fix data loss when more than one block is read from SDBM

*.dir file (suggested by Uwe Ohse <uwe@ohse.de>)

p4raw-id: //depot/perl@4082

diff --git a/ext/SDBM_File/sdbm/sdbm.c b/ext/SDBM_File/sdbm/sdbm.c
index 499871d..5952d71 100644 (file)
--- a/ext/SDBM_File/sdbm/sdbm.c
+++ b/ext/SDBM_File/sdbm/sdbm.c
@@ -431,9 +431,12 @@ getdbit(register DBM *db, register long int dbit)
        dirb = c / DBLKSIZ;
 
        if (dirb != db->dirbno) {
+               int got;
                if (lseek(db->dirf, OFF_DIR(dirb), SEEK_SET) < 0
-                   || read(db->dirf, db->dirbuf, DBLKSIZ) < 0)
+                   || (got=read(db->dirf, db->dirbuf, DBLKSIZ)) < 0)
                        return 0;
+               if (got==0) 
+                       memset(db->dirbuf,0,DBLKSIZ);
                db->dirbno = dirb;
 
                debug(("dir read: %d\n", dirb));
@@ -452,10 +455,12 @@ setdbit(register DBM *db, register long int dbit)
        dirb = c / DBLKSIZ;
 
        if (dirb != db->dirbno) {
-               (void) memset(db->dirbuf, 0, DBLKSIZ);
+               int got;
                if (lseek(db->dirf, OFF_DIR(dirb), SEEK_SET) < 0
-                   || read(db->dirf, db->dirbuf, DBLKSIZ) < 0)
+                   || (got=read(db->dirf, db->dirbuf, DBLKSIZ)) < 0)
                        return 0;
+               if (got==0) 
+                       memset(db->dirbuf,0,DBLKSIZ);
                db->dirbno = dirb;
 
                debug(("dir read: %d\n", dirb));
@@ -463,8 +468,13 @@ setdbit(register DBM *db, register long int dbit)
 
        db->dirbuf[c % DBLKSIZ] |= (1 << dbit % BYTESIZ);
 
+#if 0
        if (dbit >= db->maxbno)
                db->maxbno += DBLKSIZ * BYTESIZ;
+#else
+       if (OFF_DIR((dirb+1))*BYTESIZ > db->maxbno) 
+               db->maxbno=OFF_DIR((dirb+1))*BYTESIZ;
+#endif
 
        if (lseek(db->dirf, OFF_DIR(dirb), SEEK_SET) < 0
            || write(db->dirf, db->dirbuf, DBLKSIZ) < 0)