gdb trouble with stdin redirection

Question

Hi, I'm writing a program to implement Dinic's max-flow algorithm over a network. The networks can be written either by hand or loaded from a file using stdin redirection. I've been able to use gdb to debug the program with small files (around 30 lines), but I'm having trouble when I try to debug the program with bigger files (>1000 lines). The code itself is this:

uint32_t read_lines = 0;
while(!feof(stdin))
{
    err = fscanf(stdin, "%u %u %u\n", &n1, &n2, &c);
    if (err != 3)
    {
         printf("read_lines=%u\n", read_lines); /*for debugging purposes*/
    }
    read_lines += 1;
    /* write to debug file */
    fprintf(debug, "line %u: %u %u %u\n", read_lines, n1, n2, c);
}

If I run the program without gdb, it runs, not ok as it generates a segmentation fault (which is the reason I'm trying to use gdb), but it goes through this part of "parsing" the input file (and writing it into the output debugging file). However, if I type:

gdb --args ./dinic --mode=NUM --verbose=LOW
(gdb) b 61
(gdb) run < tests/numterc.in

I get:

(gdb) Program exited with 01 code.

and when I open the debugging file it's about 2000 lines, when it should be at most 1000, which is the input file length.

I repeat, this happens with "big" files, it works correct with small ones. The question would be, ¿am I missing something when using gdb, or is this a gdb bug? Thanks in advance

Answer 1

Ok, I could finally get a work-around. It seems that the --args option ain't working well, at least in my case. I have gdb 6.8-debian and debian 5.0.4.

What I had to do was run gdb without the --args option:

$gdb ./dinic
(gdb) b 61
(gdb) run --mode=NUM --verbose=LOW < tests/numterc.in

and it worked well. Maybe someone can find this useful.