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path: root/sysdeps/unix/sysv/linux/if_index.c
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Diffstat (limited to 'sysdeps/unix/sysv/linux/if_index.c')
-rw-r--r--sysdeps/unix/sysv/linux/if_index.c107
1 files changed, 83 insertions, 24 deletions
diff --git a/sysdeps/unix/sysv/linux/if_index.c b/sysdeps/unix/sysv/linux/if_index.c
index 615a81d14a..7d7fc02717 100644
--- a/sysdeps/unix/sysv/linux/if_index.c
+++ b/sysdeps/unix/sysv/linux/if_index.c
@@ -113,62 +113,85 @@ if_nameindex (void)
int fd = opensock ();
struct ifconf ifc;
unsigned int rq_ifs = 4, nifs, i;
+ int rq_len;
struct if_nameindex *idx = NULL;
+#ifdef SIOCGIFCOUNT
+ static int siocgifcount_works = 1;
+#endif
if (fd < 0)
return NULL;
+#ifdef SIOCGIFCOUNT
+ /* We may be able to find out how many interfaces really exist, rather
+ than guessing. This ioctl is not present in kernels before version
+ 2.1.50. */
+ if (siocgifcount_works)
+ {
+ int serrno = errno;
+
+ if (ioctl (fd, SIOCGIFCOUNT, &nifs) < 0)
+ {
+ if (errno == EINVAL)
+ {
+ siocgifcount_works = 0;
+ __set_errno (serrno);
+ }
+ }
+ else
+ rq_ifs = nifs + 1;
+ }
+#endif
+
ifc.ifc_buf = NULL;
/* Read all the interfaces out of the kernel. */
do
{
- rq_ifs *= 2;
- ifc.ifc_len = rq_ifs * sizeof (struct ifreq);
- ifc.ifc_buf = realloc (ifc.ifc_buf, ifc.ifc_len);
- if (ifc.ifc_buf == NULL)
+ rq_len = ifc.ifc_len = rq_ifs * sizeof (struct ifreq);
+ ifc.ifc_buf = alloca (ifc.ifc_len);
+ if ((ifc.ifc_buf == NULL) || (ioctl (fd, SIOCGIFCONF, &ifc) < 0))
{
- close(fd);
+ close (fd);
return NULL;
}
- if (ioctl (fd, SIOCGIFCONF, &ifc) < 0)
- goto jump;
+ rq_ifs *= 2;
}
- while ((unsigned int) ifc.ifc_len == (rq_ifs * sizeof (struct ifreq)));
+ while (ifc.ifc_len == rq_len);
nifs = ifc.ifc_len / sizeof (struct ifreq);
- ifc.ifc_buf = realloc (ifc.ifc_buf, ifc.ifc_len);
- idx = malloc ((nifs+1) * sizeof (struct if_nameindex));
+ idx = malloc ((nifs + 1) * sizeof (struct if_nameindex));
if (idx == NULL)
- goto jump;
+ {
+ close (fd);
+ return NULL;
+ }
for (i = 0; i < nifs; ++i)
{
struct ifreq *ifr = &ifc.ifc_req[i];
- if ((idx[i].if_name = malloc (strlen (ifr->ifr_name)+1)) == NULL)
- {
- free (idx);
- idx = NULL;
- goto jump;
- }
- strcpy (idx[i].if_name, ifr->ifr_name);
- if (ioctl (fd, SIOGIFINDEX, ifr) < 0)
+ idx[i].if_name = __strdup (ifr->ifr_name);
+ if (idx[i].if_name == NULL
+ || ioctl (fd, SIOGIFINDEX, ifr) < 0)
{
int saved_errno = errno;
+ unsigned int j;
+
+ for (j = 0; j < i; ++j)
+ free (idx[j].if_name);
free (idx);
- idx = NULL;
+ close (fd);
if (saved_errno == EINVAL)
__set_errno (ENOSYS);
- goto jump;
+ return NULL;
}
idx[i].if_index = ifr->ifr_ifindex;
}
+
idx[i].if_index = 0;
idx[i].if_name = NULL;
-jump:
- free (ifc.ifc_buf);
close (fd);
return idx;
#endif
@@ -181,10 +204,46 @@ if_indextoname (unsigned int ifindex, char *ifname)
__set_errno (ENOSYS);
return NULL;
#else
- struct if_nameindex *idx = if_nameindex ();
+ struct if_nameindex *idx;
struct if_nameindex *p;
char *result = NULL;
+#ifdef SIOGIFNAME
+ /* We may be able to do the conversion directly, rather than searching a
+ list. This ioctl is not present in kernels before version 2.1.50. */
+ struct ifreq ifr;
+ int fd;
+ static int siogifname_works = 1;
+
+ if (siogifname_works)
+ {
+ int serrno = errno;
+
+ fd = opensock ();
+
+ if (fd < 0)
+ return NULL;
+
+ ifr.ifr_ifindex = ifindex;
+ if (ioctl (fd, SIOGIFNAME, &ifr) < 0)
+ {
+ if (errno == EINVAL)
+ siogifname_works = 0; /* Don't make the same mistake twice. */
+ }
+ else
+ {
+ close (fd);
+ return strncpy (ifname, ifr.ifr_name, IFNAMSIZ);
+ }
+
+ close (fd);
+
+ __set_errno (serrno);
+ }
+#endif
+
+ idx = if_nameindex ();
+
if (idx != NULL)
{
for (p = idx; p->if_index || p->if_name; ++p)