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authorMattias Andrée <maandree@operamail.com>2014-05-02 18:13:19 +0200
committerMattias Andrée <maandree@operamail.com>2014-05-02 18:13:19 +0200
commitbf5d5439499cbf62225ce744f2444d3c465d3f2f (patch)
tree0673799e7d30903ba57361821842ec55230e5add
parentsome re-exec stuff (diff)
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some more work on re-exec
Signed-off-by: Mattias Andrée <maandree@operamail.com>
-rw-r--r--src/mds-server.c150
-rw-r--r--src/mds-server.h8
2 files changed, 141 insertions, 17 deletions
diff --git a/src/mds-server.c b/src/mds-server.c
index 7a50e7f..7bd49e1 100644
--- a/src/mds-server.c
+++ b/src/mds-server.c
@@ -22,6 +22,7 @@
#include <libmdsserver/fd-table.h>
#include <libmdsserver/mds-message.h>
+#include <alloca.h>
#include <signal.h>
#include <stdio.h>
#include <string.h>
@@ -102,7 +103,6 @@ int main(int argc_, char** argv_)
int unparsed_args_ptr = 1;
char* unparsed_args[ARGC_LIMIT + LIBEXEC_ARGC_EXTRA_LIMIT + 1];
int i;
- pid_t pid;
pthread_t _slave_thread;
@@ -198,6 +198,8 @@ int main(int argc_, char** argv_)
if (is_respawn == 0)
{
+ pid_t pid;
+
/* Run mdsinitrc. */
pid = fork();
if (pid == (pid_t)-1)
@@ -223,19 +225,37 @@ int main(int argc_, char** argv_)
if (linked_list_create(&client_list, 32))
{
perror(*argv);
+ fd_table_destroy(&client_map, NULL, NULL);
linked_list_destroy(&client_list);
return 1;
}
+ /* Make the server update without all slaves dying on SIGUSR1. */
+ {
+ struct sigaction action;
+ sigset_t sigset;
+
+ sigemptyset(&sigset);
+ action.sa_handler = sigusr1_trap;
+ action.sa_mask = sigset;
+ action.sa_flags = 0;
+
+ if (sigaction(SIGUSR1, &action, NULL) < 0)
+ {
+ perror(*argv);
+ fd_table_destroy(&client_map, NULL, NULL);
+ linked_list_destroy(&client_list);
+ return 1;
+ }
+ }
+
+
/* Create mutex and condition for slave counter. */
pthread_mutex_init(&slave_mutex, NULL);
pthread_cond_init(&slave_cond, NULL);
- /* TODO make the server update without all slaves dying on SIGUSR1 */
-
-
/* Accepting incoming connections. */
while (running && (reexecing == 0))
{
@@ -296,23 +316,85 @@ int main(int argc_, char** argv_)
/* Release resources. */
fd_table_destroy(&client_map, NULL, NULL);
linked_list_destroy(&client_list);
+ pthread_mutex_destroy(&slave_mutex);
+ pthread_cond_destroy(&slave_cond);
return 0;
reexec:
- /* Join with all slaves threads. */
- pthread_mutex_lock(&slave_mutex);
- while (running_slaves > 0)
- pthread_cond_wait(&slave_cond, &slave_mutex);
- pthread_mutex_unlock(&slave_mutex);
-
- /* TODO: marshal and exec */
-
- /* Returning non-zero is important, otherwise the server cannot
- be respawn if the re-exec fails. */
- perror(*argv);
- return 1;
+ {
+ char* state_buf = NULL;
+ char* state_buf_;
+ size_t state_n;
+ ssize_t wrote;
+ int pipe_rw[2];
+ char readlink_buf[PATH_MAX];
+ ssize_t readlink_ptr;
+ char** reexec_args;
+ char** reexec_args_;
+ char reexec_arg[24];
+#if INT_MAX > UINT64_MAX
+# error It seems int:s are really big, you might need to increase the size of reexec_arg.
+#endif
+
+ /* Release resources. */
+ pthread_mutex_destroy(&slave_mutex);
+ pthread_cond_destroy(&slave_cond);
+
+ /* Join with all slaves threads. */
+ pthread_mutex_lock(&slave_mutex);
+ while (running_slaves > 0)
+ pthread_cond_wait(&slave_cond, &slave_mutex);
+ pthread_mutex_unlock(&slave_mutex);
+
+ /* Marshal the state of the server. */ /* TODO marshal all data. */
+ state_n = 2 * sizeof(int) + 1 * sizeof(sig_atomic_t);
+ state_buf = alloca(state_n);
+ state_buf_ = state_buf;
+ ((int*)state_buf_)[0] = MDS_SERVER_VARS_VERSION;
+ ((int*)state_buf_)[1] = socket_fd;
+ state_buf_ += 2 * sizeof(int) / sizeof(char);
+ ((sig_atomic_t*)state_buf_)[0] = running;
+ state_buf_ += 1 * sizeof(sig_atomic_t) / sizeof(char);
+ if (pipe(pipe_rw) < 0)
+ goto reexec_fail;
+ errno = 0;
+ while (state_n > 0)
+ {
+ wrote = write(pipe_rw[1], state_buf, state_n);
+ if (errno && (errno != EINTR))
+ goto reexec_fail;
+ state_n -= (size_t)(wrote < 0 ? 0 : wrote);
+ state_buf += (size_t)(wrote < 0 ? 0 : wrote);
+ }
+ close(pipe_rw[1]);
+
+ /* Re-exec the server. */
+ readlink_ptr = readlink("/proc/self/exe", readlink_buf, PATH_MAX - 1);
+ if (readlink_ptr < 0)
+ goto reexec_fail;
+ /* ‘readlink() does not append a null byte to buf.’ */
+ readlink_buf[readlink_ptr] = '\0';
+ snprintf(reexec_arg, sizeof(reexec_arg) / sizeof(char),
+ "--re-exec=%i", pipe_rw[0]);
+ reexec_args = alloca(((size_t)argc + 2) * sizeof(char*));
+ reexec_args_ = reexec_args;
+ *reexec_args_++ = *argv;
+ *reexec_args_ = reexec_arg;
+ for (i = 1; i < argc; i++)
+ reexec_args_[i] = argv[i];
+ reexec_args_[argc] = NULL;
+ execv(readlink_buf, reexec_args);
+
+ reexec_fail:
+ perror(*argv);
+ close(pipe_rw[0]);
+ close(pipe_rw[1]);
+ /* Returning non-zero is important, otherwise the server cannot
+ be respawn if the re-exec fails. */
+ return 1;
+ }
}
@@ -326,11 +408,29 @@ void* slave_loop(void* data)
{
int socket_fd = (int)(intptr_t)data;
ssize_t entry = LINKED_LIST_UNUSED;
- client_t* information;
+ client_t* information = NULL;
size_t tmp;
int r;
+ /* Make the server update without all slaves dying on SIGUSR1. */
+ {
+ struct sigaction action;
+ sigset_t sigset;
+
+ sigemptyset(&sigset);
+ action.sa_handler = sigusr1_trap;
+ action.sa_mask = sigset;
+ action.sa_flags = 0;
+
+ if (sigaction(SIGUSR1, &action, NULL) < 0)
+ {
+ perror(*argv);
+ goto fail;
+ }
+ }
+
+
/* Create information table. */
information = malloc(sizeof(client_t));
if (information == NULL)
@@ -537,3 +637,19 @@ void run_initrc(char** args)
fprintf(stderr, "%s: unable to run %s file, you might as well kill me.\n", *argv, INITRC_FILE);
}
+
+/**
+ * Called with the signal SIGUSR1 is caught.
+ * This function should cue a re-exec of the program.
+ *
+ * @param signo The caught signal
+ */
+void sigusr1_trap(int signo __attribute__((unused)))
+{
+ if (reexecing == 0)
+ {
+ reexecing = 1;
+ /* TODO send the signal to all threads. */
+ }
+}
+
diff --git a/src/mds-server.h b/src/mds-server.h
index 7b03501..db1e122 100644
--- a/src/mds-server.h
+++ b/src/mds-server.h
@@ -75,6 +75,14 @@ char* getenv_nonempty(const char* var);
*/
void run_initrc(char** args);
+/**
+ * Called with the signal SIGUSR1 is caught.
+ * This function should cue a re-exec of the program.
+ *
+ * @param signo The caught signal
+ */
+void sigusr1_trap(int signo);
+
#endif