Re: isprint core dump
On Mon, Jan 23, 2012 at 10:34 PM, Nellis, Kenneth wrote: From: Eric Blake No, but it DOES come from POSIX: http://pubs.opengroup.org/onlinepubs/9699919799/functions/isprint.html And cygwin's behavior matches POSIX on this point; the bug is in your program, not cygwin. Call me blown away by the level of support this function that dumps core is getting, when it could act sanely (IMHO) with a simple if statement! So much for defensive programming. Like it or not, this is how C works. If you want defensive programming with bounds checking and stuff, try Pascal or Java. The man page of isprint states: int isprint(int c); These functions check whether c, which must have the value of an unsigned char or EOF... ^^^ If the argument has any other value, the behavior is undefined. This is a contract between the library and you, the library user. You promise to pass an argument between -1 and 255. isprint promises to return a correct result. You didn't keep your promise, so isprint is free to do anything it wants including, but not limited to, opening your web browser at http://nooo.com/ Csaba -- GCS a+ e++ d- C++ ULS$ L+$ !E- W++ P+++$ w++$ tv+ b++ DI D++ 5++ The Tao of math: The numbers you can count are not the real numbers. Life is complex, with real and imaginary parts. Ok, it boots. Which means it must be bug-free and perfect. -- Linus Torvalds People disagree with me. I just ignore them. -- Linus Torvalds -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
Re: isprint core dump
On 23/01/2012 3:16 PM, Nellis, Kenneth wrote: I haven't had the chance to try under Linux, but isprint(3055872) is core-dumping on me. From the isprint() man page: /c/ ... must have the value of an /unsigned char/ or *EOF* The test case probably overruns some internal table by 3MB or so. Ryan -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
Re: isprint core dump
On Mon, Jan 23, 2012 at 3:16 PM, Nellis, Kenneth
kenneth.nel...@acs-inc.com wrote:
I haven't had the chance to try under Linux, but
isprint(3055872)
is core-dumping on me. Here's a STC:
==
#include stdio.h
#include ctype.h
int main (void)
{
int a = 3055872;
int b = isprint(a);
printf (%d %d\n, a, b);
return 0;
}
==
Whatever you are trying to do, you are using the wrong tool for the
job. isprint() should be passed a char, in fact it only works on
ASCII characters.
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RE: isprint core dump
From: Ryan Johnson From the isprint() man page: /c/ ... must have the value of an /unsigned char/ or *EOF* FWIW, that didn't come from the cygwin man page. --Ken Nellis -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
Re: isprint core dump
On 01/23/2012 01:44 PM, Nellis, Kenneth wrote: From: Ryan Johnson From the isprint() man page: /c/ ... must have the value of an /unsigned char/ or *EOF* FWIW, that didn't come from the cygwin man page. No, but it DOES come from POSIX: http://pubs.opengroup.org/onlinepubs/9699919799/functions/isprint.html And cygwin's behavior matches POSIX on this point; the bug is in your program, not cygwin. -- Eric Blake ebl...@redhat.com+1-919-301-3266 Libvirt virtualization library http://libvirt.org signature.asc Description: OpenPGP digital signature
RE: isprint core dump
From: Eric Blake No, but it DOES come from POSIX: http://pubs.opengroup.org/onlinepubs/9699919799/functions/isprint.html And cygwin's behavior matches POSIX on this point; the bug is in your program, not cygwin. Call me blown away by the level of support this function that dumps core is getting, when it could act sanely (IMHO) with a simple if statement! So much for defensive programming. --Ken Nellis -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
Re: isprint core dump
On 01/23/2012 02:34 PM, Nellis, Kenneth wrote: From: Eric Blake No, but it DOES come from POSIX: http://pubs.opengroup.org/onlinepubs/9699919799/functions/isprint.html And cygwin's behavior matches POSIX on this point; the bug is in your program, not cygwin. Call me blown away by the level of support this function that dumps core is getting, when it could act sanely (IMHO) with a simple if statement! So much for defensive programming. If you want defensive programming, write the defense into your program - don't call functions with invalid arguments in the first place. It costs time to process an if() statement that would be reached by every single caller, when 99.99% of the callers already comply with the standards. Meanwhile, since cygwin inherits its isprint() implementation from newlib, and newlib caters to embedded systems, you will be fighting an uphill battle to add anything that adds bloat that slows down an embedded client. We already get complaints about cygwin being too slow, and you are proposing making it slower by doing safety-net checking for buggy programs. So we ask instead that you put the if() in your program, and not in the core isprint() implementation. -- Eric Blake ebl...@redhat.com+1-919-301-3266 Libvirt virtualization library http://libvirt.org signature.asc Description: OpenPGP digital signature
Re: isprint core dump
On 23/01/2012 4:39 PM, Eric Blake wrote: On 01/23/2012 02:34 PM, Nellis, Kenneth wrote: From: Eric Blake No, but it DOES come from POSIX: http://pubs.opengroup.org/onlinepubs/9699919799/functions/isprint.html And cygwin's behavior matches POSIX on this point; the bug is in your program, not cygwin. Call me blown away by the level of support this function that dumps core is getting, when it could act sanely (IMHO) with a simple if statement! So much for defensive programming. If you want defensive programming, write the defense into your program - don't call functions with invalid arguments in the first place. It costs time to process an if() statement that would be reached by every single caller, when 99.99% of the callers already comply with the standards. That, and the if() would almost certainly mask the bug -- there's no value isprint() can return to signal an error, and if the sad state of errno and error code checking in general is any indication, the error condition would be ignored by 99.99% of buggy callers even if isprint() did signal it in some way. I, for one, prefer my invalid code to trigger a nice, predictable seg fault immediately, rather than returning undefined results and/or causing malloc() to barf at some indeterminate point in the future. Ryan -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple
