lib: "ferr" error-information system

This provides an API to pass around extra information for errors, more
than a simple return value can carry.  This is particularly used for the
Cap'n Proto interface to be able to report more useful errors.

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>

1 files changed, 147 insertions, 0 deletions

diff --git a/lib/ferr.c b/lib/ferr.c
new file mode 100644
index 0000000000..2a039d2089
--- /dev/null
+++ b/lib/ferr.c
@@ -0,0 +1,147 @@
+/*
+ * Copyright (c) 2015-16  David Lamparter, for NetDEF, Inc.
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <stdlib.h>
+#include <stdarg.h>
+#include <string.h>
+#include <pthread.h>
+#include <signal.h>
+
+#include "ferr.h"
+#include "vty.h"
+#include "jhash.h"
+#include "memory.h"
+
+DEFINE_MTYPE_STATIC(LIB, ERRINFO, "error information")
+
+static pthread_key_t errkey;
+
+static void ferr_free(void *arg)
+{
+	XFREE(MTYPE_ERRINFO, arg);
+}
+
+static void err_key_init(void) __attribute__((_CONSTRUCTOR(500)));
+static void err_key_init(void)
+{
+	pthread_key_create(&errkey, ferr_free);
+}
+
+static void err_key_fini(void) __attribute__((_DESTRUCTOR(500)));
+static void err_key_fini(void)
+{
+	pthread_key_delete(errkey);
+}
+
+const struct ferr *ferr_get_last(ferr_r errval)
+{
+	struct ferr *last_error = pthread_getspecific(errkey);
+	if (!last_error || last_error->kind == 0)
+		return NULL;
+	return last_error;
+}
+
+ferr_r ferr_clear(void)
+{
+	struct ferr *last_error = pthread_getspecific(errkey);
+	if (last_error)
+		last_error->kind = 0;
+	return ferr_ok();
+}
+
+static ferr_r ferr_set_va(const char *file, int line, const char *func,
+		enum ferr_kind kind, const char *pathname, int errno_val,
+		const char *text, va_list va)
+{
+	struct ferr *error = pthread_getspecific(errkey);
+
+	if (!error) {
+		error = XCALLOC(MTYPE_ERRINFO, sizeof(*error));
+		if (!error) {
+			/* we're screwed */
+			zlog_err("out of memory while allocating error info");
+			raise(SIGSEGV);
+		}
+
+		pthread_setspecific(errkey, error);
+	}
+
+	error->file = file;
+	error->line = line;
+	error->func = func;
+	error->kind = kind;
+
+	error->unique_id = jhash(text, strlen(text),
+			jhash(file, strlen(file), 0xd4ed0298));
+
+	error->errno_val = errno_val;
+	if (pathname)
+		snprintf(error->pathname, sizeof(error->pathname),
+				"%s", pathname);
+	else
+		error->pathname[0] = '\0';
+
+	vsnprintf(error->message, sizeof(error->message), text, va);
+	return -1;
+}
+
+ferr_r ferr_set_internal(const char *file, int line, const char *func,
+		enum ferr_kind kind, const char *text, ...)
+{
+	ferr_r rv;
+	va_list va;
+	va_start(va, text);
+	rv = ferr_set_va(file, line, func, kind, NULL, 0, text, va);
+	va_end(va);
+	return rv;
+}
+
+ferr_r ferr_set_internal_ext(const char *file, int line, const char *func,
+		enum ferr_kind kind, const char *pathname, int errno_val,
+		const char *text, ...)
+{
+	ferr_r rv;
+	va_list va;
+	va_start(va, text);
+	rv = ferr_set_va(file, line, func, kind, pathname, errno_val, text, va);
+	va_end(va);
+	return rv;
+}
+
+#define REPLACE "$ERR"
+void vty_print_error(struct vty *vty, ferr_r err, const char *msg, ...)
+{
+	char tmpmsg[512], *replacepos;
+	const struct ferr *last_error = ferr_get_last(err);
+
+	va_list va;
+	va_start(va, msg);
+	vsnprintf(tmpmsg, sizeof(tmpmsg), msg, va);
+	va_end(va);
+
+	replacepos = strstr(tmpmsg, REPLACE);
+	if (!replacepos)
+		vty_out(vty, "%s\n", tmpmsg);
+	else {
+		replacepos[0] = '\0';
+		replacepos += sizeof(REPLACE) - 1;
+		vty_out(vty, "%s%s%s\n",
+			tmpmsg,
+			last_error ? last_error->message : "(no error?)",
+			replacepos);
+	}
+}
+