[14/25] nscd: Use struct scratch_buffer instead of extend_alloca in most caches
diff mbox

Message ID bdaf35afacc8e09000439e743c099c737d2b4014.1425285061.git.fweimer@redhat.com
State New
Headers show

Commit Message

Florian Weimer March 1, 2015, 5:55 p.m. UTC
This replaces the ERANGE retry loops with loops which have heap
fallback.  Heap allocation might actually be required for extremely
large NSS results.
---
 nscd/grpcache.c      | 57 +++++++++++++++++----------------------------------
 nscd/hstcache.c      | 58 ++++++++++++++++++----------------------------------
 nscd/pwdcache.c      | 56 ++++++++++++++++----------------------------------
 nscd/servicescache.c | 56 ++++++++++++++++----------------------------------
 4 files changed, 75 insertions(+), 152 deletions(-)

Patch
diff mbox

diff --git a/nscd/grpcache.c b/nscd/grpcache.c
index eed0e3d..e32011d 100644
--- a/nscd/grpcache.c
+++ b/nscd/grpcache.c
@@ -16,7 +16,6 @@ 
    You should have received a copy of the GNU General Public License
    along with this program; if not, see <http://www.gnu.org/licenses/>.  */
 
-#include <alloca.h>
 #include <assert.h>
 #include <errno.h>
 #include <error.h>
@@ -32,6 +31,7 @@ 
 #include <sys/mman.h>
 #include <sys/socket.h>
 #include <stackinfo.h>
+#include <scratch_buffer.h>
 
 #include "nscd.h"
 #include "dbg_log.h"
@@ -437,12 +437,12 @@  addgrbyX (struct database_dyn *db, int fd, request_header *req,
      look again in the table whether the dataset is now available.  We
      simply insert it.  It does not matter if it is in there twice.  The
      pruning function only will look at the timestamp.  */
-  size_t buflen = 1024;
-  char *buffer = (char *) alloca (buflen);
+
   struct group resultbuf;
   struct group *grp;
-  bool use_malloc = false;
   int errval = 0;
+  struct scratch_buffer tmpbuf;
+  scratch_buffer_init (&tmpbuf);
 
   if (__glibc_unlikely (debug_level > 0))
     {
@@ -452,43 +452,24 @@  addgrbyX (struct database_dyn *db, int fd, request_header *req,
 	dbg_log (_("Reloading \"%s\" in group cache!"), keystr);
     }
 
-  while (lookup (req->type, key, &resultbuf, buffer, buflen, &grp) != 0
+  while (lookup (req->type, key, &resultbuf,
+		 tmpbuf.data, tmpbuf.length, &grp) != 0
 	 && (errval = errno) == ERANGE)
-    {
-      errno = 0;
-
-      if (__glibc_unlikely (buflen > 32768))
-	{
-	  char *old_buffer = buffer;
-	  buflen *= 2;
-	  buffer = (char *) realloc (use_malloc ? buffer : NULL, buflen);
-	  if (buffer == NULL)
-	    {
-	      /* We ran out of memory.  We cannot do anything but
-		 sending a negative response.  In reality this should
-		 never happen.  */
-	      grp = NULL;
-	      buffer = old_buffer;
-
-	      /* We set the error to indicate this is (possibly) a
-		 temporary error and that it does not mean the entry
-		 is not available at all.  */
-	      errval = EAGAIN;
-	      break;
-	    }
-	  use_malloc = true;
-	}
-      else
-	/* Allocate a new buffer on the stack.  If possible combine it
-	   with the previously allocated buffer.  */
-	buffer = (char *) extend_alloca (buffer, buflen, 2 * buflen);
-    }
+    if (!scratch_buffer_grow (&tmpbuf))
+      {
+	/* We ran out of memory.  We cannot do anything but sending a
+	   negative response.  In reality this should never
+	   happen.  */
+	grp = NULL;
+	/* We set the error to indicate this is (possibly) a temporary
+	   error and that it does not mean the entry is not available
+	   at all.  */
+	errval = EAGAIN;
+	break;
+      }
 
   time_t timeout = cache_addgr (db, fd, req, keystr, grp, uid, he, dh, errval);
-
-  if (use_malloc)
-    free (buffer);
-
+  scratch_buffer_free (&tmpbuf);
   return timeout;
 }
 
diff --git a/nscd/hstcache.c b/nscd/hstcache.c
index e6db064..1b76ca1 100644
--- a/nscd/hstcache.c
+++ b/nscd/hstcache.c
@@ -34,6 +34,7 @@ 
 #include <arpa/nameser.h>
 #include <sys/mman.h>
 #include <stackinfo.h>
+#include <scratch_buffer.h>
 
 #include "nscd.h"
 #include "dbg_log.h"
@@ -463,11 +464,8 @@  addhstbyX (struct database_dyn *db, int fd, request_header *req,
      look again in the table whether the dataset is now available.  We
      simply insert it.  It does not matter if it is in there twice.  The
      pruning function only will look at the timestamp.  */
-  int buflen = 1024;
-  char *buffer = (char *) alloca (buflen);
   struct hostent resultbuf;
   struct hostent *hst;
-  bool use_malloc = false;
   int errval = 0;
   int32_t ttl = INT32_MAX;
 
@@ -487,46 +485,30 @@  addhstbyX (struct database_dyn *db, int fd, request_header *req,
 	dbg_log (_("Reloading \"%s\" in hosts cache!"), (char *) str);
     }
 
-  while (lookup (req->type, key, &resultbuf, buffer, buflen, &hst, &ttl) != 0
+  struct scratch_buffer tmpbuf;
+  scratch_buffer_init (&tmpbuf);
+
+  while (lookup (req->type, key, &resultbuf,
+		 tmpbuf.data, tmpbuf.length, &hst, &ttl) != 0
 	 && h_errno == NETDB_INTERNAL
 	 && (errval = errno) == ERANGE)
-    {
-      errno = 0;
-
-      if (__glibc_unlikely (buflen > 32768))
-	{
-	  char *old_buffer = buffer;
-	  buflen *= 2;
-	  buffer = (char *) realloc (use_malloc ? buffer : NULL, buflen);
-	  if (buffer == NULL)
-	    {
-	      /* We ran out of memory.  We cannot do anything but
-		 sending a negative response.  In reality this should
-		 never happen.  */
-	      hst = NULL;
-	      buffer = old_buffer;
-
-	      /* We set the error to indicate this is (possibly) a
-		 temporary error and that it does not mean the entry
-		 is not available at all.  */
-	      h_errno = TRY_AGAIN;
-	      errval = EAGAIN;
-	      break;
-	    }
-	  use_malloc = true;
-	}
-      else
-	/* Allocate a new buffer on the stack.  If possible combine it
-	   with the previously allocated buffer.  */
-	buffer = (char *) extend_alloca (buffer, buflen, 2 * buflen);
-    }
+    if (!scratch_buffer_grow (&tmpbuf))
+      {
+	/* We ran out of memory.  We cannot do anything but sending a
+	   negative response.  In reality this should never
+	   happen.  */
+	hst = NULL;
+	/* We set the error to indicate this is (possibly) a temporary
+	   error and that it does not mean the entry is not
+	   available at all.  */
+	h_errno = TRY_AGAIN;
+	errval = EAGAIN;
+	break;
+      }
 
   time_t timeout = cache_addhst (db, fd, req, key, hst, uid, he, dh,
 				 h_errno == TRY_AGAIN ? errval : 0, ttl);
-
-  if (use_malloc)
-    free (buffer);
-
+  scratch_buffer_free (&tmpbuf);
   return timeout;
 }
 
diff --git a/nscd/pwdcache.c b/nscd/pwdcache.c
index b12a13d..07b9e48 100644
--- a/nscd/pwdcache.c
+++ b/nscd/pwdcache.c
@@ -16,7 +16,6 @@ 
    You should have received a copy of the GNU General Public License
    along with this program; if not, see <http://www.gnu.org/licenses/>.  */
 
-#include <alloca.h>
 #include <assert.h>
 #include <errno.h>
 #include <error.h>
@@ -32,6 +31,7 @@ 
 #include <sys/mman.h>
 #include <sys/socket.h>
 #include <stackinfo.h>
+#include <scratch_buffer.h>
 
 #include "nscd.h"
 #include "dbg_log.h"
@@ -415,12 +415,11 @@  addpwbyX (struct database_dyn *db, int fd, request_header *req,
      look again in the table whether the dataset is now available.  We
      simply insert it.  It does not matter if it is in there twice.  The
      pruning function only will look at the timestamp.  */
-  size_t buflen = 1024;
-  char *buffer = (char *) alloca (buflen);
   struct passwd resultbuf;
   struct passwd *pwd;
-  bool use_malloc = false;
   int errval = 0;
+  struct scratch_buffer tmpbuf;
+  scratch_buffer_init (&tmpbuf);
 
   if (__glibc_unlikely (debug_level > 0))
     {
@@ -430,45 +429,26 @@  addpwbyX (struct database_dyn *db, int fd, request_header *req,
 	dbg_log (_("Reloading \"%s\" in password cache!"), keystr);
     }
 
-  while (lookup (req->type, key, &resultbuf, buffer, buflen, &pwd) != 0
+  while (lookup (req->type, key, &resultbuf,
+		 tmpbuf.data, tmpbuf.length, &pwd) != 0
 	 && (errval = errno) == ERANGE)
-    {
-      errno = 0;
-
-      if (__glibc_unlikely (buflen > 32768))
-	{
-	  char *old_buffer = buffer;
-	  buflen *= 2;
-	  buffer = (char *) realloc (use_malloc ? buffer : NULL, buflen);
-	  if (buffer == NULL)
-	    {
-	      /* We ran out of memory.  We cannot do anything but
-		 sending a negative response.  In reality this should
-		 never happen.  */
-	      pwd = NULL;
-	      buffer = old_buffer;
-
-	      /* We set the error to indicate this is (possibly) a
-		 temporary error and that it does not mean the entry
-		 is not available at all.  */
-	      errval = EAGAIN;
-	      break;
-	    }
-	  use_malloc = true;
-	}
-      else
-	/* Allocate a new buffer on the stack.  If possible combine it
-	   with the previously allocated buffer.  */
-	buffer = (char *) extend_alloca (buffer, buflen, 2 * buflen);
-    }
+    if (!scratch_buffer_grow (&tmpbuf))
+      {
+	/* We ran out of memory.  We cannot do anything but sending a
+	   negative response.  In reality this should never
+	   happen.  */
+	pwd = NULL;
+	/* We set the error to indicate this is (possibly) a temporary
+	   error and that it does not mean the entry is not available
+	   at all.  */
+	errval = EAGAIN;
+	break;
+      }
 
   /* Add the entry to the cache.  */
   time_t timeout = cache_addpw (db, fd, req, keystr, pwd, c_uid, he, dh,
 				errval);
-
-  if (use_malloc)
-    free (buffer);
-
+  scratch_buffer_free (&tmpbuf);
   return timeout;
 }
 
diff --git a/nscd/servicescache.c b/nscd/servicescache.c
index 4e8ee4c..fc29d25 100644
--- a/nscd/servicescache.c
+++ b/nscd/servicescache.c
@@ -16,7 +16,6 @@ 
    You should have received a copy of the GNU General Public License
    along with this program; if not, see <http://www.gnu.org/licenses/>.  */
 
-#include <alloca.h>
 #include <assert.h>
 #include <errno.h>
 #include <libintl.h>
@@ -25,6 +24,7 @@ 
 #include <stdint.h>
 #include <sys/mman.h>
 #include <kernel-features.h>
+#include <scratch_buffer.h>
 
 #include "nscd.h"
 #include "dbg_log.h"
@@ -374,12 +374,11 @@  addservbyX (struct database_dyn *db, int fd, request_header *req,
      look again in the table whether the dataset is now available.  We
      simply insert it.  It does not matter if it is in there twice.  The
      pruning function only will look at the timestamp.  */
-  size_t buflen = 1024;
-  char *buffer = (char *) alloca (buflen);
   struct servent resultbuf;
   struct servent *serv;
-  bool use_malloc = false;
   int errval = 0;
+  struct scratch_buffer tmpbuf;
+  scratch_buffer_init (&tmpbuf);
 
   if (__glibc_unlikely (debug_level > 0))
     {
@@ -389,43 +388,24 @@  addservbyX (struct database_dyn *db, int fd, request_header *req,
 	dbg_log (_("Reloading \"%s\" in services cache!"), key);
     }
 
-  while (lookup (req->type, key, &resultbuf, buffer, buflen, &serv) != 0
+  while (lookup (req->type, key, &resultbuf,
+		 tmpbuf.data, tmpbuf.length, &serv) != 0
 	 && (errval = errno) == ERANGE)
-    {
-      errno = 0;
-
-      if (__glibc_unlikely (buflen > 32768))
-	{
-	  char *old_buffer = buffer;
-	  buflen *= 2;
-	  buffer = (char *) realloc (use_malloc ? buffer : NULL, buflen);
-	  if (buffer == NULL)
-	    {
-	      /* We ran out of memory.  We cannot do anything but
-		 sending a negative response.  In reality this should
-		 never happen.  */
-	      serv = NULL;
-	      buffer = old_buffer;
-
-	      /* We set the error to indicate this is (possibly) a
-		 temporary error and that it does not mean the entry
-		 is not available at all.  */
-	      errval = EAGAIN;
-	      break;
-	    }
-	  use_malloc = true;
-	}
-      else
-	/* Allocate a new buffer on the stack.  If possible combine it
-	   with the previously allocated buffer.  */
-	buffer = (char *) extend_alloca (buffer, buflen, 2 * buflen);
-    }
+    if (!scratch_buffer_grow (&tmpbuf))
+      {
+	/* We ran out of memory.  We cannot do anything but sending a
+	   negative response.  In reality this should never
+	   happen.  */
+	serv = NULL;
+	/* We set the error to indicate this is (possibly) a temporary
+	   error and that it does not mean the entry is not available
+	   at all.  */
+	errval = EAGAIN;
+	break;
+      }
 
   time_t timeout = cache_addserv (db, fd, req, key, serv, uid, he, dh, errval);
-
-  if (use_malloc)
-    free (buffer);
-
+  scratch_buffer_free (&tmpbuf);
   return timeout;
 }