[Bug 1130512] [NEW] accept strace block

[tony]

Public bug reported:

I used ftp (netkit-ftp-0.17) to get some files when prompt was on, the
block happened.

----
local: test1.css remote: test1.css
200 PORT command successful.
150 File status OK ; about to open data connection
(#block happened. here is wating...)
----

i used strace command to find out the reason.
the block happened when socket accepted. 
---
write(3, "RETR test1.css\r\n", 24) = 24
rt_sigaction(SIGINT, {0x805630f, [INT], SA_RESTART}, {0x805630f, [INT], SA_RESTART}, 8) = 0
read(3, "150 File status OK ; about to op"..., 1024) = 52
write(1, "150 File status OK ; about to op"..., 51) = 51
rt_sigaction(SIGINT, {0x805630f, [INT], SA_RESTART}, {0x805630f, [INT], SA_RESTART}, 8) = 0
rt_sigaction(SIGINT, {0x8057fdd, [INT], SA_RESTART}, {0x805630f, [INT], SA_RESTART}, 8) = 0
accept(5, 
(#wating...)
----

the source is below:
------
static FILE *
dataconn(const char *lmode)
{
	struct sockaddr_in from;
	int s, tos;
	socklen_t fromlen = sizeof(from);

                      if (passivemode)
                      return (fdopen(data, lmode));

	s = accept(data, (struct sockaddr *) &from, &fromlen);    --> (here is the problem which block happen.)
	if (s < 0) {
		perror("ftp: accept");
		(void) close(data), data = -1;
		return (NULL);
	}
	(void) close(data);
	data = s;
#ifdef IP_TOS
	tos = IPTOS_THROUGHPUT;
	if (setsockopt(s, IPPROTO_IP, IP_TOS, (char *)&tos, sizeof(int)) < 0)
		perror("ftp: setsockopt TOS (ignored)");
#endif
	return (fdopen(data, lmode));
}

------

i search the internet , and found accept will block the process.
is it a bug? i don't kown how to deal with it. 
can somebody give me a hand to solve it??? 
thank you.

** Affects: netkit-ftp (Ubuntu)
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1130512

Title:
  accept strace block

Status in “netkit-ftp” package in Ubuntu:
  New

Bug description:
  I used ftp (netkit-ftp-0.17) to get some files when prompt was on, the
  block happened.

  ----
  local: test1.css remote: test1.css
  200 PORT command successful.
  150 File status OK ; about to open data connection
  (#block happened. here is wating...)
  ----

  i used strace command to find out the reason.
  the block happened when socket accepted. 
  ---
  write(3, "RETR test1.css\r\n", 24) = 24
  rt_sigaction(SIGINT, {0x805630f, [INT], SA_RESTART}, {0x805630f, [INT], SA_RESTART}, 8) = 0
  read(3, "150 File status OK ; about to op"..., 1024) = 52
  write(1, "150 File status OK ; about to op"..., 51) = 51
  rt_sigaction(SIGINT, {0x805630f, [INT], SA_RESTART}, {0x805630f, [INT], SA_RESTART}, 8) = 0
  rt_sigaction(SIGINT, {0x8057fdd, [INT], SA_RESTART}, {0x805630f, [INT], SA_RESTART}, 8) = 0
  accept(5, 
  (#wating...)
  ----

  the source is below:
  ------
  static FILE *
  dataconn(const char *lmode)
  {
  	struct sockaddr_in from;
  	int s, tos;
  	socklen_t fromlen = sizeof(from);

                        if (passivemode)
                        return (fdopen(data, lmode));

  	s = accept(data, (struct sockaddr *) &from, &fromlen);    --> (here is the problem which block happen.)
  	if (s < 0) {
  		perror("ftp: accept");
  		(void) close(data), data = -1;
  		return (NULL);
  	}
  	(void) close(data);
  	data = s;
  #ifdef IP_TOS
  	tos = IPTOS_THROUGHPUT;
  	if (setsockopt(s, IPPROTO_IP, IP_TOS, (char *)&tos, sizeof(int)) < 0)
  		perror("ftp: setsockopt TOS (ignored)");
  #endif
  	return (fdopen(data, lmode));
  }

  ------

  i search the internet , and found accept will block the process.
  is it a bug? i don't kown how to deal with it. 
  can somebody give me a hand to solve it??? 
  thank you.

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