Compile warning due to calloc parameter reversal

[garybuhrmaster]

Compile warning due to calloc parameter reversal

When compiling libhdhomerun with a recent gcc one may receive warnings of the form:

hdhomerun_discover.c: In function ‘hdhomerun_discover_sock_add_ipv6’:
hdhomerun_discover.c:123:99: warning: ‘calloc’ sizes specified with ‘sizeof’ in the earlier argument and not in the later argument [-Wcalloc-transposed-args]
  123 |         struct hdhomerun_discover_sock_t *dss = (struct hdhomerun_discover_sock_t *)calloc(sizeof(struct hdhomerun_discover_sock_t), 1);
      |                                                                                                   ^~~~~~
hdhomerun_discover.c:123:99: note: earlier argument should specify number of elements, later size of each element

Both hdhomerun_discover.c and hdhomerun_sock_netdevice.c have the reversed order of the parameters (other uses in the library call calloc correctly)

In practice the resulting buffer will be the same size (n elements of size 1, and 1 element of size n, should end up with the same number of bytes), but recent gcc's can detect the misuse when the -Wcalloc-transposed-args is used.

Proposed fix (compile tested only):

diff --git a/hdhomerun_discover.c b/hdhomerun_discover.c
index 8dae716..24e3cb5 100644
--- a/hdhomerun_discover.c
+++ b/hdhomerun_discover.c
@@ -120,7 +120,7 @@ static void hdhomerun_discover_sock_add_ipv6(void *arg, uint32_t ifindex, const
        }
 
        /* Create socket. */
-       struct hdhomerun_discover_sock_t *dss = (struct hdhomerun_discover_sock_t *)calloc(sizeof(struct hdhomerun_discover_sock_t), 1);
+       struct hdhomerun_discover_sock_t *dss = (struct hdhomerun_discover_sock_t *)calloc(1, sizeof(struct hdhomerun_discover_sock_t));
        if (!dss) {
                hdhomerun_debug_printf(ds->dbg, "discover: resource error\n");
                return;
@@ -181,7 +181,7 @@ static void hdhomerun_discover_sock_add_ipv4(void *arg, uint32_t ifindex, const
        }
 
        /* Create socket. */
-       struct hdhomerun_discover_sock_t *dss = (struct hdhomerun_discover_sock_t *)calloc(sizeof(struct hdhomerun_discover_sock_t), 1);
+       struct hdhomerun_discover_sock_t *dss = (struct hdhomerun_discover_sock_t *)calloc(1, sizeof(struct hdhomerun_discover_sock_t));
        if (!dss) {
                hdhomerun_debug_printf(ds->dbg, "discover: resource error\n");
                return;
@@ -347,7 +347,7 @@ static void hdhomerun_discover_sock_detect_ipv6_localhost(struct hdhomerun_disco
                return;
        }
 
-       struct hdhomerun_discover_sock_t *dss = (struct hdhomerun_discover_sock_t *)calloc(sizeof(struct hdhomerun_discover_sock_t), 1);
+       struct hdhomerun_discover_sock_t *dss = (struct hdhomerun_discover_sock_t *)calloc(1, sizeof(struct hdhomerun_discover_sock_t));
        if (!dss) {
                return;
        }
@@ -378,7 +378,7 @@ static void hdhomerun_discover_sock_detect_ipv4_localhost(struct hdhomerun_disco
                return;
        }
 
-       struct hdhomerun_discover_sock_t *dss = (struct hdhomerun_discover_sock_t *)calloc(sizeof(struct hdhomerun_discover_sock_t), 1);
+       struct hdhomerun_discover_sock_t *dss = (struct hdhomerun_discover_sock_t *)calloc(1, sizeof(struct hdhomerun_discover_sock_t));
        if (!dss) {
                return;
        }
@@ -820,7 +820,7 @@ static void hdhomerun_discover_recv_internal_device_type(struct hdhomerun_discov
                p = p->next;
        }
 
-       struct hdhomerun_discover2_device_type_t *new_type = (struct hdhomerun_discover2_device_type_t *)calloc(sizeof(struct hdhomerun_discover2_device_type_t), 1);
+       struct hdhomerun_discover2_device_type_t *new_type = (struct hdhomerun_discover2_device_type_t *)calloc(1, sizeof(struct hdhomerun_discover2_device_type_t));
        if (!new_type) {
                return;
        }
@@ -1231,8 +1231,8 @@ static bool hdhomerun_discover_recvfrom(struct hdhomerun_discover_t *ds, struct
                return activity;
        }
 
-       struct hdhomerun_discover2_device_t *device = (struct hdhomerun_discover2_device_t *)calloc(sizeof(struct hdhomerun_discover2_device_t), 1);
-       struct hdhomerun_discover2_device_if_t *device_if = (struct hdhomerun_discover2_device_if_t *)calloc(sizeof(struct hdhomerun_discover2_device_if_t), 1);
+       struct hdhomerun_discover2_device_t *device = (struct hdhomerun_discover2_device_t *)calloc(1, sizeof(struct hdhomerun_discover2_device_t));
+       struct hdhomerun_discover2_device_if_t *device_if = (struct hdhomerun_discover2_device_if_t *)calloc(1, sizeof(struct hdhomerun_discover2_device_if_t));
        if (!device || !device_if) {
                if (device) {
                        free(device);
diff --git a/hdhomerun_sock_netdevice.c b/hdhomerun_sock_netdevice.c
index cd3eb2b..0d8901e 100644
--- a/hdhomerun_sock_netdevice.c
+++ b/hdhomerun_sock_netdevice.c
@@ -59,7 +59,7 @@ bool hdhomerun_local_ip_info2(int af, hdhomerun_local_ip_info2_callback_t callba
        }
 
        int ifreq_buffer_size = 128 * sizeof(struct ifreq);
-       char *ifreq_buffer = (char *)calloc(ifreq_buffer_size, 1);
+       char *ifreq_buffer = (char *)calloc(1, ifreq_buffer_size);
        if (!ifreq_buffer) {
                close(sock);
                return false;

[garybuhrmaster]

minor edit to add a space after a comma in the first loc change for legibility.

[nickkelsey]

Good catch... will get it changed. Thanks

[garybuhrmaster]

Good catch... will get it changed. Thanks

Thanks. Obviously low priority in the grand scheme of things.

TBH, I didn't catch anything (and I probably would not have on my own as I usually use others packages), but gcc did as part of my initial/early/preliminary builds of packages for (the future) CentOS Stream 10 that I find of interest at this time, and it was a warning that I could easily understand how to address.