X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=coreutils%2Ftail.c;h=39f87679e95db8523ddab7964269cd4786b3ebcc;hb=47cfbf32fd66563f8c4e09ad6cced6abfbe2fad5;hp=2f997a9f6c61e788a72ecf072ccd457fdc3810b9;hpb=69ca5a70fd4ae30f8a3beabec4d705f7dd32e3f3;p=oweals%2Fbusybox.git diff --git a/coreutils/tail.c b/coreutils/tail.c index 2f997a9f6..39f87679e 100644 --- a/coreutils/tail.c +++ b/coreutils/tail.c @@ -4,7 +4,7 @@ * * 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) */ @@ -24,19 +24,39 @@ * 7) lseek attempted when count==0 even if arg was +0 (from top) */ -#include "libbb.h" +//kbuild:lib-$(CONFIG_TAIL) += tail.o + +//usage:#define tail_trivial_usage +//usage: "[OPTIONS] [FILE]..." +//usage:#define tail_full_usage "\n\n" +//usage: "Print last 10 lines of each FILE (or stdin) to stdout.\n" +//usage: "With more than one FILE, precede each with a filename header.\n" +//usage: "\n -f Print data as file grows" +//usage: "\n -c [+]N[kbm] Print last N bytes" +//usage: "\n -n N[kbm] Print last N lines" +//usage: "\n -n +N[kbm] Start on Nth line and print the rest" +//usage: IF_FEATURE_FANCY_TAIL( +//usage: "\n -q Never print headers" +//usage: "\n -s SECONDS Wait SECONDS between reads with -f" +//usage: "\n -v Always print headers" +//usage: "\n -F Same as -f, but keep retrying" +//usage: "\n" +//usage: "\nN may be suffixed by k (x1024), b (x512), or m (x1024^2)." +//usage: ) +//usage: +//usage:#define tail_example_usage +//usage: "$ tail -n 1 /etc/resolv.conf\n" +//usage: "nameserver 10.0.0.1\n" -static const struct suffix_mult tail_suffixes[] = { - { "b", 512 }, - { "k", 1024 }, - { "m", 1024*1024 }, - { } -}; +#include "libbb.h" +#include "common_bufsiz.h" struct globals { - bool status; -}; -#define G (*(struct globals*)&bb_common_bufsiz1) + 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) { @@ -47,26 +67,17 @@ static void tail_xprint_header(const char *fmt, const char *filename) static ssize_t tail_read(int fd, char *buf, size_t count) { ssize_t r; - off_t current; - struct stat sbuf; - - /* (A good comment is missing here) */ - current = lseek(fd, 0, SEEK_CUR); - /* /proc files report zero st_size, don't lseek them. */ - if (fstat(fd, &sbuf) == 0 && sbuf.st_size) - if (sbuf.st_size < current) - lseek(fd, 0, SEEK_SET); r = full_read(fd, buf, count); if (r < 0) { bb_perror_msg(bb_msg_read_error); - G.status = EXIT_FAILURE; + G.exitcode = EXIT_FAILURE; } return r; } -static const char header_fmt[] ALIGN1 = "\n==> %s <==\n"; +#define header_fmt_str "\n==> %s <==\n" static unsigned eat_num(const char *p) { @@ -74,9 +85,9 @@ static unsigned eat_num(const char *p) p++; else if (*p == '+') { p++; - G.status = 1; /* mark that we saw "+" */ + G.from_top = 1; } - return xatou_sfx(p, tail_suffixes); + return xatou_sfx(p, bkm_suffixes); } int tail_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; @@ -84,63 +95,69 @@ 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; char *tailbuf; size_t tailbufsize; - int taillen = 0; - int newlines_seen = 0; - int nfiles, nread, nwrite, seen, i, opt; + unsigned header_threshhold = 1; + unsigned nfiles; + int i, opt; int *fds; - char *s, *buf; const char *fmt; + int prev_fd; + + INIT_G(); #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]); + count = eat_num(argv[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)); + /* -s NUM, -F imlies -f */ + IF_FEATURE_FANCY_TAIL(opt_complementary = "s+: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 - if (opt & 0x8) header_threshhold = INT_MAX; // -q + /* 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 argc -= optind; argv += optind; - from_top = G.status; /* 1 if there was "-c +N" or "-n +N" */ - G.status = EXIT_SUCCESS; /* open all the files */ - fds = xmalloc(sizeof(int) * (argc + 1)); + fds = xmalloc(sizeof(fds[0]) * (argc + 1)); if (!argv[0]) { struct stat statbuf; - if (!fstat(STDIN_FILENO, &statbuf) && S_ISFIFO(statbuf.st_mode)) { + if (fstat(STDIN_FILENO, &statbuf) == 0 + && S_ISFIFO(statbuf.st_mode) + ) { opt &= ~1; /* clear FOLLOW */ } - *argv = (char *) bb_msg_standard_input; + argv[0] = (char *) bb_msg_standard_input; } nfiles = i = 0; do { int fd = open_or_warn_stdin(argv[i]); - if (fd < 0) { - G.status = EXIT_FAILURE; + if (fd < 0 && !FOLLOW_RETRY) { + G.exitcode = EXIT_FAILURE; continue; } fds[nfiles] = fd; @@ -152,52 +169,88 @@ int tail_main(int argc, char **argv) /* prepare the buffer */ tailbufsize = BUFSIZ; - if (!from_top && COUNT_BYTES) { + if (!G.from_top && COUNT_BYTES) { if (tailbufsize < count + BUFSIZ) { tailbufsize = count + BUFSIZ; } } - tailbuf = xmalloc(tailbufsize); + /* tail -c1024m REGULAR_FILE doesn't really need 1G mem block. + * (In fact, it doesn't need ANY memory). So delay allocation. + */ + tailbuf = NULL; /* 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 { + 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; } - /* 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_BYTES && !from_top) { - off_t current = lseek(fds[i], 0, SEEK_END); + if (!G.from_top) { + off_t current = lseek(fd, 0, SEEK_END); if (current > 0) { - if (count == 0) - continue; /* showing zero lines is easy :) */ - current -= count; + 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(fds[i], current, SEEK_SET); - bb_copyfd_size(fds[i], STDOUT_FILENO, count); - continue; + 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; newlines_seen = 0; - while ((nread = tail_read(fds[i], buf, tailbufsize-taillen)) > 0) { - if (from_top) { - nwrite = nread; + while ((nread = tail_read(fd, buf, tailbufsize - taillen)) > 0) { + if (G.from_top) { + int nwrite = nread; if (seen < count) { + /* 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) { @@ -206,11 +259,12 @@ int tail_main(int argc, char **argv) } while (nwrite); } } - xwrite(STDOUT_FILENO, buf + nread - nwrite, nwrite); + if (nwrite > 0) + xwrite(STDOUT_FILENO, buf + nread - nwrite, nwrite); } else if (count) { if (COUNT_BYTES) { taillen += nread; - if (taillen > count) { + if (taillen > (int)count) { memmove(tailbuf, tailbuf + taillen - count, count); taillen = count; } @@ -225,11 +279,12 @@ int tail_main(int argc, char **argv) } } while (k); - if (newlines_seen + newlines_in_buf < count) { + 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; @@ -243,7 +298,7 @@ int tail_main(int argc, char **argv) memmove(tailbuf, s, taillen); newlines_seen = count - extra; } - if (tailbufsize < taillen + BUFSIZ) { + if (tailbufsize < (size_t)taillen + BUFSIZ) { tailbufsize = taillen + BUFSIZ; tailbuf = xrealloc(tailbuf, tailbufsize); } @@ -251,33 +306,80 @@ int tail_main(int argc, char **argv) buf = tailbuf + taillen; } } /* while (tail_read() > 0) */ - if (!from_top) { + if (!G.from_top) { xwrite(STDOUT_FILENO, tailbuf, taillen); } } while (++i < nfiles); + prev_fd = fds[i-1]; - buf = xrealloc(tailbuf, BUFSIZ); + 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; + fmt = header_fmt_str; } - while ((nread = tail_read(fds[i], buf, BUFSIZ)) > 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; } - xwrite(STDOUT_FILENO, buf, nread); + xwrite(STDOUT_FILENO, tailbuf, nread); } } while (++i < nfiles); - } + } /* while (1) */ + if (ENABLE_FEATURE_CLEAN_UP) { free(fds); + free(tailbuf); } - return G.status; + return G.exitcode; }