diff options
Diffstat (limited to 'util/sbase/tail.c')
| -rw-r--r-- | util/sbase/tail.c | 229 |
1 files changed, 229 insertions, 0 deletions
diff --git a/util/sbase/tail.c b/util/sbase/tail.c new file mode 100644 index 00000000..bbc5ad58 --- /dev/null +++ b/util/sbase/tail.c @@ -0,0 +1,229 @@ +/* See LICENSE file for copyright and license details. */ +#include <sys/stat.h> + +#include <fcntl.h> +#include <unistd.h> +#include <stdint.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <unistd.h> + +#include "utf.h" +#include "util.h" + +static char mode = 'n'; + +static int +dropinit(int fd, const char *fname, size_t count) +{ + Rune r; + char buf[BUFSIZ], *p; + ssize_t n; + int nr; + + if (count < 2) + goto copy; + count--; /* numbering starts at 1 */ + while (count && (n = read(fd, buf, sizeof(buf))) > 0) { + switch (mode) { + case 'n': /* lines */ + for (p = buf; count && n > 0; p++, n--) { + if (*p == '\n') + count--; + } + break; + case 'c': /* bytes */ + if (count > n) { + count -= n; + } else { + p = buf + count; + n -= count; + count = 0; + } + break; + case 'm': /* runes */ + for (p = buf; count && n > 0; p += nr, n -= nr, count--) { + nr = charntorune(&r, p, n); + if (!nr) { + /* we don't have a full rune, move + * remaining data to beginning and read + * again */ + memmove(buf, p, n); + break; + } + } + break; + } + } + if (count) { + if (n < 0) + weprintf("read %s:", fname); + if (n <= 0) + return n; + } + + /* write the rest of the buffer */ + if (writeall(1, p, n) < 0) + eprintf("write:"); +copy: + switch (concat(fd, fname, 1, "<stdout>")) { + case -1: /* read error */ + return -1; + case -2: /* write error */ + exit(1); + default: + return 0; + } +} + +static int +taketail(int fd, const char *fname, size_t count) +{ + static char *buf = NULL; + static size_t size = 0; + char *p; + size_t len = 0, left; + ssize_t n; + + if (!count) + return 0; + for (;;) { + if (len + BUFSIZ > size) { + /* make sure we have at least BUFSIZ to read */ + size += 2 * BUFSIZ; + buf = erealloc(buf, size); + } + n = read(fd, buf + len, size - len); + if (n < 0) { + weprintf("read %s:", fname); + return -1; + } + if (n == 0) + break; + len += n; + switch (mode) { + case 'n': /* lines */ + /* ignore the last character; if it is a newline, it + * ends the last line */ + for (p = buf + len - 2, left = count; p >= buf; p--) { + if (*p != '\n') + continue; + left--; + if (!left) { + p++; + break; + } + } + break; + case 'c': /* bytes */ + p = count < len ? buf + len - count : buf; + break; + case 'm': /* runes */ + for (p = buf + len - 1, left = count; p >= buf; p--) { + /* skip utf-8 continuation bytes */ + if (UTF8_POINT(*p)) + continue; + left--; + if (!left) + break; + } + break; + } + if (p > buf) { + len -= p - buf; + memmove(buf, p, len); + } + } + if (writeall(1, buf, len) < 0) + eprintf("write:"); + return 0; +} + +static void +usage(void) +{ + eprintf("usage: %s [-f] [-c num | -m num | -n num | -num] [file ...]\n", argv0); +} + +int +main(int argc, char *argv[]) +{ + struct stat st1, st2; + int fd; + size_t n = 10; + int fflag = 0, ret = 0, newline = 0, many = 0; + char *numstr; + int (*tail)(int, const char *, size_t) = taketail; + + ARGBEGIN { + case 'f': + fflag = 1; + break; + case 'c': + case 'm': + case 'n': + mode = ARGC(); + numstr = EARGF(usage()); + n = MIN(llabs(estrtonum(numstr, LLONG_MIN + 1, + MIN(LLONG_MAX, SIZE_MAX))), SIZE_MAX); + if (strchr(numstr, '+')) + tail = dropinit; + break; + ARGNUM: + n = ARGNUMF(); + break; + default: + usage(); + } ARGEND + + if (!argc) { + if (tail(0, "<stdin>", n) < 0) + ret = 1; + } else { + if ((many = argc > 1) && fflag) + usage(); + for (newline = 0; *argv; argc--, argv++) { + if (!strcmp(*argv, "-")) { + *argv = "<stdin>"; + fd = 0; + } else if ((fd = open(*argv, O_RDONLY)) < 0) { + weprintf("open %s:", *argv); + ret = 1; + continue; + } + if (many) + printf("%s==> %s <==\n", newline ? "\n" : "", *argv); + if (fstat(fd, &st1) < 0) + eprintf("fstat %s:", *argv); + if (!(S_ISFIFO(st1.st_mode) || S_ISREG(st1.st_mode))) + fflag = 0; + newline = 1; + if (tail(fd, *argv, n) < 0) { + ret = 1; + fflag = 0; + } + + if (!fflag) { + if (fd != 0) + close(fd); + continue; + } + for (;;) { + if (concat(fd, *argv, 1, "<stdout>") < 0) + exit(1); + if (fstat(fd, &st2) < 0) + eprintf("fstat %s:", *argv); + if (st2.st_size < st1.st_size) { + fprintf(stderr, "%s: file truncated\n", *argv); + if (lseek(fd, SEEK_SET, 0) < 0) + eprintf("lseek:"); + } + st1 = st2; + sleep(1); + } + } + } + + return ret; +} |