[Xen-devel] [PATCH v2] xenstored: log tdb message via xenstored's logging mechanisms

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

TDB provides us with a callback for this purpose. Use it in both
xenstored and xs_tdb_dump.

While at it make the existing log() macro tollerate memory failures.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
v2: Use &tdb_logger consistently.
    Did not: move location of talloc_free, since talloc_free(NULL)
    returns an error.
---
 tools/xenstore/xenstored_core.c |   39 +++++++++++++++++++++++++++++++++------
 tools/xenstore/xs_tdb_dump.c    |   12 +++++++++++-
 2 files changed, 44 insertions(+), 7 deletions(-)

diff --git a/tools/xenstore/xenstored_core.c b/tools/xenstore/xenstored_core.c
index 4eaff57..3fd9a20 100644
--- a/tools/xenstore/xenstored_core.c
+++ b/tools/xenstore/xenstored_core.c
@@ -89,9 +89,14 @@ static void check_store(void);
 #define log(...)                                                       \
        do {                                                            \
                char *s = talloc_asprintf(NULL, __VA_ARGS__);           \
-               trace("%s\n", s);                                       \
-               syslog(LOG_ERR, "%s",  s);                              \
-               talloc_free(s);                                         \
+               if (s) {                                                \
+                       trace("%s\n", s);                               \
+                       syslog(LOG_ERR, "%s",  s);                      \
+                       talloc_free(s);                                 \
+               } else {                                                \
+                       trace("talloc failure during logging\n");       \
+                       syslog(LOG_ERR, "talloc failure during logging\n"); \
+               }                                                       \
        } while (0)
 
 
@@ -1479,13 +1484,35 @@ static void manual_node(const char *name, const char 
*child)
        talloc_free(node);
 }
 
+static void tdb_logger(TDB_CONTEXT *tdb, int level, const char * fmt, ...)
+{
+       va_list ap;
+       char *s;
+
+       va_start(ap, fmt);
+       s = talloc_vasprintf(NULL, fmt, ap);
+       va_end(ap);
+
+       if (s) {
+               trace("TDB: %s\n", s);
+               syslog(LOG_ERR, "TDB: %s",  s);
+               if (verbose)
+                       xprintf("TDB: %s", s);
+               talloc_free(s);
+       } else {
+               trace("talloc failure during logging\n");
+               syslog(LOG_ERR, "talloc failure during logging\n");
+       }
+}
+
 static void setup_structure(void)
 {
        char *tdbname;
        tdbname = talloc_strdup(talloc_autofree_context(), xs_daemon_tdb());
 
        if (!(tdb_flags & TDB_INTERNAL))
-               tdb_ctx = tdb_open(tdbname, 0, tdb_flags, O_RDWR, 0);
+               tdb_ctx = tdb_open_ex(tdbname, 0, tdb_flags, O_RDWR, 0,
+                                     &tdb_logger, NULL);
 
        if (tdb_ctx) {
                /* XXX When we make xenstored able to restart, this will have
@@ -1516,8 +1543,8 @@ static void setup_structure(void)
                talloc_free(tlocal);
        }
        else {
-               tdb_ctx = tdb_open(tdbname, 7919, tdb_flags, O_RDWR|O_CREAT,
-                                  0640);
+               tdb_ctx = tdb_open_ex(tdbname, 7919, tdb_flags, O_RDWR|O_CREAT,
+                                     0640, &tdb_logger, NULL);
                if (!tdb_ctx)
                        barf_perror("Could not create tdb file %s", tdbname);
 
diff --git a/tools/xenstore/xs_tdb_dump.c b/tools/xenstore/xs_tdb_dump.c
index b91cdef..9f636f9 100644
--- a/tools/xenstore/xs_tdb_dump.c
+++ b/tools/xenstore/xs_tdb_dump.c
@@ -33,6 +33,15 @@ static char perm_to_char(enum xs_perm_type perm)
                '?';
 }
 
+static void tdb_logger(TDB_CONTEXT *tdb, int level, const char * fmt, ...)
+{
+       va_list ap;
+
+       va_start(ap, fmt);
+       vfprintf(stderr, fmt, ap);
+       va_end(ap);
+}
+
 int main(int argc, char *argv[])
 {
        TDB_DATA key;
@@ -41,7 +50,8 @@ int main(int argc, char *argv[])
        if (argc != 2)
                barf("Usage: xs_tdb_dump <tdbfile>");
 
-       tdb = tdb_open(talloc_strdup(NULL, argv[1]), 0, 0, O_RDONLY, 0);
+       tdb = tdb_open_ex(talloc_strdup(NULL, argv[1]), 0, 0, O_RDONLY, 0,
+                         &tdb_logger, NULL);
        if (!tdb)
                barf_perror("Could not open %s", argv[1]);
 
-- 
1.7.10.4


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