gno/usr.bin/sort/linecount.c

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1996-01-28 00:52:48 +00:00
#ifdef __CCFRONT__
#include <14:pragma.h>
#endif
#include "common.h"
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
/*
* unsigned long int linecount (char *filename, size_t *maxlinelen);
*
* Pre: <filename> is the name of the file for which we need to know
* the number of lines. The file must be closed.
*
* Post: Returns the number of newline characters in the file. On
* return, the file is again closed and *maxlinelen is the length
* of the longest line in <filename> (length is calculated to
* include the newline character but not the null terminator.
* Returns zero on failure or if there are no newlines.
*
* Uses Globals:
* v_flag
*/
unsigned long int linecount (char *filename, size_t *maxlinelen) {
char *buff; /* the input buffer */
unsigned long result; /* the number of newlines */
int count; /* the number of chars last read */
int fd; /* file descriptor for <filename> */
short done;
int i;
size_t linelen; /* length of current line */
/* init some variables */
done = 0;
result = 0;
*maxlinelen = 0;
linelen = 0;
/* open <filename> for unbuffered I/O */
if ((fd = open(filename,O_RDONLY)) == -1) {
if (v_flag) perror("linecount: couldn't open input file");
return 0lu;
}
/* get an input buffer */
if ((buff = malloc(BUFFERSIZE)) == NULL) {
if (v_flag) perror ("linecount: couldn't allocate buffer");
close(fd);
return 0lu;
}
/* repeatedly fill the buffer and increment the newline count */
while (!done) {
count = read (fd, buff, BUFFERSIZE);
switch (count) {
case -1: /* file error */
if (v_flag) perror ("linecount");
close(fd);
free(buff);
return 0lu;
/* NOTREACHED */
break;
case 0: /* EOF */
done = 1;
break;
default: /* got some info in the buffer */
for (i=0; i<count; i++) {
linelen++;
if (buff[i] == NEWLINE) {
result++;
if (linelen > *maxlinelen) *maxlinelen = linelen;
linelen = 0;
}
}
break;
}
}
/* clean up and return */
close(fd);
free(buff);
return result;
}