Hi all,
I've started using libiberty's hashtab in libgfortran for some of my
gfortran work to track memory allocations in the library. I store
custom structures in a hash table, each structure containing a unique
pointer (it is a malloc'ed address) that is used for the hash. When I
traverse the table elements after having inserted a few, I get twice
the number I expect. It's probably a beginner's mistake, and will be
easy to spot, but I haven't managed to understand what I'm doing
wrong.
Here is a small, self-contained testcase of what I'm doing:
#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include "hashtab.h"
static htab_t tab = NULL;
typedef struct
{
void *p;
const char *file;
} allocation_t;
static hashval_t hashval (const void *a)
{
return htab_hash_pointer (a);
}
static int hasheq (const void *a, const void *b)
{
return (((allocation_t *) a)->p == ((allocation_t *) b)->p);
}
static void do_nothing (void *a __attribute__((unused))) { ; }
void add_entry (const char *file)
{
void *p = malloc (1);
allocation_t *a;
/* Register this allocation. */
a = (allocation_t *) htab_find_slot (tab, p, INSERT);
a->p = p;
a->file = file;
printf ("Inserted at slot: %p\n", a);
}
static int
report_callback (void **slot, void *ptr __attribute__((unused)))
{
printf ("Slot %p in file '%s'\n", slot, ((allocation_t *) slot)->file);
return 1;
}
void
report ()
{
printf ("Number of elements: %lu\n", (unsigned long) htab_elements (tab));
htab_traverse_noresize (tab, report_callback, NULL);
htab_delete (tab);
}
int main (void)
{
tab = htab_create_alloc (128, hashval, hasheq, do_nothing, calloc, free);
add_entry ("foo");
add_entry ("bar");
add_entry ("gee");
report ();
return 0;
}
So, I store three allocation_t structures in the table, each
containing a pointer and a pointer to a constant character string. At
the end, when traversing the hash table, the callback function is
called 6 times:
gcc hash.c -I ../../trunk/include/ -liberty -L lib64 -W -Wall && ./a.out
Inserted at slot: 0x503210
Inserted at slot: 0x503230
Inserted at slot: 0x503250
Number of elements: 3
Slot 0x503210 in file 'foo'
Slot 0x503218 in file '(null)'
Slot 0x503230 in file 'bar'
Slot 0x503238 in file '(null)'
Slot 0x503250 in file 'gee'
Slot 0x503258 in file '(null)'
I'd be glad if someone familiar with libiberty could give me a hint of
what's going wrong.
Thanks,
FX
--
FX Coudert
http://www.homepages.ucl.ac.uk/~uccafco/
