virbpf: Set errno instead of reporting errors

The virbpf module wraps syscalls to BPF. However, if the kernel
headers used at the compile time don't have support for BPF the
module offers stubs which return a negative one to signal error
to the caller. But there is a slight discrepancy between real
functions and these stubs. While the former set errno and return
-1 the latter report an error (without setting the errno) and
return -1. This is not optimal because the caller might see stale
errno and overwrite the error message with a less accurate one.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NDaniel Henrique Barboza <danielhb413@gmail.com>

po/POTFILES.in

@@ -227,7 +227,6 @@
 @SRCDIR@/src/util/virauth.c
 @SRCDIR@/src/util/virauthconfig.c
 @SRCDIR@/src/util/virbitmap.c
-@SRCDIR@/src/util/virbpf.c
 @SRCDIR@/src/util/vircgroup.c
 @SRCDIR@/src/util/vircgroupbackend.c
 @SRCDIR@/src/util/vircgroupbackend.h

src/util/virbpf.c

@@ -302,8 +302,7 @@ virBPFCreateMap(unsigned int mapType G_GNUC_UNUSED,
                 unsigned int valSize G_GNUC_UNUSED,
                 unsigned int maxEntries G_GNUC_UNUSED)
 {
-    virReportSystemError(ENOSYS, "%s",
-                         _("BPF not supported with this kernel"));
+    errno = ENOSYS;
     return -1;
 }
 
@@ -313,8 +312,7 @@ virBPFLoadProg(struct bpf_insn *insns G_GNUC_UNUSED,
                int progType G_GNUC_UNUSED,
                unsigned int insnCnt G_GNUC_UNUSED)
 {
-    virReportSystemError(ENOSYS, "%s",
-                         _("BPF not supported with this kernel"));
+    errno = ENOSYS;
     return -1;
 }
 
@@ -324,8 +322,7 @@ virBPFAttachProg(int progfd G_GNUC_UNUSED,
                  int targetfd G_GNUC_UNUSED,
                  int attachType G_GNUC_UNUSED)
 {
-    virReportSystemError(ENOSYS, "%s",
-                         _("BPF not supported with this kernel"));
+    errno = ENOSYS;
     return -1;
 }
 
@@ -335,8 +332,7 @@ virBPFDetachProg(int progfd G_GNUC_UNUSED,
                  int targetfd G_GNUC_UNUSED,
                  int attachType G_GNUC_UNUSED)
 {
-    virReportSystemError(ENOSYS, "%s",
-                         _("BPF not supported with this kernel"));
+    errno = ENOSYS;
     return -1;
 }
 
@@ -348,8 +344,7 @@ virBPFQueryProg(int targetfd G_GNUC_UNUSED,
                 unsigned int *progcnt G_GNUC_UNUSED,
                 void *progids G_GNUC_UNUSED)
 {
-    virReportSystemError(ENOSYS, "%s",
-                         _("BPF not supported with this kernel"));
+    errno = ENOSYS;
     return -1;
 }
 
@@ -357,8 +352,7 @@ virBPFQueryProg(int targetfd G_GNUC_UNUSED,
 int
 virBPFGetProg(unsigned int id G_GNUC_UNUSED)
 {
-    virReportSystemError(ENOSYS, "%s",
-                         _("BPF not supported with this kernel"));
+    errno = ENOSYS;
     return -1;
 }
 
@@ -368,8 +362,7 @@ virBPFGetProgInfo(int progfd G_GNUC_UNUSED,
                   struct bpf_prog_info *info G_GNUC_UNUSED,
                   unsigned int **mapIDs G_GNUC_UNUSED)
 {
-    virReportSystemError(ENOSYS, "%s",
-                         _("BPF not supported with this kernel"));
+    errno = ENOSYS;
     return -1;
 }
 
@@ -377,8 +370,7 @@ virBPFGetProgInfo(int progfd G_GNUC_UNUSED,
 int
 virBPFGetMap(unsigned int id G_GNUC_UNUSED)
 {
-    virReportSystemError(ENOSYS, "%s",
-                         _("BPF not supported with this kernel"));
+    errno = ENOSYS;
     return -1;
 }
 
@@ -387,8 +379,7 @@ int
 virBPFGetMapInfo(int mapfd G_GNUC_UNUSED,
                  struct bpf_map_info *info G_GNUC_UNUSED)
 {
-    virReportSystemError(ENOSYS, "%s",
-                         _("BPF not supported with this kernel"));
+    errno = ENOSYS;
     return -1;
 }
 
@@ -398,8 +389,7 @@ virBPFLookupElem(int mapfd G_GNUC_UNUSED,
                  void *key G_GNUC_UNUSED,
                  void *val G_GNUC_UNUSED)
 {
-    virReportSystemError(ENOSYS, "%s",
-                         _("BPF not supported with this kernel"));
+    errno = ENOSYS;
     return -1;
 }
 
@@ -409,8 +399,7 @@ virBPFGetNextElem(int mapfd G_GNUC_UNUSED,
                   void *key G_GNUC_UNUSED,
                   void *nextKey G_GNUC_UNUSED)
 {
-    virReportSystemError(ENOSYS, "%s",
-                         _("BPF not supported with this kernel"));
+    errno = ENOSYS;
     return -1;
 }
 
@@ -420,8 +409,7 @@ virBPFUpdateElem(int mapfd G_GNUC_UNUSED,
                  void *key G_GNUC_UNUSED,
                  void *val G_GNUC_UNUSED)
 {
-    virReportSystemError(ENOSYS, "%s",
-                         _("BPF not supported with this kernel"));
+    errno = ENOSYS;
     return -1;
 }
 
@@ -430,8 +418,7 @@ int
 virBPFDeleteElem(int mapfd G_GNUC_UNUSED,
                  void *key G_GNUC_UNUSED)
 {
-    virReportSystemError(ENOSYS, "%s",
-                         _("BPF not supported with this kernel"));
+    errno = ENOSYS;
     return -1;
 }
 #endif /* !HAVE_SYS_SYSCALL_H || !HAVE_DECL_BPF_PROG_QUERY */