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comm.c
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C/C++ Source or Header
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1990-07-15
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4KB
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192 lines
/* comm - select lines from two sorted files Author: Martin C. Atkins */
/*
* This program was written by:
* Martin C. Atkins,
* University of York,
* Heslington,
* York. Y01 5DD
* England
* and is released into the public domain, on the condition
* that this comment is always included without alteration.
*/
#include <sys/types.h>
#include <fcntl.h>
#define BUFSIZ (512)
#define LINMAX (600)
struct file {
char *name; /* the file's name */
int fd; /* the file descripter */
char buf[BUFSIZ]; /* buffer storage */
char *next; /* the next character to read */
char *endp; /* the first invalid character */
int seeneof; /* an end of file has been seen */
} files[2];
char lines[2][LINMAX];
int colflgs[3] = {1, 2, 3}; /* number of tabs + 1: 0 => no column */
static char *umsg = "Usage: comm [-[123]] file1 file2\n";
main(argc, argv)
int argc;
char *argv[];
{
int cnt;
if (argc > 1 && argv[1][0] == '-' && argv[1][1] != '\0') {
char *ap;
for (ap = &argv[1][1]; *ap; ap++) switch (*ap) {
case '1':
case '2':
case '3':
cnt = *ap - '1';
if (colflgs[cnt] == 0) break;
colflgs[cnt] = 0;
for (cnt++; cnt < 3; cnt++) colflgs[cnt]--;
break;
default: usage();
}
argc--;
argv++;
}
if (argc != 3) usage();
eopen(argv[1], &files[0]);
eopen(argv[2], &files[1]);
comm();
exit(0);
}
usage()
{
std_err(umsg);
exit(1);
}
error(s, f)
char *s, *f;
{
std_err("comm: ");
std_err(s);
if (f) std_err(f);
std_err("\n");
exit(1);
}
int eopen(fn, file)
char *fn;
struct file *file;
{
file->name = fn;
file->next = file->endp = &file->buf[0];
file->seeneof = 0;
if (fn[0] == '-' && fn[1] == '\0')
file->fd = 0;
else if ((file->fd = open(fn, O_RDONLY)) < 0)
error("can't open ", fn);
}
int getbuf(file)
struct file *file;
{
/* Get a buffer-full from the file. Return true if no characters
* were obtained because we are at end of file.
*/
int n;
if (file->seeneof) return(1);
if ((n = read(file->fd, &file->buf[0], BUFSIZ)) < 0)
error("read error on ", file->name);
if (n == 0) {
file->seeneof++;
return 1;
}
file->next = &file->buf[0];
file->endp = &file->buf[n];
return(0);
}
int readline(fno)
int fno;
{
/* Read up to the next '\n' character to buf.
* Return a complete line, even if end of file occurs within a line.
* Return false at end of file/
*/
register struct file *file = &files[fno];
char *buf = lines[fno];
if (file->next == file->endp && getbuf(file)) return(0);
while ((*buf++ = *file->next++) != '\n')
if (file->next == file->endp && getbuf(file)) {
*buf++ = '\n';
*buf = '\0';
return(1);
}
*buf = '\0';
return(1);
}
comm()
{
register int res;
if (!readline(0)) {
cpycol(1);
return;
}
if (!readline(1)) {
putcol(0, lines[0]);
cpycol(0);
return;
}
for (;;) {
if ((res = strcmp(lines[0], lines[1])) != 0) {
res = res > 0;
putcol(res, lines[res]);
if (!readline(res)) {
putcol(!res, lines[!res]);
cpycol(!res);
return;
}
} else {
putcol(2, lines[0]); /* files[1]lin == f2lin */
if (!readline(0)) {
cpycol(1);
return;
}
if (!readline(1)) {
putcol(0, lines[0]);
cpycol(0);
return;
}
}
}
/* NOTREACHED */
}
putcol(col, buf)
int col;
char *buf;
{
int cnt;
if (colflgs[col] == 0) return;
for (cnt = 0; cnt < colflgs[col] - 1; cnt++) prints("\t");
prints("%s", buf);
}
cpycol(col)
int col;
{
if (colflgs[col]) while (readline(col))
putcol(col, lines[col]);
}