find: fix -prune more. Add big comment about it.

diff --git a/findutils/find.c b/findutils/find.c
index 3eea53db0504399dcccabd2a399810f629c477ea..594eafca44f5ec58b7ae37219cf13be8c5d8470e 100644 (file)
--- a/findutils/find.c
+++ b/findutils/find.c
@@ -120,20 +120,34 @@ static int exec_actions(action ***appp, const char *fileName, struct stat *statb
 {
        int cur_group;
        int cur_action;
-       int rc = TRUE;
+       int rc = 0;
        action **app, *ap;
 
+       /* "action group" is a set of actions ANDed together.
+        * groups are ORed together.
+        * We simply evaluate each group until we find one in which all actions
+        * succeed. */
+
+       /* -prune is special: if it is encountered, then we won't
+        * descend into current directory. It doesn't matter whether
+        * action group (in which -prune sits) will succeed or not:
+        * find * -prune -name 'f*' -o -name 'm*' -- prunes every dir
+        * find * -name 'f*' -o -prune -name 'm*' -- prunes all dirs
+        *     not starting with 'f' */
+
+       /* We invert TRUE bit (bit 0). Now 1 there means 'failure'.
+        * and bitwise OR in "rc |= TRUE ^ ap->f()" will:
+        * (1) make SKIP (-prune) bit stick; and (2) detect 'failure'.
+        * On return, bit is restored.  */
+
        cur_group = -1;
        while ((app = appp[++cur_group])) {
-               /* We invert TRUE bit (bit 0). Now 1 there means 'failure'.
-                * and bitwise OR in "rc |= TRUE ^ ap->f()" will:
-                * (1) make SKIP bit stick; and (2) detect 'failure' */
-               rc = 0; /* 'success' so far */
+               rc &= ~TRUE; /* 'success' so far, clear TRUE bit */
                cur_action = -1;
                while (1) {
                        ap = app[++cur_action];
                        if (!ap) /* all actions in group were successful */
-                               return rc ^ TRUE;
+                               return rc ^ TRUE; /* restore TRUE bit */
                        rc |= TRUE ^ ap->f(fileName, statbuf, ap);
 #if ENABLE_FEATURE_FIND_NOT
                        if (ap->invert) rc ^= TRUE;
@@ -142,7 +156,7 @@ static int exec_actions(action ***appp, const char *fileName, struct stat *statb
                                break;
                }
        }
-       return rc ^ TRUE; /* straighten things out */
+       return rc ^ TRUE; /* restore TRUE bit */
 }