[Libguestfs] [PATCH nbdkit v2 3/5] server: Introduce threadlocal_{set,get}_last_error

Plus a function to clear the last_error field. --- server/internal.h | 3 +++ server/threadlocal.c | 40 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 43 insertions(+) diff --git a/server/internal.h b/server/internal.h index 8102ccdefd..c45384a69c 100644 --- a/server/internal.h +++ b/server/internal.h @@ -571,6 +571,9 @@ extern void threadlocal_set_instance_num (size_t instance_num); extern size_t threadlocal_get_instance_num (void); extern void threadlocal_set_errno (int err); extern int threadlocal_get_errno (void); +extern void threadlocal_set_last_error (char *msg); +extern void threadlocal_clear_last_error (void); +extern const char *threadlocal_get_last_error (void); extern void *threadlocal_buffer (size_t size); extern void threadlocal_set_conn (struct connection *conn); extern struct connection *threadlocal_get_conn (void); diff --git a/server/threadlocal.c b/server/threadlocal.c index 9bb656bc4a..74a3c4e52b 100644 --- a/server/threadlocal.c +++ b/server/threadlocal.c @@ -56,6 +56,7 @@ struct threadlocal { char *name; /* Can be NULL. */ size_t instance_num; /* Can be 0. */ int err; + char *last_error; /* Can be NULL. */ void *buffer; /* Can be NULL. */ size_t buffer_size; struct connection *conn; /* Can be NULL. */ @@ -70,6 +71,7 @@ free_threadlocal (void *threadlocalv) struct threadlocal *threadlocal = threadlocalv; free (threadlocal->name); + free (threadlocal->last_error); free (threadlocal->buffer); free (threadlocal); } @@ -176,6 +178,44 @@ threadlocal_get_errno (void) return threadlocal ? threadlocal->err : 0; } +/* Set the last_error field. The ownership of the 'msg' string is + * passed to the threadlocal and will be freed here. + */ +void +threadlocal_set_last_error (char *msg) +{ + struct threadlocal *threadlocal = pthread_getspecific (threadlocal_key); + + if (threadlocal) { + free (threadlocal->last_error); + threadlocal->last_error = msg; + } + else { + /* ... otherwise throw it away, it's informational. */ + free (msg); + } +} + +void +threadlocal_clear_last_error (void) +{ + threadlocal_set_last_error (NULL); +} + +/* Get the last_error field. If successful, this returns a non-NULL + * string. This is valid until something calls nbdkit_error() in the + * same thread, so it should be used quickly. Returning NULL is not + * necessarily an error. The last_error is informational and may not + * be available. + */ +const char * +threadlocal_get_last_error (void) +{ + struct threadlocal *threadlocal = pthread_getspecific (threadlocal_key); + + return threadlocal ? threadlocal->last_error : NULL; +} + /* Return the single pread/pwrite buffer for this thread. The buffer * size is increased to ‘size’ bytes if required. * -- 2.44.0