X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;ds=sidebyside;f=coreutils%2Ftail.c;h=df881a37a19263c94b59800a6a856e7c5766672f;hb=982aa263a0cef10ee4f4c06084a87af736c449ac;hp=52bacb7ed10e44fd4d2e6f01b169dc626d7c4461;hpb=06af2165288cd6516b89001ec9e24992619230e0;p=oweals%2Fbusybox.git diff --git a/coreutils/tail.c b/coreutils/tail.c index 52bacb7ed..df881a37a 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) */ @@ -24,16 +24,19 @@ * 7) lseek attempted when count==0 even if arg was +0 (from top) */ -#include "busybox.h" +#include "libbb.h" static const struct suffix_mult tail_suffixes[] = { { "b", 512 }, { "k", 1024 }, { "m", 1024*1024 }, - { NULL, 0 } + { "", 0 } }; -static int status; +struct globals { + bool status; +} FIX_ALIASING; +#define G (*(struct globals*)&bb_common_bufsiz1) static void tail_xprint_header(const char *fmt, const char *filename) { @@ -44,149 +47,192 @@ 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, end; + off_t current; 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); - r = safe_read(fd, buf, count); + /* /proc files report zero st_size, don't lseek them. */ + if (fstat(fd, &sbuf) == 0 && sbuf.st_size > 0) { + current = lseek(fd, 0, SEEK_CUR); + if (sbuf.st_size < current) + xlseek(fd, 0, SEEK_SET); + } + + r = full_read(fd, buf, count); if (r < 0) { bb_perror_msg(bb_msg_read_error); - status = EXIT_FAILURE; + G.status = EXIT_FAILURE; } return r; } -static const char header_fmt[] = "\n==> %s <==\n"; +#define header_fmt_str "\n==> %s <==\n" -static unsigned eat_num(const char *p) { - if (*p == '-') p++; - else if (*p == '+') { p++; status = 1; } +static unsigned eat_num(const char *p) +{ + if (*p == '-') + p++; + else if (*p == '+') { + p++; + G.status = 1; /* mark that we saw "+" */ + } return xatou_sfx(p, tail_suffixes); } -int tail_main(int argc, char **argv); +int tail_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; 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; + const char *str_c, *str_n; char *tailbuf; size_t tailbufsize; - int taillen = 0; - int newline = 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; #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] == '-') + if (argv[1] && (argv[1][0] == '+' || argv[1][0] == '-') && isdigit(argv[1][1]) ) { - argv[0] = (char*)"-n"; - argv--; - argc++; + count = eat_num(argv[1]); + argv++; + argc--; } #endif - opt = getopt32(argc, argv, "fc:n:" USE_FEATURE_FANCY_TAIL("qs:v"), &str_c, &str_n, &str_s); + /* -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 - if (opt & 0x10) sleep_period = xatou(str_s); // -s + /* 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 = status; + 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)); - status = nfiles = i = 0; - if (argc == 0) { + 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; - goto DO_STDIN; + argv[0] = (char *) bb_msg_standard_input; } - + nfiles = i = 0; 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; + int fd = open_or_warn_stdin(argv[i]); + if (fd < 0 && !FOLLOW_RETRY) { + G.status = EXIT_FAILURE; + continue; } - argv[nfiles] = argv[i]; - ++nfiles; + fds[nfiles] = fd; + argv[nfiles++] = argv[i]; } while (++i < argc); if (!nfiles) bb_error_msg_and_die("no files"); + /* prepare the buffer */ tailbufsize = BUFSIZ; - - /* tail the files */ if (!from_top && COUNT_BYTES) { - if (tailbufsize < count) { + if (tailbufsize < count + BUFSIZ) { tailbufsize = count + BUFSIZ; } } + tailbuf = xmalloc(tailbufsize); - buf = tailbuf = xmalloc(tailbufsize); - - fmt = header_fmt + 1; /* Skip header leading newline on first output. */ + /* tail the files */ + fmt = header_fmt_str + 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; - } + 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 -E */ if (nfiles > header_threshhold) { tail_xprint_header(fmt, argv[i]); - fmt = header_fmt; + fmt = header_fmt_str; + } + + if (!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 + } } 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) { + newlines_seen = 0; + while ((nread = tail_read(fd, buf, tailbufsize-taillen)) > 0) { if (from_top) { - nwrite = nread; + int nwrite = nread; if (seen < count) { + /* We need to skip a few more bytes/lines */ if (COUNT_BYTES) { nwrite -= (count - seen); seen = count; } else { - s = buf; + char *s = buf; do { --nwrite; if (*s++ == '\n' && ++seen == count) { @@ -195,84 +241,112 @@ 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; } } 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 (!from_top) { xwrite(STDOUT_FILENO, tailbuf, taillen); } - - taillen = 0; } while (++i < nfiles); - 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, sizeof(buf))) > 0) { + while ((nread = tail_read(fd, tailbuf, BUFSIZ)) > 0) { if (fmt) { - tail_xprint_header(fmt, argv[i]); + tail_xprint_header(fmt, filename); fmt = NULL; } - xwrite(STDOUT_FILENO, buf, nread); + xwrite(STDOUT_FILENO, tailbuf, nread); } } while (++i < nfiles); } - - return status; + if (ENABLE_FEATURE_CLEAN_UP) { + free(fds); + free(tailbuf); + } + return G.status; }