system: always support staged sysupgrade

[project/procd.git] / utils / utils.c

diff --git a/utils/utils.c b/utils/utils.c
index a67c004..e239eda 100644 (file)
--- a/utils/utils.c
+++ b/utils/utils.c
@@ -12,6 +12,7 @@
  * GNU General Public License for more details.
  */
 
+#define _GNU_SOURCE
 #include <libubox/avl.h>
 #include <libubox/avl-cmp.h>
 #include "utils.h"
@@ -20,6 +21,14 @@
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
+#include <string.h>
+#include <errno.h>
+
+#include "../log.h"
+
+#ifndef O_PATH
+#define O_PATH         010000000
+#endif
 
 void
 __blobmsg_list_init(struct blobmsg_list *list, int offset, int len, blobmsg_list_cmp cmp)
@@ -152,3 +161,53 @@ char* get_cmdline_val(const char* name, char* out, int len)
 
        return NULL;
 }
+
+int patch_fd(const char *device, int fd, int flags)
+{
+       int dfd, nfd;
+
+       if (device == NULL)
+               device = "/dev/null";
+
+       if (*device != '/') {
+               dfd = open("/dev", O_PATH|O_DIRECTORY);
+
+               if (dfd < 0)
+                       return -1;
+
+               nfd = openat(dfd, device, flags);
+
+               close(dfd);
+       } else {
+               nfd = open(device, flags);
+       }
+
+       if (nfd < 0 && strcmp(device, "/dev/null"))
+               nfd = open("/dev/null", flags);
+
+       if (nfd < 0)
+               return -1;
+
+       fd = dup2(nfd, fd);
+
+       if (nfd > STDERR_FILENO)
+               close(nfd);
+
+       return (fd < 0) ? -1 : 0;
+}
+
+int patch_stdio(const char *device)
+{
+       int fd, rv = 0;
+       const char *fdname[3] = { "stdin", "stdout", "stderr" };
+
+       for (fd = STDIN_FILENO; fd <= STDERR_FILENO; fd++) {
+               if (patch_fd(device, fd, fd ? O_WRONLY : O_RDONLY)) {
+                       ERROR("Failed to redirect %s to %s: %d (%s)\n",
+                             fdname[fd], device, errno, strerror(errno));
+                       rv = -1;
+               }
+       }
+
+       return rv;
+}