On Tuesday, 29 November 2016 at 15:30:33 UTC, Anders S wrote:
Hi guys,
I want to write into a fifo pipe using write( ...)
Now a gather my data into my own struct IOREQ so in order to
write I have to cast into an char buffer.
My problem in dlang is that it doesn't accept the casting
(IOREQ *) I get:
Error: Cannot implicitly convert expression (&sbuf) of type
char [1024] to IOREQ*
define FC_GETSTATUS 501;
typedef struct {
SHORT fc; /* function code */
SHORT rs; /* return code */
INT size; /* size of this request,
including header */
SHORT src; /* source */
....
INT argv[1]; /* list of arguments */
} IOREQ;
int WritePipe(int fd, int mess, int argc)
{
struct IOREQ * io; // my array of data
char sbuf[1024];
io = (IOREQ *)buf; // Not accepted in dlang
io.fc = FC_GETSTATUS;
io.src = getpid(); // works
..... // add more data
st = write(fd, sbuf, 1024); //
return st;
}
First, instead of:
typedef struct {
SHORT fc; /* function code */
SHORT rs; /* return code */
INT size; /* size of this request, including */
SHORT src; /* source */
....
INT argv[1]; /* list of arguments */
} IOREQ;
just
struct IOREQ {
SHORT fc; /* function code */
SHORT rs; /* return code */
INT size; /* size of this request, including */
SHORT src; /* source */
....
INT argv[1]; /* list of arguments */
} IOREQ;
Then, `write` has the following definition:
https://github.com/dlang/druntime/blob/master/src/core/sys/posix/unistd.d#L100
`ssize_t write(int, in void*, size_t);`
so, it accepts pointer to anything, no need to mess with `char[]`:
IOREQ mystruct;
mystruct.src = getpid();
// etc...
// write it out
write(fd, &mystruct, mystruct.sizeof); // todo: Don't forget
to check for
// the return value,
etc.
