master
Karchnu 3 years ago
parent b50e46b262
commit e785e9bbc1

@ -0,0 +1,9 @@
CC ?= clang
CFLAGS ?= -Wall -Wextra -std=c11
all: compilation
compilation: by-line
by-line: by-line.c
$(Q)$(CC) -o by-line $(CFLAGS) $(LDFLAGS) $^

@ -0,0 +1,104 @@
#include <stdio.h> // printf
#include <fcntl.h>
#include <string.h> // memchr
#include <unistd.h> // read write
#include <stdint.h> // uint32_t
#include <stdlib.h> // exit
#include <poll.h> // poll
// OUTPUT: line-by-line strings
#define line_size_exceeded "line exeeded max buffer size\n"
#define MAXBUFFER 64000
char buf[MAXBUFFER];
void err(int error, const char *str) {
fprintf (stderr, "%s\n", str);
exit(error);
}
int main(int argc, const char **argv)
{
if (argc > 1) {
printf ("usage: %s\n", argv[0]);
return 0;
}
// fcntl(0, F_SETFL, O_SYNC);
uint32_t tot_read = 0;
uint32_t n_read = 0;
struct pollfd pfd[1];
int nready;
pfd[0].fd = 0;
while (1) {
pfd[0].events = POLLIN;
nready = poll(pfd, 1, 60 * 1000);
if (nready == -1)
err (1, "poll");
if (nready == 0) {
fprintf (stderr, "time out\n");
}
if ((pfd[0].revents & (POLLERR|POLLNVAL))) {
fprintf (stderr, "bad fd %d", pfd[0].fd);
err (1, "bad fd");
}
if ((pfd[0].revents & (POLLIN|POLLHUP))) {
n_read = read(0, buf, sizeof(buf));
if (n_read > 0) {
// fprintf (stderr, "read %u characters\n", n_read);
tot_read += n_read;
// fprintf(stderr, "total read %u\n", tot_read);
// fprintf(stderr, "could still read %u\n", MAXBUFFER - tot_read);
if (tot_read == MAXBUFFER) {
// print anyway
write (1, buf, tot_read);
write (2, line_size_exceeded, strlen(line_size_exceeded));
printf(buf);
n_read = 0;
tot_read = 0;
continue;
}
// print line by line (if any)
char * p = NULL;
while ((p = memchr(buf, '\n', tot_read)) != NULL) {
uint32_t remaining = tot_read - (p - buf) - 1;
write (1, buf, tot_read - remaining);
// fprintf (stderr, "found retline, %u remaining chars\n", remaining);
for (uint32_t i = 0; i < remaining ; i++) {
buf[i] = buf[i + tot_read - remaining];
}
tot_read = remaining;
n_read = 0;
}
}
else if (n_read == 0) {
// fprintf (stderr, "EOF\n");
break;
}
else {
err (1, "read");
}
}
}
if (tot_read > 0) {
// fprintf(stderr, "print the %u characters remaining in the buffer\n", tot_read);
write (1, buf, tot_read);
}
// fprintf (stderr, "end of the loop\n");
return 0;
}
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