chiark / gitweb /
nss-myhostname: use _cleanup_ and split function into two
authorZbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
Sat, 30 Mar 2013 14:46:04 +0000 (10:46 -0400)
committerZbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
Sun, 31 Mar 2013 18:32:32 +0000 (14:32 -0400)
The triply nested loop is just too much. Let's split out the
middle loop's body, so the whole thing is easier to read. Also
modernize the style a bit, using structure initialization to
avoid memset and such.

src/nss-myhostname/netlink.c

index 53c3b50..2329f00 100644 (file)
 #include <stdlib.h>
 
 #include "ifconf.h"
+#include "macro.h"
+#include "util.h"
 
-int ifconf_acquire_addresses(struct address **_list, unsigned *_n_list) {
+#define SEQ 4711
 
+static int read_reply(int fd, struct address **list, unsigned *n_list) {
+        ssize_t bytes;
+        struct cmsghdr *cmsg;
+        struct ucred *ucred;
+        struct nlmsghdr *p;
+        uint8_t cred_buffer[CMSG_SPACE(sizeof(struct ucred))];
         struct {
                 struct nlmsghdr hdr;
-                struct rtgenmsg gen;
-        } req;
-        struct rtgenmsg *gen;
-        int fd, r, on = 1;
-        uint32_t seq = 4711;
-        struct address *list = NULL;
-        unsigned n_list = 0;
-
-        fd = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE);
-        if (fd < 0)
+                struct ifaddrmsg ifaddrmsg;
+                uint8_t payload[16*1024];
+        } resp;
+        struct iovec iov = {
+                .iov_base = &resp,
+                .iov_len = sizeof(resp),
+        };
+        struct msghdr msg = {
+                .msg_name = NULL,
+                .msg_namelen = 0,
+                .msg_iov = &iov,
+                .msg_iovlen = 1,
+                .msg_control = cred_buffer,
+                .msg_controllen = sizeof(cred_buffer),
+                .msg_flags = 0,
+        };
+
+        assert(fd >= 0);
+        assert(list);
+
+        bytes = recvmsg(fd, &msg, 0);
+        if (bytes < 0)
                 return -errno;
 
-        if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on)) < 0) {
-                r = -errno;
-                goto finish;
-        }
+        cmsg = CMSG_FIRSTHDR(&msg);
+        if (!cmsg || cmsg->cmsg_type != SCM_CREDENTIALS)
+                return -EIO;
 
-        memset(&req, 0, sizeof(req));
-        req.hdr.nlmsg_len = NLMSG_LENGTH(sizeof(struct rtgenmsg));
-        req.hdr.nlmsg_type = RTM_GETADDR;
-        req.hdr.nlmsg_flags = NLM_F_REQUEST|NLM_F_DUMP|NLM_F_ACK;
-        req.hdr.nlmsg_seq = seq;
-        req.hdr.nlmsg_pid = 0;
+        ucred = (struct ucred*) CMSG_DATA(cmsg);
+        if (ucred->uid != 0 || ucred->pid != 0)
+                return 0;
 
-        gen = NLMSG_DATA(&req.hdr);
-        gen->rtgen_family = AF_UNSPEC;
+        for (p = &resp.hdr; bytes > 0; p = NLMSG_NEXT(p, bytes)) {
+                struct ifaddrmsg *ifaddrmsg;
+                struct rtattr *a;
+                size_t l;
+                void *local = NULL, *address = NULL;
 
-        if (send(fd, &req, req.hdr.nlmsg_len, 0) < 0) {
-                r = -errno;
-                goto finish;
-        }
+                if (!NLMSG_OK(p, (size_t) bytes))
+                        return -EIO;
 
-        for (;;) {
-                ssize_t bytes;
-                struct msghdr msg;
-                struct cmsghdr *cmsg;
-                struct ucred *ucred;
-                struct iovec iov;
-                struct nlmsghdr *p;
-                uint8_t cred_buffer[CMSG_SPACE(sizeof(struct ucred))];
-                struct {
-                        struct nlmsghdr hdr;
-                        struct ifaddrmsg ifaddrmsg;
-                        uint8_t payload[16*1024];
-                } resp;
-
-                memset(&iov, 0, sizeof(iov));
-                iov.iov_base = &resp;
-                iov.iov_len = sizeof(resp);
-
-                memset(&msg, 0, sizeof(msg));
-                msg.msg_name = NULL;
-                msg.msg_namelen = 0;
-                msg.msg_iov = &iov;
-                msg.msg_iovlen = 1;
-                msg.msg_control = cred_buffer;
-                msg.msg_controllen = sizeof(cred_buffer);
-                msg.msg_flags = 0;
-
-                bytes = recvmsg(fd, &msg, 0);
-                if (bytes < 0) {
-                        r = -errno;
-                        goto finish;
-                }
+                if (p->nlmsg_seq != SEQ)
+                        continue;
+
+                if (p->nlmsg_type == NLMSG_DONE)
+                        return 1;
+
+                if (p->nlmsg_type == NLMSG_ERROR) {
+                        struct nlmsgerr *nlmsgerr;
 
-                cmsg = CMSG_FIRSTHDR(&msg);
-                if (!cmsg || cmsg->cmsg_type != SCM_CREDENTIALS) {
-                        r = -EIO;
-                        goto finish;
+                        nlmsgerr = NLMSG_DATA(p);
+                        return -nlmsgerr->error;
                 }
 
-                ucred = (struct ucred*) CMSG_DATA(cmsg);
-                if (ucred->uid != 0 || ucred->pid != 0)
+                if (p->nlmsg_type != RTM_NEWADDR)
                         continue;
 
-                for (p = &resp.hdr; bytes > 0; p = NLMSG_NEXT(p, bytes)) {
-                        struct ifaddrmsg *ifaddrmsg;
-                        struct rtattr *a;
-                        size_t l;
-                        void *local = NULL, *address = NULL;
+                ifaddrmsg = NLMSG_DATA(p);
 
-                        if (!NLMSG_OK(p, (size_t) bytes)) {
-                                r = -EIO;
-                                goto finish;
-                        }
+                if (ifaddrmsg->ifa_family != AF_INET &&
+                    ifaddrmsg->ifa_family != AF_INET6)
+                        continue;
 
-                        if (p->nlmsg_seq != seq)
-                                continue;
+                if (ifaddrmsg->ifa_scope == RT_SCOPE_HOST ||
+                    ifaddrmsg->ifa_scope == RT_SCOPE_NOWHERE)
+                        continue;
 
-                        if (p->nlmsg_type == NLMSG_DONE) {
-                                r = 0;
-                                goto finish;
-                        }
+                if (ifaddrmsg->ifa_flags & IFA_F_DEPRECATED)
+                        continue;
 
-                        if (p->nlmsg_type == NLMSG_ERROR) {
-                                struct nlmsgerr *nlmsgerr;
+                l = NLMSG_PAYLOAD(p, sizeof(struct ifaddrmsg));
+                a = IFA_RTA(ifaddrmsg);
 
-                                nlmsgerr = NLMSG_DATA(p);
-                                r = -nlmsgerr->error;
-                                goto finish;
-                        }
+                while (RTA_OK(a, l)) {
 
-                        if (p->nlmsg_type != RTM_NEWADDR)
-                                continue;
+                        if (a->rta_type == IFA_ADDRESS)
+                                address = RTA_DATA(a);
+                        else if (a->rta_type == IFA_LOCAL)
+                                local = RTA_DATA(a);
 
-                        ifaddrmsg = NLMSG_DATA(p);
+                        a = RTA_NEXT(a, l);
+                }
 
-                        if (ifaddrmsg->ifa_family != AF_INET &&
-                            ifaddrmsg->ifa_family != AF_INET6)
-                                continue;
+                if (local)
+                        address = local;
 
-                        if (ifaddrmsg->ifa_scope == RT_SCOPE_HOST ||
-                            ifaddrmsg->ifa_scope == RT_SCOPE_NOWHERE)
-                                continue;
+                if (!address)
+                        continue;
 
-                        if (ifaddrmsg->ifa_flags & IFA_F_DEPRECATED)
-                                continue;
+                *list = realloc(*list, (*n_list+1) * sizeof(struct address));
+                if (!*list)
+                        return -ENOMEM;
 
-                        l = NLMSG_PAYLOAD(p, sizeof(struct ifaddrmsg));
-                        a = IFA_RTA(ifaddrmsg);
+                (*list)[*n_list].family = ifaddrmsg->ifa_family;
+                (*list)[*n_list].scope = ifaddrmsg->ifa_scope;
+                memcpy((*list)[*n_list].address,
+                       address, ifaddrmsg->ifa_family == AF_INET ? 4 : 16);
+                (*list)[*n_list].ifindex = ifaddrmsg->ifa_index;
 
-                        while (RTA_OK(a, l)) {
+                (*n_list)++;
+        }
 
-                                if (a->rta_type == IFA_ADDRESS)
-                                        address = RTA_DATA(a);
-                                else if (a->rta_type == IFA_LOCAL)
-                                        local = RTA_DATA(a);
+        return 0;
+}
 
-                                a = RTA_NEXT(a, l);
-                        }
 
-                        if (local)
-                                address = local;
+int ifconf_acquire_addresses(struct address **_list, unsigned *_n_list) {
 
-                        if (!address)
-                                continue;
+        struct {
+                struct nlmsghdr hdr;
+                struct rtgenmsg gen;
+        } req = { {
+                        .nlmsg_len = NLMSG_LENGTH(sizeof(struct rtgenmsg)),
+                        .nlmsg_type = RTM_GETADDR,
+                        .nlmsg_flags = NLM_F_REQUEST|NLM_F_DUMP|NLM_F_ACK,
+                        .nlmsg_seq = SEQ,
+                        .nlmsg_pid = 0,
+                }, {
+                        .rtgen_family = AF_UNSPEC,
+                }
+        };
+        int r, on = 1;
+        struct address *list = NULL;
+        unsigned n_list = 0;
+        int _cleanup_close_ fd;
 
-                        list = realloc(list, (n_list+1) * sizeof(struct address));
-                        if (!list) {
-                                r = -ENOMEM;
-                                goto finish;
-                        }
+        fd = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE);
+        if (fd < 0)
+                return -errno;
 
-                        list[n_list].family = ifaddrmsg->ifa_family;
-                        list[n_list].scope = ifaddrmsg->ifa_scope;
-                        memcpy(list[n_list].address, address, ifaddrmsg->ifa_family == AF_INET ? 4 : 16);
-                        list[n_list].ifindex = ifaddrmsg->ifa_index;
+        if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on)) < 0)
+                return -errno;
 
-                        n_list++;
-                }
-        }
+        if (send(fd, &req, req.hdr.nlmsg_len, 0) < 0)
+                return -errno;
 
-finish:
-        close(fd);
+        while((r = read_reply(fd, &list, &n_list)) == 0)
+                ;
 
-        if (r < 0)
+        if (r < 0) {
                 free(list);
-        else {
-                qsort(list, n_list, sizeof(struct address), address_compare);
-
-                *_list = list;
-                *_n_list = n_list;
+                return r;
         }
 
-        return r;
+        assert(n_list == 0 || list);
+        qsort(list, n_list, sizeof(struct address), address_compare);
+
+        *_list = list;
+        *_n_list = n_list;
+
+        return 0;
 }