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/*
std2fifo, a std{in,out} <-> <dir>/<env var>/{in,out} proxy
This is free and unencumbered software released into the public
domain.
*/
#include <config.h>
#include <syslog.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <signal.h>
#define MAX_BUF_SIZE 4096
#define DIR_MODE S_IRWXU | S_IRWXG | S_IWGRP | S_IRGRP
#define FIFO_IN_MODE S_IRUSR | S_IWUSR | S_IWGRP
#define FIFO_OUT_MODE S_IRUSR | S_IWUSR | S_IRGRP
#define max(x,y) ((x) > (y) ? (x) : (y))
int chdir_err (const char *dir)
{
if (chdir(dir)) {
syslog(LOG_ERR, "Can't change directory to %s: %s", dir, strerror(errno));
return -1;
}
return 0;
}
int fifo_open (const char *path,
mode_t mode,
int flag)
{
if (mkfifo(path, mode) && errno != EEXIST) {
syslog(LOG_ERR, "Failed to create FIFO %s: %s", path, strerror(errno));
return -1;
}
return open(path, flag);
}
int write_all (int fd,
const char *buffer,
ssize_t count,
const char *err)
{
ssize_t written, ret;
for (written = 0; written < count; written += ret) {
ret = write (fd, buffer + written, count - written);
if (! ret) {
syslog(LOG_ERR, "write() has returned 0");
return -1;
} else if (ret < 0) {
if (err != NULL)
syslog(LOG_WARNING, "Failed to write to %s: %s", err, strerror(errno));
return -1;
}
}
return 0;
}
int run (const char *dir,
const char *val,
int continuous)
{
int in = -1, out = -1;
fd_set rfds;
int select_val, max_fd;
ssize_t len;
static char buffer[MAX_BUF_SIZE + 1];
if (chdir_err(dir))
return -1;
/* Create the directory if it doesn't exist */
if (mkdir(val, DIR_MODE) && errno != EEXIST) {
syslog(LOG_ERR, "Failed to create directory %s: %s", val, strerror(errno));
return -1;
}
if (chdir_err(val))
return -1;
in = fifo_open("in", FIFO_IN_MODE, O_RDONLY | O_NONBLOCK);
if (in == -1)
return -1;
for (;;) {
FD_ZERO(&rfds);
FD_SET(in, &rfds);
FD_SET(STDIN_FILENO, &rfds);
max_fd = max(STDIN_FILENO, in);
select_val = select(max_fd + 1, &rfds, NULL, NULL, NULL);
if (select_val == -1) {
/* error */
syslog(LOG_ERR, "select() failure: %s", strerror(errno));
break;
} else {
/* stdin to FIFO */
if (FD_ISSET(STDIN_FILENO, &rfds)) {
len = read(STDIN_FILENO, buffer, MAX_BUF_SIZE);
if (len < 0) {
/* Error: quit */
syslog(LOG_ERR, "Failed to read from stdin: %s", strerror(errno));
break;
} else if (len == 0) {
/* EOF: quit, but without error */
close(in);
return 0;
}
/* Open, write, close */
/* Only open once in the continuous streams mode */
if ((continuous && out == -1) || ! continuous) {
out = fifo_open("out", FIFO_OUT_MODE, O_WRONLY);
if (out == -1) {
syslog(LOG_ERR, "Failed to open 'out': %s", strerror(errno));
break;
}
}
if (write_all(out, buffer, len, "FIFO"))
break;
/* Do not close in the continuous streams mode */
if (! continuous)
close(out);
}
/* FIFO to stdout */
if (FD_ISSET(in, &rfds)) {
len = read(in, buffer, MAX_BUF_SIZE);
if (len < 0) {
/* Error: quit */
syslog(LOG_ERR, "Failed to read from FIFO: %s", strerror(errno));
break;
} else if (len == 0) {
/* EOF: reopen or quit, unless in continuous streams mode */
close(in);
if (continuous)
break;
in = fifo_open("in", FIFO_IN_MODE, O_RDONLY | O_NONBLOCK);
if (in == -1) {
syslog(LOG_ERR, "Failed to reopen 'in': %s", strerror(errno));
break;
}
} else if (write_all(STDOUT_FILENO, buffer, len, "stdout"))
break;
}
}
}
/* It's an error if we've got here */
if (in >= 0)
close(in);
if (out >= 0)
close(out);
return -1;
}
void print_help (const char *name)
{
printf("Usage: %s [option ...] <dir>\n", name);
puts("Options:");
puts(" -v <var> an environment variable name");
puts(" -c continuous streams");
puts(" -i <ident> syslog ident to use");
puts(" -e print messages into stderr, in addition to syslog");
puts(" -h print this help message and exit");
}
int main (int argc,
char **argv)
{
int c;
char *ident = "std2fifo";
int syslog_options = 0, continuous = 0;
char *var = "SHA256", *val, *dir;
int ret;
struct sigaction sigact;
while ((c = getopt (argc, argv, "v:ci:eh")) != -1)
switch (c)
{
case 'v': var = optarg; break;
case 'c': continuous = 1; break;
case 'i': ident = optarg; break;
case 'e': syslog_options |= LOG_PERROR; break;
case 'h': print_help(argv[0]); return 0;
default: print_help(argv[0]); return 1;
}
if (argc <= optind) {
print_help(argv[0]);
return 1;
}
dir = argv[optind];
val = getenv(var);
if (! val) {
print_help(argv[0]);
return 1;
}
/* Prepare */
openlog(ident, syslog_options, LOG_USER);
/* Ignore SIGPIPE */
sigact.sa_handler = SIG_IGN;
sigact.sa_flags = 0;
sigaction(SIGPIPE, &sigact, NULL);
/* Run */
ret = run(dir, val, continuous);
/* Done */
closelog();
return ret;
}
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