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-rw-r--r--src/inotify.c288
1 files changed, 288 insertions, 0 deletions
diff --git a/src/inotify.c b/src/inotify.c
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--- /dev/null
+++ b/src/inotify.c
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+/* dnsmasq is Copyright (c) 2000-2015 Simon Kelley
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; version 2 dated June, 1991, or
+ (at your option) version 3 dated 29 June, 2007.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "dnsmasq.h"
+#ifdef HAVE_INOTIFY
+
+#include <sys/inotify.h>
+#include <sys/param.h> /* For MAXSYMLINKS */
+
+/* the strategy is to set a inotify on the directories containing
+ resolv files, for any files in the directory which are close-write
+ or moved into the directory.
+
+ When either of those happen, we look to see if the file involved
+ is actually a resolv-file, and if so, call poll-resolv with
+ the "force" argument, to ensure it's read.
+
+ This adds one new error condition: the directories containing
+ all specified resolv-files must exist at start-up, even if the actual
+ files don't.
+*/
+
+static char *inotify_buffer;
+#define INOTIFY_SZ (sizeof(struct inotify_event) + NAME_MAX + 1)
+
+/* If path is a symbolic link, return the path it
+ points to, made absolute if relative.
+ If path doesn't exist or is not a symlink, return NULL.
+ Return value is malloc'ed */
+static char *my_readlink(char *path)
+{
+ ssize_t rc, size = 64;
+ char *buf;
+
+ while (1)
+ {
+ buf = safe_malloc(size);
+ rc = readlink(path, buf, (size_t)size);
+
+ if (rc == -1)
+ {
+ /* Not link or doesn't exist. */
+ if (errno == EINVAL || errno == ENOENT)
+ return NULL;
+ else
+ die(_("cannot access path %s: %s"), path, EC_MISC);
+ }
+ else if (rc < size-1)
+ {
+ char *d;
+
+ buf[rc] = 0;
+ if (buf[0] != '/' && ((d = strrchr(path, '/'))))
+ {
+ /* Add path to relative link */
+ char *new_buf = safe_malloc((d - path) + strlen(buf) + 2);
+ *(d+1) = 0;
+ strcpy(new_buf, path);
+ strcat(new_buf, buf);
+ free(buf);
+ buf = new_buf;
+ }
+ return buf;
+ }
+
+ /* Buffer too small, increase and retry */
+ size += 64;
+ free(buf);
+ }
+}
+
+void inotify_dnsmasq_init()
+{
+ struct resolvc *res;
+ inotify_buffer = safe_malloc(INOTIFY_SZ);
+ daemon->inotifyfd = inotify_init1(IN_NONBLOCK | IN_CLOEXEC);
+
+ if (daemon->inotifyfd == -1)
+ die(_("failed to create inotify: %s"), NULL, EC_MISC);
+
+ for (res = daemon->resolv_files; res; res = res->next)
+ {
+ char *d, *new_path, *path = safe_malloc(strlen(res->name) + 1);
+ int links = MAXSYMLINKS;
+
+ strcpy(path, res->name);
+
+ /* Follow symlinks until we reach a non-symlink, or a non-existant file. */
+ while ((new_path = my_readlink(path)))
+ {
+ if (links-- == 0)
+ die(_("too many symlinks following %s"), res->name, EC_MISC);
+ free(path);
+ path = new_path;
+ }
+
+ res->wd = -1;
+
+ if ((d = strrchr(path, '/')))
+ {
+ *d = 0; /* make path just directory */
+ res->wd = inotify_add_watch(daemon->inotifyfd, path, IN_CLOSE_WRITE | IN_MOVED_TO);
+
+ res->file = d+1; /* pointer to filename */
+ *d = '/';
+
+ if (res->wd == -1 && errno == ENOENT)
+ die(_("directory %s for resolv-file is missing, cannot poll"), res->name, EC_MISC);
+ }
+
+ if (res->wd == -1)
+ die(_("failed to create inotify for %s: %s"), res->name, EC_MISC);
+
+ }
+}
+
+
+/* initialisation for dynamic-dir. Set inotify watch for each directory, and read pre-existing files */
+void set_dynamic_inotify(int flag, int total_size, struct crec **rhash, int revhashsz)
+{
+ struct hostsfile *ah;
+
+ for (ah = daemon->dynamic_dirs; ah; ah = ah->next)
+ {
+ DIR *dir_stream = NULL;
+ struct dirent *ent;
+ struct stat buf;
+
+ if (!(ah->flags & flag))
+ continue;
+
+ if (stat(ah->fname, &buf) == -1 || !(S_ISDIR(buf.st_mode)))
+ {
+ my_syslog(LOG_ERR, _("bad dynamic directory %s: %s"),
+ ah->fname, strerror(errno));
+ continue;
+ }
+
+ if (!(ah->flags & AH_WD_DONE))
+ {
+ ah->wd = inotify_add_watch(daemon->inotifyfd, ah->fname, IN_CLOSE_WRITE | IN_MOVED_TO);
+ ah->flags |= AH_WD_DONE;
+ }
+
+ /* Read contents of dir _after_ calling add_watch, in the hope of avoiding
+ a race which misses files being added as we start */
+ if (ah->wd == -1 || !(dir_stream = opendir(ah->fname)))
+ {
+ my_syslog(LOG_ERR, _("failed to create inotify for %s: %s"),
+ ah->fname, strerror(errno));
+ continue;
+ }
+
+ while ((ent = readdir(dir_stream)))
+ {
+ size_t lendir = strlen(ah->fname);
+ size_t lenfile = strlen(ent->d_name);
+ char *path;
+
+ /* ignore emacs backups and dotfiles */
+ if (lenfile == 0 ||
+ ent->d_name[lenfile - 1] == '~' ||
+ (ent->d_name[0] == '#' && ent->d_name[lenfile - 1] == '#') ||
+ ent->d_name[0] == '.')
+ continue;
+
+ if ((path = whine_malloc(lendir + lenfile + 2)))
+ {
+ strcpy(path, ah->fname);
+ strcat(path, "/");
+ strcat(path, ent->d_name);
+
+ /* ignore non-regular files */
+ if (stat(path, &buf) != -1 && S_ISREG(buf.st_mode))
+ {
+ if (ah->flags & AH_HOSTS)
+ total_size = read_hostsfile(path, ah->index, total_size, rhash, revhashsz);
+#ifdef HAVE_DHCP
+ else if (ah->flags & (AH_DHCP_HST | AH_DHCP_OPT))
+ option_read_dynfile(path, ah->flags);
+#endif
+ }
+
+ free(path);
+ }
+ }
+ }
+}
+
+int inotify_check(time_t now)
+{
+ int hit = 0;
+ struct hostsfile *ah;
+
+ while (1)
+ {
+ int rc;
+ char *p;
+ struct resolvc *res;
+ struct inotify_event *in;
+
+ while ((rc = read(daemon->inotifyfd, inotify_buffer, INOTIFY_SZ)) == -1 && errno == EINTR);
+
+ if (rc <= 0)
+ break;
+
+ for (p = inotify_buffer; rc - (p - inotify_buffer) >= (int)sizeof(struct inotify_event); p += sizeof(struct inotify_event) + in->len)
+ {
+ in = (struct inotify_event*)p;
+
+ for (res = daemon->resolv_files; res; res = res->next)
+ if (res->wd == in->wd && in->len != 0 && strcmp(res->file, in->name) == 0)
+ hit = 1;
+
+ /* ignore emacs backups and dotfiles */
+ if (in->len == 0 ||
+ in->name[in->len - 1] == '~' ||
+ (in->name[0] == '#' && in->name[in->len - 1] == '#') ||
+ in->name[0] == '.')
+ continue;
+
+ for (ah = daemon->dynamic_dirs; ah; ah = ah->next)
+ if (ah->wd == in->wd)
+ {
+ size_t lendir = strlen(ah->fname);
+ char *path;
+
+ if ((path = whine_malloc(lendir + in->len + 2)))
+ {
+ strcpy(path, ah->fname);
+ strcat(path, "/");
+ strcat(path, in->name);
+
+ my_syslog(LOG_INFO, _("inotify, new or changed file %s"), path);
+
+ if (ah->flags & AH_HOSTS)
+ {
+ read_hostsfile(path, ah->index, 0, NULL, 0);
+#ifdef HAVE_DHCP
+ if (daemon->dhcp || daemon->doing_dhcp6)
+ {
+ /* Propogate the consequences of loading a new dhcp-host */
+ dhcp_update_configs(daemon->dhcp_conf);
+ lease_update_from_configs();
+ lease_update_file(now);
+ lease_update_dns(1);
+ }
+#endif
+ }
+#ifdef HAVE_DHCP
+ else if (ah->flags & AH_DHCP_HST)
+ {
+ if (option_read_dynfile(path, AH_DHCP_HST))
+ {
+ /* Propogate the consequences of loading a new dhcp-host */
+ dhcp_update_configs(daemon->dhcp_conf);
+ lease_update_from_configs();
+ lease_update_file(now);
+ lease_update_dns(1);
+ }
+ }
+ else if (ah->flags & AH_DHCP_OPT)
+ option_read_dynfile(path, AH_DHCP_OPT);
+#endif
+
+ free(path);
+ }
+ }
+ }
+ }
+ return hit;
+}
+
+#endif /* INOTIFY */
+
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