From 9cf92379d5fcf0076c25dae0935daab446c992cd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Karel=20Ko=C4=8D=C3=AD?= <cynerd@email.cz>
Date: Wed, 30 Aug 2017 21:37:53 +0200
Subject: Initial commit

Adding work done so far.
---
 qtmips_machine/programloader.cpp | 81 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 81 insertions(+)
 create mode 100644 qtmips_machine/programloader.cpp

(limited to 'qtmips_machine/programloader.cpp')

diff --git a/qtmips_machine/programloader.cpp b/qtmips_machine/programloader.cpp
new file mode 100644
index 0000000..0b0e294
--- /dev/null
+++ b/qtmips_machine/programloader.cpp
@@ -0,0 +1,81 @@
+#include "programloader.h"
+#include <exception>
+#include <unistd.h>
+#include <fcntl.h>
+#include <iostream>
+#include <errno.h>
+#include <cstring>
+#include "qtmipsexception.h"
+
+ProgramLoader::ProgramLoader(char *file) {
+    // Initialize elf library
+    if (elf_version(EV_CURRENT) == EV_NONE)
+        throw QTMIPS_EXCEPTION(Input, "Elf library initialization failed", elf_errmsg(-1));
+    // Open source file
+    if ((this->fd = open(file, O_RDONLY, 0)) < 0)
+        throw QTMIPS_EXCEPTION(Input, "Can't open input elf file for reading", std::strerror(errno));
+    // Initialize elf
+    if (!(this->elf = elf_begin(this->fd, ELF_C_READ, NULL)))
+        throw QTMIPS_EXCEPTION(Input, "Elf read begin failed", elf_errmsg(-1));
+    // Check elf kind
+    if (elf_kind(this->elf) != ELF_K_ELF)
+        throw QTMIPS_EXCEPTION(Input, "Invalid input file elf format, plain elf file expected", "");
+
+    if (!gelf_getehdr(this->elf, &this->hdr))
+        throw QTMIPS_EXCEPTION(Input, "Getting elf file header failed", elf_errmsg(-1));
+    // Check elf file format, executable expected, nothing else.
+    if (this->hdr.e_type != ET_EXEC)
+        throw QTMIPS_EXCEPTION(Input, "Invalid input file type", "");
+    // Check elf file architecture, of course only mips is supported.
+    if (this->hdr.e_machine != EM_MIPS)
+        throw QTMIPS_EXCEPTION(Input, "Invalid input file architecture", "");
+    // Check elf file class, only 32bit architecture is supported.
+    int elf_class;
+    if ((elf_class = gelf_getclass(this->elf)) == ELFCLASSNONE)
+        throw QTMIPS_EXCEPTION(Input, "Getting elf class failed", elf_errmsg(-1));
+    if (elf_class != ELFCLASS32)
+        throw QTMIPS_EXCEPTION(Input, "Only supported architecture is 32bit", "");
+    // TODO check endianity!
+
+    // Get number of program sections in elf file
+    if (elf_getphdrnum(this->elf, &this->n_secs))
+        throw QTMIPS_EXCEPTION(Input, "Elf program sections count query failed", elf_errmsg(-1));
+    // Get program sections headers
+    if (!(this->phdrs = elf32_getphdr(this->elf)))
+        throw QTMIPS_EXCEPTION(Input, "Elf program sections get failed", elf_errmsg(-1));
+    // We want only LOAD sections so we create map of those sections
+    for (unsigned i = 1; i < this->n_secs; i++) {
+        // TODO handle endianity
+        if (this->phdrs[i].p_type != PT_LOAD)
+            continue;
+        this->map.push_back(i);
+    }
+    // TODO instead of direct access should we be using sections and elf_data? And if so how to link program header and section?
+}
+
+ProgramLoader::~ProgramLoader() {
+    // Close elf
+    elf_end(this->elf);
+    // Close file
+    close(this->fd);
+}
+
+size_t ProgramLoader::get_nsec() {
+    return this->map.size();
+}
+
+std::uint32_t ProgramLoader::get_address(size_t sec) {
+    SANITY_ASSERT(sec > this->get_nsec(), "Requesting too big section");
+    return this->phdrs[this->map[sec]].p_vaddr;
+}
+
+std::vector<std::uint8_t> ProgramLoader::get_data(size_t sec) {
+    SANITY_ASSERT(sec > this->get_nsec(), "Requesting too big section");
+    std::vector<std::uint8_t> d;
+    char *f = elf_rawfile(this->elf, NULL);
+    size_t phdrs_i = this->map[sec];
+    for (unsigned i = 0; i < this->phdrs[phdrs_i].p_filesz; i++) {
+        d.push_back((std::uint8_t) f[this->phdrs[phdrs_i].p_offset + i]);
+    }
+    return d;
+}
-- 
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