scanner: Make fail() function use va_list and elaborate a few errors

diff --git a/src/scanner.c b/src/scanner.c
index 81ca1f6..a96d3e7 100644 (file)
--- a/src/scanner.c
+++ b/src/scanner.c
@@ -255,10 +255,16 @@ desc_dump(char *desc, const char *fmt, ...)
 }
 
 static void
-fail(struct location *loc, const char *msg)
+fail(struct location *loc, const char *msg, ...)
 {
-       fprintf(stderr, "%s:%d: error: %s\n",
-               loc->filename, loc->line_number, msg);
+       va_list ap;
+
+       va_start(ap, msg);
+       fprintf(stderr, "%s:%d: error: ",
+               loc->filename, loc->line_number);
+       vfprintf(stderr, msg, ap);
+       fprintf(stderr, "\n");
+       va_end(ap);
        exit(EXIT_FAILURE);
 }
 
@@ -378,7 +384,8 @@ start_element(void *data, const char *element_name, const char **atts)
                if (since != NULL) {
                        version = strtol(since, &end, 0);
                        if (errno == EINVAL || end == since || *end != '\0')
-                               fail(&ctx->loc, "invalid integer\n");
+                               fail(&ctx->loc,
+                                    "invalid integer (%s)\n", since);
                        if (version < ctx->interface->since)
                                fail(&ctx->loc, "since version not increasing\n");
                        ctx->interface->since = version;
@@ -414,7 +421,7 @@ start_element(void *data, const char *element_name, const char **atts)
                } else if (strcmp(type, "object") == 0) {
                        arg->type = OBJECT;
                } else {
-                       fail(&ctx->loc, "unknown type");
+                       fail(&ctx->loc, "unknown type (%s)", type);
                }
 
                switch (arg->type) {
@@ -431,7 +438,7 @@ start_element(void *data, const char *element_name, const char **atts)
                        break;
                default:
                        if (interface_name != NULL)
-                               fail(&ctx->loc, "interface not allowed");
+                               fail(&ctx->loc, "interface attribute not allowed for type %s", type);
                        break;
                }
 
@@ -440,7 +447,7 @@ start_element(void *data, const char *element_name, const char **atts)
                else if (strcmp(allow_null, "true") == 0)
                        arg->nullable = 1;
                else
-                       fail(&ctx->loc, "invalid value for allow-null attribute");
+                       fail(&ctx->loc, "invalid value for allow-null attribute (%s)", allow_null);
 
                if (allow_null != NULL && !is_nullable_type(arg))
                        fail(&ctx->loc, "allow-null is only valid for objects, strings, and arrays");