X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=coreutils%2Ftail.c;h=e352ab627b2e86b9e45c6ae59b1b17e4b0dd6ff1;hb=2a17fbe88a0cc064248db4ce8939f0fbc357922d;hp=eac982735b8b232ec451becf070b8f2a8efa9ea9;hpb=34425389e09353a8dacdd6b23a62553f699c544c;p=oweals%2Fbusybox.git diff --git a/coreutils/tail.c b/coreutils/tail.c index eac982735..e352ab627 100644 --- a/coreutils/tail.c +++ b/coreutils/tail.c @@ -24,25 +24,24 @@ * 7) lseek attempted when count==0 even if arg was +0 (from top) */ +//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: "\nOptions:" //usage: "\n -f Print data as file grows" -//usage: IF_FEATURE_FANCY_TAIL( -//usage: "\n -s SECONDS Wait SECONDS between reads with -f" -//usage: ) +//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 -c N[kbm] Print last N bytes" //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: "\nIf N starts with a '+', output begins with the Nth item from the start" -//usage: "\nof each file, not from the end." //usage: ) //usage: //usage:#define tail_example_usage @@ -51,17 +50,12 @@ #include "libbb.h" -static const struct suffix_mult tail_suffixes[] = { - { "b", 512 }, - { "k", 1024 }, - { "m", 1024*1024 }, - { "", 0 } -}; - struct globals { - bool status; + bool from_top; + bool exitcode; } FIX_ALIASING; #define G (*(struct globals*)&bb_common_bufsiz1) +#define INIT_G() do { } while (0) static void tail_xprint_header(const char *fmt, const char *filename) { @@ -72,20 +66,11 @@ 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; - - /* /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); - G.status = EXIT_FAILURE; + G.exitcode = EXIT_FAILURE; } return r; @@ -99,9 +84,9 @@ 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; @@ -109,7 +94,6 @@ int tail_main(int argc, char **argv) { unsigned count = 10; unsigned sleep_period = 1; - bool from_top; const char *str_c, *str_n; char *tailbuf; @@ -120,6 +104,9 @@ int tail_main(int argc, char **argv) int *fds; 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. */ @@ -152,8 +139,6 @@ int tail_main(int argc, char **argv) #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(fds[0]) * (argc + 1)); @@ -171,7 +156,7 @@ int tail_main(int argc, char **argv) do { int fd = open_or_warn_stdin(argv[i]); if (fd < 0 && !FOLLOW_RETRY) { - G.status = EXIT_FAILURE; + G.exitcode = EXIT_FAILURE; continue; } fds[nfiles] = fd; @@ -183,15 +168,19 @@ 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_str + 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; @@ -202,14 +191,14 @@ int tail_main(int argc, char **argv) int fd = fds[i]; if (ENABLE_FEATURE_FANCY_TAIL && fd < 0) - continue; /* may happen with -E */ + continue; /* may happen with -F */ if (nfiles > header_threshhold) { tail_xprint_header(fmt, argv[i]); fmt = header_fmt_str; } - if (!from_top) { + if (!G.from_top) { off_t current = lseek(fd, 0, SEEK_END); if (current > 0) { unsigned off; @@ -242,20 +231,23 @@ int tail_main(int argc, char **argv) } } + 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(fd, buf, tailbufsize-taillen)) > 0) { - if (from_top) { + 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 { char *s = buf; do { @@ -313,10 +305,11 @@ 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]; tailbuf = xrealloc(tailbuf, BUFSIZ); @@ -360,18 +353,32 @@ int tail_main(int argc, char **argv) if (nfiles > header_threshhold) { fmt = header_fmt_str; } - while ((nread = tail_read(fd, tailbuf, BUFSIZ)) > 0) { - if (fmt) { + 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, tailbuf, nread); } } while (++i < nfiles); - } + } /* while (1) */ + if (ENABLE_FEATURE_CLEAN_UP) { free(fds); free(tailbuf); } - return G.status; + return G.exitcode; }