3 files changed, 60 insertions, 21 deletions

diff --git a/tools/preproc/c_file.cpp b/tools/preproc/c_file.cpp
index b996a048c..f7ca4365c 100644
--- a/tools/preproc/c_file.cpp
+++ b/tools/preproc/c_file.cpp
@@ -23,32 +23,58 @@
 #include <stdexcept>
 #include <string>
 #include <memory>
+#include <cstring>
 #include "preproc.h"
 #include "c_file.h"
 #include "char_util.h"
 #include "utf8.h"
 #include "string_parser.h"
 
-CFile::CFile(std::string filename) : m_filename(filename)
+CFile::CFile(const char * filenameCStr, bool isStdin)
 {
-    FILE *fp = std::fopen(filename.c_str(), "rb");
+    FILE *fp;
+
+    if (isStdin) {
+        fp = stdin;
+        m_filename = std::string{"<stdin>/"}.append(filenameCStr);
+    } else {
+        fp = std::fopen(filenameCStr, "rb");
+        m_filename = std::string(filenameCStr);
+    }
+
+    std::string& filename = m_filename;
 
     if (fp == NULL)
         FATAL_ERROR("Failed to open \"%s\" for reading.\n", filename.c_str());
 
-    std::fseek(fp, 0, SEEK_END);
-
-    m_size = std::ftell(fp);
+    m_size = 0;
+    m_buffer = (char *)malloc(CHUNK_SIZE + 1);
+    if (m_buffer == NULL) {
+        FATAL_ERROR("Failed to allocate memory to process file \"%s\"!", filename.c_str());
+    }
 
-    if (m_size < 0)
-        FATAL_ERROR("File size of \"%s\" is less than zero.\n", filename.c_str());
+    std::size_t numAllocatedBytes = CHUNK_SIZE + 1;
+    std::size_t bufferOffset = 0;
+    std::size_t count;
 
-    m_buffer = new char[m_size + 1];
+    while ((count = std::fread(m_buffer + bufferOffset, 1, CHUNK_SIZE, fp)) != 0) {
+        if (!std::ferror(fp)) {
+            m_size += count;
 
-    std::rewind(fp);
+            if (std::feof(fp)) {
+                break;
+            }
 
-    if (std::fread(m_buffer, m_size, 1, fp) != 1)
-        FATAL_ERROR("Failed to read \"%s\".\n", filename.c_str());
+            numAllocatedBytes += CHUNK_SIZE;
+            bufferOffset += CHUNK_SIZE;
+            m_buffer = (char *)realloc(m_buffer, numAllocatedBytes);
+            if (m_buffer == NULL) {
+                FATAL_ERROR("Failed to allocate memory to process file \"%s\"!", filename.c_str());
+            }
+        } else {
+            FATAL_ERROR("Failed to read \"%s\". (error: %s)", filename.c_str(), std::strerror(errno));
+        }
+    }
 
     m_buffer[m_size] = 0;
 
@@ -56,6 +82,7 @@ CFile::CFile(std::string filename) : m_filename(filename)
 
     m_pos = 0;
     m_lineNum = 1;
+    m_isStdin = isStdin;
 }
 
 CFile::CFile(CFile&& other) : m_filename(std::move(other.m_filename))
@@ -64,13 +91,14 @@ CFile::CFile(CFile&& other) : m_filename(std::move(other.m_filename))
     m_pos = other.m_pos;
     m_size = other.m_size;
     m_lineNum = other.m_lineNum;
+    m_isStdin = other.m_isStdin;
 
-    other.m_buffer = nullptr;
+    other.m_buffer = NULL;
 }
 
 CFile::~CFile()
 {
-    delete[] m_buffer;
+    free(m_buffer);
 }
 
 void CFile::Preproc()
diff --git a/tools/preproc/c_file.h b/tools/preproc/c_file.h
index 7369aba85..49e633a18 100644
--- a/tools/preproc/c_file.h
+++ b/tools/preproc/c_file.h
@@ -30,7 +30,7 @@
 class CFile
 {
 public:
-    CFile(std::string filename);
+    CFile(const char * filenameCStr, bool isStdin);
     CFile(CFile&& other);
     CFile(const CFile&) = delete;
     ~CFile();
@@ -42,6 +42,7 @@ private:
     long m_size;
     long m_lineNum;
     std::string m_filename;
+    bool m_isStdin;
 
     bool ConsumeHorizontalWhitespace();
     bool ConsumeNewline();
@@ -55,4 +56,6 @@ private:
     void RaiseWarning(const char* format, ...);
 };
 
+#define CHUNK_SIZE 4096
+
 #endif // C_FILE_H
diff --git a/tools/preproc/preproc.cpp b/tools/preproc/preproc.cpp
index c9c6042df..02950a296 100644
--- a/tools/preproc/preproc.cpp
+++ b/tools/preproc/preproc.cpp
@@ -103,9 +103,9 @@ void PreprocAsmFile(std::string filename)
     }
 }
 
-void PreprocCFile(std::string filename)
+void PreprocCFile(const char * filename, bool isStdin)
 {
-    CFile cFile(filename);
+    CFile cFile(filename, isStdin);
     cFile.Preproc();
 }
 
@@ -132,9 +132,9 @@ char* GetFileExtension(char* filename)
 
 int main(int argc, char **argv)
 {
-    if (argc != 3)
+    if (argc < 3 || argc > 4)
     {
-        std::fprintf(stderr, "Usage: %s SRC_FILE CHARMAP_FILE", argv[0]);
+        std::fprintf(stderr, "Usage: %s SRC_FILE CHARMAP_FILE [-i]\nwhere -i denotes if input is from stdin", argv[0]);
         return 1;
     }
 
@@ -147,9 +147,17 @@ int main(int argc, char **argv)
 
     if ((extension[0] == 's') && extension[1] == 0)
         PreprocAsmFile(argv[1]);
-    else if ((extension[0] == 'c' || extension[0] == 'i') && extension[1] == 0)
-        PreprocCFile(argv[1]);
-    else
+    else if ((extension[0] == 'c' || extension[0] == 'i') && extension[1] == 0) {
+        if (argc == 4) {
+            if (argv[3][0] == '-' && argv[3][1] == 'i' && argv[3][2] == '\0') {
+                PreprocCFile(argv[1], true);
+            } else {
+                FATAL_ERROR("unknown argument flag \"%s\".\n", argv[3]);
+            }
+        } else {
+            PreprocCFile(argv[1], false);
+        }
+    } else
         FATAL_ERROR("\"%s\" has an unknown file extension of \"%s\".\n", argv[1], extension);
 
     return 0;