출처 : http://www.pell.portland.or.us/~orc/Code/bsd/bsd-current/tail/tail.c
/* $OpenBSD: tail.c,v 1.4 1997/01/15 23:43:18 millert Exp $ */ /*- * Copyright (c) 1991, 1993 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley by * Edward Sze-Tyan Wang. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #ifndef lint static char copyright[] = "@(#) Copyright (c) 1991, 1993\n\ The Regents of the University of California. All rights reserved.\n"; #endif /* not lint */ #ifndef lint #if 0 static char sccsid[] = "@(#)tail.c 8.1 (Berkeley) 6/6/93"; #endif static char rcsid[] = "$OpenBSD: tail.c,v 1.4 1997/01/15 23:43:18 millert Exp $"; #endif /* not lint */ #include <sys/types.h> #include <sys/stat.h> #include <err.h> #include <errno.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include "extern.h" int fflag, rflag, rval; char *fname; static void obsolete __P((char **)); static void usage __P((void)); char *__progname; int main(argc, argv) int argc; char *argv[]; { struct stat sb; FILE *fp; long off = 0; enum STYLE style; int ch, first; char *p; __progname = basename(argv[0]); /* * Tail's options are weird. First, -n10 is the same as -n-10, not * -n+10. Second, the number options are 1 based and not offsets, * so -n+1 is the first line, and -c-1 is the last byte. Third, the * number options for the -r option specify the number of things that * get displayed, not the starting point in the file. The one major * incompatibility in this version as compared to historical versions * is that the 'r' option couldn't be modified by the -lbc options, * i.e. it was always done in lines. This version treats -rc as a * number of characters in reverse order. Finally, the default for * -r is the entire file, not 10 lines. */ #define ARG(units, forward, backward) { \ if (style) \ usage(); \ off = strtol(optarg, &p, 10) * (units); \ if (*p) \ errx(1, "illegal offset -- %s", optarg); \ switch(optarg[0]) { \ case '+': \ if (off) \ off -= (units); \ style = (forward); \ break; \ case '-': \ off = -off; \ /* FALLTHROUGH */ \ default: \ style = (backward); \ break; \ } \ } obsolete(argv); style = NOTSET; while ((ch = getopt(argc, argv, "b:c:fn:r")) != -1) switch(ch) { case 'b': ARG(512, FBYTES, RBYTES); break; case 'c': ARG(1, FBYTES, RBYTES); break; case 'f': fflag = 1; break; case 'n': ARG(1, FLINES, RLINES); break; case 'r': rflag = 1; break; case '?': default: usage(); } argc -= optind; argv += optind; if (fflag && argc > 1) errx(1, "-f option only appropriate for a single file"); /* * If displaying in reverse, don't permit follow option, and convert * style values. */ if (rflag) { if (fflag) usage(); if (style == FBYTES) style = RBYTES; else if (style == FLINES) style = RLINES; } /* * If style not specified, the default is the whole file for -r, and * the last 10 lines if not -r. */ if (style == NOTSET) if (rflag) { off = 0; style = REVERSE; } else { off = 10; style = RLINES; } if (*argv) for (first = 1; (fname = *argv++);) { if ((fp = fopen(fname, "r")) == NULL || fstat(fileno(fp), &sb)) { ierr(); continue; } if (argc > 1) { (void)printf("%s==> %s <==\n", first ? "" : "\n", fname); first = 0; (void)fflush(stdout); } if (rflag) reverse(fp, style, off, &sb); else forward(fp, style, off, &sb); (void)fclose(fp); } else { fname = "stdin"; if (fstat(fileno(stdin), &sb)) { ierr(); exit(1); } /* * Determine if input is a pipe. 4.4BSD will set the SOCKET * bit in the st_mode field for pipes. Fix this then. */ if (lseek(fileno(stdin), (off_t)0, SEEK_CUR) == -1 && errno == ESPIPE) { errno = 0; fflag = 0; /* POSIX.2 requires this. */ } if (rflag) reverse(stdin, style, off, &sb); else forward(stdin, style, off, &sb); } exit(rval); } /* * Convert the obsolete argument form into something that getopt can handle. * This means that anything of the form [+-][0-9][0-9]*[lbc][fr] that isn't * the option argument for a -b, -c or -n option gets converted. */ static void obsolete(argv) char *argv[]; { register char *ap, *p, *t; int len; char *start; while ((ap = *++argv)) { /* Return if "--" or not an option of any form. */ if (ap[0] != '-') { if (ap[0] != '+') return; } else if (ap[1] == '-') return; switch(*++ap) { /* Old-style option. */ case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': case '8': case '9': /* Malloc space for dash, new option and argument. */ len = strlen(*argv); if ((start = p = malloc(len + 3)) == NULL) err(1, NULL); *p++ = '-'; /* * Go to the end of the option argument. Save off any * trailing options (-3lf) and translate any trailing * output style characters. */ t = *argv + len - 1; if (*t == 'f' || *t == 'r') { *p++ = *t; *t-- = '\0'; } switch(*t) { case 'b': *p++ = 'b'; *t = '\0'; break; case 'c': *p++ = 'c'; *t = '\0'; break; case 'l': *t = '\0'; /* FALLTHROUGH */ case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': case '8': case '9': *p++ = 'n'; break; default: errx(1, "illegal option -- %s", *argv); } *p++ = *argv[0]; (void)strcpy(p, ap); *argv = start; continue; /* * Options w/ arguments, skip the argument and continue * with the next option. */ case 'b': case 'c': case 'n': if (!ap[1]) ++argv; /* FALLTHROUGH */ /* Options w/o arguments, continue with the next option. */ case 'f': case 'r': continue; /* Illegal option, return and let getopt handle it. */ default: return; } } } static void usage() { (void)fprintf(stderr, "usage: tail [-f | -r] [-b # | -c # | -n #] [file ...]\n"); exit(1); }
