lagertonne/ifupdown-ng
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refactoring locking, make it per-interface to avoid deadlocks

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This commit is contained in:
Ariadne Conill 2020-07-29 03:10:55 -06:00
parent 91115edeee
commit 0ca8e42ee6
2 changed files with 72 additions and 63 deletions
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133
cmd/ifupdown.c
View file

@ -34,6 +34,7 @@ static bool up;
static struct lif_execute_opts exec_opts = {
.executor_path = EXECUTOR_PATH,
.interfaces_file = INTERFACES_FILE,
.state_file = STATE_FILE,
};
void
@ -67,9 +68,65 @@ is_ifdown()
return false;
}
int
acquire_state_lock(const char *state_path, const char *lifname)
{
if (exec_opts.mock || exec_opts.no_lock)
return -1;
char lockpath[4096] = {};
snprintf(lockpath, sizeof lockpath, "%s.%s.lock", state_path, lifname);
int fd = open(lockpath, O_CREAT | O_WRONLY | O_TRUNC);
if (fd < 0)
{
fprintf(stderr, "opening lockfile %s: %s\n", lockpath, strerror(errno));
return -1;
}
int flags = fcntl(fd, F_GETFD);
if (flags < 0)
{
close(fd);
fprintf(stderr, "getting flags for lockfile: %s\n", strerror(errno));
return -1;
}
flags |= FD_CLOEXEC;
if (fcntl(fd, F_SETFD, flags) == -1)
{
close(fd);
fprintf(stderr, "setting lockfile close-on-exec: %s\n", strerror(errno));
return -1;
}
struct flock fl = {
.l_type = F_WRLCK,
.l_whence = SEEK_SET
};
if (exec_opts.verbose)
fprintf(stderr, "ifupdown: acquiring lock on %s\n", lockpath);
if (fcntl(fd, F_SETLKW, &fl) == -1)
{
close(fd);
fprintf(stderr, "locking lockfile: %s\n", strerror(errno));
return -1;
}
return fd;
}
bool
change_interface(struct lif_interface *iface, struct lif_dict *collection, struct lif_dict *state, const char *ifname)
{
int lockfd = acquire_state_lock(exec_opts.state_file, ifname);
if (exec_opts.verbose)
{
fprintf(stderr, "%s: changing state of interface %s to '%s'\n",
@ -80,9 +137,16 @@ change_interface(struct lif_interface *iface, struct lif_dict *collection, struc
{
fprintf(stderr, "%s: failed to change interface %s state to '%s'\n",
argv0, ifname, up ? "up" : "down");
if (lockfd != -1)
close(lockfd);
return false;
}
if (lockfd != -1)
close(lockfd);
return true;
}
@ -114,54 +178,6 @@ change_auto_interfaces(struct lif_dict *collection, struct lif_dict *state, stru
return true;
}
int
acquire_state_lock(const char *state_path)
{
char lockpath[4096] = {};
snprintf(lockpath, sizeof lockpath, "%s.lock", state_path);
int fd = open(lockpath, O_CREAT | O_WRONLY | O_TRUNC);
if (fd < 0)
{
fprintf(stderr, "opening lockfile %s: %s\n", lockpath, strerror(errno));
return -1;
}
int flags = fcntl(fd, F_GETFD);
if (flags < 0)
{
close(fd);
fprintf(stderr, "getting flags for lockfile: %s\n", strerror(errno));
return -1;
}
flags |= FD_CLOEXEC;
if (fcntl(fd, F_SETFD, flags) == -1)
{
close(fd);
fprintf(stderr, "setting lockfile close-on-exec: %s\n", strerror(errno));
return -1;
}
struct flock fl = {
.l_type = F_WRLCK,
.l_whence = SEEK_SET
};
if (fcntl(fd, F_SETLKW, &fl) == -1)
{
close(fd);
fprintf(stderr, "locking lockfile: %s\n", strerror(errno));
return -1;
}
return fd;
}
int
ifupdown_main(int argc, char *argv[])
{
@ -185,9 +201,6 @@ ifupdown_main(int argc, char *argv[])
{NULL, 0, 0, 0}
};
struct match_options match_opts = {};
char *state_file = STATE_FILE;
int lockfd = -1;
bool no_lock = false;
for (;;)
{
@ -215,7 +228,7 @@ ifupdown_main(int argc, char *argv[])
match_opts.exclude_pattern = optarg;
break;
case 'S':
state_file = optarg;
exec_opts.state_file = optarg;
break;
case 'n':
exec_opts.mock = true;
@ -230,17 +243,14 @@ ifupdown_main(int argc, char *argv[])
case 'f':
break;
case 'L':
no_lock = true;
exec_opts.no_lock = true;
break;
}
}
if (!exec_opts.mock && !no_lock)
lockfd = acquire_state_lock(state_file);
if (!lif_state_read_path(&state, state_file))
if (!lif_state_read_path(&state, exec_opts.state_file))
{
fprintf(stderr, "%s: could not parse %s\n", argv0, state_file);
fprintf(stderr, "%s: could not parse %s\n", argv0, exec_opts.state_file);
return EXIT_FAILURE;
}
@ -300,15 +310,12 @@ ifupdown_main(int argc, char *argv[])
return EXIT_FAILURE;
}
if (!exec_opts.mock && !lif_state_write_path(&state, state_file))
if (!exec_opts.mock && !lif_state_write_path(&state, exec_opts.state_file))
{
fprintf(stderr, "%s: could not update %s\n", argv0, state_file);
fprintf(stderr, "%s: could not update %s\n", argv0, exec_opts.state_file);
return EXIT_FAILURE;
}
if (lockfd >= 0)
close(lockfd);
return EXIT_SUCCESS;
}

2
libifupdown/execute.h
View file

@ -22,8 +22,10 @@
struct lif_execute_opts {
bool verbose;
bool mock;
bool no_lock;
const char *executor_path;
const char *interfaces_file;
const char *state_file;
};
extern bool lif_execute_fmt(const struct lif_execute_opts *opts, char *const envp[], const char *fmt, ...);