Debugging with GDB Manual (5900-1473; WDB 6.2; January 2011)

return -1;
}
fd = open("testfile", O_RDWR);
if ( fd == -1 )
{
perror("open");
return -1;
}
p = mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
assert( p != (void *)-1 );
q = mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE, devzfd, 0);
assert( q != (void *)-1 );
r = mmap(NULL, 4096, PROT_READ, MAP_PRIVATE, fd, 0);
assert( r != (void *)-1 );
s = mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
assert( s != (void *)-1 );
t = mmap(NULL, 4096, PROT_READ, MAP_SHARED, fd, 0);
assert( t != (void *)-1 );
fd2 = open("testfile2", O_RDWR);
if ( fd2 == -1 )
{
perror("open");
return -1;
}
u = mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_SHARED, fd2, 0);
if (u == MAP_FAILED)
printf("PROT_READ|PROT_WRITE, MAP_SHARED failed, errno = %d\n", errno);
else
assert( u != (void *)-1 );
printf("p %p q %p r %p s %p t %p u %p\n", p, q, r, s, t, u);
abort();
return 0;
}
Compile and run the program to generate a core.
$ aCC -Ae -o mmap_test -g mmap.c
$ ./mmap_test
p 7aadc000 q 7aadb000 r 7aada000 s 7aad9000 t c1a91000 u c4406000 ABORT instruction (core dumped)
Now, debug the core file with gdb.
$ gdb mmap_test core
…
Core was generated by `mmap_test'.
Program terminated with signal 6, Aborted.
#0 0x60000000c035d750:0 in kill+0x30 () from /usr/lib/hpux32/libc.so.1
(gdb) frame 3
#3 0x4001400:0 in main () at mmap.c:55
55 abort();
(gdb) p p
$2 = 0x200000007aadc000 ""
(gdb) p q
$3 = 0x200000007aadb000 ""
(gdb) p r
$4 = 0x200000007aada000 <Address 0x200000007aada000 out of bounds>(gdb) p s
$5 = 0x200000007aad9000 "#include <stdlib.h>\n#include <stdio.h>\nint main(){\n foo();\n
bar();\n return 0;\n}\nint foo(){\n int * res = malloc(4);\n printf(\"*res %d\\n\", *res);\n
return 1;\n}\nint bar(){\n printf(\"Hel"...
(gdb) p t
$6 = 0x60000000c1a91000 <Address 0x60000000c1a91000 out of bounds>
14.15 Debugging Core Files 201