D 1.5 90/06/24 18:32:22 trent 5 4 00001/00001/00272
MRs:
COMMENTS:
signal int to void
D 1.4 86/06/05 23:06:42 lepreau 4 3 00011/00011/00262
MRs:
COMMENTS:
lint
D 1.3 86/06/05 22:59:31 lepreau 3 2 00167/00101/00106
MRs:
COMMENTS:
handle stdin via temp file. This code needlessly uses temp file
in case 'tac <file' but who's going to do that? Also should stat the temp
file to determine optimum klsize for write's to it.
D 1.2 86/01/11 00:51:35 lepreau 2 1 00004/00003/00203
MRs:
COMMENTS:
give pike some credit
D 1.1 85/06/09 01:42:35 lepreau 1 0 00206/00000/00000
MRs:
COMMENTS:
date and time created 85/06/09 01:42:35 by lepreau
1.1 #ifndef lint
1.1 static char sccsid[] = "@(#)tac.c 1.5 06/24/90";
1.1 #endif
1.1
1.1 /*
1.1 * tac.c - Print file segments in reverse order
1.1 *
1.1 * Original line-only version by unknown author off the net.
1.3 * Rewritten in 1985 by Jay Lepreau, Univ of Utah, to allocate memory
1.3 * dynamically, handle string bounded segments (suggested by Rob Pike),
1.3 * and handle pipes.
1.1 */
1.1
1.1 #include <sys/types.h>
1.1 #include <sys/stat.h>
1.1 #include <stdio.h>
1.3 #include <signal.h>
1.1
1.1 /*
1.1 * This should be defined for BSD releases later than 4.2 and for Sys V.2,
1.1 * at least. fwrite is faster than putc only if you have a new speedy fwrite.
1.1 */
1.1 #define FAST_FWRITE
1.1
1.1 #ifdef DEBUG /* dbx can't handle registers */
1.1 #include <ctype.h>
1.1 # define register
1.1 #endif
1.1
1.1 /* Default target string and bound */
1.1 int right = 1; /* right or left bounded segments? */
1.1 char *targ = "\n";
1.1
1.3 char *tfile;
1.3 char *buf;
1.3
1.1 int readsize = 4096; /* significantly faster than 1024 */
1.1 int bufsize;
1.1 int targlen;
1.1 int numerr;
1.1
1.3 int cleanup();
1.1 extern off_t lseek();
1.4 extern char *strcpy(), *malloc(), *realloc(), *mktemp();
1.1
1.1 main(argc, argv)
1.1 int argc;
1.1 char **argv;
1.1 {
1.1
1.1 #ifdef DEBUG
1.3 if (argc > 1 && isdigit(*argv[1])) {
1.1 readsize = atoi(argv[1]);
1.1 argc--, argv++;
1.1 }
1.1 #endif
1.1
1.3 if (argc > 1 && (argv[1][0] == '+' || argv[1][0] == '-') && argv[1][1]) {
1.1 targ = &argv[1][1];
1.1 right = (argv[1][0] == '+');
1.1 argc--; argv++;
1.1 }
1.1 targlen = strlen(targ);
1.1
1.1 bufsize = (readsize << 1) + targlen + 2;
1.1 if ((buf = malloc((unsigned) bufsize)) == NULL) {
1.1 perror("tac: initial malloc");
1.1 exit(1);
1.1 }
1.1
1.1 (void) strcpy(buf, targ); /* stop string at beginning */
1.1 buf += targlen;
1.1
1.3 if (argc == 1)
1.3 tacstdin();
1.1 while (--argc) {
1.3 if (strcmp(*++argv, "-") == 0)
1.3 tacstdin();
1.3 else
1.3 tacit(*argv);
1.3 }
1.3 exit(numerr > 0 ? 1 : 0);
1.3 }
1.1
1.3 tacstdin()
1.3 {
1.1
1.5 void (*sigint)(), (*sighup)(), (*sigterm)();
1.3
1.3 if ((sigint = signal(SIGINT, SIG_IGN)) != SIG_IGN)
1.4 (void) signal(SIGINT, cleanup);
1.3 if ((sighup = signal(SIGHUP, SIG_IGN)) != SIG_IGN)
1.4 (void) signal(SIGHUP, cleanup);
1.3 if ((sigterm = signal(SIGTERM, SIG_IGN)) != SIG_IGN)
1.4 (void) signal(SIGTERM, cleanup);
1.3
1.3 savestdin();
1.3 tacit(tfile);
1.4 (void) unlink(tfile);
1.3
1.4 (void) signal(SIGINT, sigint);
1.4 (void) signal(SIGHUP, sighup);
1.4 (void) signal(SIGTERM, sigterm);
1.3 }
1.3
1.3 char template[] = "/tmp/tacXXXXXX";
1.3 char workplate[sizeof template];
1.3
1.3 savestdin()
1.3 {
1.3 int fd;
1.3 register int n;
1.3
1.4 (void) strcpy(workplate, template);
1.3 tfile = mktemp(workplate);
1.3 if ((fd = creat(tfile, 0600)) < 0) {
1.3 prterr(tfile);
1.3 cleanup();
1.3 }
1.3 while ((n = read(0, buf, readsize)) > 0)
1.3 if (write(fd, buf, n) != n) {
1.3 prterr(tfile);
1.3 cleanup();
1.1 }
1.4 (void) close(fd);
1.3 if (n < 0) {
1.3 prterr("stdin read");
1.3 cleanup();
1.3 }
1.3 }
1.1
1.3 tacit(name)
1.3 char *name;
1.3 {
1.3 register char *p, *pastend;
1.3 register int firstchar, targm1len; /* target length minus 1 */
1.3 struct stat st;
1.3 off_t off;
1.3 int fd, i;
1.3
1.3 firstchar = *targ;
1.3 targm1len = targlen - 1;
1.3
1.3 if (stat(name, &st) < 0) {
1.3 prterr(name);
1.3 numerr++;
1.3 return;
1.3 }
1.3 if ((off = st.st_size) == 0)
1.3 return;
1.3 if ((fd = open(name, 0)) < 0) {
1.3 prterr(name);
1.3 numerr++;
1.3 return;
1.3 }
1.3
1.3 /*
1.3 * Arrange for the first read to lop off enough to
1.3 * leave the rest of the file a multiple of readsize.
1.3 * Since readsize can change, this may not always hold during
1.3 * the pgm run, but since it usually will, leave it here
1.3 * for i/o efficiency (page/sector boundaries and all that).
1.3 * Note: the efficiency gain has not been verified.
1.3 */
1.3 if ((i = off % readsize) == 0)
1.3 i = readsize;
1.3 off -= i;
1.3
1.3 (void) lseek(fd, off, 0);
1.3 if (read(fd, buf, i) != i) {
1.3 prterr(name);
1.3 (void) close(fd);
1.3 numerr++;
1.3 return;
1.3 }
1.3 p = pastend = buf + i; /* pastend always points to end+1 */
1.3 p -= targm1len;
1.3
1.3 for (;;) {
1.3 while ( *--p != firstchar ||
1.3 (targm1len && strncmp(p+1, targ+1, targm1len)) )
1.3 continue;
1.3 if (p < buf) { /* backed off front of buffer */
1.3 if (off == 0) {
1.3 /* beginning of file: dump last segment */
1.3 output(p + targlen, pastend);
1.3 (void) close(fd);
1.3 break;
1.3 }
1.3 if ((i = pastend - buf) > readsize) {
1.3 char *tbuf;
1.3 int newbufsize = (readsize << 2) + targlen + 2;
1.3
1.3 if ((tbuf = realloc(buf-targlen, (unsigned) newbufsize)) == NULL) {
1.3 /* If realloc fails, old buf contents may be lost. */
1.3 perror("tac: segment too long; may have garbage here");
1.1 numerr++;
1.3 i = readsize;
1.1 }
1.3 else {
1.3 tbuf += targlen; /* skip over the stop string */
1.3 p += tbuf - buf;
1.3 pastend += tbuf - buf;
1.3 buf = tbuf;
1.3 bufsize = newbufsize;
1.3 readsize = readsize << 1;
1.3 /* guaranteed to fit now (I think!) */
1.3 }
1.1 }
1.3 if (off - readsize < 0) {
1.3 readsize = off;
1.3 off = 0;
1.3 }
1.3 else
1.3 off -= readsize;
1.3 (void) lseek(fd, off, 0); /* back up */
1.3 /* Shift pending old data right to make room for new */
1.3 bcopy(buf, p = buf + readsize, i);
1.3 pastend = p + i;
1.3 if (read(fd, buf, readsize) != readsize) {
1.3 prterr(name);
1.3 numerr++;
1.3 (void) close(fd);
1.3 break;
1.3 }
1.3 continue;
1.1 }
1.3 /* Found a real instance of the target string */
1.3 output(right ? p + targlen : p, pastend);
1.3 pastend = p;
1.3 p -= targm1len;
1.1 }
1.1 }
1.1
1.1 /*
1.1 * Dump chars from p to pastend-1. If right-bounded by target
1.1 * and not the first time through, append the target string.
1.1 */
1.1 output(p, pastend)
1.1 register char *p;
1.1 char *pastend;
1.1 {
1.1 static short first = 1;
1.1
1.1 #ifdef FAST_FWRITE
1.1 (void) fwrite(p, 1, pastend - p, stdout);
1.1 #else
1.1 while (p < pastend)
1.1 (void) putc(*p++, stdout);
1.1 #endif
1.1 if (right && !first)
1.1 (void) fwrite(targ, 1, targlen, stdout);
1.1 first = 0;
1.1 if ferror(stdout) {
1.1 perror("tac: fwrite/putc");
1.1 exit(++numerr > 1 ? numerr : 1);
1.1 }
1.1 }
1.1
1.1 prterr(s)
1.1 char *s;
1.1 {
1.1
1.1 fprintf(stderr, "tac: ");
1.1 perror(s);
1.3 }
1.3
1.3 cleanup()
1.3 {
1.3
1.4 (void) unlink(tfile);
1.3 exit(1);
1.1 }