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[libvirt] [PATCH] Introduce virStrncpy.



Add the virStrncpy function, which takes a dst string, source string,
the number of bytes to copy and the number of bytes available in the
dest string.  If the source string is too large to fit into the
destination string, including the \0 byte, then no data is copied and
the function returns NULL.  Otherwise, this function copies n bytes
from source into dst, including the \0, and returns a pointer to the
dst string.  This function is intended to replace all unsafe uses
of strncpy in the code base, since strncpy does *not* guarantee that
the buffer terminates with a \0.

Signed-off-by: Chris Lalancette <clalance redhat com>
---
 HACKING                     |   31 +++++++++
 cfg.mk                      |    6 ++
 daemon/Makefile.am          |    3 +-
 daemon/libvirtd.c           |    6 +-
 daemon/remote.c             |    8 ++-
 proxy/libvirt_proxy.c       |    6 ++-
 src/datatypes.c             |    9 ++-
 src/esx/esx_driver.c        |   11 +++-
 src/esx/esx_vmx.c           |   30 +++-------
 src/lxc/lxc_controller.c    |    6 ++-
 src/lxc/lxc_driver.c        |   12 +++-
 src/nodeinfo.c              |    4 +-
 src/opennebula/one_client.c |   11 ++--
 src/openvz/openvz_conf.c    |   33 +++++++---
 src/phyp/phyp_driver.c      |    2 +-
 src/qemu/qemu_conf.c        |   16 +++---
 src/qemu/qemu_driver.c      |   12 +++-
 src/remote/remote_driver.c  |   19 ++++--
 src/test/test_driver.c      |   24 +++++--
 src/uml/uml_driver.c        |   17 ++++--
 src/util/bridge.c           |   89 ++++++++-------------------
 src/util/util.c             |   36 +++++++++--
 src/util/util.h             |    4 +
 src/xen/proxy_internal.c    |    5 +-
 src/xen/xen_hypervisor.c    |   22 +++++--
 src/xen/xend_internal.c     |   65 ++++++++++++-------
 src/xen/xm_internal.c       |  145 ++++++++++++++++++++++++++++---------------
 27 files changed, 399 insertions(+), 233 deletions(-)

diff --git a/HACKING b/HACKING
index da28e98..bcff8c6 100644
--- a/HACKING
+++ b/HACKING
@@ -231,6 +231,37 @@ one of the following semantically named macros
 
 
 
+String copying
+==============
+
+Do not use the strncpy function.  According to the man page, it does
+*not* guarantee a NULL-terminated buffer, which makes it extremely dangerous
+to use.  Instead, use one of the functionally equivalent functions:
+
+  - virStrncpy(char *dest, const char *src, size_t n, size_t destbytes)
+      The first three arguments have the same meaning as for strncpy; namely the
+      destination, source, and number of bytes to copy, respectively.  The last
+      argument is the number of bytes available in the destination string; if a
+      copy of the source string (including a \0) will not fit into the
+      destination, no bytes are copied and the routine returns NULL.
+      Otherwise, n bytes from the source are copied into the destination and a
+      trailing \0 is appended.
+
+  - virStrcpy(char *dest, const char *src, size_t destbytes)
+      Use this variant if you know you want to copy the entire src string
+      into dest.  Note that this is a macro, so arguments could be
+      evaluated more than once.  This is equivalent to
+      virStrncpy(dest, src, strlen(src), destbytes)
+
+  - virStrcpyStatic(char *dest, const char *src)
+      Use this variant if you know you want to copy the entire src string
+      into dest *and* you know that your destination string is a static string
+      (i.e. that sizeof(dest) returns something meaningful).  Note that
+      this is a macro, so arguments could be evaluated more than once.  This is
+      equivalent to virStrncpy(dest, src, strlen(src), sizeof(dest)).
+
+
+
 Variable length string buffer
 =============================
 
diff --git a/cfg.mk b/cfg.mk
index 64bd26e..2d2dd7e 100644
--- a/cfg.mk
+++ b/cfg.mk
@@ -91,6 +91,12 @@ sc_prohibit_asprintf:
 	msg='use virAsprintf, not a'sprintf				\
 	  $(_prohibit_regexp)
 
+sc_prohibit_strncpy:
+	@grep -nE 'strncpy *\('						\
+	    $$($(VC_LIST) | grep -v 'src/util.c') &&			\
+	  { echo '$(ME): use virStrncpy, not strncpy'			\
+		1>&2; exit 1; } || :
+
 sc_prohibit_VIR_ERR_NO_MEMORY:
 	@re='\<V''IR_ERR_NO_MEMORY\>'					\
 	msg='use virReportOOMError, not V'IR_ERR_NO_MEMORY		\
diff --git a/daemon/Makefile.am b/daemon/Makefile.am
index 61822ec..8d9f00f 100644
--- a/daemon/Makefile.am
+++ b/daemon/Makefile.am
@@ -73,9 +73,10 @@ libvirtd_LDADD =					\
 	$(SASL_LIBS)					\
 	$(POLKIT_LIBS)
 
+libvirtd_LDADD += ../src/libvirt_util.la
+
 if WITH_DRIVER_MODULES
   libvirtd_LDADD += ../src/libvirt_driver.la
-  libvirtd_LDADD += ../src/libvirt_util.la
 else
 if WITH_QEMU
     libvirtd_LDADD += ../src/libvirt_driver_qemu.la
diff --git a/daemon/libvirtd.c b/daemon/libvirtd.c
index 07960e1..2bae782 100644
--- a/daemon/libvirtd.c
+++ b/daemon/libvirtd.c
@@ -507,11 +507,13 @@ static int qemudListenUnix(struct qemud_server *server,
 
     memset(&addr, 0, sizeof(addr));
     addr.sun_family = AF_UNIX;
-    strncpy(addr.sun_path, path, sizeof(addr.sun_path)-1);
+    if (virStrcpyStatic(addr.sun_path, path) == NULL) {
+        VIR_ERROR(_("Path %s too long for unix socket"), path);
+        goto cleanup;
+    }
     if (addr.sun_path[0] == '@')
         addr.sun_path[0] = '\0';
 
-
     oldgrp = getgid();
     oldmask = umask(readonly ? ~unix_sock_ro_mask : ~unix_sock_rw_mask);
     if (server->privileged)
diff --git a/daemon/remote.c b/daemon/remote.c
index 17426cd..6d4cc1c 100644
--- a/daemon/remote.c
+++ b/daemon/remote.c
@@ -556,9 +556,11 @@ remoteDispatchDomainSetSchedulerParameters (struct qemud_server *server ATTRIBUT
 
     /* Deserialise parameters. */
     for (i = 0; i < nparams; ++i) {
-        strncpy (params[i].field, args->params.params_val[i].field,
-                 VIR_DOMAIN_SCHED_FIELD_LENGTH);
-        params[i].field[VIR_DOMAIN_SCHED_FIELD_LENGTH-1] = '\0';
+        if (virStrcpyStatic(params[i].field, args->params.params_val[i].field) == NULL) {
+            remoteDispatchFormatError(rerr, _("Field %s too big for destination"),
+                                      args->params.params_val[i].field);
+            return -1;
+        }
         params[i].type = args->params.params_val[i].value.type;
         switch (params[i].type) {
         case VIR_DOMAIN_SCHED_FIELD_INT:
diff --git a/proxy/libvirt_proxy.c b/proxy/libvirt_proxy.c
index aa20d28..e5298fd 100644
--- a/proxy/libvirt_proxy.c
+++ b/proxy/libvirt_proxy.c
@@ -170,7 +170,11 @@ proxyListenUnixSocket(const char *path) {
     memset(&addr, 0, sizeof(addr));
     addr.sun_family = AF_UNIX;
     addr.sun_path[0] = '\0';
-    strncpy(&addr.sun_path[1], path, (sizeof(addr) - 4) - 2);
+    if (virStrcpy(&addr.sun_path[1], path, sizeof(addr.sun_path) - 1) == NULL) {
+        fprintf(stderr, "Path %s too long to fit into destination\n", path);
+        close(fd);
+        return -1;
+    }
 
     /*
      * now bind the socket to that address and listen on it
diff --git a/src/datatypes.c b/src/datatypes.c
index d7cf2ee..530076c 100644
--- a/src/datatypes.c
+++ b/src/datatypes.c
@@ -26,6 +26,7 @@
 #include "logging.h"
 #include "memory.h"
 #include "uuid.h"
+#include "util.h"
 
 #define VIR_FROM_THIS VIR_FROM_NONE
 
@@ -926,8 +927,12 @@ virGetStorageVol(virConnectPtr conn, const char *pool, const char *name, const c
             virReportOOMError(conn);
             goto error;
         }
-        strncpy(ret->key, key, sizeof(ret->key)-1);
-        ret->key[sizeof(ret->key)-1] = '\0';
+        if (virStrcpyStatic(ret->key, key) == NULL) {
+            virMutexUnlock(&conn->lock);
+            virLibConnError(conn, VIR_ERR_INTERNAL_ERROR,
+                            _("Volume key %s too large for destination"), key);
+            goto error;
+        }
         ret->magic = VIR_STORAGE_VOL_MAGIC;
         ret->conn = conn;
 
diff --git a/src/esx/esx_driver.c b/src/esx/esx_driver.c
index 8fad457..1ef894f 100644
--- a/src/esx/esx_driver.c
+++ b/src/esx/esx_driver.c
@@ -755,9 +755,14 @@ esxNodeGetInfo(virConnectPtr conn, virNodeInfoPtr nodeinfo)
                 ++ptr;
             }
 
-            strncpy (nodeinfo->model, dynamicProperty->val->string,
-                     sizeof (nodeinfo->model) - 1);
-            nodeinfo->model[sizeof (nodeinfo->model) - 1] = '\0';
+            if (virStrncpy(nodeinfo->model, dynamicProperty->val->string,
+                           sizeof(nodeinfo->model) - 1,
+                           sizeof(nodeinfo->model)) == NULL) {
+                ESX_ERROR(conn, VIR_ERR_INTERNAL_ERROR,
+                          "CPU Model %s too long for destination",
+                          dynamicProperty->val->string);
+                goto failure;
+            }
         } else {
             VIR_WARN("Unexpected '%s' property", dynamicProperty->name);
         }
diff --git a/src/esx/esx_vmx.c b/src/esx/esx_vmx.c
index 6bd6b93..9a0191e 100644
--- a/src/esx/esx_vmx.c
+++ b/src/esx/esx_vmx.c
@@ -877,35 +877,21 @@ failure:
 char *
 esxVMX_IndexToDiskName(virConnectPtr conn, int idx, const char *prefix)
 {
-    char buffer[32] = "";
     char *name = NULL;
-    size_t length = strlen(prefix);
 
-    if (length > sizeof (buffer) - 2 - 1) {
+    if (idx < 0) {
         ESX_ERROR(conn, VIR_ERR_INTERNAL_ERROR,
-                  "Disk name prefix '%s' is too long", prefix);
-        return NULL;
-    }
-
-    strncpy(buffer, prefix, sizeof (buffer) - 1);
-    buffer[sizeof (buffer) - 1] = '\0';
-
-    if (idx < 26) {
-        buffer[length] = 'a' + idx;
+                  "Disk index %d is negative", idx);
+    } else if (idx < 26) {
+        if (virAsprintf(&name, "%s%c", prefix, 'a' + idx) < 0)
+            virReportOOMError(conn);
     } else if (idx < 702) {
-        buffer[length] = 'a' + idx / 26 - 1;
-        buffer[length + 1] = 'a' + idx % 26;
+        if (virAsprintf(&name, "%s%c%c", prefix, 'a' + idx / 26 - 1,
+                        'a' + (idx % 26)) < 0)
+            virReportOOMError(conn);
     } else {
         ESX_ERROR(conn, VIR_ERR_INTERNAL_ERROR,
                   "Disk index %d is too large", idx);
-        return NULL;
-    }
-
-    name = strdup(buffer);
-
-    if (name == NULL) {
-        virReportOOMError(conn);
-        return NULL;
     }
 
     return name;
diff --git a/src/lxc/lxc_controller.c b/src/lxc/lxc_controller.c
index a0db602..bca721b 100644
--- a/src/lxc/lxc_controller.c
+++ b/src/lxc/lxc_controller.c
@@ -178,7 +178,11 @@ static int lxcMonitorServer(const char *sockpath)
     unlink(sockpath);
     memset(&addr, 0, sizeof(addr));
     addr.sun_family = AF_UNIX;
-    strncpy(addr.sun_path, sockpath, sizeof(addr.sun_path));
+    if (virStrcpyStatic(addr.sun_path, sockpath) == NULL) {
+        lxcError(NULL, NULL, VIR_ERR_INTERNAL_ERROR,
+                 _("Socket path %s too long for destination"), sockpath);
+        goto error;
+    }
 
     if (bind(fd, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
         virReportSystemError(NULL, errno,
diff --git a/src/lxc/lxc_driver.c b/src/lxc/lxc_driver.c
index eafd8ba..b98074e 100644
--- a/src/lxc/lxc_driver.c
+++ b/src/lxc/lxc_driver.c
@@ -719,7 +719,11 @@ static int lxcMonitorClient(virConnectPtr conn,
 
     memset(&addr, 0, sizeof(addr));
     addr.sun_family = AF_UNIX;
-    strncpy(addr.sun_path, sockpath, sizeof(addr.sun_path));
+    if (virStrcpyStatic(addr.sun_path, sockpath) == NULL) {
+        lxcError(conn, NULL, VIR_ERR_INTERNAL_ERROR,
+                 _("Socket path %s too big for destination"), sockpath);
+        goto error;
+    }
 
     if (connect(fd, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
         virReportSystemError(conn, errno, "%s",
@@ -1738,7 +1742,11 @@ static int lxcGetSchedulerParameters(virDomainPtr domain,
     if (virCgroupGetCpuShares(group, &val) != 0)
         goto cleanup;
     params[0].value.ul = val;
-    strncpy(params[0].field, "cpu_shares", sizeof(params[0].field));
+    if (virStrcpyStatic(params[0].field, "cpu_shares") == NULL) {
+        lxcError(NULL, domain, VIR_ERR_INTERNAL_ERROR,
+                 "%s", _("Field cpu_shares too big for destination"));
+        goto cleanup;
+    }
     params[0].type = VIR_DOMAIN_SCHED_FIELD_ULLONG;
 
     ret = 0;
diff --git a/src/nodeinfo.c b/src/nodeinfo.c
index 0a211a7..7d26b2b 100644
--- a/src/nodeinfo.c
+++ b/src/nodeinfo.c
@@ -141,8 +141,8 @@ int nodeGetInfo(virConnectPtr conn,
 
     uname(&info);
 
-    strncpy(nodeinfo->model, info.machine, sizeof(nodeinfo->model)-1);
-    nodeinfo->model[sizeof(nodeinfo->model)-1] = '\0';
+    if (virStrcpyStatic(nodeinfo->model, info.machine) == NULL)
+        return -1;
 
 #else /* !HAVE_UNAME */
 
diff --git a/src/opennebula/one_client.c b/src/opennebula/one_client.c
index 21f303a..39bb1ea 100644
--- a/src/opennebula/one_client.c
+++ b/src/opennebula/one_client.c
@@ -24,6 +24,8 @@
 #include <fcntl.h>
 #include <unistd.h>
 #include "one_client.h"
+#include "datatypes.h"
+#include "util.h"
 
 oneClient one_client;
 
@@ -171,7 +173,7 @@ int c_oneFinalize(int vmid)
     return c_oneAction(vmid, (char *)"finalize");
 }
 
-int c_oneVmInfo(int vmid, char* ret_info,int length)
+int c_oneVmInfo(int vmid, char* ret_info, int length)
 {
     xmlrpc_value *resultP;
     int return_code;
@@ -186,10 +188,9 @@ int c_oneVmInfo(int vmid, char* ret_info,int length)
 
     if( return_code )
     {
-        strncpy(ret_info, return_string, length-1);
-        ret_info[length-1] = '\0';
-
-        retval = 0;
+        if (virStrncpy(ret_info, return_string, length-1, length) != NULL)
+            /* Only set the return value to 0 if we succeeded */
+            retval = 0;
     }
 
     xmlrpc_DECREF(resultP);
diff --git a/src/openvz/openvz_conf.c b/src/openvz/openvz_conf.c
index be94b9e..403f537 100644
--- a/src/openvz/openvz_conf.c
+++ b/src/openvz/openvz_conf.c
@@ -260,8 +260,11 @@ openvzReadNetworkConf(virConnectPtr conn,
                     if (VIR_ALLOC_N(net->ifname, len+1) < 0)
                         goto no_memory;
 
-                    strncpy(net->ifname, p, len);
-                    net->ifname[len] = '\0';
+                    if (virStrncpy(net->ifname, p, len, len+1) == NULL) {
+                        openvzError(conn, VIR_ERR_INTERNAL_ERROR,
+                                    _("Network ifname %s too long for destination"), p);
+                        goto error;
+                    }
                 } else if (STRPREFIX(p, "bridge=")) {
                     p += 7;
                     len = next - p;
@@ -274,8 +277,11 @@ openvzReadNetworkConf(virConnectPtr conn,
                     if (VIR_ALLOC_N(net->data.bridge.brname, len+1) < 0)
                         goto no_memory;
 
-                    strncpy(net->data.bridge.brname, p, len);
-                    net->data.bridge.brname[len] = '\0';
+                    if (virStrncpy(net->data.bridge.brname, p, len, len+1) == NULL) {
+                        openvzError(conn, VIR_ERR_INTERNAL_ERROR,
+                                    _("Bridge name %s too long for destination"), p);
+                        goto error;
+                    }
                 } else if (STRPREFIX(p, "mac=")) {
                     p += 4;
                     len = next - p;
@@ -284,8 +290,11 @@ openvzReadNetworkConf(virConnectPtr conn,
                               "%s", _("Wrong length MAC address"));
                         goto error;
                     }
-                    strncpy(cpy_temp, p, len);
-                    cpy_temp[len] = '\0';
+                    if (virStrncpy(cpy_temp, p, len, sizeof(cpy_temp)) == NULL) {
+                        openvzError(conn, VIR_ERR_INTERNAL_ERROR,
+                                    _("MAC address %s too long for destination"), p);
+                        goto error;
+                    }
                     if (virParseMacAddr(cpy_temp, net->mac) < 0) {
                         openvzError(conn, VIR_ERR_INTERNAL_ERROR,
                               "%s", _("Wrong MAC address"));
@@ -628,8 +637,10 @@ openvzReadConfigParam(const char * conf_file ,const char * param, char *value, i
             if (sf[0] == '=' && sf[1] != '\0' ) {
                 sf ++;
                 if ((token = strtok_r(sf,"\"\t\n", &saveptr)) != NULL) {
-                    strncpy(value, token, maxlen) ;
-                    value[maxlen-1] = '\0';
+                    if (virStrcpy(value, token, maxlen) == NULL) {
+                        ret = -1;
+                        break;
+                    }
                     found = 1;
                 }
             }
@@ -810,6 +821,7 @@ openvzGetVPSUUID(int vpsid, char *uuidstr, size_t len)
     char uuidbuf[1024];
     char iden[1024];
     int fd, ret;
+    int retval = 0;
 
     if (openvzLocateConfFile(vpsid, conf_file, PATH_MAX, "conf")<0)
        return -1;
@@ -832,13 +844,14 @@ openvzGetVPSUUID(int vpsid, char *uuidstr, size_t len)
 
         sscanf(line, "%s %s\n", iden, uuidbuf);
         if(STREQ(iden, "#UUID:")) {
-            strncpy(uuidstr, uuidbuf, len);
+            if (virStrcpy(uuidstr, uuidbuf, len) == NULL)
+                retval = -1;
             break;
         }
     }
     close(fd);
 
-    return 0;
+    return retval;
 }
 
 /* Do actual checking for UUID presence in conf file,
diff --git a/src/phyp/phyp_driver.c b/src/phyp/phyp_driver.c
index e2a2caf..fbb8982 100644
--- a/src/phyp/phyp_driver.c
+++ b/src/phyp/phyp_driver.c
@@ -1451,7 +1451,7 @@ escape_specialcharacters(char *src, char *dst, size_t dstlen)
     }
     temp_buffer[j] = '\0';
 
-    if (strncpy(dst, temp_buffer, dstlen) == NULL)
+    if (virStrcpy(dst, temp_buffer, dstlen) == NULL)
         return -1;
 
     return 0;
diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c
index 273aeca..d4f062d 100644
--- a/src/qemu/qemu_conf.c
+++ b/src/qemu/qemu_conf.c
@@ -1391,18 +1391,18 @@ static int qemudBuildCommandLineChrDevStr(virDomainChrDefPtr dev,
 {
     switch (dev->type) {
     case VIR_DOMAIN_CHR_TYPE_NULL:
-        strncpy(buf, "null", buflen);
-        buf[buflen-1] = '\0';
+        if (virStrcpy(buf, "null", buflen) == NULL)
+            return -1;
         break;
 
     case VIR_DOMAIN_CHR_TYPE_VC:
-        strncpy(buf, "vc", buflen);
-        buf[buflen-1] = '\0';
+        if (virStrcpy(buf, "vc", buflen) == NULL)
+            return -1;
         break;
 
     case VIR_DOMAIN_CHR_TYPE_PTY:
-        strncpy(buf, "pty", buflen);
-        buf[buflen-1] = '\0';
+        if (virStrcpy(buf, "pty", buflen) == NULL)
+            return -1;
         break;
 
     case VIR_DOMAIN_CHR_TYPE_DEV:
@@ -1424,8 +1424,8 @@ static int qemudBuildCommandLineChrDevStr(virDomainChrDefPtr dev,
         break;
 
     case VIR_DOMAIN_CHR_TYPE_STDIO:
-        strncpy(buf, "stdio", buflen);
-        buf[buflen-1] = '\0';
+        if (virStrcpy(buf, "stdio", buflen) == NULL)
+            return -1;
         break;
 
     case VIR_DOMAIN_CHR_TYPE_UDP:
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 942aff2..af215ca 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -1010,7 +1010,11 @@ qemudOpenMonitorUnix(virConnectPtr conn,
 
     memset(&addr, 0, sizeof(addr));
     addr.sun_family = AF_UNIX;
-    strncpy(addr.sun_path, monitor, sizeof(addr.sun_path));
+    if (virStrcpyStatic(addr.sun_path, monitor) == NULL) {
+        qemudReportError(conn, NULL, NULL, VIR_ERR_INTERNAL_ERROR,
+                         _("Monitor path %s too big for destination"), monitor);
+        goto error;
+    }
 
     do {
         ret = connect(monfd, (struct sockaddr *) &addr, sizeof(addr));
@@ -6559,8 +6563,12 @@ static int qemuGetSchedulerParameters(virDomainPtr dom,
         goto cleanup;
     }
     params[0].value.ul = val;
-    strncpy(params[0].field, "cpu_shares", sizeof(params[0].field));
     params[0].type = VIR_DOMAIN_SCHED_FIELD_ULLONG;
+    if (virStrcpyStatic(params[0].field, "cpu_shares") == NULL) {
+        qemudReportError(dom->conn, dom, NULL, VIR_ERR_INTERNAL_ERROR,
+                         "%s", _("Field cpu_shares too long for destination"));
+        goto cleanup;
+    }
 
     ret = 0;
 
diff --git a/src/remote/remote_driver.c b/src/remote/remote_driver.c
index 24bef73..cf12bf5 100644
--- a/src/remote/remote_driver.c
+++ b/src/remote/remote_driver.c
@@ -654,7 +654,11 @@ doRemoteOpen (virConnectPtr conn,
 
         memset (&addr, 0, sizeof addr);
         addr.sun_family = AF_UNIX;
-        strncpy (addr.sun_path, sockname, UNIX_PATH_MAX (addr));
+        if (virStrcpyStatic(addr.sun_path, sockname) == NULL) {
+            errorf(conn, VIR_ERR_INTERNAL_ERROR,
+                   _("Socket %s too big for destination"), sockname);
+            goto failed;
+        }
         if (addr.sun_path[0] == '@')
             addr.sun_path[0] = '\0';
 
@@ -1569,8 +1573,8 @@ remoteNodeGetInfo (virConnectPtr conn, virNodeInfoPtr info)
               (xdrproc_t) xdr_remote_node_get_info_ret, (char *) &ret) == -1)
         goto done;
 
-    strncpy (info->model, ret.model, 32);
-    info->model[31] = '\0';
+    if (virStrcpyStatic(info->model, ret.model) == NULL)
+        goto done;
     info->memory = ret.memory;
     info->cpus = ret.cpus;
     info->mhz = ret.mhz;
@@ -3001,9 +3005,12 @@ remoteDomainGetSchedulerParameters (virDomainPtr domain,
 
     /* Deserialise the result. */
     for (i = 0; i < *nparams; ++i) {
-        strncpy (params[i].field, ret.params.params_val[i].field,
-                 VIR_DOMAIN_SCHED_FIELD_LENGTH);
-        params[i].field[VIR_DOMAIN_SCHED_FIELD_LENGTH-1] = '\0';
+        if (virStrcpyStatic(params[i].field, ret.params.params_val[i].field) == NULL) {
+            errorf(domain->conn, VIR_ERR_INTERNAL_ERROR,
+                   _("Parameter %s too big for destination"),
+                   ret.params.params_val[i].field);
+            goto cleanup;
+        }
         params[i].type = ret.params.params_val[i].value.type;
         switch (params[i].type) {
         case VIR_DOMAIN_SCHED_FIELD_INT:
diff --git a/src/test/test_driver.c b/src/test/test_driver.c
index 10ec141..cb48f64 100644
--- a/src/test/test_driver.c
+++ b/src/test/test_driver.c
@@ -412,10 +412,13 @@ static char *testBuildFilename(const char *relativeTo,
     offset = strrchr(relativeTo, '/');
     if ((baseLen = (offset-relativeTo+1))) {
         char *absFile;
-        if (VIR_ALLOC_N(absFile, baseLen + strlen(filename) + 1) < 0)
+        int totalLen = baseLen + strlen(filename) + 1;
+        if (VIR_ALLOC_N(absFile, totalLen) < 0)
             return NULL;
-        strncpy(absFile, relativeTo, baseLen);
-        absFile[baseLen] = '\0';
+        if (virStrncpy(absFile, relativeTo, baseLen, totalLen) == NULL) {
+            VIR_FREE(absFile);
+            return NULL;
+        }
         strcat(absFile, filename);
         return absFile;
     } else {
@@ -568,8 +571,11 @@ static int testOpenFromFile(virConnectPtr conn,
 
     privconn->nextDomID = 1;
     privconn->numCells = 0;
-    strncpy(privconn->path, file, PATH_MAX-1);
-    privconn->path[PATH_MAX-1] = '\0';
+    if (virStrcpyStatic(privconn->path, file) == NULL) {
+        testError(NULL, VIR_ERR_INTERNAL_ERROR,
+                  _("Path %s too big for destination"), file);
+        goto error;
+    }
     memmove(&privconn->nodeInfo, &defaultNodeInfo, sizeof(defaultNodeInfo));
 
     nodeInfo = &privconn->nodeInfo;
@@ -625,8 +631,12 @@ static int testOpenFromFile(virConnectPtr conn,
 
     str = virXPathString(conn, "string(/node/cpu/model[1])", ctxt);
     if (str != NULL) {
-        strncpy(nodeInfo->model, str, sizeof(nodeInfo->model)-1);
-        nodeInfo->model[sizeof(nodeInfo->model)-1] = '\0';
+        if (virStrcpyStatic(nodeInfo->model, str) == NULL) {
+            testError(NULL, VIR_ERR_INTERNAL_ERROR,
+                      _("Model %s too big for destination"), str);
+            VIR_FREE(str);
+            goto error;
+        }
         VIR_FREE(str);
     }
 
diff --git a/src/uml/uml_driver.c b/src/uml/uml_driver.c
index 7db94e9..f0d5fd4 100644
--- a/src/uml/uml_driver.c
+++ b/src/uml/uml_driver.c
@@ -563,6 +563,7 @@ static int umlMonitorAddress(virConnectPtr conn,
                              virDomainObjPtr vm,
                              struct sockaddr_un *addr) {
     char *sockname;
+    int retval = 0;
 
     if (virAsprintf(&sockname, "%s/%s/mconsole",
                     driver->monitorDir, vm->def->name) < 0) {
@@ -572,10 +573,13 @@ static int umlMonitorAddress(virConnectPtr conn,
 
     memset(addr, 0, sizeof *addr);
     addr->sun_family = AF_UNIX;
-    strncpy(addr->sun_path, sockname, sizeof(addr->sun_path)-1);
-    NUL_TERMINATE(addr->sun_path);
+    if (virStrcpyStatic(addr->sun_path, sockname) == NULL) {
+        umlReportError(conn, NULL, NULL, VIR_ERR_INTERNAL_ERROR,
+                       _("Unix path %s too long for destination"), sockname);
+        retval = -1;
+    }
     VIR_FREE(sockname);
-    return 0;
+    return retval;
 }
 
 static int umlOpenMonitor(virConnectPtr conn,
@@ -669,8 +673,11 @@ static int umlMonitorCommand(virConnectPtr conn,
                              cmd, req.length);
         return -1;
     }
-    strncpy(req.data, cmd, req.length);
-    req.data[req.length] = '\0';
+    if (virStrcpyStatic(req.data, cmd) == NULL) {
+        umlReportError(conn, NULL, NULL, VIR_ERR_INTERNAL_ERROR,
+                       _("Command %s too long for destination"), cmd);
+        return -1;
+    }
 
     if (sendto(vm->monitor, &req, sizeof req, 0,
                (struct sockaddr *)&addr, sizeof addr) != (sizeof req)) {
diff --git a/src/util/bridge.c b/src/util/bridge.c
index 414d87b..f9a7668 100644
--- a/src/util/bridge.c
+++ b/src/util/bridge.c
@@ -149,23 +149,19 @@ brHasBridge(brControl *ctl,
             const char *name)
 {
     struct ifreq ifr;
-    int len;
 
     if (!ctl || !name) {
         errno = EINVAL;
         return -1;
     }
 
-    if ((len = strlen(name)) >= BR_IFNAME_MAXLEN) {
+    memset(&ifr, 0, sizeof(struct ifreq));
+
+    if (virStrcpyStatic(ifr.ifr_name, name) == NULL) {
         errno = EINVAL;
         return -1;
     }
 
-    memset(&ifr, 0, sizeof(struct ifreq));
-
-    strncpy(ifr.ifr_name, name, len);
-    ifr.ifr_name[len] = '\0';
-
     if (ioctl(ctl->fd, SIOCGIFFLAGS, &ifr))
         return -1;
 
@@ -216,18 +212,14 @@ brAddDelInterface(brControl *ctl,
                   const char *iface)
 {
     struct ifreq ifr;
-    int len;
 
     if (!ctl || !ctl->fd || !bridge || !iface)
         return EINVAL;
 
-    if ((len = strlen(bridge)) >= BR_IFNAME_MAXLEN)
-        return EINVAL;
-
     memset(&ifr, 0, sizeof(struct ifreq));
 
-    strncpy(ifr.ifr_name, bridge, len);
-    ifr.ifr_name[len] = '\0';
+    if (virStrcpyStatic(ifr.ifr_name, bridge) == NULL)
+        return EINVAL;
 
     if (!(ifr.ifr_ifindex = if_nametoindex(iface)))
         return ENODEV;
@@ -305,23 +297,19 @@ brDeleteInterface(brControl *ctl ATTRIBUTE_UNUSED,
 static int ifGetMtu(brControl *ctl, const char *ifname)
 {
     struct ifreq ifr;
-    int len;
 
     if (!ctl || !ifname) {
         errno = EINVAL;
         return -1;
     }
 
-    if ((len = strlen(ifname)) >=  BR_IFNAME_MAXLEN) {
+    memset(&ifr, 0, sizeof(struct ifreq));
+
+    if (virStrcpyStatic(ifr.ifr_name, ifname) == NULL) {
         errno = EINVAL;
         return -1;
     }
 
-    memset(&ifr, 0, sizeof(struct ifreq));
-
-    strncpy(ifr.ifr_name, ifname, len);
-    ifr.ifr_name[len] = '\0';
-
     if (ioctl(ctl->fd, SIOCGIFMTU, &ifr))
         return -1;
 
@@ -343,18 +331,14 @@ static int ifGetMtu(brControl *ctl, const char *ifname)
 static int ifSetMtu(brControl *ctl, const char *ifname, int mtu)
 {
     struct ifreq ifr;
-    int len;
 
     if (!ctl || !ifname)
         return EINVAL;
 
-    if ((len = strlen(ifname)) >=  BR_IFNAME_MAXLEN)
-        return EINVAL;
-
     memset(&ifr, 0, sizeof(struct ifreq));
 
-    strncpy(ifr.ifr_name, ifname, len);
-    ifr.ifr_name[len] = '\0';
+    if (virStrcpyStatic(ifr.ifr_name, ifname) == NULL)
+        return EINVAL;
     ifr.ifr_mtu = mtu;
 
     return ioctl(ctl->fd, SIOCSIFMTU, &ifr) == 0 ? 0 : errno;
@@ -466,7 +450,7 @@ brAddTap(brControl *ctl,
          int vnet_hdr,
          int *tapfd)
 {
-    int fd, len;
+    int fd;
     struct ifreq ifr;
 
     if (!ctl || !ctl->fd || !bridge || !ifname)
@@ -486,17 +470,14 @@ brAddTap(brControl *ctl,
     (void) vnet_hdr;
 #endif
 
-    strncpy(ifr.ifr_name, *ifname, IFNAMSIZ-1);
-
-    if (ioctl(fd, TUNSETIFF, &ifr) < 0)
-        goto error;
-
-    len = strlen(ifr.ifr_name);
-    if (len >= BR_IFNAME_MAXLEN - 1) {
+    if (virStrcpyStatic(ifr.ifr_name, *ifname) == NULL) {
         errno = EINVAL;
         goto error;
     }
 
+    if (ioctl(fd, TUNSETIFF, &ifr) < 0)
+        goto error;
+
     /* We need to set the interface MTU before adding it
      * to the bridge, because the bridge will have its
      * MTU adjusted automatically when we add the new interface.
@@ -527,7 +508,6 @@ int brDeleteTap(brControl *ctl,
                 const char *ifname)
 {
     struct ifreq try;
-    int len;
     int fd;
 
     if (!ctl || !ctl->fd || !ifname)
@@ -539,15 +519,11 @@ int brDeleteTap(brControl *ctl,
     memset(&try, 0, sizeof(struct ifreq));
     try.ifr_flags = IFF_TAP|IFF_NO_PI;
 
-    len = strlen(ifname);
-    if (len >= BR_IFNAME_MAXLEN - 1) {
+    if (virStrcpyStatic(try.ifr_name, ifname) == NULL) {
         errno = EINVAL;
         goto error;
     }
 
-    strncpy(try.ifr_name, ifname, len);
-    try.ifr_name[len] = '\0';
-
     if (ioctl(fd, TUNSETIFF, &try) == 0) {
         if ((errno = ioctl(fd, TUNSETPERSIST, 0)))
             goto error;
@@ -576,19 +552,15 @@ brSetInterfaceUp(brControl *ctl,
                  int up)
 {
     struct ifreq ifr;
-    int len;
     int flags;
 
     if (!ctl || !ifname)
         return EINVAL;
 
-    if ((len = strlen(ifname)) >= BR_IFNAME_MAXLEN)
-        return EINVAL;
-
     memset(&ifr, 0, sizeof(struct ifreq));
 
-    strncpy(ifr.ifr_name, ifname, len);
-    ifr.ifr_name[len] = '\0';
+    if (virStrcpyStatic(ifr.ifr_name, ifname) == NULL)
+        return EINVAL;
 
     if (ioctl(ctl->fd, SIOCGIFFLAGS, &ifr) < 0)
         return errno;
@@ -621,18 +593,14 @@ brGetInterfaceUp(brControl *ctl,
                  int *up)
 {
     struct ifreq ifr;
-    int len;
 
     if (!ctl || !ifname || !up)
         return EINVAL;
 
-    if ((len = strlen(ifname)) >= BR_IFNAME_MAXLEN)
-        return EINVAL;
-
     memset(&ifr, 0, sizeof(struct ifreq));
 
-    strncpy(ifr.ifr_name, ifname, len);
-    ifr.ifr_name[len] = '\0';
+    if (virStrcpyStatic(ifr.ifr_name, ifname) == NULL)
+        return EINVAL;
 
     if (ioctl(ctl->fd, SIOCGIFFLAGS, &ifr) < 0)
         return errno;
@@ -654,18 +622,15 @@ brSetInetAddr(brControl *ctl,
     } s;
     struct ifreq ifr;
     struct in_addr inaddr;
-    int len, ret;
+    int ret;
 
     if (!ctl || !ctl->fd || !ifname || !addr)
         return EINVAL;
 
-    if ((len = strlen(ifname)) >= BR_IFNAME_MAXLEN)
-        return EINVAL;
-
     memset(&ifr, 0, sizeof(struct ifreq));
 
-    strncpy(ifr.ifr_name, ifname, len);
-    ifr.ifr_name[len] = '\0';
+    if (virStrcpyStatic(ifr.ifr_name, ifname) == NULL)
+        return EINVAL;
 
     if ((ret = inet_pton(AF_INET, addr, &inaddr)) < 0)
         return errno;
@@ -692,18 +657,14 @@ brGetInetAddr(brControl *ctl,
 {
     struct ifreq ifr;
     struct in_addr *inaddr;
-    int len;
 
     if (!ctl || !ctl->fd || !ifname || !addr)
         return EINVAL;
 
-    if ((len = strlen(ifname)) >= BR_IFNAME_MAXLEN)
-        return EINVAL;
-
     memset(&ifr, 0, sizeof(struct ifreq));
 
-    strncpy(ifr.ifr_name, ifname, len);
-    ifr.ifr_name[len] = '\0';
+    if (virStrcpyStatic(ifr.ifr_name, ifname) == NULL)
+        return EINVAL;
 
     if (ioctl(ctl->fd, cmd, &ifr) < 0)
         return errno;
diff --git a/src/util/util.c b/src/util/util.c
index 1878e33..6b202c9 100644
--- a/src/util/util.c
+++ b/src/util/util.c
@@ -1123,9 +1123,8 @@ char *virFindFileInPath(const char *file)
     char fullpath[PATH_MAX];
 
     /* copy PATH env so we can tweak it */
-    strncpy(pathenv, getenv("PATH"), PATH_MAX);
-    pathenv[PATH_MAX - 1] = '\0';
-
+    if (virStrcpyStatic(pathenv, getenv("PATH")) == NULL)
+        return NULL;
 
     /* for each path segment, append the file to search for and test for
      * it. return it if found.
@@ -1157,8 +1156,8 @@ int virFileMakePath(const char *path)
     if (stat(path, &st) >= 0)
         return 0;
 
-    strncpy(parent, path, PATH_MAX);
-    parent[PATH_MAX - 1] = '\0';
+    if (virStrcpyStatic(parent, path) == NULL)
+        return EINVAL;
 
     if (!(p = strrchr(parent, '/')))
         return EINVAL;
@@ -1575,6 +1574,33 @@ virAsprintf(char **strp, const char *fmt, ...)
     return ret;
 }
 
+/**
+ * virStrncpy
+ *
+ * A safe version of strncpy.  The last parameter is the number of bytes
+ * available in the destination string, *not* the number of bytes you want
+ * to copy.  If the destination is not large enough to hold all n of the
+ * src string bytes plus a \0, NULL is returned and no data is copied.
+ * If the destination is large enough to hold the n bytes plus \0, then the
+ * string is copied and a pointer to the destination string is returned.
+ */
+char *
+virStrncpy(char *dest, const char *src, size_t n, size_t destbytes)
+{
+    char *ret;
+
+    if (n > (destbytes - 1))
+        return NULL;
+
+    ret = strncpy(dest, src, n);
+    /* strncpy NULL terminates iff the last character is \0.  Therefore
+     * force the last byte to be \0
+     */
+    dest[n] = '\0';
+
+    return ret;
+}
+
 /* Compare two MAC addresses, ignoring differences in case,
  * as well as leading zeros.
  */
diff --git a/src/util/util.h b/src/util/util.h
index f9715ab..2489f63 100644
--- a/src/util/util.h
+++ b/src/util/util.h
@@ -164,6 +164,10 @@ void virSkipSpaces(const char **str);
 int virParseNumber(const char **str);
 int virAsprintf(char **strp, const char *fmt, ...)
     ATTRIBUTE_FMT_PRINTF(2, 3);
+char *virStrncpy(char *dest, const char *src, size_t n, size_t destbytes)
+    ATTRIBUTE_RETURN_CHECK;
+#define virStrcpy(dest, src, destbytes) virStrncpy(dest, src, strlen(src), destbytes)
+#define virStrcpyStatic(dest, src) virStrncpy(dest, src, strlen(src), sizeof(dest))
 
 #define VIR_MAC_BUFLEN 6
 #define VIR_MAC_PREFIX_BUFLEN 3
diff --git a/src/xen/proxy_internal.c b/src/xen/proxy_internal.c
index 49127d7..f9d2fad 100644
--- a/src/xen/proxy_internal.c
+++ b/src/xen/proxy_internal.c
@@ -197,7 +197,10 @@ retry:
     memset(&addr, 0, sizeof(addr));
     addr.sun_family = AF_UNIX;
     addr.sun_path[0] = '\0';
-    strncpy(&addr.sun_path[1], path, (sizeof(addr) - 4) - 2);
+    if (virStrcpy(&addr.sun_path[1], path, sizeof(addr.sun_path) - 1) == NULL) {
+        close(fd);
+        return -1;
+    }
 
     /*
      * now bind the socket to that address and listen on it
diff --git a/src/xen/xen_hypervisor.c b/src/xen/xen_hypervisor.c
index 9f3f5fe..3aa3c30 100644
--- a/src/xen/xen_hypervisor.c
+++ b/src/xen/xen_hypervisor.c
@@ -1209,13 +1209,19 @@ xenHypervisorGetSchedulerParameters(virDomainPtr domain,
                 if (ret < 0)
                     return(-1);
 
-                strncpy (params[0].field, str_weight, VIR_DOMAIN_SCHED_FIELD_LENGTH);
-                params[0].field[VIR_DOMAIN_SCHED_FIELD_LENGTH-1] = '\0';
+                if (virStrcpyStatic(params[0].field, str_weight) == NULL) {
+                    virXenError (domain->conn, VIR_ERR_INTERNAL_ERROR,
+                                 "Weight %s too big for destination", str_weight);
+                    return -1;
+                }
                 params[0].type = VIR_DOMAIN_SCHED_FIELD_UINT;
                 params[0].value.ui = op_dom.u.getschedinfo.u.credit.weight;
 
-                strncpy (params[1].field, str_cap, VIR_DOMAIN_SCHED_FIELD_LENGTH);
-                params[1].field[VIR_DOMAIN_SCHED_FIELD_LENGTH-1] = '\0';
+                if (virStrcpyStatic(params[1].field, str_cap) == NULL) {
+                    virXenError (domain->conn, VIR_ERR_INTERNAL_ERROR,
+                                 "Cap %s too big for destination", str_cap);
+                    return -1;
+                }
                 params[1].type = VIR_DOMAIN_SCHED_FIELD_UINT;
                 params[1].value.ui = op_dom.u.getschedinfo.u.credit.cap;
 
@@ -2427,9 +2433,11 @@ xenHypervisorMakeCapabilitiesInternal(virConnectPtr conn,
         while (fgets (line, sizeof line, cpuinfo)) {
             if (regexec (&flags_hvm_rec, line, sizeof(subs)/sizeof(regmatch_t), subs, 0) == 0
                 && subs[0].rm_so != -1) {
-                strncpy (hvm_type,
-                         &line[subs[1].rm_so], subs[1].rm_eo-subs[1].rm_so+1);
-                hvm_type[subs[1].rm_eo-subs[1].rm_so] = '\0';
+                if (virStrncpy(hvm_type,
+                               &line[subs[1].rm_so],
+                               subs[1].rm_eo-subs[1].rm_so,
+                               sizeof(hvm_type)) == NULL)
+                    return NULL;
             } else if (regexec (&flags_pae_rec, line, 0, NULL, 0) == 0)
                 host_pae = 1;
         }
diff --git a/src/xen/xend_internal.c b/src/xen/xend_internal.c
index 350ef8c..49bdba9 100644
--- a/src/xen/xend_internal.c
+++ b/src/xen/xend_internal.c
@@ -763,7 +763,8 @@ xenDaemonOpen_unix(virConnectPtr conn, const char *path)
     addr = (struct sockaddr_un *)&priv->addr;
     addr->sun_family = AF_UNIX;
     memset(addr->sun_path, 0, sizeof(addr->sun_path));
-    strncpy(addr->sun_path, path, sizeof(addr->sun_path));
+    if (virStrcpyStatic(addr->sun_path, path) == NULL)
+        return -1;
 
     return (0);
 }
@@ -1433,7 +1434,7 @@ xenDaemonParseSxprChar(virConnectPtr conn,
                        const char *value,
                        const char *tty)
 {
-    char prefix[10];
+    const char *prefix;
     char *tmp;
     virDomainChrDefPtr def;
 
@@ -1442,18 +1443,17 @@ xenDaemonParseSxprChar(virConnectPtr conn,
         return NULL;
     }
 
-    strncpy(prefix, value, sizeof(prefix)-1);
-    NUL_TERMINATE(prefix);
+    prefix = value;
 
     if (value[0] == '/') {
         def->type = VIR_DOMAIN_CHR_TYPE_DEV;
     } else {
-        if ((tmp = strchr(prefix, ':')) != NULL) {
+        if ((tmp = strchr(value, ':')) != NULL) {
             *tmp = '\0';
-            value += (tmp - prefix) + 1;
+            value = tmp + 1;
         }
 
-        if (STREQ(prefix, "telnet")) {
+        if (STRPREFIX(prefix, "telnet")) {
             def->type = VIR_DOMAIN_CHR_TYPE_TCP;
             def->data.tcp.protocol = VIR_DOMAIN_CHR_TCP_PROTOCOL_TELNET;
         } else {
@@ -1647,8 +1647,13 @@ xenDaemonParseSxprDisks(virConnectPtr conn,
 
                 if (VIR_ALLOC_N(disk->driverName, (offset-src)+1) < 0)
                     goto no_memory;
-                strncpy(disk->driverName, src, (offset-src));
-                disk->driverName[offset-src] = '\0';
+                if (virStrncpy(disk->driverName, src, offset-src,
+                              (offset-src)+1) == NULL) {
+                    virXendError(conn, VIR_ERR_INTERNAL_ERROR,
+                                 _("Driver name %s too big for destination"),
+                                 src);
+                    goto error;
+                }
 
                 src = offset + 1;
 
@@ -1662,8 +1667,13 @@ xenDaemonParseSxprDisks(virConnectPtr conn,
 
                     if (VIR_ALLOC_N(disk->driverType, (offset-src)+1)< 0)
                         goto no_memory;
-                    strncpy(disk->driverType, src, (offset-src));
-                    disk->driverType[offset-src] = '\0';
+                    if (virStrncpy(disk->driverType, src, offset-src,
+                                   (offset-src)+1) == NULL) {
+                        virXendError(conn, VIR_ERR_INTERNAL_ERROR,
+                                     _("Driver type %s too big for destination"),
+                                     src);
+                        goto error;
+                    }
 
                     src = offset + 1;
                     /* Its possible to use blktap driver for block devs
@@ -1891,13 +1901,12 @@ xenDaemonParseSxprSound(virConnectPtr conn,
                 len = (offset2 - offset);
             else
                 len = strlen(offset);
-            if (len > (sizeof(model)-1)) {
+            if (virStrncpy(model, offset, len, sizeof(model)) == NULL) {
                 virXendError(conn, VIR_ERR_INTERNAL_ERROR,
-                                 _("unexpected sound model %s"), offset);
+                                 _("Sound model %s too big for destination"),
+                             offset);
                 goto error;
             }
-            strncpy(model, offset, len);
-            model[len] = '\0';
 
             if (VIR_ALLOC(sound) < 0)
                 goto no_memory;
@@ -4798,13 +4807,20 @@ xenDaemonGetSchedulerParameters(virDomainPtr domain,
                 goto error;
             }
 
-            strncpy (params[0].field, str_weight, VIR_DOMAIN_SCHED_FIELD_LENGTH);
-            params[0].field[VIR_DOMAIN_SCHED_FIELD_LENGTH-1] = '\0';
+            if (virStrcpyStatic(params[0].field, str_weight) == NULL) {
+                virXendError(domain->conn, VIR_ERR_INTERNAL_ERROR,
+                             _("Weight %s too big for destination"),
+                             str_weight);
+                goto error;
+            }
             params[0].type = VIR_DOMAIN_SCHED_FIELD_UINT;
             params[0].value.ui = sexpr_int(root, "domain/cpu_weight");
 
-            strncpy (params[1].field, str_cap, VIR_DOMAIN_SCHED_FIELD_LENGTH);
-            params[1].field[VIR_DOMAIN_SCHED_FIELD_LENGTH-1] = '\0';
+            if (virStrcpyStatic(params[1].field, str_cap) == NULL) {
+                virXendError(domain->conn, VIR_ERR_INTERNAL_ERROR,
+                             _("Cap %s too big for destination"), str_cap);
+                goto error;
+            }
             params[1].type = VIR_DOMAIN_SCHED_FIELD_UINT;
             params[1].value.ui = sexpr_int(root, "domain/cpu_cap");
             *nparams = XEN_SCHED_CRED_NPARAM;
@@ -5860,6 +5876,7 @@ virDomainXMLDevID(virDomainPtr domain,
 {
     xenUnifiedPrivatePtr priv = domain->conn->privateData;
     char *xref;
+    char *tmp;
 
     if (dev->type == VIR_DOMAIN_DEVICE_DISK) {
         if (dev->data.disk->driverName &&
@@ -5877,9 +5894,10 @@ virDomainXMLDevID(virDomainPtr domain,
         if (xref == NULL)
             return -1;
 
-        strncpy(ref, xref, ref_len);
+        tmp = virStrcpy(ref, xref, ref_len);
         free(xref);
-        ref[ref_len - 1] = '\0';
+        if (tmp == NULL)
+            return -1;
     } else if (dev->type == VIR_DOMAIN_DEVICE_NET) {
         char mac[30];
         virDomainNetDefPtr def = dev->data.net;
@@ -5896,9 +5914,10 @@ virDomainXMLDevID(virDomainPtr domain,
         if (xref == NULL)
             return -1;
 
-        strncpy(ref, xref, ref_len);
+        tmp = virStrcpy(ref, xref, ref_len);
         free(xref);
-        ref[ref_len - 1] = '\0';
+        if (tmp == NULL)
+            return -1;
     } else if (dev->type == VIR_DOMAIN_DEVICE_HOSTDEV &&
                dev->data.hostdev->mode == VIR_DOMAIN_HOSTDEV_MODE_SUBSYS &&
                dev->data.hostdev->source.subsys.type == VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_PCI) {
diff --git a/src/xen/xm_internal.c b/src/xen/xm_internal.c
index 960b17a..9c78f0d 100644
--- a/src/xen/xm_internal.c
+++ b/src/xen/xm_internal.c
@@ -872,8 +872,13 @@ xenXMDomainConfigParse(virConnectPtr conn, virConfPtr conf) {
             } else {
                 if (VIR_ALLOC_N(disk->src, (offset - head) + 1) < 0)
                     goto no_memory;
-                strncpy(disk->src, head, (offset - head));
-                disk->src[(offset-head)] = '\0';
+                if (virStrncpy(disk->src, head, offset - head,
+                               (offset - head) + 1) == NULL) {
+                    xenXMError(conn, VIR_ERR_INTERNAL_ERROR,
+                               _("Source file %s too big for destination"),
+                               head);
+                    goto cleanup;
+                }
             }
             head = offset + 1;
 
@@ -886,8 +891,12 @@ xenXMDomainConfigParse(virConnectPtr conn, virConfPtr conf) {
                 goto skipdisk;
             if (VIR_ALLOC_N(disk->dst, (offset - head) + 1) < 0)
                 goto no_memory;
-            strncpy(disk->dst, head, (offset - head));
-            disk->dst[(offset-head)] = '\0';
+            if (virStrncpy(disk->dst, head, offset - head,
+                           (offset - head) + 1) == NULL) {
+                xenXMError(conn, VIR_ERR_INTERNAL_ERROR,
+                           _("Dest file %s too big for destination"), head);
+                goto cleanup;
+            }
             head = offset + 1;
 
 
@@ -897,8 +906,14 @@ xenXMDomainConfigParse(virConnectPtr conn, virConfPtr conf) {
                 if ((tmp = strchr(disk->src, ':')) != NULL) {
                     if (VIR_ALLOC_N(disk->driverName, (tmp - disk->src) + 1) < 0)
                         goto no_memory;
-                    strncpy(disk->driverName, disk->src, (tmp - disk->src));
-                    disk->driverName[tmp - disk->src] = '\0';
+                    if (virStrncpy(disk->driverName, disk->src,
+                                   (tmp - disk->src),
+                                   (tmp - disk->src) + 1) == NULL) {
+                        xenXMError(conn, VIR_ERR_INTERNAL_ERROR,
+                                   _("Driver name %s too big for destination"),
+                                   disk->src);
+                        goto cleanup;
+                    }
 
                     /* Strip the prefix we found off the source file name */
                     memmove(disk->src, disk->src+(tmp-disk->src)+1,
@@ -912,8 +927,14 @@ xenXMDomainConfigParse(virConnectPtr conn, virConfPtr conf) {
                         goto skipdisk;
                     if (VIR_ALLOC_N(disk->driverType, (tmp - disk->src) + 1) < 0)
                         goto no_memory;
-                    strncpy(disk->driverType, disk->src, (tmp - disk->src));
-                    disk->driverType[tmp - disk->src] = '\0';
+                    if (virStrncpy(disk->driverType, disk->src,
+                                   (tmp - disk->src),
+                                   (tmp - disk->src) + 1) == NULL) {
+                        xenXMError(conn, VIR_ERR_INTERNAL_ERROR,
+                                   _("Driver type %s too big for destination"),
+                                   disk->src);
+                        goto cleanup;
+                    }
 
                     /* Strip the prefix we found off the source file name */
                     memmove(disk->src, disk->src+(tmp-disk->src)+1,
@@ -1023,41 +1044,51 @@ xenXMDomainConfigParse(virConnectPtr conn, virConfPtr conf) {
                 data++;
 
                 if (STRPREFIX(key, "mac=")) {
-                    int len = nextkey ? (nextkey - data) : 17;
-                    if (len > 17)
-                        len = 17;
-                    strncpy(mac, data, len);
-                    mac[len] = '\0';
+                    int len = nextkey ? (nextkey - data) : sizeof(mac) - 1;
+                    if (virStrncpy(mac, data, len, sizeof(mac)) == NULL) {
+                        xenXMError(conn, VIR_ERR_INTERNAL_ERROR,
+                                   _("MAC address %s too big for destination"),
+                                   data);
+                        goto skipnic;
+                    }
                 } else if (STRPREFIX(key, "bridge=")) {
-                    int len = nextkey ? (nextkey - data) : sizeof(bridge)-1;
-                    if (len > (sizeof(bridge)-1))
-                        len = sizeof(bridge)-1;
-                    strncpy(bridge, data, len);
-                    bridge[len] = '\0';
+                    int len = nextkey ? (nextkey - data) : sizeof(bridge) - 1;
+                    if (virStrncpy(bridge, data, len, sizeof(bridge)) == NULL) {
+                        xenXMError(conn, VIR_ERR_INTERNAL_ERROR,
+                                   _("Bridge %s too big for destination"),
+                                   data);
+                        goto skipnic;
+                    }
                 } else if (STRPREFIX(key, "script=")) {
-                    int len = nextkey ? (nextkey - data) : PATH_MAX-1;
-                    if (len > (PATH_MAX-1))
-                        len = PATH_MAX-1;
-                    strncpy(script, data, len);
-                    script[len] = '\0';
+                    int len = nextkey ? (nextkey - data) : sizeof(script) - 1;
+                    if (virStrncpy(script, data, len, sizeof(script)) == NULL) {
+                        xenXMError(conn, VIR_ERR_INTERNAL_ERROR,
+                                   _("Script %s too big for destination"),
+                                   data);
+                        goto skipnic;
+                    }
                 } else if (STRPREFIX(key, "model=")) {
-                    int len = nextkey ? (nextkey - data) : sizeof(model)-1;
-                    if (len > (sizeof(model)-1))
-                        len = sizeof(model)-1;
-                    strncpy(model, data, len);
-                    model[len] = '\0';
+                    int len = nextkey ? (nextkey - data) : sizeof(model) - 1;
+                    if (virStrncpy(model, data, len, sizeof(model)) == NULL) {
+                        xenXMError(conn, VIR_ERR_INTERNAL_ERROR,
+                                   _("Model %s too big for destination"), data);
+                        goto skipnic;
+                    }
                 } else if (STRPREFIX(key, "vifname=")) {
-                    int len = nextkey ? (nextkey - data) : sizeof(vifname)-1;
-                    if (len > (sizeof(vifname)-1))
-                        len = sizeof(vifname)-1;
-                    strncpy(vifname, data, len);
-                    vifname[len] = '\0';
+                    int len = nextkey ? (nextkey - data) : sizeof(vifname) - 1;
+                    if (virStrncpy(vifname, data, len, sizeof(vifname)) == NULL) {
+                        xenXMError(conn, VIR_ERR_INTERNAL_ERROR,
+                                   _("Vifname %s too big for destination"),
+                                   data);
+                        goto skipnic;
+                    }
                 } else if (STRPREFIX(key, "ip=")) {
-                    int len = nextkey ? (nextkey - data) : 15;
-                    if (len > 15)
-                        len = 15;
-                    strncpy(ip, data, len);
-                    ip[len] = '\0';
+                    int len = nextkey ? (nextkey - data) : sizeof(ip) - 1;
+                    if (virStrncpy(ip, data, len, sizeof(ip)) == NULL) {
+                        xenXMError(conn, VIR_ERR_INTERNAL_ERROR,
+                                   _("IP %s too big for destination"), data);
+                        goto skipnic;
+                    }
                 }
 
                 while (nextkey && (nextkey[0] == ',' ||
@@ -1156,32 +1187,41 @@ xenXMDomainConfigParse(virConnectPtr conn, virConfPtr conf) {
             if (!(nextkey = strchr(key, ':')))
                 goto skippci;
 
-            if ((nextkey - key) > (sizeof(domain)-1))
+            if (virStrncpy(domain, key, (nextkey - key), sizeof(domain)) == NULL) {
+                xenXMError(conn, VIR_ERR_INTERNAL_ERROR,
+                           _("Domain %s too big for destination"), key);
                 goto skippci;
-
-            strncpy(domain, key, sizeof(domain));
-            domain[sizeof(domain)-1] = '\0';
+            }
 
             key = nextkey + 1;
             if (!(nextkey = strchr(key, ':')))
                 goto skippci;
 
-            strncpy(bus, key, sizeof(bus));
-            bus[sizeof(bus)-1] = '\0';
+            if (virStrncpy(bus, key, (nextkey - key), sizeof(bus)) == NULL) {
+                xenXMError(conn, VIR_ERR_INTERNAL_ERROR,
+                           _("Bus %s too big for destination"), key);
+                goto skippci;
+            }
 
             key = nextkey + 1;
             if (!(nextkey = strchr(key, '.')))
                 goto skippci;
 
-            strncpy(slot, key, sizeof(slot));
-            slot[sizeof(slot)-1] = '\0';
+            if (virStrncpy(slot, key, (nextkey - key), sizeof(slot)) == NULL) {
+                xenXMError(conn, VIR_ERR_INTERNAL_ERROR,
+                           _("Slot %s too big for destination"), key);
+                goto skippci;
+            }
 
             key = nextkey + 1;
             if (strlen(key) != 1)
                 goto skippci;
 
-            strncpy(func, key, sizeof(func));
-            func[sizeof(func)-1] = '\0';
+            if (virStrncpy(func, key, 1, sizeof(func)) == NULL) {
+                xenXMError(conn, VIR_ERR_INTERNAL_ERROR,
+                           _("Function %s too big for destination"), key);
+                goto skippci;
+            }
 
             if (virStrToLong_i(domain, NULL, 16, &domainID) < 0)
                 goto skippci;
@@ -1292,8 +1332,13 @@ xenXMDomainConfigParse(virConnectPtr conn, virConfPtr conf) {
             list->list->str) {
             char vfb[MAX_VFB];
             char *key = vfb;
-            strncpy(vfb, list->list->str, MAX_VFB-1);
-            vfb[MAX_VFB-1] = '\0';
+
+            if (virStrcpyStatic(vfb, list->list->str) == NULL) {
+                xenXMError(conn, VIR_ERR_INTERNAL_ERROR,
+                           _("VFB %s too big for destination"),
+                           list->list->str);
+                goto cleanup;
+            }
 
             if (VIR_ALLOC(graphics) < 0)
                 goto no_memory;
-- 
1.6.0.6


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