source: asp3_tinet_ecnl_rx/trunk/musl-1.1.18/src/passwd/nscd_query.c@ 337

#include <sys/socket.h>
#include <byteswap.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <limits.h>
#include "nscd.h"

static const struct {
        short sun_family;
        char sun_path[21];
} addr = {
        AF_UNIX,
        "/var/run/nscd/socket"
};

FILE *__nscd_query(int32_t req, const char *key, int32_t *buf, size_t len, int *swap)
{
        size_t i;
        int fd;
        FILE *f = 0;
        int32_t req_buf[REQ_LEN] = {
                NSCDVERSION,
                req,
                strnlen(key,LOGIN_NAME_MAX)+1
        };
        struct msghdr msg = {
                .msg_iov = (struct iovec[]){
                        {&req_buf, sizeof(req_buf)},
                        {(char*)key, strlen(key)+1}
                },
                .msg_iovlen = 2
        };
        int errno_save = errno;

        *swap = 0;
retry:
        memset(buf, 0, len);
        buf[0] = NSCDVERSION;

        fd = socket(PF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0);
        if (fd < 0) return NULL;

        if(!(f = fdopen(fd, "r"))) {
                close(fd);
                return 0;
        }

        if (req_buf[2] > LOGIN_NAME_MAX)
                return f;

        if (connect(fd, (struct sockaddr*)&addr, sizeof(addr)) < 0) {
                /* If there isn't a running nscd we simulate a "not found"
                 * result and the caller is responsible for calling
                 * fclose on the (unconnected) socket. The value of
                 * errno must be left unchanged in this case.  */
                if (errno == EACCES || errno == ECONNREFUSED || errno == ENOENT) {
                        errno = errno_save;
                        return f;
                }
                goto error;
        }

        if (sendmsg(fd, &msg, MSG_NOSIGNAL) < 0)
                goto error;

        if (!fread(buf, len, 1, f)) {
                /* If the VERSION entry mismatches nscd will disconnect. The
                 * most likely cause is that the endianness mismatched. So, we
                 * byteswap and try once more. (if we already swapped, just
                 * fail out)
                 */
                if (ferror(f)) goto error;
                if (!*swap) {
                        fclose(f);
                        for (i = 0; i < sizeof(req_buf)/sizeof(req_buf[0]); i++) {
                                req_buf[i] = bswap_32(req_buf[i]);
                        }
                        *swap = 1;
                        goto retry;
                } else {
                        errno = EIO;
                        goto error;
                }
        }

        if (*swap) {
                for (i = 0; i < len/sizeof(buf[0]); i++) {
                        buf[i] = bswap_32(buf[i]);
                }
        }

        /* The first entry in every nscd response is the version number. This
         * really shouldn't happen, and is evidence of some form of malformed
         * response.
         */
        if(buf[0] != NSCDVERSION) {
                errno = EIO;
                goto error;
        }

        return f;
error:
        fclose(f);
        return 0;
}