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// This program is able to listen to a datagram unix socket displaying
// a linefeed at each receive. Useful when other program wants scrutinize
// syslog forwarded outputs for example (like in omuxsock module by rsyslog
// does).
//
// compile with gcc/clang -o syslog-listen syslog-listen.c
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/un.h>
#include <unistd.h>
#define PERROR(code, msg) { if ((code) == -1) { perror((msg)); exit(1); } }
int main(int argc, const char** argv)
{
if (argc < 2) {
fprintf(stderr, "Usage: syslog-listen </path>\n");
exit(1);
}
struct sockaddr_un sock_file;
memset(&sock_file, 0, sizeof(sock_file));
sock_file.sun_family = AF_UNIX;
strncpy(sock_file.sun_path, argv[1], sizeof(sock_file.sun_path));
int sock = socket(AF_UNIX, SOCK_DGRAM, 0);
PERROR(sock, "socket");
unlink(argv[1]); // no need to test ret as bind will crash if needed
umask(0007); // by default allow user/group calling the program
int ret = bind(sock, (struct sockaddr*)&sock_file, sizeof(sock_file));
PERROR(ret, "bind");
char buf[8192 + 1];
int received;
while (1) {
received = recv(sock, buf, sizeof(buf)-1, 0);
PERROR(received, "recv");
buf[received] = '\n';
write(1, buf, received+1);
}
return 0;
}
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