krb5 commit: Avoid rereading non-regular profile files

[Greg Hudson]

https://github.com/krb5/krb5/commit/2c26419ad7ea4800995180292ce39db863672fa9
commit 2c26419ad7ea4800995180292ce39db863672fa9
Author: Greg Hudson <ghudson at mit.edu>
Date:   Sun Mar 18 21:41:02 2018 -0400

    Avoid rereading non-regular profile files
    
    If a profile file is a special device such as a pipe, then reloading
    it will cause us to discard its contents.  Repurpose the first
    PROFILE_FILE flag bit to indicate that the file should not be
    reloaded.  In profile_update_file_data_locked(), set the flag on the
    first load if stat() doesn't indicate a regular file, and check the
    flag before testing whether we need to perform any subsequent reload.
    
    Later on in profile_update_file_data_locked(), specifically unset the
    DIRTY flag rather than unsetting all flags other than SHARED, so that
    we don't clear the NO_RELOAD flag.
    
    ticket: 8651

 src/util/profile/prof_file.c |    9 ++++++++-
 src/util/profile/prof_int.h  |    5 +----
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/src/util/profile/prof_file.c b/src/util/profile/prof_file.c
index 907c119..e80a1d7 100644
--- a/src/util/profile/prof_file.c
+++ b/src/util/profile/prof_file.c
@@ -312,6 +312,9 @@ errcode_t profile_update_file_data_locked(prf_data_t data, char **ret_modspec)
     FILE *f;
     int isdir = 0;
 
+    if ((data->flags & PROFILE_FILE_NO_RELOAD) && data->root != NULL)
+        return 0;
+
 #ifdef HAVE_STAT
     now = time(0);
     if (now == data->last_stat && data->root != NULL) {
@@ -339,6 +342,10 @@ errcode_t profile_update_file_data_locked(prf_data_t data, char **ret_modspec)
         profile_free_node(data->root);
         data->root = 0;
     }
+
+    /* Only try to reload regular files, not devices such as pipes. */
+    if ((st.st_mode & S_IFMT) != S_IFREG)
+        data->flags |= PROFILE_FILE_NO_RELOAD;
 #else
     /*
      * If we don't have the stat() call, assume that our in-core
@@ -362,7 +369,7 @@ errcode_t profile_update_file_data_locked(prf_data_t data, char **ret_modspec)
     }
 
     data->upd_serial++;
-    data->flags &= PROFILE_FILE_SHARED;  /* FIXME same as '=' operator */
+    data->flags &= ~PROFILE_FILE_DIRTY;
 
     if (isdir) {
         retval = profile_process_directory(data->filespec, &data->root);
diff --git a/src/util/profile/prof_int.h b/src/util/profile/prof_int.h
index 73f7fad..b42fd7b 100644
--- a/src/util/profile/prof_int.h
+++ b/src/util/profile/prof_int.h
@@ -72,11 +72,8 @@ typedef struct _prf_file_t *prf_file_t;
 
 /*
  * The profile flags
- *
- * Deprecated use of read/write profile flag.
- * Check whether file is writable lazily so we don't call access as often.
  */
-#define PROFILE_FILE_DEPRECATED_RW	0x0001
+#define PROFILE_FILE_NO_RELOAD		0x0001
 #define PROFILE_FILE_DIRTY		0x0002
 #define PROFILE_FILE_SHARED		0x0004