ERR: Add new building blocks for reporting errors

The new building block are ERR_new(), ERR_set_debug(),
ERR_set_error(), ERR_vset_error(), which allocate a new error record
and set the diverse data in them.  They are designed in such a way
that it's reasonably easy to create macros that use all of them but
then rely completely on the function signature of ERR_set_error() or
ERR_vset_error().

Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/9452)

2 files changed, 114 insertions, 1 deletions

diff --git a/crypto/err/build.info b/crypto/err/build.info
index 6163d95b74..c010ea4cb9 100644
--- a/crypto/err/build.info
+++ b/crypto/err/build.info
@@ -1,3 +1,3 @@
 LIBS=../../libcrypto
 SOURCE[../../libcrypto]=\
-        err.c err_all.c err_prn.c
+        err_blocks.c err.c err_all.c err_prn.c
diff --git a/crypto/err/err_blocks.c b/crypto/err/err_blocks.c
new file mode 100644
index 0000000000..49086bd0c2
--- /dev/null
+++ b/crypto/err/err_blocks.c
@@ -0,0 +1,113 @@
+/*
+ * Copyright 2019 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License 2.0 (the "License").  You may not use
+ * this file except in compliance with the License.  You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+
+#include <string.h>
+#include <openssl/err.h>
+#include "err_locl.h"
+
+void ERR_new(void)
+{
+    ERR_STATE *es;
+
+    es = ERR_get_state();
+    if (es == NULL)
+        return;
+
+    /* Allocate a slot */
+    err_get_slot(es);
+    err_clear(es, es->top, 0);
+}
+
+void ERR_set_debug(const char *file, int line, const char *func)
+{
+    ERR_STATE *es;
+
+    es = ERR_get_state();
+    if (es == NULL)
+        return;
+
+    err_set_debug(es, es->top, file, line, func);
+}
+
+void ERR_set_error(int lib, int reason, const char *fmt, ...)
+{
+    va_list args;
+
+    va_start(args, fmt);
+    ERR_vset_error(lib, reason, fmt, args);
+    va_end(args);
+}
+
+void ERR_vset_error(int lib, int reason, const char *fmt, va_list args)
+{
+    ERR_STATE *es;
+    char *buf = NULL;
+    size_t buf_size = 0;
+    unsigned long flags = 0;
+    size_t i;
+
+    es = ERR_get_state();
+    if (es == NULL)
+        return;
+    i = es->top;
+
+    if (fmt != NULL) {
+        int printed_len = 0;
+        char *rbuf = NULL;
+
+        buf = es->err_data[i];
+        buf_size = es->err_data_size[i];
+
+        /*
+         * To protect the string we just grabbed from tampering by other
+         * functions we may call, or to protect them from freeing a pointer
+         * that may no longer be valid at that point, we clear away the
+         * data pointer and the flags.  We will set them again at the end
+         * of this function.
+         */
+        es->err_data[i] = NULL;
+        es->err_data_flags[i] = 0;
+
+        /*
+         * Try to maximize the space available.  If that fails, we use what
+         * we have.
+         */
+        if (buf_size < ERR_MAX_DATA_SIZE
+            && (rbuf = OPENSSL_realloc(buf, ERR_MAX_DATA_SIZE)) != NULL) {
+            buf = rbuf;
+            buf_size = ERR_MAX_DATA_SIZE;
+        }
+
+        if (buf != NULL) {
+            printed_len = BIO_vsnprintf(buf, ERR_MAX_DATA_SIZE, fmt, args);
+        }
+        if (printed_len < 0)
+            printed_len = 0;
+        buf[printed_len] = '\0';
+
+        /*
+         * Try to reduce the size, but only if we maximized above.  If that
+         * fails, we keep what we have.
+         * (According to documentation, realloc leaves the old buffer untouched
+         * if it fails)
+         */
+        if ((rbuf = OPENSSL_realloc(buf, printed_len + 1)) != NULL) {
+            buf = rbuf;
+            buf_size = printed_len + 1;
+        }
+
+        if (buf != NULL)
+            flags = ERR_TXT_MALLOCED | ERR_TXT_STRING;
+    }
+
+    err_clear_data(es, es->top, 0);
+    err_set_error(es, es->top, lib, reason);
+    if (fmt != NULL)
+        err_set_data(es, es->top, buf, buf_size, flags);
+}