default: - bb_show_usage(); - } - } - - /* open all the files */ - fds = (int *)xmalloc(sizeof(int) * (argc - optind + 1)); - + argc -= optind; argv += optind; - nfiles = i = 0; - if ((argc -= optind) == 0) { + /* open all the files */ + fds = xmalloc(sizeof(fds[0]) * (argc + 1)); + if (!argv[0]) { struct stat statbuf; - if (!fstat(STDIN_FILENO, &statbuf) && S_ISFIFO(statbuf.st_mode)) { - follow = 0; + if (fstat(STDIN_FILENO, &statbuf) == 0 + && S_ISFIFO(statbuf.st_mode) + ) { + opt &= ~1; /* clear FOLLOW */ } - /* --argv; */ - *argv = (char *) bb_msg_standard_input; - goto DO_STDIN; + argv[0] = (char *) bb_msg_standard_input; } - + nfiles = i = 0; do { - if ((argv[i][0] == '-') && !argv[i][1]) { - DO_STDIN: - fds[nfiles] = STDIN_FILENO; - } else if ((fds[nfiles] = open(argv[i], O_RDONLY)) < 0) { - bb_perror_msg("%s", argv[i]); - status = EXIT_FAILURE; + int fd = open_or_warn_stdin(argv[i]); + if (fd < 0 && !FOLLOW_RETRY) { + G.exitcode = EXIT_FAILURE; continue; } - argv[nfiles] = argv[i]; - ++nfiles; + fds[nfiles] = fd; + argv[nfiles++] = argv[i]; } while (++i < argc); - if (!nfiles) { + if (!nfiles) bb_error_msg_and_die("no files"); - } + /* prepare the buffer */ tailbufsize = BUFSIZ; - - /* tail the files */ - if (from_top < count_bytes) { /* Each is 0 or 1, so true iff 0 < 1. */ - /* Hence, !from_top && count_bytes */ - if (tailbufsize < count) { + if (!G.from_top && COUNT_BYTES) { + if (tailbufsize < count + BUFSIZ) { tailbufsize = count + BUFSIZ; } } + /* tail -c1024m REGULAR_FILE doesn't really need 1G mem block. + * (In fact, it doesn't need ANY memory). So delay allocation. + */ + tailbuf = NULL; - buf = tailbuf = xmalloc(tailbufsize); + /* tail the files */ - fmt = header_fmt + 1; /* Skip header leading newline on first output. */ + fmt = header_fmt_str + 1; /* skip leading newline in the header on the 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; - } + char *buf; + int taillen; + int newlines_seen; + unsigned seen; + int nread; + int fd = fds[i]; + + if (ENABLE_FEATURE_FANCY_TAIL && fd < 0) + continue; /* may happen with -F */ if (nfiles > header_threshhold) { tail_xprint_header(fmt, argv[i]); - fmt = header_fmt; + fmt = header_fmt_str; + } + + if (!G.from_top) { + off_t current = lseek(fd, 0, SEEK_END); + if (current > 0) { + unsigned off; + if (COUNT_BYTES) { + /* Optimizing count-bytes case if the file is seekable. + * Beware of backing up too far. + * Also we exclude files with size 0 (because of /proc/xxx) */ + if (count == 0) + continue; /* showing zero bytes is easy :) */ + current -= count; + if (current < 0) + current = 0; + xlseek(fd, current, SEEK_SET); + bb_copyfd_size(fd, STDOUT_FILENO, count); + continue; + } +#if 1 /* This is technically incorrect for *LONG* strings, but very useful */ + /* Optimizing count-lines case if the file is seekable. + * We assume the lines are <64k. + * (Users complain that tail takes too long + * on multi-gigabyte files) */ + off = (count | 0xf); /* for small counts, be more paranoid */ + 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; + /* "We saw 1st line/byte". + * Used only by +N code ("start from Nth", 1-based): */ seen = 1; - newline = 0; - - while ((nread = tail_read(fds[i], buf, tailbufsize-taillen)) > 0) { - if (from_top) { - nwrite = nread; + 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) { + /* We need to skip a few more bytes/lines */ + if (COUNT_BYTES) { nwrite -= (count - seen); - seen = count; + seen += nread; } else { - s = buf; + char *s = buf; do { --nwrite; - if ((*s++ == '\n') && (++seen == count)) { + if (*s++ == '\n' && ++seen == count) { break; } } while (nwrite); } } - tail_xbb_full_write(buf + nread - nwrite, nwrite); + if (nwrite > 0) + xwrite(STDOUT_FILENO, buf + nread - nwrite, nwrite); } else if (count) { - if (count_bytes) { + if (COUNT_BYTES) { taillen += nread; - if (taillen > count) { + if (taillen > (int)count) { memmove(tailbuf, tailbuf + taillen - count, count); taillen = count; } } else { int k = nread; - int nbuf = 0; + int newlines_in_buf = 0; - while (k) { - --k; + do { /* count '\n' in last read */ + k--; if (buf[k] == '\n') { - ++nbuf; + newlines_in_buf++; } - } + } while (k); - if (newline + nbuf < count) { - newline += nbuf; + if (newlines_seen + newlines_in_buf < (int)count) { + newlines_seen += newlines_in_buf; taillen += nread; - } else { - int extra = 0; - if (buf[nread-1] != '\n') { - extra = 1; - } + int extra = (buf[nread-1] != '\n'); + char *s; - k = newline + nbuf + extra - count; + k = newlines_seen + newlines_in_buf + extra - count; s = tailbuf; while (k) { if (*s == '\n') { - --k; + k--; } - ++s; + s++; } - taillen += nread - (s - tailbuf); memmove(tailbuf, s, taillen); - newline = count - extra; + newlines_seen = count - extra; } - if (tailbufsize < taillen + BUFSIZ) { + if (tailbufsize < (size_t)taillen + BUFSIZ) { tailbufsize = taillen + BUFSIZ; tailbuf = xrealloc(tailbuf, tailbufsize); } } buf = tailbuf + taillen; } + } /* while (tail_read() > 0) */ + if (!G.from_top) { + xwrite(STDOUT_FILENO, tailbuf, taillen); } - - if (!from_top) { - tail_xbb_full_write(tailbuf, taillen); - } - - taillen = 0; } while (++i < nfiles); + prev_fd = fds[i-1]; - buf = xrealloc(tailbuf, BUFSIZ); + tailbuf = xrealloc(tailbuf, BUFSIZ); fmt = NULL; - while (follow) { + 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; + fmt = header_fmt_str; } - while ((nread = tail_read(fds[i], buf, sizeof(buf))) > 0) { - if (fmt) { - tail_xprint_header(fmt, argv[i]); + for (;;) { + /* tail -f keeps following files even if they are truncated */ + struct stat sbuf; + /* /proc files report zero st_size, don't lseek them */ + 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; } - tail_xbb_full_write(buf, nread); + xwrite(STDOUT_FILENO, tailbuf, nread); } } while (++i < nfiles); - } + } /* while (1) */ - return status; + if (ENABLE_FEATURE_CLEAN_UP) { + free(fds); + free(tailbuf); + } + return G.exitcode; }