Generalize ef_extend() to non-file-backed tables

[empserver] / src / lib / common / file.c

diff --git a/src/lib/common/file.c b/src/lib/common/file.c
index a4f728591262373465ad56cfbd75b30165ef3827..f75ada44418ae655d8b4cacc62184e343b475ac0 100644 (file)
--- a/src/lib/common/file.c
+++ b/src/lib/common/file.c
@@ -46,8 +46,10 @@
 #include "nsc.h"
 #include "prototypes.h"
 
+static int ef_remap_cache(struct empfile *, int);
 static int fillcache(struct empfile *, int);
 static int do_write(struct empfile *, void *, int, int);
+static void ef_blank(struct empfile *, void *, int, int);
 
 /*
  * Open the file-backed table TYPE (EF_SECTOR, ...).
@@ -61,7 +63,7 @@ ef_open(int type, int how)
 {
     struct empfile *ep;
     struct flock lock;
-    int oflags, fd, fsiz, size;
+    int oflags, fd, fsiz, nslots;
 
     if (ef_check(type) < 0)
        return 0;
@@ -116,18 +118,13 @@ ef_open(int type, int how)
            }
        }
     } else {
-       if (how & EFF_MEM)
-           ep->csize = ep->fids;
-       else
-           ep->csize = blksize(fd) / ep->size;
-       /* 0 could lead to null cache, which confuses assertions */
-       if (!ep->csize)
-           ep->csize++;
-       size = ep->csize * ep->size;
        if (CANT_HAPPEN(ep->cache))
            free(ep->cache);
-       ep->cache = malloc(size);
-       if (ep->cache == NULL) {
+       if (how & EFF_MEM)
+           nslots = ep->fids;
+       else
+           nslots = blksize(fd) / ep->size;
+       if (!ef_remap_cache(ep, nslots)) {
            logerror("Can't open %s: out of memory", ep->file);
            close(fd);
            return 0;
@@ -151,6 +148,31 @@ ef_open(int type, int how)
     return 1;
 }
 
+static int
+ef_remap_cache(struct empfile *ep, int nslots)
+{
+    void *cache;
+
+    if (CANT_HAPPEN(ep->flags & EFF_STATIC))
+       return 0;
+    if (CANT_HAPPEN(nslots < 0))
+       nslots = 0;
+
+    /*
+     * Avoid zero slots, because that can lead to null cache, which
+     * would be interpreted as unmapped cache.
+     */
+    if (nslots == 0)
+       nslots++;
+    cache = realloc(ep->cache, nslots * ep->size);
+    if (!cache)
+       return 0;
+
+    ep->cache = cache;
+    ep->csize = nslots;
+    return 1;
+}
+
 /*
  * Close the file-backed table TYPE (EF_SECTOR, ...).
  * Return non-zero on success, zero on failure.
@@ -384,47 +406,66 @@ ef_write(int type, int id, void *from)
 }
 
 /*
- * Extend the file-backed table TYPE by COUNT elements.
- * Can't extend privately mapped tables.
+ * Extend table TYPE by COUNT elements.
+ * Any pointers obtained from ef_ptr() become invalid.
  * Return non-zero on success, zero on failure.
  */
 int
 ef_extend(int type, int count)
 {
     struct empfile *ep;
-    void *tmpobj;
-    int id, i, how;
+    char *p;
+    int i, id;
 
     if (ef_check(type) < 0)
        return 0;
     ep = &empfile[type];
-    if (CANT_HAPPEN(ep->fd < 0 || count < 0))
+    if (CANT_HAPPEN(count < 0))
        return 0;
-    if (CANT_HAPPEN(ep->flags & EFF_PRIVATE))
-       return 0;               /* not implemented */
 
-    tmpobj = calloc(1, ep->size);
     id = ep->fids;
-    for (i = 0; i < count; i++) {
-       if (ep->init)
-           ep->init(id + i, tmpobj);
-       if (do_write(ep, tmpobj, id + i, 1) < 0)
-           break;
-    }
-    free(tmpobj);
-
     if (ep->flags & EFF_MEM) {
-       /* FIXME lazy bastards...  do this right */
-       /* XXX this will cause problems if there are ef_ptrs (to the
-        * old allocated structure) active when we do the re-open */
-       how = ep->flags & ~EFF_IMMUTABLE;
-       ef_close(type);
-       ef_open(type, how);
+       if (id + count > ep->csize) {
+           if (ep->flags & EFF_STATIC)
+               return 0;
+           if (!ef_remap_cache(ep, id + count))
+               return 0;
+       }
+       p = ep->cache + id * ep->size;
+       ef_blank(ep, p, id, count);
+       if (!(ep->flags & EFF_PRIVATE)) {
+           if (do_write(ep, p, id, count) < 0)
+               return 0;
+       }
+       ep->cids += count;
     } else {
-       ep->fids += i;
+       /* need a buffer, steal last cache slot */
+       if (ep->cids == ep->csize)
+           ep->cids--;
+       p = ep->cache + ep->cids * ep->size;
+       for (i = 0; i < count; i++) {
+           ef_blank(ep, p, id + i, 1);
+           if (do_write(ep, p, id + i, 1) < 0)
+               return 0;
+       }
     }
+    ep->fids += count;
+    return 1;
+}
+
+/*
+ * Initialize COUNT elements of EP in BUF, starting with element ID.
+ */
+static void
+ef_blank(struct empfile *ep, void *buf, int id, int count)
+{
+    int i;
 
-    return i == count;
+    memset(buf, 0, count * ep->size);
+    if (ep->init) {
+       for (i = 0; i < count; i++)
+           ep->init(id + i, (char *)buf + i * ep->size);
+    }
 }
 
 struct castr *