Linux Programming

Quote:

RETURN VALUE
If the connection or binding succeeds, zero is returned. On error, -1 is returned, and errno is set appropriately.

ERRORS
The following are general socket errors only. There may be other domain-specific error codes.

EACCES For UNIX domain sockets, which are identified by pathname: Write permission is denied on the socket file, or
search permission is denied for one of the directories in the path prefix. (See also path_resolution(7).)

EACCES, EPERM
The user tried to connect to a broadcast address without having the socket broadcast flag enabled or the connec‐
tion request failed because of a local firewall rule.

EADDRINUSE
Local address is already in use.

... etc ...

Richard MacCutchan wrote:

The perror() function has been around for years and has always been fairly succinct in its output. The important information is the actual errno value. It is a fairly simple matter to write your own function to display the value and the error message (see strerror(3) - Linux manual page[^]).

Vaclav_ wrote:

check the return value first , then let perror describe the state.

Quote:

The important information is the actual errno value. It is a fairly simple matter to write your own function to display the value and the error message (see strerror(3) - Linux manual page[^]).

Quote:

perror posts “operation now in progress “ which is great to know
BUT connect return “status “ is -1 .
To whom do I trust ?

len = 8;
max_rsp = 255;
flags = IREQ_CACHE_FLUSH;
ii = (inquiry_info*) malloc(max_rsp * sizeof(inquiry_info));
cout << "TASK run hci_inquiry same as hcitoo scan  - takes time  @line "
        << dec << __LINE__ << endl;
num_rsp = hci_inquiry(dev_id, len, max_rsp, NULL, &ii, flags);
perror("STATUS hci_inquiry");
errno = 0;                 // reset !

if (num_rsp < 0)
    perror("FAILED (?) hci_inquiry");

for (i = 0; i < num_rsp; i++) {
    ba2str(&(ii + i)->bdaddr, addr);
    memset(name, 0, sizeof(name));
    if (hci_read_remote_name(dev_descriptor, &(ii + i)->bdaddr,
            sizeof(name), name, 0) < 0)
        strcpy(name, "[unknown]");
    printf("remote address  %s  remote name  %s\n", addr, name);
}

ba2str(&(ii + i)->bdaddr, addr);

char addr[18];
// ...
for( /* ... */ ) {
    sockaddr_rc addr;
    // ...
    ba2str(/* ... */ );
}
// ...

for (i = 0; i < num_rsp; i++) {
// convert bdaddr to array addr for print
    ba2str(&(ii + i)->bdaddr, (char*)addr); // cast addr to a char* : but this may still be a problem
    memset(name, 0, sizeof(name));
    if (hci_read_remote_name(dev_descriptor, &(ii + i)->bdaddr,
            sizeof(name), name, 0) < 0)
        strcpy(name, "[unknown]");
    printf("remote address  %s  remote name  %s\n", addr, name);
}

Description	Resource	Path	Location	Type
invalid cast from type ‘sockaddr_rc’ to type ‘char*’	CBT.cpp	/RPI_BT_CLIENT_ARM_/src/MODULES/M_CBT	line 286	C/C++ Problem

ba2str(&(ii + i)->bdaddr, (char*)&addr); // cast &addr to a char* : but this may still be a problem