emo/busybox
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

tail: -50 text bytes

Browse Source
This commit is contained in:
Denis Vlasenko 2006-12-22 16:06:16 +00:00
parent f4c52b32db
commit e31f721e14
1 changed files with 48 additions and 88 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

136
coreutils/tail.c
View File

@ -29,44 +29,30 @@
static const struct suffix_mult tail_suffixes[] = { static const struct suffix_mult tail_suffixes[] = {
{ "b", 512 }, { "b", 512 },
{ "k", 1024 }, { "k", 1024 },
{ "m", 1048576 }, { "m", 1024*1024 },
{ NULL, 0 } { NULL, 0 }
}; };
static int status; static int status;
static void tail_xbb_full_write(const char *buf, size_t len)
{
/* If we get a write error, there is really no sense in continuing. */
if (full_write(STDOUT_FILENO, buf, len) < 0)
bb_perror_nomsg_and_die();
}
static void tail_xprint_header(const char *fmt, const char *filename) static void tail_xprint_header(const char *fmt, const char *filename)
{ {
#if defined __GLIBC__ if (fdprintf(STDOUT_FILENO, fmt, filename) < 0)
if (dprintf(STDOUT_FILENO, fmt, filename) < 0) {
bb_perror_nomsg_and_die(); bb_perror_nomsg_and_die();
}
#else
int hdr_len = strlen(fmt) + strlen(filename);
char *hdr = xzalloc(hdr_len);
sprintf(hdr, filename, filename);
tail_xbb_full_write(hdr, hdr_len);
#endif
} }
static ssize_t tail_read(int fd, char *buf, size_t count) static ssize_t tail_read(int fd, char *buf, size_t count)
{ {
ssize_t r; ssize_t r;
off_t current,end; off_t current, end;
struct stat sbuf; struct stat sbuf;
end = current = lseek(fd, 0, SEEK_CUR); end = current = lseek(fd, 0, SEEK_CUR);
if (!fstat(fd, &sbuf)) if (!fstat(fd, &sbuf))
end = sbuf.st_size; end = sbuf.st_size;
lseek(fd, end < current ? 0 : current, SEEK_SET); lseek(fd, end < current ? 0 : current, SEEK_SET);
if ((r = safe_read(fd, buf, count)) < 0) { r = safe_read(fd, buf, count);
if (r < 0) {
bb_perror_msg(bb_msg_read_error); bb_perror_msg(bb_msg_read_error);
status = EXIT_FAILURE; status = EXIT_FAILURE;
} }
@ -74,82 +60,55 @@ static ssize_t tail_read(int fd, char *buf, size_t count)
return r; return r;
} }
static const char tail_opts[] =
"fn:c:"
#if ENABLE_FEATURE_FANCY_TAIL
"qs:v"
#endif
;
static const char header_fmt[] = "\n==> %s <==\n"; static const char header_fmt[] = "\n==> %s <==\n";
int tail_main(int argc, char **argv) int tail_main(int argc, char **argv)
{ {
long count = 10; unsigned count = 10;
unsigned sleep_period = 1; unsigned sleep_period = 1;
int from_top = 0; int from_top = 0;
int follow = 0;
int header_threshhold = 1; int header_threshhold = 1;
int count_bytes = 0; const char *str_c, *str_n, *str_s;
char *tailbuf; char *tailbuf;
size_t tailbufsize; size_t tailbufsize;
int taillen = 0; int taillen = 0;
int newline = 0; int newline = 0;
int nfiles, nread, nwrite, seen, i, opt;
int *fds, nfiles, nread, nwrite, seen, i, opt; int *fds;
char *s, *buf; char *s, *buf;
const char *fmt; const char *fmt;
void eat_num(const char *p) {
if (*p == '-') p++;
else if (*p == '+') { p++; from_top = 1; }
count = xatou_sfx(p, tail_suffixes);
}
#if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_TAIL #if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_TAIL
/* Allow legacy syntax of an initial numeric option without -n. */ /* Allow legacy syntax of an initial numeric option without -n. */
if (argc >= 2 && (argv[1][0] == '+' || argv[1][0] == '-') if (argc >= 2 && (argv[1][0] == '+' || argv[1][0] == '-')
&& isdigit(argv[1][1]) && isdigit(argv[1][1])
) { ) {
optind = 2; argv[0] = "-n";
optarg = argv[1]; argv--;
goto GET_COUNT; argc++;
} }
#endif #endif
while ((opt = getopt(argc, argv, tail_opts)) > 0) { opt = getopt32(argc, argv, "fc:n:" USE_FEATURE_FANCY_TAIL("qs:v"), &str_c, &str_n, &str_s);
switch (opt) { #define FOLLOW (opt & 0x1)
case 'f': #define COUNT_BYTES (opt & 0x2)
follow = 1; //if (opt & 0x1) // -f
break; if (opt & 0x2) eat_num(str_c); // -c
case 'c': if (opt & 0x4) eat_num(str_n); // -n
count_bytes = 1;
/* FALLS THROUGH */
case 'n':
#if ENABLE_INCLUDE_SUSv2 || ENABLE_FEATURE_FANCY_TAIL
GET_COUNT:
#endif
from_top = 0;
if (*optarg == '+') {
++optarg;
from_top = 1;
}
count = xatol_sfx(optarg, tail_suffixes);
/* Note: Leading whitespace is an error trapped above. */
if (count < 0) {
count = -count;
}
break;
#if ENABLE_FEATURE_FANCY_TAIL #if ENABLE_FEATURE_FANCY_TAIL
case 'q': if (opt & 0x8) header_threshhold = INT_MAX; // -q
header_threshhold = INT_MAX; if (opt & 0x10) sleep_period = xatou(str_s); // -s
break; if (opt & 0x20) header_threshhold = 0; // -v
case 's':
sleep_period = xatou(optarg);
break;
case 'v':
header_threshhold = 0;
break;
#endif #endif
default:
bb_show_usage();
}
}
argc -= optind; argc -= optind;
argv += optind; argv += optind;
@ -160,34 +119,35 @@ int tail_main(int argc, char **argv)
struct stat statbuf; struct stat statbuf;
if (!fstat(STDIN_FILENO, &statbuf) && S_ISFIFO(statbuf.st_mode)) { if (!fstat(STDIN_FILENO, &statbuf) && S_ISFIFO(statbuf.st_mode)) {
follow = 0; opt &= ~1; /* clear FOLLOW */
} }
*argv = (char *) bb_msg_standard_input; *argv = (char *) bb_msg_standard_input;
goto DO_STDIN; goto DO_STDIN;
} }
do { do {
if (LONE_DASH(argv[i])) { if (NOT_LONE_DASH(argv[i])) {
DO_STDIN: fds[nfiles] = open(argv[i], O_RDONLY);
if (fds[nfiles] < 0) {
bb_perror_msg("%s", argv[i]);
status = EXIT_FAILURE;
continue;
}
} else {
DO_STDIN: /* "-" */
fds[nfiles] = STDIN_FILENO; fds[nfiles] = STDIN_FILENO;
} else if ((fds[nfiles] = open(argv[i], O_RDONLY)) < 0) {
bb_perror_msg("%s", argv[i]);
status = EXIT_FAILURE;
continue;
} }
argv[nfiles] = argv[i]; argv[nfiles] = argv[i];
++nfiles; ++nfiles;
} while (++i < argc); } while (++i < argc);
if (!nfiles) { if (!nfiles)
bb_error_msg_and_die("no files"); bb_error_msg_and_die("no files");
}
tailbufsize = BUFSIZ; tailbufsize = BUFSIZ;
/* tail the files */ /* tail the files */
if (from_top < count_bytes) { /* Each is 0 or 1, so true iff 0 < 1. */ if (!from_top && COUNT_BYTES) {
/* Hence, !from_top && count_bytes */
if (tailbufsize < count) { if (tailbufsize < count) {
tailbufsize = count + BUFSIZ; tailbufsize = count + BUFSIZ;
} }
@ -203,7 +163,7 @@ int tail_main(int argc, char **argv)
* starting file position may not be the beginning of the file. * starting file position may not be the beginning of the file.
* Beware of backing up too far. See example in wc.c. * Beware of backing up too far. See example in wc.c.
*/ */
if ((!(count|from_top)) && (lseek(fds[i], 0, SEEK_END) >= 0)) { if (!(count|from_top) && lseek(fds[i], 0, SEEK_END) >= 0) {
continue; continue;
} }
@ -221,22 +181,22 @@ int tail_main(int argc, char **argv)
if (from_top) { if (from_top) {
nwrite = nread; nwrite = nread;
if (seen < count) { if (seen < count) {
if (count_bytes) { if (COUNT_BYTES) {
nwrite -= (count - seen); nwrite -= (count - seen);
seen = count; seen = count;
} else { } else {
s = buf; s = buf;
do { do {
--nwrite; --nwrite;
if ((*s++ == '\n') && (++seen == count)) { if (*s++ == '\n' && ++seen == count) {
break; break;
} }
} while (nwrite); } while (nwrite);
} }
} }
tail_xbb_full_write(buf + nread - nwrite, nwrite); xwrite(STDOUT_FILENO, buf + nread - nwrite, nwrite);
} else if (count) { } else if (count) {
if (count_bytes) { if (COUNT_BYTES) {
taillen += nread; taillen += nread;
if (taillen > count) { if (taillen > count) {
memmove(tailbuf, tailbuf + taillen - count, count); memmove(tailbuf, tailbuf + taillen - count, count);
@ -286,7 +246,7 @@ int tail_main(int argc, char **argv)
} }
if (!from_top) { if (!from_top) {
tail_xbb_full_write(tailbuf, taillen); xwrite(STDOUT_FILENO, tailbuf, taillen);
} }
taillen = 0; taillen = 0;
@ -296,7 +256,7 @@ int tail_main(int argc, char **argv)
fmt = NULL; fmt = NULL;
while (follow) { if (FOLLOW) while (1) {
sleep(sleep_period); sleep(sleep_period);
i = 0; i = 0;
do { do {
@ -308,7 +268,7 @@ int tail_main(int argc, char **argv)
tail_xprint_header(fmt, argv[i]); tail_xprint_header(fmt, argv[i]);
fmt = NULL; fmt = NULL;
} }
tail_xbb_full_write(buf, nread); xwrite(STDOUT_FILENO, buf, nread);
} }
} while (++i < nfiles); } while (++i < nfiles);
} }