Filesystem: Add and use rtems_filesystem_chmod()

Implement POSIX requirements in the high-level file system layer.

3 files changed, 47 insertions, 9 deletions

diff --git a/cpukit/libcsupport/include/rtems/libio_.h b/cpukit/libcsupport/include/rtems/libio_.h
index 55156c0fa8..4a0623eea0 100644
--- a/cpukit/libcsupport/include/rtems/libio_.h
+++ b/cpukit/libcsupport/include/rtems/libio_.h
@@ -566,6 +566,11 @@ int rtems_filesystem_mknod(
 
 int rtems_filesystem_chdir( rtems_filesystem_location_info_t *loc );
 
+int rtems_filesystem_chmod(
+  const rtems_filesystem_location_info_t *loc,
+  mode_t mode
+);
+
 int rtems_filesystem_chown(
   const char *path,
   uid_t owner,
diff --git a/cpukit/libcsupport/src/chmod.c b/cpukit/libcsupport/src/chmod.c
index 8b91b60eae..a8785d40d3 100644
--- a/cpukit/libcsupport/src/chmod.c
+++ b/cpukit/libcsupport/src/chmod.c
@@ -33,7 +33,7 @@ int chmod( const char *path, mode_t mode )
   const rtems_filesystem_location_info_t *currentloc =
     rtems_filesystem_eval_path_start( &ctx, path, eval_flags );
 
-  rv = (*currentloc->mt_entry->ops->fchmod_h)( currentloc, mode );
+  rv = rtems_filesystem_chmod( currentloc, mode );
 
   rtems_filesystem_eval_path_cleanup( &ctx );
 
diff --git a/cpukit/libcsupport/src/fchmod.c b/cpukit/libcsupport/src/fchmod.c
index 94e82647fc..b8f4d333fb 100644
--- a/cpukit/libcsupport/src/fchmod.c
+++ b/cpukit/libcsupport/src/fchmod.c
@@ -22,6 +22,42 @@
 
 #include <rtems/libio_.h>
 
+int rtems_filesystem_chmod(
+  const rtems_filesystem_location_info_t *loc,
+  mode_t mode
+)
+{
+  const rtems_filesystem_mount_table_entry_t *mt_entry = loc->mt_entry;
+  int rv;
+
+  if ( mt_entry->writeable || rtems_filesystem_location_is_null( loc ) ) {
+    struct stat st;
+
+    memset( &st, 0, sizeof(st) );
+
+    rv = (*loc->handlers->fstat_h)( loc, &st );
+    if ( rv == 0 ) {
+      uid_t uid = geteuid();
+
+      if ( uid == 0 || st.st_uid == uid ) {
+        mode_t mask = S_IRWXU | S_IRWXG | S_IRWXO | S_ISUID | S_ISGID | S_ISVTX;
+
+        mode = (st.st_mode & ~mask) | (mode & mask);
+
+        rv = (*mt_entry->ops->fchmod_h)( loc, mode );
+      } else {
+        errno = EPERM;
+        rv = -1;
+      }
+    }
+  } else {
+    errno = EROFS;
+    rv = -1;
+  }
+
+  return rv;
+}
+
 /**
  *  POSIX 1003.1b 5.6.4 - Change File Modes
  */
@@ -34,14 +70,11 @@ int fchmod( int fd, mode_t mode )
   iop = rtems_libio_iop( fd );
   rtems_libio_check_is_open(iop);
 
-  if (iop->pathinfo.mt_entry->writeable) {
-    rtems_filesystem_instance_lock( &iop->pathinfo );
-    rv = (*iop->pathinfo.mt_entry->ops->fchmod_h)( &iop->pathinfo, mode );
-    rtems_filesystem_instance_unlock( &iop->pathinfo );
-  } else {
-    errno = EROFS;
-    rv = -1;
-  }
+  rtems_filesystem_instance_lock( &iop->pathinfo );
+
+  rv = rtems_filesystem_chmod( &iop->pathinfo, mode );
+
+  rtems_filesystem_instance_unlock( &iop->pathinfo );
 
   return rv;
 }