1 files changed, 118 insertions, 0 deletions
diff --git a/src/coff_image.cpp b/src/coff_image.cpp
new file mode 100644
index 0000000..c9717c1
--- /dev/null
+++ b/src/coff_image.cpp
@@ -0,0 +1,118 @@
+/* SPDX-License-Identifier: Unlicense
+ */
+
+#include "coff_image.h"
+
+#include <cassert>
+#include <cstdarg>
+#include <cstdlib>
+#include <cstring>
+
+#ifdef __GNUC__
+#define _PRINTF(strindex, first) __attribute__((format(printf, strindex, first)))
+#else
+#define _PRINTF(strindex, first)
+#endif
+
+
+static _PRINTF(1, 2) char *Error(const char *fmt, ...)
+{
+    if (0 == strlen(fmt)) {
+        return nullptr;
+    }
+    char *error{};
+    size_t size{};
+    FILE *error_stream = open_memstream(&error, &size);
+    assert(error_stream);
+    va_list ap;
+    va_start(ap, fmt);
+    vfprintf(error_stream, fmt, ap);
+    va_end(ap);
+    fclose(error_stream);
+    assert(error != nullptr);
+    assert(*error != '\0');
+    return error;
+}
+
+static char *ValidateCOFF(const DataView& d)
+{
+    using namespace COFF;
+    size_t expected_size = kFileHeaderSize;
+    if (d.size < expected_size) {
+        return Error(
+                "data size (%zu) is too low, expected at least %zu: "
+                "COFF header could not fit",
+                d.size,
+                expected_size);
+    }
+    const auto header = FileHeader::FromBytes(d.buffer);
+    if (header.magic != FileHeader::kMagicSierraM68k) {
+        return Error(
+                "COFF Magic is invalid: expected 0x%04x, got 0x%04x",
+                FileHeader::kMagicSierraM68k,
+                header.magic);
+    }
+    const size_t oh_nbytes = header.optional_header_nbytes;
+    if (oh_nbytes && oh_nbytes < kOptionalHeaderSize) {
+        return Error(
+                "COFF optional header size is invalid: expected 0 or at least %zu, got %zu",
+                kOptionalHeaderSize,
+                oh_nbytes);
+    }
+    expected_size += oh_nbytes;
+    if (d.size < expected_size) {
+        return Error(
+                "data size (%zu) is too low, expected at least %zu: "
+                "COFF optional header could not fit",
+                d.size,
+                expected_size);
+    }
+    expected_size += header.nsections * kSectionHeaderSize;
+    if (d.size < expected_size) {
+        return Error(
+                "data size (%zu) is too low, expected at least %zu: "
+                "%u sections headers could not fit",
+                d.size,
+                expected_size,
+                header.nsections);
+    }
+    if (header.symtable_offset > d.size) {
+        return Error(
+                "COFF symbol table offset is too big to fit into the file: "
+                "expected (<=%zu), got (%zu)",
+                size_t(d.size),
+                size_t(header.symtable_offset));
+    }
+    for (size_t i = 0; i < header.nsections; i++) {
+        const auto section = SectionHeader::FromBytes(d.buffer + COFF::kFileHeaderSize +
+                header.optional_header_nbytes + COFF::kSectionHeaderSize * i);
+        const size_t section_end = section.section_offset + section.size;
+        if (section_end > d.size) {
+            return Error(
+                    "data size (%zu) is too low, expected at least %zu: "
+                    "section %zu (%.8s) data could not fit",
+                    d.size,
+                    section_end,
+                    i,
+                    section.name);
+        }
+    }
+    return nullptr;
+}
+
+COFF::Image::Image(DataBuffer&& data)
+    : _data(static_cast<DataBuffer&&>(data))
+    , _error(ValidateCOFF(_data.View()))
+    , _file_header(_error ? COFF::FileHeader{} : COFF::FileHeader::FromBytes(_data.View().buffer))
+    , _has_optional_header(_error ? false : _file_header.optional_header_nbytes >= kOptionalHeaderSize)
+    , _optional_header(_has_optional_header
+            ? COFF::OptionalHeader::FromBytes(_data.View().buffer)
+            : COFF::OptionalHeader{})
+{}
+
+COFF::Image::~Image()
+{
+    if (_error) {
+        free(_error);
+    }
+}