Added a library module for generation of cryptographically secure

[libucw.git] / lib / bucket.c

diff --git a/lib/bucket.c b/lib/bucket.c
index d5733c59160fc9abc890fc1a36887314d96d16e5..e35f99f8cc011805f6a000ad724eeb3aa6a07ff4 100644 (file)
--- a/lib/bucket.c
+++ b/lib/bucket.c
@@ -11,6 +11,7 @@
 #include "lib/conf.h"
 
 #include <string.h>
+#include <stdlib.h>
 #include <fcntl.h>
 #include <unistd.h>
 #include <sys/file.h>
@@ -25,11 +26,13 @@ static sh_off_t bucket_start;
 
 byte *obuck_name = "not/configured";
 static int obuck_io_buflen = 65536;
+static int obuck_shake_buflen = 1048576;
 
 static struct cfitem obuck_config[] = {
   { "Buckets",         CT_SECTION,     NULL },
   { "BucketFile",      CT_STRING,      &obuck_name },
   { "BufSize",         CT_INT,         &obuck_io_buflen },
+  { "ShakeBufSize",    CT_INT,         &obuck_shake_buflen },
   { NULL,              CT_STOP,        NULL }
 };
 
@@ -43,25 +46,46 @@ static void CONSTRUCTOR obuck_init_config(void)
 static void
 obuck_broken(char *msg)
 {
-  die("Object pool corrupted: %s (pos=%Lx)", msg, (long long) bucket_start);   /* FIXME */
+  die("Object pool corrupted: %s (pos=%Lx)", msg, (long long) bucket_start);
+}
+
+/*
+ *  Unfortunately we cannot use flock() here since it happily permits
+ *  locking a shared fd (e.g., after fork()) multiple times. The fcntl
+ *  locks are very ugly and they don't support 64-bit offsets, but we
+ *  can work around the problem by always locking the first header
+ *  in the file.
+ */
+
+static inline void
+obuck_do_lock(int type)
+{
+  struct flock fl;
+
+  fl.l_type = type;
+  fl.l_whence = SEEK_SET;
+  fl.l_start = 0;
+  fl.l_len = sizeof(struct obuck_header);
+  if (fcntl(obuck_fd, F_SETLKW, &fl) < 0)
+    die("fcntl lock: %m");
 }
 
 static inline void
 obuck_lock_read(void)
 {
-  flock(obuck_fd, LOCK_SH);
+  obuck_do_lock(F_RDLCK);
 }
 
 static inline void
 obuck_lock_write(void)
 {
-  flock(obuck_fd, LOCK_EX);
+  obuck_do_lock(F_WRLCK);
 }
 
 static inline void
 obuck_unlock(void)
 {
-  flock(obuck_fd, LOCK_UN);
+  obuck_do_lock(F_UNLCK);
 }
 
 /*** FastIO emulation ***/
@@ -89,9 +113,7 @@ obuck_fb_refill(struct fastbuf *f)
   obuck_remains -= limit;
   if (!obuck_remains)  /* Should check the trailer */
     {
-      u32 check;
-      memcpy(&check, f->buffer + size - 4, 4);
-      if (check != OBUCK_TRAILER)
+      if (GET_U32(f->buffer + size - 4) != OBUCK_TRAILER)
        obuck_broken("Missing trailer");
     }
   return limit;
@@ -163,7 +185,7 @@ obuck_cleanup(void)
   bclose(obuck_fb);
 }
 
-void                                   /* FIXME: Call somewhere :) */
+void
 obuck_sync(void)
 {
   bflush(obuck_fb);
@@ -294,6 +316,101 @@ obuck_delete(oid_t oid)
   obuck_unlock();
 }
 
+/*** Shakedown ***/
+
+void
+obuck_shakedown(int (*kibitz)(struct obuck_header *old, oid_t new, byte *buck))
+{
+  byte *rbuf, *wbuf;
+  sh_off_t rstart, wstart, w_bucket_start;
+  int roff, woff, rsize, l;
+  struct obuck_header *rhdr, *whdr;
+
+  rbuf = xmalloc(obuck_shake_buflen);
+  wbuf = xmalloc(obuck_shake_buflen);
+  rstart = wstart = 0;
+  roff = woff = rsize = 0;
+
+  /* We need to be the only accessor, all the object ID's are becoming invalid */
+  obuck_lock_write();
+
+  for(;;)
+    {
+      bucket_start = rstart + roff;
+      w_bucket_start = wstart + woff;
+      if (rsize - roff < OBUCK_ALIGN)
+       goto reread;
+      rhdr = (struct obuck_header *)(rbuf + roff);
+      if (rhdr->magic != OBUCK_MAGIC ||
+         rhdr->oid != OBUCK_OID_DELETED && rhdr->oid != (bucket_start >> OBUCK_SHIFT))
+       obuck_broken("header mismatch during shakedown");
+      l = (sizeof(struct obuck_header) + rhdr->length + 4 + OBUCK_ALIGN - 1) & ~(OBUCK_ALIGN-1);
+      if (rsize - roff < l)
+       goto reread;
+      if (GET_U32(rbuf + roff + l - 4) != OBUCK_TRAILER)
+       obuck_broken("missing trailer during shakedown");
+      if (rhdr->oid != OBUCK_OID_DELETED)
+       {
+         if (kibitz(rhdr, w_bucket_start >> OBUCK_SHIFT, (byte *)(rhdr+1)))
+           {
+             if (bucket_start == w_bucket_start)
+               {
+                 /* No copying needed now nor ever in the past, hence woff==0 */
+                 wstart += l;
+               }
+             else
+               {
+                 if (obuck_shake_buflen - woff < l)
+                   {
+                     if (sh_pwrite(obuck_fd, wbuf, woff, wstart) != woff)
+                       die("obuck_shakedown write failed: %m");
+                     wstart += woff;
+                     woff = 0;
+                   }
+                 whdr = (struct obuck_header *)(wbuf+woff);
+                 memcpy(whdr, rhdr, l);
+                 whdr->oid = w_bucket_start >> OBUCK_SHIFT;
+                 woff += l;
+               }
+           }
+       }
+      else
+       kibitz(rhdr, OBUCK_OID_DELETED, NULL);
+      roff += l;
+      continue;
+
+    reread:
+      if (roff)
+       {
+         memmove(rbuf, rbuf+roff, rsize-roff);
+         rsize -= roff;
+         rstart += roff;
+         roff = 0;
+       }
+      l = sh_pread(obuck_fd, rbuf+rsize, obuck_shake_buflen-rsize, rstart+rsize);
+      if (l < 0)
+       die("obuck_shakedown read error: %m");
+      if (!l)
+       {
+         if (!rsize)
+           break;
+         obuck_broken("unexpected EOF during shakedown");
+       }
+      rsize += l;
+    }
+  if (woff)
+    {
+      if (sh_pwrite(obuck_fd, wbuf, woff, wstart) != woff)
+       die("obuck_shakedown write failed: %m");
+      wstart += woff;
+    }
+  sh_ftruncate(obuck_fd, wstart);
+
+  obuck_unlock();
+  xfree(rbuf);
+  xfree(wbuf);
+}
+
 /*** Testing ***/
 
 #ifdef TEST
@@ -313,7 +430,10 @@ int main(int argc, char **argv)
   log_init(NULL);
   if (cf_getopt(argc, argv, CF_SHORT_OPTS, CF_NO_LONG_OPTS, NULL) >= 0 ||
       optind < argc)
-    die("This program has no command-line arguments.");
+  {
+    fputs("This program supports only the following command-line arguments:\n" CF_USAGE, stderr);
+    exit(1);
+  }
 
   unlink(obuck_name);
   obuck_init(1);