🚀 go-pugleaf

re: bug in istream "get" function.

If you do a "get(buf, len, delim)" which happens to return zero
characters because the delim is the very next character then failbit
is incorrectly set.

The problem seems to be in libg++/iostream/igetline.C where it sets
failbit if count <= 0 (this is done in a couple of places).  Does it
make sense to change that to "< 0"?

>From igetline.C ...

istream& istream::getline(char* buf, int len, char delim)
{
    _gcount = 0;
    if (ipfx1()) {
        long count = rdbuf()->sgetline(buf, len, delim, 0);
        _gcount = count;
        if (count <= 0 || count == len-1)  // <--
            set(ios::failbit);
    }
    return *this;
}

------------------------

Example demonstrating inconsistency between AT&T iostream and
libg++2.2.  ...

Script started on Tue Nov 17 15:26:17 1992
Lindy:/main/niz[1]> cat iobug.C
#include <iostream.h>
//  Demonstrates a bug in libg++ 2.2 istream "get" procedure.
main() {
   char buf[100];
   do {
      cin.get(buf, 100, '\n');
      cout << "returns: '" << buf << "'" << endl;
      char ch; cin.get(ch);
   } while (cin.good());
   cout << "eof=" << cin.eof() << ", fail=" << cin.fail() << endl;
}

Lindy:/main/niz[2]> CC iobug.C
Lindy:/main/niz[3]> a.out
null line follows

returns: 'null line follows'
returns: ''
now more lines follow
returns: 'now more lines follow'
end of file is next
returns: 'end of file is next'
^D
returns: 'end of file is next'
eof=1, fail=2
Lindy:/main/niz[4]> g++ -v iobug.C
Reading specs from /usr/local/lib/gcc-lib/sparc-sun-sunos4.1/2.3.1/specs
gcc version 2.3.1
 /usr/local/lib/gcc-lib/sparc-sun-sunos4.1/2.3.1/cpp -lang-c++ -v -undef -D__GNUC__=2 -D__GNUG__=2 -D__cplusplus -Dsparc -Dsun -Dunix -D__sparc__ -D__sun__ -D__unix__ -D__sparc -D__sun -D__unix iobug.C /usr/tmp/cca06172.i
GNU CPP version 2.3.1 (sparc)
 /usr/local/lib/gcc-lib/sparc-sun-sunos4.1/2.3.1/cc1plus /usr/tmp/cca06172.i -quiet -dumpbase iobug.cc -version -o /usr/tmp/cca06172.s
GNU C++ version 2.3.1 (sparc) compiled by GNU C version 2.3.1.
 as -o /usr/tmp/cca061721.o /usr/tmp/cca06172.s
 /usr/local/lib/gcc-lib/sparc-sun-sunos4.1/2.3.1/ld -e start -dc -dp /lib/crt0.o -L/usr/local/lib/gcc-lib/sparc-sun-sunos4.1/2.3.1 -L/usr/local/lib /usr/tmp/cca061721.o -lg++ -lgcc -lc -lgcc
Lindy:/main/niz[5]> a.out
null line follows
returns: 'null line follows'
returns: ''

eof=0, fail=2
^D
Lindy:/main/niz[6]> exit
script done on Tue Nov 17 15:28:19 1992