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/* ISC license. */
#include <sys/types.h>
#include <sys/uio.h>
#include <errno.h>
#include <skalibs/allreadwrite.h>
#include <skalibs/sgetopt.h>
#include <skalibs/bytestr.h>
#include <skalibs/types.h>
#include <skalibs/buffer.h>
#include <skalibs/siovec.h>
#include <skalibs/strerr.h>
#include <skalibs/djbunix.h>
#define USAGE "s6-head [ -S ] [ -1..9 | -n lines | -c chars ] [ file... ]"
#define dieusage() strerr_dieusage(100, USAGE)
typedef int head_func (int, size_t) ;
typedef head_func *head_func_ref ;
static int head_dolines (int fd, size_t lines)
{
char buf[BUFFER_INSIZE] ;
buffer in = BUFFER_INIT(&buffer_read, fd, buf, BUFFER_INSIZE) ;
buffer out = BUFFER_INIT(&buffer_write, 1, buf, BUFFER_INSIZE) ;
struct iovec v[2] ;
while (lines)
{
size_t w = 0 ;
ssize_t r = buffer_fill(&in) ;
if (r <= 0) return !r ;
out.c.n = in.c.n ; out.c.p = in.c.p ;
buffer_rpeek(&in, v) ;
for (;;)
{
size_t n = siovec_len(v, 2) ;
size_t i ;
if (!n) break ;
i = siovec_bytechr(v, 2, '\n') ;
if (i < n)
{
w += i+1 ;
siovec_seek(v, 2, i+1) ;
if (!--lines)
{
out.c.n = (out.c.p + w) % out.c.a ;
break ;
}
}
else siovec_seek(v, 2, i) ;
}
if (!buffer_flush(&out)) return 0 ;
in.c.n = out.c.n ; in.c.p = out.c.p ;
}
return 1 ;
}
static int head_safedolines (int fd, size_t lines)
{
char tmp[lines] ;
while (lines)
{
size_t r ;
errno = 0 ;
r = allread(fd, tmp, lines) ;
if (r < lines && errno) return 0 ;
lines -= byte_count(tmp, r, '\n') ;
if (buffer_put(buffer_1, tmp, r) < (ssize_t)r) return 0 ;
}
if (!buffer_flush(buffer_1)) return 0 ;
return 1 ;
}
static int head_safedochars (int fd, size_t chars)
{
return (fd_catn(fd, 1, chars) >= chars) ;
}
int main (int argc, char const *const *argv)
{
head_func_ref f ;
unsigned int lines = 10 ;
int islines = 1, safe = 0 ;
PROG = "s6-head" ;
{
subgetopt l = SUBGETOPT_ZERO ;
int done = 0 ;
for (;;)
{
int opt = subgetopt_r(argc, argv, "S123456789n:c:", &l) ;
if (opt == -1) break ;
switch (opt)
{
case 'S' : safe = 1 ; break ;
case '1' :
case '2' :
case '3' :
case '4' :
case '5' :
case '6' :
case '7' :
case '8' :
case '9' :
{
if (done) dieusage() ;
islines = 1 ;
lines = opt - '0' ;
done = 1 ;
break ;
}
case 'n' :
{
if (done || !uint0_scan(l.arg, &lines))
strerr_dieusage(100, USAGE) ;
islines = 1 ;
done = 1 ;
break ;
}
case 'c' :
{
if (done || !uint0_scan(l.arg, &lines))
strerr_dieusage(100, USAGE) ;
islines = 0 ;
done = 1 ;
break ;
}
default : strerr_dieusage(100, USAGE) ;
}
}
argc -= l.ind ; argv += l.ind ;
}
if (argc) safe = 0 ;
f = islines ? safe ? &head_safedolines : &head_dolines : &head_safedochars ;
if (!argc)
{
if (!(*f)(0, lines))
strerr_diefu1sys(111, "head stdin") ;
}
else
{
unsigned int i = 0 ;
for (; argv[i] ; i++)
{
int fd ;
if (argc >= 2)
{
if (i) buffer_putnoflush(buffer_1, "\n", 1) ;
buffer_putnoflush(buffer_1, "==> ", 4) ;
if ((buffer_puts(buffer_1, argv[i]) <= 0)
|| (buffer_putflush(buffer_1, " <==\n", 5) < 0))
strerr_diefu1sys(111, "write to stdout") ;
}
if ((argv[i][0] == '-') && !argv[i][1]) fd = 0 ;
else fd = open_readb(argv[i]) ;
if (fd == -1)
strerr_diefu3sys(111, "open ", argv[i], " for reading") ;
if (!(*f)(fd, lines))
strerr_diefu2sys(111, "head ", argv[i]) ;
fd_close(fd) ;
}
}
return 0 ;
}
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