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#include <AK/Vector.h>
#include <errno.h>
#include <fcntl.h>
#include <getopt.h>
#include <signal.h>
#include <stdio.h>
#include <unistd.h>
static Vector<int> collect_fds(int argc, char** argv, int start, bool aflag, bool* err)
{
int oflag;
mode_t mode;
if (aflag) {
oflag = O_APPEND;
mode = 0;
} else {
oflag = O_CREAT | O_WRONLY | O_TRUNC;
mode = S_IROTH | S_IWOTH | S_IRGRP | S_IWGRP | S_IRUSR | S_IWUSR;
}
Vector<int> fds;
for (int i = start; i < argc; ++i) {
int fd = open(argv[i], oflag, mode);
if (fd < 0) {
perror("failed to open file for writing");
*err = true;
} else {
fds.append(fd);
}
}
fds.append(STDOUT_FILENO);
return fds;
}
static void copy_stdin(Vector<int>& fds, bool* err)
{
for (;;) {
char buf[4096];
ssize_t nread = read(STDIN_FILENO, buf, sizeof(buf));
if (nread == 0)
break;
if (nread < 0) {
perror("read() error");
*err = true;
// a failure to read from stdin should lead to an early exit
return;
}
Vector<int> broken_fds;
for (int i = 0; i < fds.size(); ++i) {
auto fd = fds.at(i);
int twrite = 0;
while (twrite != nread) {
ssize_t nwrite = write(fd, buf + twrite, nread - twrite);
if (nwrite < 0) {
if (errno == EINTR) {
continue;
} else {
perror("write() failed");
*err = true;
broken_fds.append(fd);
// write failures to a successfully opened fd shall
// prevent further writes, but shall not block writes
// to the other open fds
break;
}
} else {
twrite += nwrite;
}
}
}
// remove any fds which we can no longer write to for subsequent copies
for (auto to_remove : broken_fds)
fds.remove_first_matching([&](int fd) { return to_remove == fd; });
}
}
static void close_fds(Vector<int>& fds)
{
for (int fd : fds) {
int closed = close(fd);
if (closed < 0) {
perror("failed to close output file");
}
}
}
static void int_handler(int)
{
// pass
}
int main(int argc, char** argv)
{
bool aflag = false, iflag = false;
int c = 0;
while ((c = getopt(argc, argv, "ai")) != -1) {
switch (c) {
case 'a':
aflag = true;
break;
case 'i':
iflag = true;
break;
}
}
if (iflag) {
if (signal(SIGINT, int_handler) == SIG_ERR) {
perror("failed to install SIGINT handler");
}
}
bool err_open = false;
bool err_write = false;
auto fds = collect_fds(argc, argv, optind, aflag, &err_open);
copy_stdin(fds, &err_write);
close_fds(fds);
return (err_open || err_write) ? 1 : 0;
}
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