X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=coreutils%2Ftail.c;h=df881a37a19263c94b59800a6a856e7c5766672f;hb=4c46d854690595bb2c5487aedccebab8de8aafda;hp=340697f888576cc8a551e48c0431d53f577b3a75;hpb=e8419c90f1f3880f96ff335c4ee0bdd7a86ab0c6;p=oweals%2Fbusybox.git diff --git a/coreutils/tail.c b/coreutils/tail.c index 340697f88..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) */ @@ -30,12 +30,12 @@ static const struct suffix_mult tail_suffixes[] = { { "b", 512 }, { "k", 1024 }, { "m", 1024*1024 }, - { } + { "", 0 } }; struct globals { bool status; -}; +} FIX_ALIASING; #define G (*(struct globals*)&bb_common_bufsiz1) static void tail_xprint_header(const char *fmt, const char *filename) @@ -50,12 +50,12 @@ static ssize_t tail_read(int fd, char *buf, size_t count) 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 (fstat(fd, &sbuf) == 0 && sbuf.st_size > 0) { + current = lseek(fd, 0, SEEK_CUR); if (sbuf.st_size < current) - lseek(fd, 0, SEEK_SET); + xlseek(fd, 0, SEEK_SET); + } r = full_read(fd, buf, count); if (r < 0) { @@ -66,7 +66,7 @@ static ssize_t tail_read(int fd, char *buf, size_t count) 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) { @@ -85,46 +85,45 @@ 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; - USE_FEATURE_FANCY_TAIL(const char *str_s;) 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; #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]) ) { - /* replacing arg[0] with "-n" can segfault, so... */ - argv[1] = xasprintf("-n%s", argv[1]); -#if 0 /* If we ever decide to make tail NOFORK */ - char *s = alloca(strlen(argv[1]) + 3); - sprintf(s, "-n%s", argv[1]); - argv[1] = s; -#endif + count = eat_num(argv[1]); + argv++; + argc--; } #endif - opt = getopt32(argv, "fc:n:" USE_FEATURE_FANCY_TAIL("qs:v"), - &str_c, &str_n USE_FEATURE_FANCY_TAIL(,&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; @@ -132,23 +131,25 @@ int tail_main(int argc, char **argv) G.status = EXIT_SUCCESS; /* open all the files */ - fds = xmalloc(sizeof(int) * (argc + 1)); - 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; + argv[0] = (char *) bb_msg_standard_input; } + nfiles = i = 0; do { - FILE* fil = fopen_or_warn_stdin(argv[i]); - if (!fil) { + int fd = open_or_warn_stdin(argv[i]); + if (fd < 0 && !FOLLOW_RETRY) { G.status = EXIT_FAILURE; continue; } - fds[nfiles] = fileno(fil); + fds[nfiles] = fd; argv[nfiles++] = argv[i]; } while (++i < argc); @@ -165,48 +166,73 @@ int tail_main(int argc, char **argv) tailbuf = xmalloc(tailbufsize); /* tail the files */ - fmt = header_fmt + 1; /* Skip header leading newline on first output. */ + fmt = header_fmt_str + 1; /* skip header leading newline on first output */ i = 0; do { - off_t current; + 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; } - /* 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) */ - current = lseek(fds[i], 0, SEEK_END); - if (current > 0) { - if (!from_top) { - if (count == 0) - continue; /* showing zero lines is easy :) */ + 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(fds[i], current, SEEK_SET); - bb_copyfd_size(fds[i], STDOUT_FILENO, count); + 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; newlines_seen = 0; - while ((nread = tail_read(fds[i], buf, tailbufsize-taillen)) > 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) { @@ -215,11 +241,12 @@ 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; } @@ -234,11 +261,12 @@ 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; @@ -252,7 +280,7 @@ 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); } @@ -265,28 +293,60 @@ int tail_main(int argc, char **argv) } } 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, BUFSIZ)) > 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); } if (ENABLE_FEATURE_CLEAN_UP) { free(fds); + free(tailbuf); } return G.status; }