Socket: Created control socket & pid file directories.

@alejandro-colomar reported an issue on GitHub whereby Unit would fail
to start due to not being able to create the control socket (a Unix
Domain Socket)

  2022/08/05 20:12:22 [alert] 21613#21613 bind(6,
  unix:/opt/local/unit/var/run/unit/control.unit.sock.tmp)
  failed (2: No such file or directory)

This could happen if the control socket was set to a directory that
doesn't exist. A common place to put the control socket would be under
/run/unit, and while /run will exist, /run/unit may well not (/run
is/should be cleared on each boot).

The pid file would also generally go under /run/unit, though this is
created after the control socket, however it could go someplace else so
we should also ensure its directory exists.

This commit will try to create the pid file and control sockets parent
directory. In some cases the user will need to ensure that the rest of
the path already exists.

This adds a new nxt_fs_mkdir_parent() function that given a full path
to a file (or directory), strips the last component off before passing
the remaining directory path to nxt_fs_mkdir().

Cc: Konstantin Pavlov <thresh@nginx.com>
Closes: <https://github.com/nginx/unit/issues/742>
Reported-by: Alejandro Colomar <alx@nginx.com>
Reviewed-by: Alejandro Colomar <alx@nginx.com>
Tested-by: Alejandro Colomar <alx@nginx.com>
Signed-off-by: Andrew Clayton <a.clayton@nginx.com>

4 files changed, 36 insertions, 0 deletions

diff --git a/src/nxt_controller.c b/src/nxt_controller.c
index 09168821..99c7ca10 100644
--- a/src/nxt_controller.c
+++ b/src/nxt_controller.c
@@ -666,6 +666,14 @@ nxt_runtime_controller_socket(nxt_task_t *task, nxt_runtime_t *rt)
 #endif
     ls->handler = nxt_controller_conn_init;
 
+#if (NXT_HAVE_UNIX_DOMAIN)
+    if (ls->sockaddr->u.sockaddr.sa_family == AF_UNIX) {
+        const char *path = ls->sockaddr->u.sockaddr_un.sun_path;
+
+        nxt_fs_mkdir_parent((const u_char *) path, 0755);
+    }
+#endif
+
     if (nxt_listen_socket_create(task, rt->mem_pool, ls) != NXT_OK) {
         return NXT_ERROR;
     }
diff --git a/src/nxt_fs.c b/src/nxt_fs.c
index 71498f99..35850798 100644
--- a/src/nxt_fs.c
+++ b/src/nxt_fs.c
@@ -273,6 +273,31 @@ nxt_fs_mkdir_all(const u_char *dir, mode_t mode)
 }
 
 
+nxt_int_t
+nxt_fs_mkdir_parent(const u_char *path, mode_t mode)
+{
+    char       *ptr, *dir;
+    nxt_int_t  ret;
+
+    dir = nxt_strdup(path);
+    if (nxt_slow_path(dir == NULL)) {
+        return NXT_ERROR;
+    }
+
+    ret = NXT_OK;
+
+    ptr = strrchr(dir, '/');
+    if (nxt_fast_path(ptr != NULL)) {
+        *ptr = '\0';
+        ret = nxt_fs_mkdir((const u_char *) dir, mode);
+    }
+
+    nxt_free(dir);
+
+    return ret;
+}
+
+
 static nxt_int_t
 nxt_fs_mkdir(const u_char *dir, mode_t mode)
 {
diff --git a/src/nxt_fs.h b/src/nxt_fs.h
index ff589979..af9585b8 100644
--- a/src/nxt_fs.h
+++ b/src/nxt_fs.h
@@ -36,6 +36,7 @@ typedef struct {
 } nxt_fs_mount_t;
 
 
+nxt_int_t nxt_fs_mkdir_parent(const u_char *path, mode_t mode);
 nxt_int_t nxt_fs_mkdir_all(const u_char *dir, mode_t mode);
 nxt_int_t nxt_fs_mount(nxt_task_t *task, nxt_fs_mount_t *mnt);
 void nxt_fs_unmount(const u_char *path);
diff --git a/src/nxt_runtime.c b/src/nxt_runtime.c
index d9c9f2ef..c7e4455e 100644
--- a/src/nxt_runtime.c
+++ b/src/nxt_runtime.c
@@ -1369,6 +1369,8 @@ nxt_runtime_pid_file_create(nxt_task_t *task, nxt_file_name_t *pid_file)
 
     file.name = pid_file;
 
+    nxt_fs_mkdir_parent(pid_file, 0755);
+
     n = nxt_file_open(task, &file, O_WRONLY, O_CREAT | O_TRUNC,
                       NXT_FILE_DEFAULT_ACCESS);