#pragma prototyped
static const char usage[] =
"+[-?\n@(#)$Id: tail (AT&T Research) 2010-05-09 $\n]"
USAGE_LICENSE
"[+NAME?tail - output trailing portion of one or more files ]"
"[+DESCRIPTION?\btail\b copies one or more input files to standard output "
"starting at a designated point for each file. Copying starts "
"at the point indicated by the options and is unlimited in size.]"
"[+?By default a header of the form \b==> \b\afilename\a\b <==\b "
"is output before all but the first file but this can be changed "
"with the \b-q\b and \b-v\b options.]"
"[+?If no \afile\a is given, or if the \afile\a is \b-\b, \btail\b "
"copies from standard input. The start of the file is defined "
"as the current offset.]"
"[+?The option argument for \b-c\b can optionally be "
"followed by one of the following characters to specify a different "
"unit other than a single byte:]{"
"[+b?512 bytes.]"
"[+k?1 KiB.]"
"[+m?1 MiB.]"
"[+g?1 GiB.]"
"}"
"[+?For backwards compatibility, \b-\b\anumber\a is equivalent to "
"\b-n\b \anumber\a and \b+\b\anumber\a is equivalent to "
"\b-n -\b\anumber\a. \anumber\a may also have these option "
"suffixes: \bb c f g k l m r\b.]"
"[n:lines]:[lines:=10?Copy \alines\a lines from each file. A negative value "
"for \alines\a indicates an offset from the end of the file.]"
"[b:blocks?Copy units of 512 bytes.]"
"[c:bytes]:?[chars?Copy \achars\a bytes from each file. A negative value "
"for \achars\a indicates an offset from the end of the file.]"
"[f:forever|follow?Loop forever trying to read more characters as the "
"end of each file to copy new data. Ignored if reading from a pipe "
"or fifo.]"
"[h!:headers?Output filename headers.]"
"[l:lines?Copy units of lines. This is the default.]"
"[L:log?When a \b--forever\b file times out via \b--timeout\b, verify that "
"the curent file has not been renamed and replaced by another file "
"of the same name (a common log file practice) before giving up on "
"the file.]"
"[q:quiet?Don't output filename headers. For GNU compatibility.]"
"[r:reverse?Output lines in reverse order.]"
"[s:silent?Don't warn about timeout expiration and log file changes.]"
"[t:timeout?Stop checking after \atimeout\a elapses with no additional "
"\b--forever\b output. A separate elapsed time is maintained for "
"each file operand. There is no timeout by default. The default "
"\atimeout\a unit is seconds. \atimeout\a may be a catenation of 1 "
"or more integers, each followed by a 1 character suffix. The suffix "
"may be omitted from the last integer, in which case it is "
"interpreted as seconds. The supported suffixes are:]:[timeout]{"
"[+s?seconds]"
"[+m?minutes]"
"[+h?hours]"
"[+d?days]"
"[+w?weeks]"
"[+M?months]"
"[+y?years]"
"[+S?scores]"
"}"
"[v:verbose?Always ouput filename headers.]"
"\n"
"\n[file ...]\n"
"\n"
"[+EXIT STATUS?]{"
"[+0?All files copied successfully.]"
"[+>0?One or more files did not copy.]"
"}"
"[+SEE ALSO?\bcat\b(1), \bhead\b(1), \brev\b(1)]"
;
#include <cmd.h>
#include <ctype.h>
#include <ls.h>
#include <tm.h>
#include <rev.h>
#define COUNT (1<<0)
#define ERROR (1<<1)
#define FOLLOW (1<<2)
#define HEADERS (1<<3)
#define LINES (1<<4)
#define LOG (1<<5)
#define NEGATIVE (1<<6)
#define POSITIVE (1<<7)
#define REVERSE (1<<8)
#define SILENT (1<<9)
#define TIMEOUT (1<<10)
#define VERBOSE (1<<11)
#define NOW (unsigned long)time(NiL)
#define DEFAULT 10
#ifdef S_ISSOCK
#define FIFO(m) (S_ISFIFO(m)||S_ISSOCK(m))
#else
#define FIFO(m) S_ISFIFO(m)
#endif
struct Tail_s; typedef struct Tail_s Tail_t;
struct Tail_s
{
Tail_t* next;
char* name;
Sfio_t* sp;
Sfoff_t cur;
Sfoff_t end;
unsigned long expire;
long dev;
long ino;
int fifo;
};
static const char header_fmt[] = "\n==> %s <==\n";
static Sfoff_t
tailpos(register Sfio_t* fp, register Sfoff_t number, int delim)
{
register size_t n;
register Sfoff_t offset;
register Sfoff_t first;
register Sfoff_t last;
register char* s;
register char* t;
struct stat st;
last = sfsize(fp);
if ((first = sfseek(fp, (Sfoff_t)0, SEEK_CUR)) < 0)
return last || fstat(sffileno(fp), &st) || st.st_size || FIFO(st.st_mode) ? -1 : 0;
if (delim < 0)
{
if ((offset = last - number) < first)
return first;
return offset;
}
for (;;)
{
if ((offset = last - SF_BUFSIZE) < first)
offset = first;
sfseek(fp, offset, SEEK_SET);
n = last - offset;
if (!(s = sfreserve(fp, n, SF_LOCKR)))
return -1;
t = s + n;
while (t > s)
if (*--t == delim && number-- <= 0)
{
sfread(fp, s, 0);
return offset + (t - s) + 1;
}
sfread(fp, s, 0);
if (offset == first)
break;
last = offset;
}
return first;
}
static void
pipetail(Sfio_t* infile, Sfio_t* outfile, Sfoff_t number, int delim)
{
register Sfio_t* out;
register Sfoff_t n;
register Sfoff_t nleft = number;
register size_t a = 2 * SF_BUFSIZE;
register int fno = 0;
Sfoff_t offset[2];
Sfio_t* tmp[2];
if (delim < 0 && a > number)
a = number;
out = tmp[0] = sftmp(a);
tmp[1] = sftmp(a);
offset[0] = offset[1] = 0;
while ((n = sfmove(infile, out, number, delim)) > 0)
{
offset[fno] = sftell(out);
if ((nleft -= n) <= 0)
{
out = tmp[fno= !fno];
sfseek(out, (Sfoff_t)0, SEEK_SET);
nleft = number;
}
}
if (nleft == number)
{
offset[fno] = 0;
fno= !fno;
}
sfseek(tmp[0], (Sfoff_t)0, SEEK_SET);
if (offset[fno])
{
sfseek(tmp[1], (Sfoff_t)0, SEEK_SET);
if ((n = number - nleft) > 0)
sfmove(tmp[!fno], NiL, n, delim);
if ((n = offset[!fno] - sftell(tmp[!fno])) > 0)
sfmove(tmp[!fno], outfile, n, -1);
}
else
fno = !fno;
sfmove(tmp[fno], outfile, offset[fno], -1);
sfclose(tmp[0]);
sfclose(tmp[1]);
}
static int
init(Tail_t* tp, Sfoff_t number, int delim, int flags, const char** format)
{
Sfoff_t offset;
Sfio_t* op;
struct stat st;
tp->fifo = 0;
if (tp->sp)
{
offset = 0;
if (tp->sp == sfstdin)
tp->sp = 0;
}
else
offset = 1;
if (!tp->name || streq(tp->name, "-"))
{
tp->name = "/dev/stdin";
tp->sp = sfstdin;
}
else if (!(tp->sp = sfopen(tp->sp, tp->name, "r")))
{
error(ERROR_system(0), "%s: cannot open", tp->name);
return -1;
}
sfset(tp->sp, SF_SHARE, 0);
if (offset)
{
if (number < 0 || !number && (flags & POSITIVE))
{
sfset(tp->sp, SF_SHARE, !(flags & FOLLOW));
if (number < -1)
{
sfmove(tp->sp, NiL, -number - 1, delim);
offset = sfseek(tp->sp, (Sfoff_t)0, SEEK_CUR);
}
else
offset = 0;
}
else if ((offset = tailpos(tp->sp, number, delim)) >= 0)
sfseek(tp->sp, offset, SEEK_SET);
else if (fstat(sffileno(tp->sp), &st))
{
error(ERROR_system(0), "%s: cannot stat", tp->name);
goto bad;
}
else if (!FIFO(st.st_mode))
{
error(ERROR_SYSTEM|2, "%s: cannot position file to tail", tp->name);
goto bad;
}
else
{
tp->fifo = 1;
if (flags & (HEADERS|VERBOSE))
{
sfprintf(sfstdout, *format, tp->name);
*format = header_fmt;
}
op = (flags & REVERSE) ? sftmp(4*SF_BUFSIZE) : sfstdout;
pipetail(tp->sp ? tp->sp : sfstdin, op, number, delim);
if (flags & REVERSE)
{
sfseek(op, (Sfoff_t)0, SEEK_SET);
rev_line(op, sfstdout, (Sfoff_t)0);
sfclose(op);
}
}
}
tp->cur = tp->end = offset;
if (flags & LOG)
{
if (fstat(sffileno(tp->sp), &st))
{
error(ERROR_system(0), "%s: cannot stat", tp->name);
goto bad;
}
tp->dev = st.st_dev;
tp->ino = st.st_ino;
}
return 0;
bad:
if (tp->sp != sfstdin)
sfclose(tp->sp);
tp->sp = 0;
return -1;
}
static intmax_t
num(register const char* s, char** e, int* f, int o)
{
intmax_t number;
char* t;
int c;
*f &= ~(ERROR|NEGATIVE|POSITIVE);
if ((c = *s) == '-')
{
*f |= NEGATIVE;
s++;
}
else if (c == '+')
{
*f |= POSITIVE;
s++;
}
while (*s == '0' && isdigit(*(s + 1)))
s++;
errno = 0;
number = strtonll(s, &t, NiL, 0);
if (t == s)
number = DEFAULT;
if (o && *t)
{
number = 0;
*f |= ERROR;
error(2, "-%c: %s: invalid numeric argument -- unknown suffix", o, s);
}
else if (errno)
{
*f |= ERROR;
if (o)
error(2, "-%c: %s: invalid numeric argument -- out of range", o, s);
else
error(2, "%s: invalid numeric argument -- out of range", s);
}
else
{
*f |= COUNT;
if (t > s && isalpha(*(t - 1)))
*f &= ~LINES;
if (c == '-')
number = -number;
}
if (e)
*e = t;
return number;
}
int
b_tail(int argc, char** argv, void* context)
{
register Sfio_t* ip;
register int n;
register int i;
int delim;
int flags = HEADERS|LINES;
int blocks = 0;
char* s;
char* t;
char* r;
char* file;
Sfoff_t offset;
Sfoff_t number = DEFAULT;
unsigned long timeout = 0;
struct stat st;
const char* format = header_fmt+1;
ssize_t z;
ssize_t w;
Sfio_t* op;
register Tail_t* fp;
register Tail_t* pp;
register Tail_t* hp;
Tail_t* files;
cmdinit(argc, argv, context, ERROR_CATALOG, 0);
for (;;)
{
switch (n = optget(argv, usage))
{
case 0:
if (!(flags & FOLLOW) && argv[opt_info.index] && (argv[opt_info.index][0] == '-' || argv[opt_info.index][0] == '+') && !argv[opt_info.index][1])
{
number = argv[opt_info.index][0] == '-' ? 10 : -10;
flags |= LINES;
opt_info.index++;
continue;
}
break;
case 'b':
blocks = 512;
flags &= ~LINES;
if (opt_info.option[0] == '+')
number = -number;
continue;
case 'c':
flags &= ~LINES;
if (opt_info.arg == argv[opt_info.index - 1])
{
strtol(opt_info.arg, &s, 10);
if (*s)
{
opt_info.index--;
t = "";
goto suffix;
}
}
else if (opt_info.arg && isalpha(*opt_info.arg))
{
t = opt_info.arg;
goto suffix;
}
case 'n':
flags |= COUNT;
if (s = opt_info.arg)
number = num(s, &s, &flags, n);
else
{
number = DEFAULT;
flags &= ~(ERROR|NEGATIVE|POSITIVE);
s = "";
}
if (n != 'n' && s && isalpha(*s))
{
t = s;
goto suffix;
}
if (flags & ERROR)
continue;
if (flags & (NEGATIVE|POSITIVE))
number = -number;
if (opt_info.option[0]=='+')
number = -number;
continue;
case 'f':
flags |= FOLLOW;
continue;
case 'h':
if (opt_info.num)
flags |= HEADERS;
else
flags &= ~HEADERS;
continue;
case 'l':
flags |= LINES;
if (opt_info.option[0] == '+')
number = -number;
continue;
case 'L':
flags |= LOG;
continue;
case 'q':
flags &= ~HEADERS;
continue;
case 'r':
flags |= REVERSE;
continue;
case 's':
flags |= SILENT;
continue;
case 't':
flags |= TIMEOUT;
timeout = strelapsed(opt_info.arg, &s, 1);
if (*s)
error(ERROR_exit(1), "%s: invalid elapsed time [%s]", opt_info.arg, s);
continue;
case 'v':
flags |= VERBOSE;
continue;
case ':':
if (!(r = argv[opt_info.index]) || !opt_info.offset)
{
error(2, "%s", opt_info.arg);
break;
}
s = r + opt_info.offset - 1;
if (i = *(s - 1) == '-' || *(s - 1) == '+')
s--;
if ((number = num(s, &t, &flags, 0)) && i)
number = -number;
goto compatibility;
suffix:
r = 0;
if (opt_info.option[0] == '+')
number = -number;
compatibility:
for (;;)
{
switch (*t++)
{
case 0:
if (r)
opt_info.offset = t - r - 1;
break;
case 'c':
flags &= ~LINES;
continue;
case 'f':
flags |= FOLLOW;
continue;
case 'l':
flags |= LINES;
continue;
case 'r':
flags |= REVERSE;
continue;
default:
error(2, "%s: invalid suffix", t - 1);
if (r)
opt_info.offset = strlen(r);
break;
}
break;
}
continue;
case '?':
error(ERROR_usage(2), "%s", opt_info.arg);
break;
}
break;
}
argv += opt_info.index;
if (!*argv)
{
flags &= ~HEADERS;
if (fstat(0, &st))
error(ERROR_system(0), "/dev/stdin: cannot stat");
else if (FIFO(st.st_mode))
flags &= ~FOLLOW;
}
else if (!*(argv + 1))
flags &= ~HEADERS;
delim = (flags & LINES) ? '\n' : -1;
if (blocks)
number *= blocks;
if (flags & REVERSE)
{
if (delim < 0)
error(2, "--reverse requires line mode");
if (!(flags & COUNT))
number = -1;
flags &= ~FOLLOW;
}
if ((flags & (FOLLOW|TIMEOUT)) == TIMEOUT)
{
flags &= ~TIMEOUT;
timeout = 0;
error(ERROR_warn(0), "--timeout ignored for --noforever");
}
if ((flags & (LOG|TIMEOUT)) == LOG)
{
flags &= ~LOG;
error(ERROR_warn(0), "--log ignored for --notimeout");
}
if (error_info.errors)
error(ERROR_usage(2), "%s", optusage(NiL));
if (flags & FOLLOW)
{
if (!(fp = (Tail_t*)stakalloc(argc * sizeof(Tail_t))))
error(ERROR_system(1), "out of space");
files = 0;
s = *argv;
do
{
fp->name = s;
fp->sp = 0;
if (!init(fp, number, delim, flags, &format))
{
fp->expire = timeout ? (NOW + timeout + 1) : 0;
if (files)
pp->next = fp;
else
files = fp;
pp = fp;
fp++;
}
} while (s && (s = *++argv));
if (!files)
return error_info.errors != 0;
pp->next = 0;
hp = 0;
n = 1;
while (fp = files)
{
if (n)
n = 0;
else
sleep(1);
pp = 0;
while (fp)
{
if (fstat(sffileno(fp->sp), &st))
error(ERROR_system(0), "%s: cannot stat", fp->name);
else if (fp->fifo || fp->end < st.st_size)
{
n = 1;
if (timeout)
fp->expire = NOW + timeout;
z = fp->fifo ? SF_UNBOUND : st.st_size - fp->cur;
i = 0;
if ((s = sfreserve(fp->sp, z, SF_LOCKR)) || (z = sfvalue(fp->sp)) && (s = sfreserve(fp->sp, z, SF_LOCKR)) && (i = 1))
{
z = sfvalue(fp->sp);
for (r = s + z; r > s && *(r - 1) != '\n'; r--);
if ((w = r - s) || i && (w = z))
{
if ((flags & (HEADERS|VERBOSE)) && hp != fp)
{
hp = fp;
sfprintf(sfstdout, format, fp->name);
format = header_fmt;
}
fp->cur += w;
sfwrite(sfstdout, s, w);
}
else
w = 0;
sfread(fp->sp, s, w);
fp->end += w;
}
goto next;
}
else if (!timeout || fp->expire > NOW)
goto next;
else
{
if (flags & LOG)
{
i = 3;
while (--i && stat(fp->name, &st))
sleep(1);
if (i && (fp->dev != st.st_dev || fp->ino != st.st_ino) && !init(fp, 0, 0, flags, &format))
{
if (!(flags & SILENT))
error(ERROR_warn(0), "%s: log file change", fp->name);
fp->expire = NOW + timeout;
goto next;
}
}
if (!(flags & SILENT))
error(ERROR_warn(0), "%s: %s timeout", fp->name, fmtelapsed(timeout, 1));
}
if (fp->sp && fp->sp != sfstdin)
sfclose(fp->sp);
if (pp)
pp = pp->next = fp->next;
else
files = files->next;
fp = fp->next;
continue;
next:
pp = fp;
fp = fp->next;
}
if (sfsync(sfstdout))
error(ERROR_system(1), "write error");
}
}
else
{
if (file = *argv)
argv++;
do
{
if (!file || streq(file, "-"))
{
file = "/dev/stdin";
ip = sfstdin;
}
else if (!(ip = sfopen(NiL, file, "r")))
{
error(ERROR_system(0), "%s: cannot open", file);
continue;
}
if (flags & (HEADERS|VERBOSE))
{
sfprintf(sfstdout, format, file);
format = header_fmt;
}
if (number < 0 || !number && (flags & POSITIVE))
{
sfset(ip, SF_SHARE, 1);
if (number < -1)
sfmove(ip, NiL, -number - 1, delim);
if (flags & REVERSE)
rev_line(ip, sfstdout, sfseek(ip, (Sfoff_t)0, SEEK_CUR));
else
sfmove(ip, sfstdout, SF_UNBOUND, -1);
}
else
{
sfset(ip, SF_SHARE, 0);
if ((offset = tailpos(ip, number, delim)) >= 0)
{
if (flags & REVERSE)
rev_line(ip, sfstdout, offset);
else
{
sfseek(ip, offset, SEEK_SET);
sfmove(ip, sfstdout, SF_UNBOUND, -1);
}
}
else
{
op = (flags & REVERSE) ? sftmp(4*SF_BUFSIZE) : sfstdout;
pipetail(ip, op, number, delim);
if (flags & REVERSE)
{
sfseek(op, (Sfoff_t)0, SEEK_SET);
rev_line(op, sfstdout, (Sfoff_t)0);
sfclose(op);
}
flags = 0;
}
}
if (ip != sfstdin)
sfclose(ip);
} while (file = *argv++);
}
return error_info.errors != 0;
}