First commit

1 files changed, 181 insertions, 0 deletions

diff --git a/src/search.c b/src/search.c
new file mode 100644
index 0000000..622b74c
--- /dev/null
+++ b/src/search.c
@@ -0,0 +1,181 @@
+/*
+ * nanowasm, a tiny WebAssembly/Wasm interpreter
+ * Copyright (C) 2023-2024  Xavier Del Campo Romero
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ */
+
+#include <nw/search.h>
+#include <nw/log.h>
+#include <nw/fstring.h>
+#include <nw/sections.h>
+#include <nanowasm/nw.h>
+#include <nw/types.h>
+#include <errno.h>
+#include <stdint.h>
+#include <string.h>
+
+static int ensure_export(const char *const fn,
+    const struct nw_mod *const m, FILE *const f, varuint32 *const out)
+{
+    if (!m->sections.export)
+    {
+        LOG("%s: export section not found", __func__);
+        return -1;
+    }
+    else if (fseek(f, m->sections.export, SEEK_SET))
+    {
+        LOG("%s: fseek(3): %s\n", __func__, strerror(errno));
+        return -1;
+    }
+
+    varuint32 count;
+
+    if (varuint32_read(f, &count))
+    {
+        LOG("%s: varuint32_read failed\n", __func__);
+        return -1;
+    }
+
+    for (varuint32 i = 0; i < count; i++)
+    {
+        varuint32 len;
+        bool found = false;
+
+        if (varuint32_read(f, &len))
+        {
+            LOG("%s: varuint32_read failed\n", __func__);
+            return -1;
+        }
+        else if (len != strlen(fn))
+        {
+            if (fseek(f, len, SEEK_CUR))
+            {
+                LOG("%s: fseek(3): %s\n", __func__, strerror(errno));
+                return -1;
+            }
+        }
+        else if (!fstrcmp(fn, f, false))
+            found = true;
+
+        uint8_t kind;
+
+        if (!fread(&kind, sizeof kind, 1, f))
+        {
+            LOG("%s: fread(3) failed: feof=%d, ferror=%d\n", __func__,
+                feof(f), ferror(f));
+            return -1;
+        }
+
+        varuint32 index;
+
+        if (varuint32_read(f, &index))
+        {
+            LOG("%s: varuint32_read failed\n", __func__);
+            return -1;
+        }
+        else if (found)
+        {
+            if (kind != NW_KIND_FUNCTION)
+            {
+                LOG("%s: expected kind %d, got %d\n", __func__,
+                    NW_KIND_FUNCTION, kind);
+                return -1;
+            }
+
+            *out = index;
+            return 0;
+        }
+    }
+
+    return -1;
+}
+
+static int get_function_index(const struct nw_mod *const m,
+    const varuint32 index, varuint32 *const findex)
+{
+    const size_t n = m->cfg.n_imports;
+
+    if (index < n)
+    {
+        LOG("%s: index (%lu) must be greater than number of imports (%zu)\n",
+            __func__, (unsigned long)index, n);
+        return -1;
+    }
+
+    *findex = index - n;
+    return 0;
+}
+
+static int get_fn_start(const struct nw_mod *const m, FILE *const f,
+    const varuint32 index, struct search_fn *const out)
+{
+    const struct section s =
+    {
+        .cfg = &m->cfg,
+        .f = f
+    };
+
+    struct section_function sf;
+    struct section_code c;
+
+    if (section_function(&s, m, index, &sf))
+    {
+        LOG("%s: section_function failed\n", __func__);
+        return -1;
+    }
+    else if (section_code(&s, m, index, &c))
+    {
+        LOG("%s: section_code failed\n", __func__);
+        return -1;
+    }
+
+    out->start = c.start;
+    out->index = index;
+    return 0;
+}
+
+int search_exported_fn(const char *const fn, const struct nw_mod *const m,
+    FILE *const f, struct search_fn *const out)
+{
+    varuint32 index, findex;
+
+    if (ensure_export(fn, m, f, &index))
+    {
+        LOG("%s: %s not an exported function\n", __func__, fn);
+        return -1;
+    }
+    else if (get_function_index(m, index, &findex))
+    {
+        LOG("%s: get_function_index failed\n", __func__);
+        return -1;
+    }
+    else if (get_fn_start(m, f, findex, out))
+    {
+        LOG("%s: get_fn_start %s failed\n", __func__, fn);
+        return -1;
+    }
+
+    return 0;
+}
+
+int search_fn(const varuint32 index, const struct nw_mod *const m,
+    FILE *const f, struct search_fn *const out)
+{
+    varuint32 findex;
+
+    if (get_function_index(m, index, &findex))
+    {
+        LOG("%s: get_function_index failed\n", __func__);
+        return -1;
+    }
+    else if (get_fn_start(m, f, findex, out))
+    {
+        LOG("%s: get_fn_start failed\n", __func__);
+        return -1;
+    }
+
+    return 0;
+}