cygwin1.dll (v1.1.2): dup2() with invalid newfd lead to exception: STATUS_ACCESS_VIOLATION

[Alexander Trush <trush at kbotd dot ru>]

Hi!

I have loaded the last version of the environment CygWin and attempted to compile SQUID-2.3.STABLE3. In the configurator SQUID there is a piece of the code: " checking Maximum number of filedescriptors we can open ", this code utillize the function dup2(), which one with invalid value of argument reduces to in crash of the program instead of returning an error code.

Piece of this code:

#include "confdefs.h"

#include <stdio.h>
#include <unistd.h>
#include <sys/time.h>   /* needed on FreeBSD */
#include <sys/param.h>
#include <sys/resource.h>
main() {
        FILE *fp;
        int i,j;
#if __CYGWIN32__
    /* getrlimit and sysconf returns bogous values on cygwin32.
     * Number of fds is virtually unlimited in cygwin (sys/param.h)
     */
    i = NOFILE;
#elif HAVE_SETRLIMIT
    struct rlimit rl;
#if defined(RLIMIT_NOFILE)
    if (getrlimit(RLIMIT_NOFILE, &rl) < 0) {
        perror("getrlimit: RLIMIT_NOFILE");
    } else {
        rl.rlim_cur = rl.rlim_max;      /* set it to the max */
        if (setrlimit(RLIMIT_NOFILE, &rl) < 0) {
            perror("setrlimit: RLIMIT_NOFILE");
        }
    }
#elif defined(RLIMIT_OFILE)
    if (getrlimit(RLIMIT_OFILE, &rl) < 0) {
        perror("getrlimit: RLIMIT_OFILE");
    } else {
        rl.rlim_cur = rl.rlim_max;      /* set it to the max */
        if (setrlimit(RLIMIT_OFILE, &rl) < 0) {
            perror("setrlimit: RLIMIT_OFILE");
        }
    }
#endif /* RLIMIT_NOFILE */
#endif /* HAVE_SETRLIMIT */
        /* by starting at 2^14, we will never get higher
        than 2^15 for SQUID_MAXFD */
        i = j = 1<<14;
        while (j) {
                j >>= 1;
                if (dup2(0, i) < 0) {
                        i -= j;
                } else {
                        close(i);
                        i += j;
                }
        }
        i++;
        fp = fopen("conftestval", "w");
        fprintf (fp, "%d\n", i);
        exit(0);
}
 
 
 

The elementary test routine resulting in to the same result (under Borland 5.02 all is correct - " Ret val =-1, errno=0 "):
 

test.c:
-------
#include <stdio.h>
#include <io.h>
#include <errno.h>

void main(void)
{
        printf("Ret val=%d, errno=%d", dup2(0, 1<<14), errno);
}
 
 

bash-2.04$ cd /usr/src/squid-2.3.STABLE3
bash-2.04$ gcc test.c -o test.exe
test.c: In function `main':
test.c:6: warning: return type of `main' is not `int'
bash-2.04$ ./test.exe
      0 [main] test 1008 handle_exceptions: Exception: STATUS_ACCESS_VIOLATION
   1392 [main] test 1008 stackdump: Dumping stack trace to test.exe.stackdump
bash-2.04$
 

test.exe.stackdump:
-------------------
Exception: STATUS_ACCESS_VIOLATION at eip=6101F19A
eax=0A040E08 ebx=FFFFFFFF ecx=7FFDE000 edx=61084BE8 esi=00004000 edi=0A0416B8
ebp=0246FE5C esp=0246FE40 program=c:\CygWIN\usr\src\squid-2.3.STABLE3\test.exe
cs=001B ds=0023 es=0023 fs=003B gs=0000 ss=0023
Stack trace:
Frame     Function  Args
0246FE5C  6102F23B  (61084BE8, 00000000, 00004000, 0247273B)
0246FE7C  6102F23B  (00000000, 00004000, 0246FEC8, 0246FEA4)
0246FEA4  0040107F  (00000001, 0A041688, 0A040008, 00000000)
0246FF00  61002385  (7FFDF000, 00000000, 0247DF10, 77F9D0E8)
0246FF60  610027D5  (00403010, C0059000, 0246FF90, 004011BA)
0246FF90  004011C7  (00401058, 815C04C0, 00000246, 801174E1)
0246FFC0  0040103B  (0247DF10, 00000000, 7FFDF000, 7FFDF000)
0246FFF0  77F1B9EA  (00401000, 00000000, 000000B0, 00000100)
End of stack trace