X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=coreutils%2Ftail.c;h=df881a37a19263c94b59800a6a856e7c5766672f;hb=982aa263a0cef10ee4f4c06084a87af736c449ac;hp=d45b29c4c082cec6453ddfc0b366af1af91d2244;hpb=a164c647acc613fe199a646dc5075c097f51a4a4;p=oweals%2Fbusybox.git

diff --git a/coreutils/tail.c b/coreutils/tail.c
index d45b29c4c..df881a37a 100644
--- a/coreutils/tail.c
+++ b/coreutils/tail.c
@@ -2,252 +2,351 @@
 /*
  * Mini tail implementation for busybox
  *
- *
  * Copyright (C) 2001 by Matt Kraai <kraai@alumni.carnegiemellon.edu>
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
- *
+ * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  */
 
-#include "busybox.h"
+/* 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.
+ * Bugs fixed (although I may have forgotten one or two... it was pretty bad)
+ * 1) mixing printf/write without fflush()ing stdout
+ * 2) no check that any open files are present
+ * 3) optstring had -q taking an arg
+ * 4) no error checking on write in some cases, and a warning even then
+ * 5) q and s interaction bug
+ * 6) no check for lseek error
+ * 7) lseek attempted when count==0 even if arg was +0 (from top)
+ */
 
-#include <fcntl.h>
-#include <getopt.h>
-#include <string.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <sys/types.h>
+#include "libbb.h"
 
 static const struct suffix_mult tail_suffixes[] = {
 	{ "b", 512 },
 	{ "k", 1024 },
-	{ "m", 1048576 },
-	{ NULL, 0 }
+	{ "m", 1024*1024 },
+	{ "", 0 }
 };
 
-#ifndef BB_FEATURE_SIMPLE_TAIL
-static const struct suffix_mult null_suffixes[] = {
-	{ NULL, 0 }
-};
-#endif
-
-static const int BYTES = 0;
-static const int LINES = 1;
+struct globals {
+	bool status;
+} FIX_ALIASING;
+#define G (*(struct globals*)&bb_common_bufsiz1)
 
-static char *tailbuf;
-static int taillen;
-static int newline;
+static void tail_xprint_header(const char *fmt, const char *filename)
+{
+	if (fdprintf(STDOUT_FILENO, fmt, filename) < 0)
+		bb_perror_nomsg_and_die();
+}
 
-void tailbuf_append(char *buf, int len)
+static ssize_t tail_read(int fd, char *buf, size_t count)
 {
-	tailbuf = xrealloc(tailbuf, taillen + len);
-	memcpy(tailbuf + taillen, buf, len);
-	taillen += len;
+	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;
+	}
+
+	return r;
 }
 
-void tailbuf_trunc()
+#define header_fmt_str "\n==> %s <==\n"
+
+static unsigned eat_num(const char *p)
 {
-	char *s;
-	s = memchr(tailbuf, '\n', taillen);
-	memmove(tailbuf, s + 1, taillen - ((s + 1) - tailbuf));
-	taillen -= (s + 1) - tailbuf;
-	newline = 0;
+	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) MAIN_EXTERNALLY_VISIBLE;
 int tail_main(int argc, char **argv)
 {
-	int from_top = 0, units = LINES, count = 10, sleep_period = 1;
-	int show_headers = 0, hide_headers = 0, follow = 0;
-	int *fds, nfiles = 0, status = EXIT_SUCCESS, nread, nwrite, seen = 0;
-	char *s, *start, *end, buf[BUFSIZ];
+	unsigned count = 10;
+	unsigned sleep_period = 1;
+	bool from_top;
+	const char *str_c, *str_n;
+
+	char *tailbuf;
+	size_t tailbufsize;
+	unsigned header_threshhold = 1;
+	unsigned nfiles;
 	int i, opt;
 
-	while ((opt = getopt(argc, argv, "c:fhn:q:s:v")) > 0) {
-		switch (opt) {
-			case 'f':
-				follow = 1;
-				break;
-#ifndef BB_FEATURE_SIMPLE_TAIL
-			case 'c':
-				units = BYTES;
-				/* FALLS THROUGH */
+	int *fds;
+	const char *fmt;
+
+#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]);
+		argv++;
+		argc--;
+	}
 #endif
-			case 'n':
-				count = parse_number(optarg, tail_suffixes);
-				if (count < 0)
-					count = -count;
-				if (optarg[0] == '+')
-					from_top = 1;
-				break;
-#ifndef BB_FEATURE_SIMPLE_TAIL
-			case 'q':
-				hide_headers = 1;
-				break;
-			case 's':
-				sleep_period = parse_number(optarg, null_suffixes);
-				break;
-			case 'v':
-				show_headers = 1;
-				break;
+
+	/* -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
+	/* 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:
-				usage(tail_usage);
+	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));
+	if (!argv[0]) {
+		struct stat statbuf;
+
+		if (fstat(STDIN_FILENO, &statbuf) == 0
+		 && S_ISFIFO(statbuf.st_mode)
+		) {
+			opt &= ~1; /* clear FOLLOW */
 		}
+		argv[0] = (char *) bb_msg_standard_input;
 	}
+	nfiles = i = 0;
+	do {
+		int fd = open_or_warn_stdin(argv[i]);
+		if (fd < 0 && !FOLLOW_RETRY) {
+			G.status = EXIT_FAILURE;
+			continue;
+		}
+		fds[nfiles] = fd;
+		argv[nfiles++] = argv[i];
+	} while (++i < argc);
 
-	/* open all the files */
-	fds = (int *)xmalloc(sizeof(int) * (argc - optind + 1));
-	if (argc == optind) {
-		fds[nfiles++] = STDIN_FILENO;
-		argv[optind] = "standard input";
-	} else {
-		for (i = optind; i < argc; i++) {
-			if (strcmp(argv[i], "-") == 0) {
-				fds[nfiles++] = STDIN_FILENO;
-				argv[i] = "standard input";
-			} else if ((fds[nfiles++] = open(argv[i], O_RDONLY)) < 0) {
-				perror_msg("%s", argv[i]);
-				status = EXIT_FAILURE;
-			}
+	if (!nfiles)
+		bb_error_msg_and_die("no files");
+
+	/* prepare the buffer */
+	tailbufsize = BUFSIZ;
+	if (!from_top && COUNT_BYTES) {
+		if (tailbufsize < count + BUFSIZ) {
+			tailbufsize = count + BUFSIZ;
 		}
 	}
-	
-#ifndef BB_FEATURE_SIMPLE_TAIL
+	tailbuf = xmalloc(tailbufsize);
+
 	/* tail the files */
-	if (!from_top && units == BYTES)
-		tailbuf = xmalloc(count);
+	fmt = header_fmt_str + 1; /* skip header leading newline on 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 -E */
+
+		if (nfiles > header_threshhold) {
+			tail_xprint_header(fmt, argv[i]);
+			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
+			}
+		}
 
-	for (i = 0; i < nfiles; i++) {
-		if (fds[i] == -1)
-			continue;
-		seen = 0;
-		if (show_headers || (!hide_headers && nfiles > 1))
-			printf("%s==> %s <==\n", i == 0 ? "" : "\n", argv[optind + i]);
-		while ((nread = safe_read(fds[i], buf, sizeof(buf))) > 0) {
+		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) {
-#ifndef BB_FEATURE_SIMPLE_TAIL
-				if (units == BYTES) {
-					if (count - 1 <= seen)
-						nwrite = nread;
-					else if (count - 1 <= seen + nread)
-						nwrite = nread + seen - (count - 1);
-					else
-						nwrite = 0;
-					seen += nread;
-				} else {
-#else
-				{
-#endif
-					if (count - 1 <= seen)
-						nwrite = nread;
-					else {
-						nwrite = 0;
-						for (s = memchr(buf, '\n', nread); s != NULL;
-								s = memchr(s+1, '\n', nread - (s + 1 - buf))) {
-							if (count - 1 <= ++seen) {
-								nwrite = nread - (s + 1 - buf);
+				int nwrite = nread;
+				if (seen < count) {
+					/* We need to skip a few more bytes/lines */
+					if (COUNT_BYTES) {
+						nwrite -= (count - seen);
+						seen = count;
+					} else {
+						char *s = buf;
+						do {
+							--nwrite;
+							if (*s++ == '\n' && ++seen == count) {
 								break;
 							}
-						}
+						} while (nwrite);
 					}
 				}
-				if (full_write(STDOUT_FILENO, buf + nread - nwrite,
-							nwrite) < 0) {
-					perror_msg("write");
-					status = EXIT_FAILURE;
-					break;
-				}
-			} else {
-#ifndef BB_FEATURE_SIMPLE_TAIL
-				if (units == BYTES) {
-					if (nread < count) {
-						memmove(tailbuf, tailbuf + nread, count - nread);
-						memcpy(tailbuf + count - nread, buf, nread);
-					} else {
-						memcpy(tailbuf, buf + nread - count, count);
+				if (nwrite > 0)
+					xwrite(STDOUT_FILENO, buf + nread - nwrite, nwrite);
+			} else if (count) {
+				if (COUNT_BYTES) {
+					taillen += nread;
+					if (taillen > (int)count) {
+						memmove(tailbuf, tailbuf + taillen - count, count);
+						taillen = count;
 					}
-					seen += nread;
 				} else {
-#else
-				{
-#endif
-					for (start = buf, end = memchr(buf, '\n', nread);
-							end != NULL; start = end+1,
-							end = memchr(start, '\n', nread - (start - buf))) {
-						if (newline && count <= seen)
-							tailbuf_trunc();
-						tailbuf_append(start, end - start + 1);
-						seen++;
-						newline = 1;
-					}
-					if (newline && count <= seen && nread - (start - buf) > 0)
-						tailbuf_trunc();
-					tailbuf_append(start, nread - (start - buf));
-				}
-			}
-		}
+					int k = nread;
+					int newlines_in_buf = 0;
 
-		if (nread < 0) {
-			perror_msg("read");
-			status = EXIT_FAILURE;
-		}
+					do { /* count '\n' in last read */
+						k--;
+						if (buf[k] == '\n') {
+							newlines_in_buf++;
+						}
+					} while (k);
 
-#ifndef BB_FEATURE_SIMPLE_TAIL
-		if (!from_top && units == BYTES) {
-			if (count < seen)
-				seen = count;
-			if (full_write(STDOUT_FILENO, tailbuf + count - seen, seen) < 0) {
-				perror_msg("write");
-				status = EXIT_FAILURE;
-			}
-		}
-#endif
+					if (newlines_seen + newlines_in_buf < (int)count) {
+						newlines_seen += newlines_in_buf;
+						taillen += nread;
+					} else {
+						int extra = (buf[nread-1] != '\n');
+						char *s;
 
-		if (!from_top && units == LINES) {
-			if (full_write(STDOUT_FILENO, tailbuf, taillen) < 0) {
-				perror_msg("write");
-				status = EXIT_FAILURE;
+						k = newlines_seen + newlines_in_buf + extra - count;
+						s = tailbuf;
+						while (k) {
+							if (*s == '\n') {
+								k--;
+							}
+							s++;
+						}
+						taillen += nread - (s - tailbuf);
+						memmove(tailbuf, s, taillen);
+						newlines_seen = count - extra;
+					}
+					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);
 		}
+	} while (++i < nfiles);
 
-		taillen = 0;
-	}
+	tailbuf = xrealloc(tailbuf, BUFSIZ);
 
-	while (follow) {
+	fmt = NULL;
+
+	if (FOLLOW) while (1) {
 		sleep(sleep_period);
 
-		for (i = 0; i < nfiles; i++) {
-			if (fds[i] == -1)
-				continue;
+		i = 0;
+		do {
+			int nread;
+			const char *filename = argv[i];
+			int fd = fds[i];
 
-			if ((nread = safe_read(fds[i], buf, sizeof(buf))) > 0) {
-				if (show_headers || (!hide_headers && nfiles > 1))
-					printf("\n==> %s <==\n", argv[optind + i]);
+			if (FOLLOW_RETRY) {
+				struct stat sbuf, fsbuf;
 
-				do {
-					full_write(STDOUT_FILENO, buf, nread);
-				} while ((nread = safe_read(fds[i], buf, sizeof(buf))) > 0);
-			}
+				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 (nread < 0) {
-				perror_msg("read");
-				status = EXIT_FAILURE;
+					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_str;
+			}
+			while ((nread = tail_read(fd, tailbuf, BUFSIZ)) > 0) {
+				if (fmt) {
+					tail_xprint_header(fmt, filename);
+					fmt = NULL;
+				}
+				xwrite(STDOUT_FILENO, tailbuf, nread);
+			}
+		} while (++i < nfiles);
 	}
-
-	return status;
+	if (ENABLE_FEATURE_CLEAN_UP) {
+		free(fds);
+		free(tailbuf);
+	}
+	return G.status;
 }