statefiles: add tmp helper functions

Move temporary file creation/finishing to separate functions.

Signed-off-by: David Härdeman <[email protected]>
Link: https://github.com/openwrt/odhcpd/pull/333
Signed-off-by: Álvaro Fernández Rojas <[email protected]>

diff --git a/src/statefiles.c b/src/statefiles.c
index f16e04d92e39efd64beb77ce5162f36913f0fc94..da31ca6de7696d90c2eb8f37432cee54e3d80505 100644 (file)
--- a/src/statefiles.c
+++ b/src/statefiles.c
@@ -40,6 +40,65 @@ struct write_ctxt {
        time_t wall_time;
 };
 
+static FILE *statefiles_open_tmp_file(int dirfd)
+{
+       int fd;
+       FILE *fp;
+
+       if (dirfd < 0)
+               return NULL;
+
+       fd = openat(dirfd, ODHCPD_TMP_FILE, O_CREAT | O_WRONLY | O_CLOEXEC, 0644);
+       if (fd < 0)
+               goto err;
+
+       if (lockf(fd, F_LOCK, 0) < 0)
+               goto err;
+
+       if (ftruncate(fd, 0) < 0)
+               goto err_del;
+
+       fp = fdopen(fd, "w");
+       if (!fp)
+               goto err_del;
+
+       return fp;
+
+err_del:
+       unlinkat(dirfd, ODHCPD_TMP_FILE, 0);
+err:
+       close(fd);
+       error("Failed to create temporary file: %m");
+       return NULL;
+}
+
+static void statefiles_finish_tmp_file(int dirfd, FILE **fpp, const char *prefix, const char *suffix)
+{
+       char *filename;
+
+       if (dirfd < 0 || !fpp || !*fpp || !prefix)
+               return;
+
+       if (fflush(*fpp))
+               error("Error flushing tmpfile: %m");
+
+       if (fsync(fileno(*fpp)) < 0)
+               error("Error synching tmpfile: %m");
+
+       fclose(*fpp);
+       *fpp = NULL;
+
+       if (suffix) {
+               filename = alloca(strlen(prefix) + strlen(".") + strlen(suffix) + 1);
+               sprintf(filename, "%s.%s", prefix, suffix);
+       } else {
+               filename = alloca(strlen(prefix) + 1);
+               sprintf(filename, "%s", prefix);
+       }
+
+       renameat(dirfd, ODHCPD_TMP_FILE, dirfd, filename);
+}
+
 static void statefiles_write_host(const char *ipbuf, const char *hostname, struct write_ctxt *ctxt)
 {
        char exp_dn[DNS_MAX_NAME_LEN];
@@ -93,31 +152,12 @@ static bool statefiles_write_host4(struct write_ctxt *ctxt, struct dhcpv4_lease
 static void statefiles_write_hosts(time_t now)
 {
        struct write_ctxt ctxt;
-       const char *tmp_hostsfile = ".odhcpd.hosts";
-       int fd;
 
        if (config.dhcp_hostsdir_fd < 0)
                return;
 
        avl_for_each_element(&interfaces, ctxt.iface, avl) {
-               char *hostsfile;
-
-               hostsfile = alloca(strlen(ODHCPD_HOSTS_FILE_PREFIX) + 1 + strlen(ctxt.iface->name) + 1);
-               sprintf(hostsfile, "%s.%s", ODHCPD_HOSTS_FILE_PREFIX, ctxt.iface->name);
-
-               fd = openat(config.dhcp_hostsdir_fd, tmp_hostsfile, O_CREAT | O_WRONLY | O_CLOEXEC, 0644);
-               if (fd < 0)
-                       goto err;
-
-               if (lockf(fd, F_LOCK, 0) < 0)
-                       goto err;
-
-               if (ftruncate(fd, 0) < 0)
-                       goto err;
-
-               ctxt.fp = fdopen(fd, "w");
-               if (!ctxt.fp)
-                       goto err;
+               ctxt.fp = statefiles_open_tmp_file(config.dhcp_hostsdir_fd);
 
                if (ctxt.iface->dhcpv6 == MODE_SERVER) {
                        struct dhcpv6_lease *lease;
@@ -148,16 +188,9 @@ static void statefiles_write_hosts(time_t now)
                        }
                }
 
-               fclose(ctxt.fp);
-               renameat(config.dhcp_hostsdir_fd, tmp_hostsfile,
-                        config.dhcp_hostsdir_fd, hostsfile);
+               statefiles_finish_tmp_file(config.dhcp_hostsdir_fd, &ctxt.fp,
+                                          ODHCPD_HOSTS_FILE_PREFIX, ctxt.iface->name);
        }
-
-       return;
-
-err:
-       error("Unable to write hostsfile: %m");
-       close(fd);
 }
 
 static void statefiles_write_state6_addr(struct dhcpv6_lease *lease, struct in6_addr *addr, uint8_t prefix_len,
@@ -241,30 +274,9 @@ static bool statefiles_write_state(time_t now)
                .now = now,
                .wall_time = time(NULL),
        };
-       char *tmp_statefile = NULL;
        uint8_t newmd5[16];
-       int fd;
 
-       if (config.dhcp_statedir_fd >= 0 && config.dhcp_statefile) {
-               size_t tmp_statefile_strlen = strlen(config.dhcp_statefile) + 2;
-
-               tmp_statefile = alloca(tmp_statefile_strlen);
-               sprintf(tmp_statefile, ".%s", config.dhcp_statefile);
-
-               fd = openat(config.dhcp_statedir_fd, tmp_statefile, O_CREAT | O_WRONLY | O_CLOEXEC, 0644);
-               if (fd < 0)
-                       goto err;
-
-               if (lockf(fd, F_LOCK, 0) < 0)
-                       goto err;
-
-               if (ftruncate(fd, 0) < 0)
-                       goto err;
-
-               ctxt.fp = fdopen(fd, "w");
-               if (!ctxt.fp)
-                       goto err;
-       }
+       ctxt.fp = statefiles_open_tmp_file(config.dhcp_statedir_fd);
 
        md5_begin(&ctxt.md5);
 
@@ -298,12 +310,7 @@ static bool statefiles_write_state(time_t now)
                }
        }
 
-       if (ctxt.fp) {
-               fclose(ctxt.fp);
-
-               renameat(config.dhcp_statedir_fd, tmp_statefile,
-                        config.dhcp_statedir_fd, config.dhcp_statefile);
-       }
+       statefiles_finish_tmp_file(config.dhcp_statedir_fd, &ctxt.fp, config.dhcp_statefile, NULL);
 
        md5_end(newmd5, &ctxt.md5);
        if (!memcmp(newmd5, statemd5, sizeof(newmd5)))
@@ -311,11 +318,6 @@ static bool statefiles_write_state(time_t now)
 
        memcpy(statemd5, newmd5, sizeof(statemd5));
        return true;
-
-err:
-       error("Unable to write statefile: %m");
-       close(fd);
-       return false;
 }
 
 bool statefiles_write()

diff --git a/src/statefiles.h b/src/statefiles.h
index dec1aa1382f5326c21d1e29bac130df2e2a36541..80be7468dd9c30a75cbd0fee220ec3ed0ba4894f 100644 (file)
--- a/src/statefiles.h
+++ b/src/statefiles.h
@@ -8,6 +8,7 @@
 #define _STATEFILES_H_
 
 #define ODHCPD_HOSTS_FILE_PREFIX "odhcpd.hosts"
+#define ODHCPD_TMP_FILE ".odhcpd.tmp"
 
 bool statefiles_write(void);