* TODO: updated

* include/virterror.h src/internal.h src/libvirt.c src/virterror.c
  src/xend_internal.c: commiting a first pass at adding error handling
  in the code, not finished, but it starts to work, need more coverage
  and testing.
Daniel

ChangeLog

@@ -1,3 +1,11 @@
+Mon Feb 27 17:25:48 CET 2006 Daniel Veillard <veillard@redhat.com>
+
+	* TODO: updated
+	* include/virterror.h src/internal.h src/libvirt.c src/virterror.c
+	  src/xend_internal.c: commiting a first pass at adding error handling
+	  in the code, not finished, but it starts to work, need more coverage
+	  and testing.
+
 Fri Feb 24 23:33:55 CET 2006 Daniel Veillard <veillard@redhat.com>
 
 	* src/Makefile.am src/internal.h src/libvirt.c src/libvirt_sym.version

TODO

@@ -12,6 +12,7 @@ TODO:
 - DTD/RNG/XSD schemas for the XML Domain descriptions
 - in python bindings raise an exception if a lookup or connection fails
   to return a non-None object
+- Add uuid to XML format
 
 virsh TODO:
 - decide where will be default directory for domains configurations (/etc/xen/domains/* ?)

include/libvirt/virterror.h

@@ -53,7 +53,7 @@ typedef enum {
 typedef struct _virError virError;
 typedef virError *virErrorPtr;
 struct _virError {
-    int		code;	/* The error code, e.g. an virParserError */
+    int		code;	/* The error code, a virErrorNumber */
     int		domain;	/* What part of the library raised this error */
     char       *message;/* human-readable informative error message */
     virErrorLevel level;/* how consequent is the error */
@@ -73,8 +73,14 @@ struct _virError {
  */
 typedef enum {
     VIR_ERR_OK = 0,
-    VIR_ERR_INTERNAL_ERROR, /* 1 */
+    VIR_ERR_INTERNAL_ERROR, /* internal error */
-    VIR_ERR_NO_MEMORY  /* 2 */
+    VIR_ERR_NO_MEMORY,  /* memory allocation failure */
+    VIR_ERR_NO_SUPPORT, /* no support for this connection */
+    VIR_ERR_NO_CONNECT, /* can't connect to hypervisor */
+    VIR_ERR_INVALID_CONN,/* invalid connection object */
+    VIR_ERR_INVALID_DOMAIN,/* invalid domain object */
+    VIR_ERR_INVALID_ARG,/* invalid function argument */
+    VIR_ERR_OPERATION_FAILED,/* a command to hypervisor failed */
 } virErrorNumber;
 
 /**

include/virterror.h

@@ -53,7 +53,7 @@ typedef enum {
 typedef struct _virError virError;
 typedef virError *virErrorPtr;
 struct _virError {
-    int		code;	/* The error code, e.g. an virParserError */
+    int		code;	/* The error code, a virErrorNumber */
     int		domain;	/* What part of the library raised this error */
     char       *message;/* human-readable informative error message */
     virErrorLevel level;/* how consequent is the error */
@@ -73,8 +73,14 @@ struct _virError {
  */
 typedef enum {
     VIR_ERR_OK = 0,
-    VIR_ERR_INTERNAL_ERROR, /* 1 */
+    VIR_ERR_INTERNAL_ERROR, /* internal error */
-    VIR_ERR_NO_MEMORY  /* 2 */
+    VIR_ERR_NO_MEMORY,  /* memory allocation failure */
+    VIR_ERR_NO_SUPPORT, /* no support for this connection */
+    VIR_ERR_NO_CONNECT, /* can't connect to hypervisor */
+    VIR_ERR_INVALID_CONN,/* invalid connection object */
+    VIR_ERR_INVALID_DOMAIN,/* invalid domain object */
+    VIR_ERR_INVALID_ARG,/* invalid function argument */
+    VIR_ERR_OPERATION_FAILED,/* a command to hypervisor failed */
 } virErrorNumber;
 
 /**

src/internal.h

@@ -129,6 +129,21 @@ char *		virDomainGetVMInfo	(virDomainPtr domain,
 					 const char *vm,
 		          	         const char *name);
 
+void		 __virRaiseError	(virConnectPtr conn,
+					 virDomainPtr dom,
+					 int domain,
+					 int code,
+					 virErrorLevel level,
+					 const char *str1,
+					 const char *str2,
+					 const char *str3,
+					 int int1,
+					 int int2,
+					 const char *msg,
+					 ...);
+const char *	__virErrorMsg		(virErrorNumber error,
+					 const char *info);
+
 #ifdef __cplusplus
 }
 #endif /* __cplusplus */

src/libvirt.c

@@ -33,6 +33,50 @@
  * - memory wrappers for malloc/free ?
  */
 
+/**
+ * virLibConnError:
+ * @conn: the connection if available
+ * @error: the error noumber
+ * @info: extra information string
+ *
+ * Handle an error at the connection level
+ */
+static void
+virLibConnError(virConnectPtr conn, virErrorNumber error, const char *info) {
+    const char *errmsg;
+    
+    if (error == VIR_ERR_OK)
+        return;
+
+    errmsg = __virErrorMsg(error, info);
+    __virRaiseError(conn, NULL, VIR_FROM_NONE, error, VIR_ERR_ERROR,
+                    errmsg, info, NULL, 0, 0, errmsg, info);
+}
+
+/**
+ * virLibConnError:
+ * @conn: the connection if available
+ * @error: the error noumber
+ * @info: extra information string
+ *
+ * Handle an error at the connection level
+ */
+static void
+virLibDomainError(virDomainPtr domain, virErrorNumber error, const char *info) {
+    virConnectPtr conn = NULL;
+    const char *errmsg;
+    
+    if (error == VIR_ERR_OK)
+        return;
+
+    errmsg = __virErrorMsg(error, info);
+    if (error != VIR_ERR_INVALID_DOMAIN) {
+        conn = domain->conn;
+    }
+    __virRaiseError(conn, domain, VIR_FROM_DOM, error, VIR_ERR_ERROR,
+                    errmsg, info, NULL, 0, 0, errmsg, info);
+}
+
 /**
  * virGetVersion:
  * @libVer: return value for the library version (OUT)
@@ -68,6 +112,7 @@ virGetVersion(unsigned long *libVer, const char *type, unsigned long *typeVer) {
 	    }
 	} else {
 	    *typeVer = 0;
+	    virLibConnError(NULL, VIR_ERR_NO_SUPPORT, "type");
 	    return(-1);
 	}
     }
@@ -90,19 +135,26 @@ virConnectOpen(const char *name) {
     struct xs_handle *xshandle = NULL;
 
     /* we can only talk to the local Xen supervisor ATM */
-    if (name != NULL) 
+    if (name != NULL) {
+        virLibConnError(NULL, VIR_ERR_NO_SUPPORT, name); 
         return(NULL);
+    }
 
     handle = xenHypervisorOpen();
-    if (handle == -1)
+    if (handle == -1) {
         goto failed;
+    }
     xshandle = xs_daemon_open();
-    if (xshandle == NULL)
+    if (xshandle == NULL) {
+        virLibConnError(NULL, VIR_ERR_NO_CONNECT, "XenStore"); 
         goto failed;
+    }
 
     ret = (virConnectPtr) malloc(sizeof(virConnect));
-    if (ret == NULL)
+    if (ret == NULL) {
+        virLibConnError(NULL, VIR_ERR_NO_MEMORY, "Allocating connection");
         goto failed;
+    }
     memset(ret, 0, sizeof(virConnect));
     ret->magic = VIR_CONNECT_MAGIC;
     ret->handle = handle;
@@ -143,8 +195,10 @@ virConnectOpenReadOnly(const char *name) {
     struct xs_handle *xshandle = NULL;
 
     /* we can only talk to the local Xen supervisor ATM */
-    if (name != NULL) 
+    if (name != NULL) {
+        virLibConnError(NULL, VIR_ERR_NO_SUPPORT, name); 
         return(NULL);
+    }
 
     handle = xenHypervisorOpen();
     if (handle >= 0)
@@ -157,8 +211,10 @@ virConnectOpenReadOnly(const char *name) {
         method++;
 
     ret = (virConnectPtr) malloc(sizeof(virConnect));
-    if (ret == NULL)
+    if (ret == NULL) {
+        virLibConnError(NULL, VIR_ERR_NO_MEMORY, "Allocating connection");
         goto failed;
+    }
     memset(ret, 0, sizeof(virConnect));
     ret->magic = VIR_CONNECT_MAGIC;
     ret->handle = handle;
@@ -166,9 +222,14 @@ virConnectOpenReadOnly(const char *name) {
     if (xend_setup(ret) == 0)
         method++;
     ret->domains = virHashCreate(20);
-    ret->flags = VIR_CONNECT_RO;
+    if (ret->domains == NULL)
-    if ((ret->domains == NULL) || (method == 0))
         goto failed;
+    ret->flags = VIR_CONNECT_RO;
+    if (method == 0) {
+        virLibConnError(NULL, VIR_ERR_NO_CONNECT,
+	                "could not connect to Xen Daemon nor Xen Store");
+        goto failed;
+    }
 
     return(ret);
 failed:
@@ -259,8 +320,10 @@ virConnectClose(virConnectPtr conn) {
  */
 const char *
 virConnectGetType(virConnectPtr conn) {
-    if (!VIR_IS_CONNECT(conn))
+    if (!VIR_IS_CONNECT(conn)) {
+        virLibConnError(conn, VIR_ERR_INVALID_CONN, "in virConnectGetType");
         return(NULL);
+    }
     return("Xen");
 }
 
@@ -281,11 +344,15 @@ int
 virConnectGetVersion(virConnectPtr conn, unsigned long *hvVer) {
     unsigned long ver;
 
-    if (!VIR_IS_CONNECT(conn))
+    if (!VIR_IS_CONNECT(conn)) {
+        virLibConnError(conn, VIR_ERR_INVALID_CONN, __FUNCTION__);
 	return(-1);
+    }
     
-    if (hvVer == NULL)
+    if (hvVer == NULL) {
+        virLibConnError(conn, VIR_ERR_INVALID_ARG, __FUNCTION__);
         return(-1);
+    }
     
     /* this can't be extracted from the Xenstore */
     if (conn->handle < 0) {
@@ -315,11 +382,15 @@ virConnectListDomains(virConnectPtr conn, int *ids, int maxids) {
     long id;
     char **idlist = NULL, *endptr;
 
-    if (!VIR_IS_CONNECT(conn))
+    if (!VIR_IS_CONNECT(conn)) {
+        virLibConnError(conn, VIR_ERR_INVALID_CONN, __FUNCTION__);
 	return(-1);
+    }
     
-    if ((ids == NULL) || (maxids <= 0))
+    if ((ids == NULL) || (maxids <= 0)) {
+        virLibConnError(conn, VIR_ERR_INVALID_ARG, __FUNCTION__);
         return(-1);
+    }
     
     idlist = xend_get_domains(conn);
     if (idlist != NULL) {
@@ -368,8 +439,10 @@ virConnectNumOfDomains(virConnectPtr conn) {
     unsigned int num;
     char **idlist = NULL;
 
-    if (!VIR_IS_CONNECT(conn))
+    if (!VIR_IS_CONNECT(conn)) {
+        virLibConnError(conn, VIR_ERR_INVALID_CONN, __FUNCTION__);
 	return(-1);
+    }
 
     /* 
      * try first with Xend interface
@@ -415,10 +488,15 @@ virDomainCreateLinux(virConnectPtr conn,
     char *name = NULL;
     virDomainPtr dom;
 
-    if (!VIR_IS_CONNECT(conn))
+    if (!VIR_IS_CONNECT(conn)) {
+        virLibConnError(conn, VIR_ERR_INVALID_CONN, __FUNCTION__);
 	return(NULL);
-    if (xmlDesc == NULL)
+    }
+    if (xmlDesc == NULL) {
+        virLibConnError(conn, VIR_ERR_INVALID_ARG, __FUNCTION__);
         return(NULL);
+    }
+
     sexpr = virDomainParseXMLDesc(xmlDesc, &name);
     if ((sexpr == NULL) || (name == NULL)) {
         if (sexpr != NULL)
@@ -614,10 +692,14 @@ virDomainLookupByID(virConnectPtr conn, int id) {
     char *name = NULL;
     unsigned char uuid[16];
 
-    if (!VIR_IS_CONNECT(conn))
+    if (!VIR_IS_CONNECT(conn)) {
+        virLibConnError(conn, VIR_ERR_INVALID_CONN, __FUNCTION__);
 	return(NULL);
-    if (id < 0)
+    }
+    if (id < 0) {
+        virLibConnError(conn, VIR_ERR_INVALID_ARG, __FUNCTION__);
         return(NULL);
+    }
 
     /* lookup is easier with the Xen store so try it first */
     if (conn->xshandle != NULL) {
@@ -690,10 +772,14 @@ virDomainLookupByUUID(virConnectPtr conn, const unsigned char *uuid) {
     unsigned char ident[16];
     int id = -1;
 
-    if (!VIR_IS_CONNECT(conn))
+    if (!VIR_IS_CONNECT(conn)) {
+        virLibConnError(conn, VIR_ERR_INVALID_CONN, __FUNCTION__);
 	return(NULL);
-    if (uuid == NULL)
+    }
+    if (uuid == NULL) {
+        virLibConnError(conn, VIR_ERR_INVALID_ARG, __FUNCTION__);
         return(NULL);
+    }
     names = xend_get_domains(conn);
     tmp = names;
 
@@ -753,10 +839,14 @@ virDomainLookupByName(virConnectPtr conn, const char *name) {
     int found = 0;
     struct xend_domain *xenddomain = NULL;
 
-    if (!VIR_IS_CONNECT(conn))
+    if (!VIR_IS_CONNECT(conn)) {
+        virLibConnError(conn, VIR_ERR_INVALID_CONN, __FUNCTION__);
 	return(NULL);
-    if (name == NULL)
+    }
+    if (name == NULL) {
+        virLibConnError(conn, VIR_ERR_INVALID_ARG, __FUNCTION__);
         return(NULL);
+    }
 
     /* try first though Xend */
     xenddomain = xend_get_domain(conn, name);
@@ -834,8 +924,10 @@ int
 virDomainDestroy(virDomainPtr domain) {
     int ret;
 
-    if (!VIR_IS_CONNECTED_DOMAIN(domain))
+    if (!VIR_IS_CONNECTED_DOMAIN(domain)) {
+        virLibDomainError(domain, VIR_ERR_INVALID_DOMAIN, __FUNCTION__);
 	return(-1);
+    }
 
     /*
      * try first with the xend method
@@ -865,8 +957,10 @@ virDomainDestroy(virDomainPtr domain) {
  */
 int
 virDomainFree(virDomainPtr domain) {
-    if (!VIR_IS_DOMAIN(domain))
+    if (!VIR_IS_DOMAIN(domain)) {
+        virLibDomainError(domain, VIR_ERR_INVALID_DOMAIN, __FUNCTION__);
 	return(-1);
+    }
     domain->magic = -1;
     domain->handle = -1;
     if (domain->path != NULL)
@@ -893,8 +987,11 @@ int
 virDomainSuspend(virDomainPtr domain) {
     int ret;
 
-    if (!VIR_IS_CONNECTED_DOMAIN(domain))
+    if (!VIR_IS_CONNECTED_DOMAIN(domain)) {
+        virLibDomainError(domain, VIR_ERR_INVALID_DOMAIN, __FUNCTION__);
 	return(-1);
+    }
+
     /* first try though the Xen daemon */
     ret = xend_pause(domain->conn, domain->name);
     if (ret == 0)
@@ -918,8 +1015,11 @@ int
 virDomainResume(virDomainPtr domain) {
     int ret;
 
-    if (!VIR_IS_CONNECTED_DOMAIN(domain))
+    if (!VIR_IS_CONNECTED_DOMAIN(domain)) {
+        virLibDomainError(domain, VIR_ERR_INVALID_DOMAIN, __FUNCTION__);
 	return(-1);
+    }
+
     /* first try though the Xen daemon */
     ret = xend_unpause(domain->conn, domain->name);
     if (ret == 0)
@@ -946,8 +1046,14 @@ virDomainSave(virDomainPtr domain, const char *to) {
     int ret;
     char filepath[4096];
 
-    if ((!VIR_IS_CONNECTED_DOMAIN(domain)) || (to == NULL))
+    if (!VIR_IS_CONNECTED_DOMAIN(domain)) {
+        virLibDomainError(domain, VIR_ERR_INVALID_DOMAIN, __FUNCTION__);
 	return(-1);
+    }
+    if (to == NULL) {
+        virLibDomainError(domain, VIR_ERR_INVALID_ARG, __FUNCTION__);
+	return(-1);
+    }
 
     /*
      * We must absolutize the file path as the save is done out of process
@@ -987,8 +1093,15 @@ virDomainRestore(virConnectPtr conn, const char *from) {
     int ret;
     char filepath[4096];
 
-    if ((!VIR_IS_CONNECT(conn)) || (from == NULL))
+    if (!VIR_IS_CONNECT(conn)) {
+        virLibConnError(conn, VIR_ERR_INVALID_CONN, __FUNCTION__);
 	return(-1);
+    }
+    if (from == NULL) {
+        virLibConnError(conn, VIR_ERR_INVALID_ARG, __FUNCTION__);
+	return(-1);
+    }
+
     /*
      * We must absolutize the file path as the restore is done out of process
      * TODO: check for URI when libxml2 is linked in.
@@ -1029,8 +1142,10 @@ int
 virDomainShutdown(virDomainPtr domain) {
     int ret;
 
-    if (!VIR_IS_CONNECTED_DOMAIN(domain))
+    if (!VIR_IS_CONNECTED_DOMAIN(domain)) {
+        virLibDomainError(domain, VIR_ERR_INVALID_DOMAIN, __FUNCTION__);
 	return(-1);
+    }
     
     /*
      * try first with the xend daemon
@@ -1061,8 +1176,10 @@ virDomainShutdown(virDomainPtr domain) {
  */
 const char *
 virDomainGetName(virDomainPtr domain) {
-    if (!VIR_IS_DOMAIN(domain))
+    if (!VIR_IS_DOMAIN(domain)) {
+        virLibDomainError(domain, VIR_ERR_INVALID_DOMAIN, __FUNCTION__);
 	return(NULL);
+    }
     return(domain->name);
 }
 
@@ -1077,11 +1194,18 @@ virDomainGetName(virDomainPtr domain) {
  */
 int
 virDomainGetUUID(virDomainPtr domain, unsigned char *uuid) {
-    if ((!VIR_IS_DOMAIN(domain)) || (uuid == NULL))
+    if (!VIR_IS_DOMAIN(domain)) {
+        virLibDomainError(domain, VIR_ERR_INVALID_DOMAIN, __FUNCTION__);
 	return(-1);
-    if (domain->handle == 0)
+    }
+    if (uuid == NULL) {
+        virLibDomainError(domain, VIR_ERR_INVALID_ARG, __FUNCTION__);
+	return(-1);
+    }
+
+    if (domain->handle == 0) {
         memset(uuid, 0, 16);
-    else {
+    } else {
 	if ((domain->uuid[0] == 0) && (domain->uuid[1] == 0) &&
 	    (domain->uuid[2] == 0) && (domain->uuid[3] == 0) &&
 	    (domain->uuid[4] == 0) && (domain->uuid[5] == 0) &&
@@ -1106,8 +1230,10 @@ virDomainGetUUID(virDomainPtr domain, unsigned char *uuid) {
  */
 unsigned int
 virDomainGetID(virDomainPtr domain) {
-    if (!VIR_IS_DOMAIN(domain))
+    if (!VIR_IS_DOMAIN(domain)) {
+        virLibDomainError(domain, VIR_ERR_INVALID_DOMAIN, __FUNCTION__);
 	return((unsigned int) -1);
+    }
     return(domain->handle);
 }
 
@@ -1123,8 +1249,10 @@ char *
 virDomainGetOSType(virDomainPtr domain) {
     char *vm, *str = NULL;
     
-    if (!VIR_IS_DOMAIN(domain))
+    if (!VIR_IS_DOMAIN(domain)) {
+        virLibDomainError(domain, VIR_ERR_INVALID_DOMAIN, __FUNCTION__);
 	return(NULL);
+    }
     
     vm = virDomainGetVM(domain);
     if (vm) {
@@ -1151,8 +1279,10 @@ unsigned long
 virDomainGetMaxMemory(virDomainPtr domain) {
     unsigned long ret = 0;
 
-    if (!VIR_IS_CONNECTED_DOMAIN(domain))
+    if (!VIR_IS_CONNECTED_DOMAIN(domain)) {
+        virLibDomainError(domain, VIR_ERR_INVALID_DOMAIN, __FUNCTION__);
 	return(0);
+    }
     
     if (domain->conn->flags & VIR_CONNECT_RO) {
         char *tmp;
@@ -1192,10 +1322,14 @@ virDomainSetMaxMemory(virDomainPtr domain, unsigned long memory) {
     int ret;
     char s[256], v[30];
     
-    if (!VIR_IS_CONNECTED_DOMAIN(domain))
+    if (!VIR_IS_CONNECTED_DOMAIN(domain)) {
+        virLibDomainError(domain, VIR_ERR_INVALID_DOMAIN, __FUNCTION__);
 	return(-1);
-    if (memory < 4096)
+    }
+    if (memory < 4096) {
+        virLibDomainError(domain, VIR_ERR_INVALID_ARG, __FUNCTION__);
         return(-1);
+    }
     if (domain->conn->flags & VIR_CONNECT_RO)
         return(-1);
     if (domain->conn->xshandle==NULL)
@@ -1240,10 +1374,14 @@ virDomainGetInfo(virDomainPtr domain, virDomainInfoPtr info) {
     char request[200];
 
 
-    if (!VIR_IS_CONNECTED_DOMAIN(domain))
+    if (!VIR_IS_CONNECTED_DOMAIN(domain)) {
+        virLibDomainError(domain, VIR_ERR_INVALID_DOMAIN, __FUNCTION__);
 	return(-1);
-    if (info == NULL)
+    }
+    if (info == NULL) {
+        virLibDomainError(domain, VIR_ERR_INVALID_ARG, __FUNCTION__);
 	return(-1);
+    }
     
     memset(info, 0, sizeof(virDomainInfo));
     
@@ -1352,10 +1490,14 @@ xend_info:
  */
 char *
 virDomainGetXMLDesc(virDomainPtr domain, int flags) {
-    if (!VIR_IS_DOMAIN(domain))
+    if (!VIR_IS_DOMAIN(domain)) {
+        virLibDomainError(domain, VIR_ERR_INVALID_DOMAIN, __FUNCTION__);
 	return(NULL);
-    if (flags != 0)
+    }
+    if (flags != 0) {
+        virLibDomainError(domain, VIR_ERR_INVALID_ARG, __FUNCTION__);
 	return(NULL);
+    }
 
     return(xend_get_domain_xml(domain));
 }

src/virterror.c

@@ -11,6 +11,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <stdarg.h>
 #include "libvirt.h"
 #include "virterror.h"
 #include "internal.h"
@@ -20,6 +21,43 @@ static virError     lastErr = 		/* the last error */
 static virErrorFunc virErrorHandler = NULL;/* global error handlet */
 static void        *virUserData = NULL;	/* associated data */
 
+/*
+ * Macro used to format the message as a string in __virRaiseError
+ * and borrowed from libxml2.
+ */
+#define VIR_GET_VAR_STR(msg, str) {				\
+    int       size, prev_size = -1;				\
+    int       chars;						\
+    char      *larger;						\
+    va_list   ap;						\
+								\
+    str = (char *) malloc(150);					\
+    if (str != NULL) {						\
+								\
+    size = 150;							\
+								\
+    while (1) {							\
+	va_start(ap, msg);					\
+  	chars = vsnprintf(str, size, msg, ap);			\
+	va_end(ap);						\
+	if ((chars > -1) && (chars < size)) {			\
+	    if (prev_size == chars) {				\
+		break;						\
+	    } else {						\
+		prev_size = chars;				\
+	    }							\
+	}							\
+	if (chars > -1)						\
+	    size += chars + 1;					\
+	else							\
+	    size += 100;					\
+	if ((larger = (char *) realloc(str, size)) == NULL) {	\
+	    break;						\
+	}							\
+	str = larger;						\
+    }}								\
+}
+
 /*
  * virGetLastError:
  *
@@ -173,3 +211,181 @@ virConnSetErrorFunc(virConnectPtr conn, void *userData, virErrorFunc handler) {
     conn->userData = userData;
 }
 
+/**
+ * virReportError:
+ * @err: pointer to the error.
+ *
+ * Internal routine reporting an error to stderr.
+ */
+static void
+virReportError(virErrorPtr err) {
+    const char *lvl = "", *dom = "", *domain = "";
+    int len;
+
+    if ((err == NULL) || (err->code == VIR_ERR_OK))
+        return;
+    switch (err->level) {
+        case VIR_ERR_NONE:
+	    lvl = "";
+	    break;
+        case VIR_ERR_WARNING:
+	    lvl = "warning";
+	    break;
+        case VIR_ERR_ERROR:
+	    lvl = "error";
+	    break;
+    } 
+    switch (err->domain) {
+        case VIR_FROM_NONE:
+	    dom = "";
+	    break;
+        case VIR_FROM_XEN:
+	    dom = "Xen ";
+	    break;
+        case VIR_FROM_XEND:
+	    dom = "Xen Daemon ";
+	    break;
+        case VIR_FROM_DOM:
+	    dom = "Domain ";
+	    break;
+    }
+    if ((err->dom != NULL) && (err->code != VIR_ERR_INVALID_DOMAIN)) {
+        domain = err->dom->name;
+    }
+    len = strlen(err->message);
+    if ((len == 0) || (err->message[len - 1] != '\n'))
+	fprintf(stderr, "libvir: %s%s %s: %s\n",
+	        dom, lvl, domain, err->message);
+    else 
+	fprintf(stderr, "libvir: %s%s %s: %s",
+	        dom, lvl, domain, err->message);
+}
+
+/**
+ * __virRaiseError:
+ * @conn: the connection to the hypervisor if available
+ * @dom: the domain if available
+ * @domain: the virErrorDomain indicating where it's coming from
+ * @code: the virErrorNumber code for the error
+ * @level: the virErrorLevel for the error
+ * @str1: extra string info
+ * @str2: extra string info
+ * @str3: extra string info
+ * @int1: extra int info
+ * @int2: extra int info
+ * @msg:  the message to display/transmit
+ * @...:  extra parameters for the message display
+ *
+ * Internal routine called when an error is detected. It will raise it
+ * immediately if a callback is found and store it for later handling.
+ */
+void
+__virRaiseError(virConnectPtr conn, virDomainPtr dom,
+                int domain, int code, virErrorLevel level,
+                const char *str1, const char *str2, const char *str3,
+		int int1, int int2, const char *msg, ...) {
+    virErrorPtr to = &lastErr;
+    void *userData = virUserData;
+    virErrorFunc handler = virErrorHandler;
+    char *str;
+
+    if (code == VIR_ERR_OK)
+	return;
+
+    /*
+     * try to find the best place to save and report the error
+     */
+    if (conn != NULL) {
+        to = &conn->err;
+	if (conn->handler != NULL) {
+	    handler = conn->handler;
+	    userData = conn->userData;
+	}
+    }
+
+    /*
+     * formats the message
+     */
+    if (msg == NULL) {
+        str = strdup("No error message provided");
+    } else {
+        VIR_GET_VAR_STR(msg, str);
+    }
+
+    /*
+     * Save the information about the error
+     */
+    virResetError(to);
+    to->conn = conn;
+    to->dom = dom;
+    to->domain = domain;
+    to->code = code;
+    to->message = str;
+    to->level = level;
+    if (str1 != NULL)
+        to->str1 = strdup(str1);
+    if (str2 != NULL)
+        to->str2 = strdup(str2);
+    if (str3 != NULL)
+        to->str3 = strdup(str3);
+    to->int1 = int1;
+    to->int2 = int2;
+
+    /*
+     * now, report it
+     */
+    if (handler != NULL) {
+        handler(userData, to);
+    } else {
+        virReportError(to);
+    }
+}
+
+/**
+ * __virErrorMsg:
+ * @error: the virErrorNumber
+ * @info: usually the first paprameter string
+ *
+ * Internal routine to get the message associated to an error raised
+ * from the library
+ *
+ * Returns the constant string associated to @error
+ */
+const char *
+__virErrorMsg(virErrorNumber error, const char *info) {
+    const char *errmsg = NULL;
+
+    switch (error) {
+        case VIR_ERR_OK:
+	    return(NULL);
+	case VIR_ERR_INTERNAL_ERROR:
+	    if (info != NULL)
+		errmsg = "internal error %s";
+	    else
+	        errmsg = "internal error";
+	    break;
+	case VIR_ERR_NO_MEMORY:
+	    errmsg = "out of memory";
+	    break;
+	case VIR_ERR_NO_SUPPORT:
+	    errmsg = "no support for hypervisor %s";
+	    break;
+	case VIR_ERR_NO_CONNECT:
+	    if (info == NULL)
+	        errmsg = "could not connect to hypervisor";
+	    else
+	        errmsg = "could not connect to %s";
+	    break;
+	case VIR_ERR_INVALID_CONN:
+	    errmsg = "invalid connection pointer in";
+	    break;
+	case VIR_ERR_INVALID_DOMAIN:
+	    errmsg = "invalid domain pointer in";
+	    break;
+	case VIR_ERR_INVALID_ARG:
+	    errmsg = "invalid domain pointer in";
+	    break;
+    }
+    return(errmsg);
+}
+

src/xend_internal.c

@@ -57,6 +57,28 @@ struct xend {
     struct sockaddr_in addr_in;
 };
 
+
+/**
+ * virXendError:
+ * @conn: the connection if available
+ * @error: the error noumber
+ * @info: extra information string
+ *
+ * Handle an error at the xend daemon interface
+ */
+static void
+virXendError(virConnectPtr conn, virErrorNumber error, const char *info) {
+    const char *errmsg;
+    
+    if (error == VIR_ERR_OK)
+        return;
+
+    errmsg = __virErrorMsg(error, info);
+    __virRaiseError(conn, NULL, VIR_FROM_XEND, error, VIR_ERR_ERROR,
+                    errmsg, info, NULL, 0, 0, errmsg, info);
+}
+
+
 #define foreach(iterator, start) \
        	for (_for_i = (start), *iterator = (start)->car; \
              _for_i->kind == SEXPR_CONS; \
@@ -81,10 +103,14 @@ do_connect(virConnectPtr xend)
     int serrno;
 
     s = socket(xend->type, SOCK_STREAM, 0);
-    if (s == -1)
+    if (s == -1) {
+        virXendError(xend, VIR_ERR_INTERNAL_ERROR,
+	             "failed to create a socket");
         return -1;
+    }
 
     if (connect(s, xend->addr, xend->len) == -1) {
+        virXendError(xend, VIR_ERR_NO_CONNECT, "Xen Daemon");
         serrno = errno;
         close(s);
         errno = serrno;
@@ -131,6 +157,13 @@ wr_sync(int fd, void *buffer, size_t size, int do_read)
 
         /* unrecoverable error */
         if (len == -1) {
+	    if (do_read)
+		virXendError(NULL, VIR_ERR_INTERNAL_ERROR,
+			     "faid to read from Xen Daemon");
+	    else
+		virXendError(NULL, VIR_ERR_INTERNAL_ERROR,
+			     "faid to read from Xen Daemon");
+	        
             return(-1);
         }
 
@@ -309,6 +342,11 @@ xend_get(virConnectPtr xend, const char *path,
     ret = xend_req(s, content, n_content);
     close(s);
 
+    if ((ret < 0) || (ret >= 300)) {
+	virXendError(NULL, VIR_ERR_OPERATION_FAILED,
+		     content);
+    }
+
     return ret;
 }
 
@@ -353,6 +391,11 @@ xend_post(virConnectPtr xend, const char *path, const char *ops,
     ret = xend_req(s, content, n_content);
     close(s);
 
+    if ((ret < 0) || (ret >= 300)) {
+	virXendError(NULL, VIR_ERR_OPERATION_FAILED,
+		     content);
+    }
+
     return ret;
 }