Your message dated Sun, 26 Feb 2012 20:05:12 +0000
with message-id
<CAPQ4b8kqJjzbUpQkwWh1hj+L-VV95X1Fx5JW1990A6rh=dk...@mail.gmail.com>
and subject line Re: aptitude hung in 100% cpu endless loop in prompt_string()
[patch to fix included]
has caused the Debian Bug report #352341,
regarding aptitude hung in 100% cpu endless loop in prompt_string() [patch to
fix included]
to be marked as done.
This means that you claim that the problem has been dealt with.
If this is not the case it is now your responsibility to reopen the
Bug report if necessary, and/or fix the problem forthwith.
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--
352341: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=352341
Debian Bug Tracking System
Contact [email protected] with problems
--- Begin Message ---
Package: aptitude
Version: 0.2.15.9-2
aptitude sometimes goes into an endless loop.
problem is the implementation of prompt_sting in src/cmdline/cmdline_prompt.cc
line 263 ...
static string prompt_string()
{
string rval;
char buf[1024];
cin.getline(buf, 1023);
rval+=buf;
while(!cin)
{
cin.getline(buf, 1023);
rval+=buf;
}
return rval;
}
to excercise the problem, here is a stripped down and slightly modified version
of that function, including example output:
===========================================================
#include <string>
#include <iostream>
using namespace std;
static string prompt_string_buggy()
{
string rval;
char buf[2];
cin.getline(buf, 2);
rval+=buf;
cerr << " :" << rval << endl;
while(!cin)
{
static int i = 0;
if (i++ > 10) {
cerr << "looping... exiting!" << endl;
exit(1);
}
cin.getline(buf, 2);
rval+=buf;
cerr << " :" << rval << endl;
}
return rval;
}
int main(int argc, char** argv)
{
cout << "input??" << endl;
cout << prompt_string_buggy();
return 0;
}
===========================================================
compile that into "prove-bug".
then, do
Bug Example 1: ./prove-bug < /dev/null
input??
:
:
:
:
:
:
:
:
:
:
:
:
looping... exiting!
Bug Example 2: echo 1234 | ./prove-bug
input??
:1
:1
:1
:1
:1
:1
:1
:1
:1
:1
:1
:1
looping... exiting!
whether the library implementation of getline is correct in not adjusting
the
offset (bug example 2), I don't know. this might be a different bug.
clearly the current implementation does not what is intended in the corner
cases of end-of-file or very-long-input.
a simple fix is to simply use the global getline(istream cin,string rval);
instead of that looping construct...
similar at the other places where prompt_string() or cin.getline() is used.
my suggested patch is this:
==================================================================
diff -ru aptitude-0.2.15.9/src/cmdline/cmdline_prompt.cc
aptitude-0.2.15.9_fixed/src/cmdline/cmdline_prompt.cc
--- aptitude-0.2.15.9/src/cmdline/cmdline_prompt.cc 2006-02-11
11:25:00.000000000 +0100
+++ aptitude-0.2.15.9_fixed/src/cmdline/cmdline_prompt.cc 2006-02-11
12:46:07.000000000 +0100
@@ -258,24 +258,6 @@
N_("The following packages will be upgraded:"),
};
-// Probably something like cin.getline() would work, but I don't trust that
-// for interactive use.
-static string prompt_string()
-{
- string rval;
- char buf[1024];
- cin.getline(buf, 1023);
- rval+=buf;
-
- while(!cin)
- {
- cin.getline(buf, 1023);
- rval+=buf;
- }
-
- return rval;
-}
-
/** Checks for broken/deleted essential packages and displays a big
* fat warning message about them. Returns false if the user doesn't
* want to continue.
@@ -326,15 +308,12 @@
printf(_("WARNING: Performing this action will probably cause your
system to break!\n Do NOT continue unless you know EXACTLY what you are
doing!\n"));
string prompt=_("I am aware that this is a very bad idea");
- char buf[1024];
+ string buf;
printf(_("To continue, type the phrase \"%s\":\n"), prompt.c_str());
- cin.getline(buf, 1023);
+ getline(cin,buf);
bool rval=(prompt==buf);
- while(!cin)
- cin.getline(buf, 1023);
-
return rval;
}
@@ -383,12 +362,15 @@
{
printf(_("Do you want to ignore this warning and proceed anyway?\n"));
printf(_("To continue, enter \"%s\"; to abort, enter \"%s\": "),
okstr.c_str(), abortstr.c_str());
- char buf[1024];
- cin.getline(buf, 1023);
- buf[1023]='\0';
+ string buf;
+ getline(cin,buf);
+
+ // io-error or end-of-file: do not continue.
+ if(cin.fail() || cin.eof())
+ return false;
- const bool is_ok=(strncasecmp(okstr.c_str(), buf, okstr.size())==0);
- const bool is_abort=(strncasecmp(abortstr.c_str(), buf,
abortstr.size())==0);
+ const bool is_ok=(strncasecmp(okstr.c_str(), buf.c_str(),
okstr.size())==0);
+ const bool is_abort=(strncasecmp(abortstr.c_str(), buf.c_str(),
abortstr.size())==0);
const bool rval=is_ok;
@@ -663,7 +645,8 @@
printf(_("No packages to show -- enter the package names on the line after
'i'.\n"));
printf(_("Press Return to continue."));
- prompt_string();
+ string sink;
+ getline(cin,sink);
}
// Erm. Merge w/ above?
@@ -694,7 +677,8 @@
do_cmdline_changelog(packages);
printf(_("Press Return to continue."));
- prompt_string();
+ string sink;
+ getline(cin,sink);
}
bool cmdline_do_prompt(bool as_upgrade,
@@ -732,9 +716,14 @@
printf(_("Do you want to continue? [Y/n/?] "));
fflush(stdout);
- string response=prompt_string();
- string::size_type loc=0;
+ string response;
+ getline(cin,response);
+
+ // io-error or end-of-file: do not continue.
+ if(cin.fail() || cin.eof())
+ return false;
+ string::size_type loc=0;
while(loc<response.size() && isspace(response[loc]))
++loc;
==================================================================
Thanks,
--
: Lars Ellenberg Tel +43-1-8178292-55 :
: LINBIT Information Technologies GmbH Fax +43-1-8178292-82 :
: Schoenbrunner Str. 244, A-1120 Vienna/Europe http://www.linbit.com :
--- End Message ---
--- Begin Message ---
Hello,
Thank you for your interest in improving Debian, and sorry to keep the
bug unattended for so long. There's now an effort to review the open
bugs related with aptitude and resume development.
It seems that, as the original author writes in a comment, the problem
was fixed long ago, even if it was never closed. Thus doing it now.
Please reopen the bug if it's not properly fixed yet, or if the same
code causes similar problems.
Regards.
--- End Message ---
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