Add io operation callbacks

Add `unshield_open2` and `unshield_open2_force_version` to allows overriding
`fopen`, `fseek`, `ftell`, `fread`, `fwrite`, `fclose`, `opendir`, `closedir`,
`readdir` which lets the user pipe data from a program without doing a round
trip to the hard drive

lib/file.c

@@ -317,8 +317,8 @@ static bool unshield_reader_open_volume(UnshieldReader* reader, int volume)/*{{{
 #if VERBOSE >= 2
   unshield_trace("Open volume %i", volume);
 #endif
-  
-  FCLOSE(reader->volume_file);
+
+  FCLOSE(reader->unshield, reader->volume_file);
 
   reader->volume_file = unshield_fopen_for_reading(reader->unshield, volume, CABINET_SUFFIX);
   if (!reader->volume_file)
@@ -331,8 +331,8 @@ static bool unshield_reader_open_volume(UnshieldReader* reader, int volume)/*{{{
     uint8_t tmp[COMMON_HEADER_SIZE];
     uint8_t* p = tmp;
 
-    if (COMMON_HEADER_SIZE != 
-        fread(&tmp, 1, COMMON_HEADER_SIZE, reader->volume_file))
+    if (COMMON_HEADER_SIZE !=
+        reader->unshield->io_callbacks->fread(&tmp, 1, COMMON_HEADER_SIZE, reader->volume_file, reader->unshield->io_userdata))
       goto exit;
 
     if (!unshield_read_common_header(&p, &common_header))
@@ -349,8 +349,8 @@ static bool unshield_reader_open_volume(UnshieldReader* reader, int volume)/*{{{
         uint8_t five_header[VOLUME_HEADER_SIZE_V5];
         uint8_t* p = five_header;
 
-        if (VOLUME_HEADER_SIZE_V5 != 
-            fread(&five_header, 1, VOLUME_HEADER_SIZE_V5, reader->volume_file))
+        if (VOLUME_HEADER_SIZE_V5 !=
+            reader->unshield->io_callbacks->fread(&five_header, 1, VOLUME_HEADER_SIZE_V5, reader->volume_file, reader->unshield->io_userdata))
           goto exit;
 
         reader->volume_header.data_offset                = READ_UINT32(p); p += 4;
@@ -386,8 +386,8 @@ static bool unshield_reader_open_volume(UnshieldReader* reader, int volume)/*{{{
         uint8_t six_header[VOLUME_HEADER_SIZE_V6];
         uint8_t* p = six_header;
 
-        if (VOLUME_HEADER_SIZE_V6 != 
-            fread(&six_header, 1, VOLUME_HEADER_SIZE_V6, reader->volume_file))
+        if (VOLUME_HEADER_SIZE_V6 !=
+            reader->unshield->io_callbacks->fread(&six_header, 1, VOLUME_HEADER_SIZE_V6, reader->volume_file, reader->unshield->io_userdata))
           goto exit;
 
         reader->volume_header.data_offset                       = READ_UINT32(p); p += 4;
@@ -543,7 +543,7 @@ static bool unshield_reader_read(UnshieldReader* reader, void* buffer, size_t si
       goto exit;
     }
 
-    if (bytes_to_read != fread(p, 1, bytes_to_read, reader->volume_file))
+    if (bytes_to_read != reader->unshield->io_callbacks->fread(p, 1, bytes_to_read, reader->volume_file, reader->unshield->io_userdata))
     {
       unshield_error("Failed to read 0x%08x bytes of file %i (%s) from volume %i. Current offset = 0x%08x",
           bytes_to_read, reader->index, 
@@ -586,14 +586,14 @@ static bool unshield_reader_read(UnshieldReader* reader, void* buffer, size_t si
   return success;
 }/*}}}*/
 
-int copy_file(FILE* infile, FILE* outfile) {
+int copy_file(Unshield* unshield, FILE* infile, FILE* outfile) {
 #define SIZE (1024*1024)
 
     char buffer[SIZE];
     size_t bytes;
 
-    while (0 < (bytes = fread(buffer, 1, sizeof(buffer), infile)))
-        fwrite(buffer, 1, bytes, outfile);
+    while (0 < (bytes = unshield->io_callbacks->fread(buffer, 1, sizeof(buffer), infile, unshield->io_userdata)))
+        unshield->io_callbacks->fwrite(buffer, 1, bytes, outfile, unshield->io_userdata);
 
     return 0;
 }
@@ -629,7 +629,7 @@ static UnshieldReader* unshield_reader_create_external(/*{{{*/
     }
 
     if (file_descriptor->flags & FILE_COMPRESSED) {
-        long file_size = FSIZE(reader->volume_file);
+        long file_size = FSIZE(unshield, reader->volume_file);
         FILE *temporary_file = NULL;
 
         /*
@@ -642,7 +642,7 @@ static UnshieldReader* unshield_reader_create_external(/*{{{*/
         if (diff > 0) {
             diff = MIN(sizeof(END_OF_CHUNK), diff);
             temporary_file = tmpfile();
-            copy_file(reader->volume_file, temporary_file);
+            copy_file(reader->unshield, reader->volume_file, temporary_file);
             fwrite(END_OF_CHUNK + sizeof(END_OF_CHUNK) - diff, 1, diff, temporary_file);
             fseek(temporary_file, 0, SEEK_SET);
 
@@ -722,7 +722,7 @@ static void unshield_reader_destroy(UnshieldReader* reader)/*{{{*/
 {
   if (reader)
   {
-    FCLOSE(reader->volume_file);
+    FCLOSE(reader->unshield, reader->volume_file);
     free(reader);
   }
 }/*}}}*/
@@ -774,7 +774,7 @@ bool unshield_file_save (Unshield* unshield, int index, const char* filename)/*{
     goto exit;
   }
 
-  if (unshield_fsize(reader->volume_file) == (long)file_descriptor->data_offset)
+  if (unshield_fsize(unshield, reader->volume_file) == (long)file_descriptor->data_offset)
   {
     unshield_error("File %i is not inside the cabinet.", index);
     goto exit;
@@ -910,7 +910,7 @@ bool unshield_file_save (Unshield* unshield, int index, const char* filename)/*{
 
 exit:
   unshield_reader_destroy(reader);
-  FCLOSE(output);
+  FCLOSE(unshield, output);
   FREE(input_buffer);
   FREE(output_buffer);
   return success;
@@ -977,7 +977,7 @@ bool unshield_file_save_raw(Unshield* unshield, int index, const char* filename)
     goto exit;
   }
 
-  if (unshield_fsize(reader->volume_file) == (long)file_descriptor->data_offset)
+  if (unshield_fsize(unshield, reader->volume_file) == (long)file_descriptor->data_offset)
   {
     unshield_error("File %i is not inside the cabinet.", index);
     goto exit;
@@ -1027,7 +1027,7 @@ bool unshield_file_save_raw(Unshield* unshield, int index, const char* filename)
 
 exit:
   unshield_reader_destroy(reader);
-  FCLOSE(output);
+  FCLOSE(unshield, output);
   FREE(input_buffer);
   FREE(output_buffer);
   return success;
@@ -1095,7 +1095,7 @@ bool unshield_file_save_old(Unshield* unshield, int index, const char* filename)
     goto exit;
   }
 
-  if (unshield_fsize(reader->volume_file) == (long)file_descriptor->data_offset)
+  if (unshield_fsize(unshield, reader->volume_file) == (long)file_descriptor->data_offset)
   {
       unshield_error("File %i is not inside the cabinet. Trying external file!", index);
       unshield_reader_destroy(reader);
@@ -1280,7 +1280,7 @@ bool unshield_file_save_old(Unshield* unshield, int index, const char* filename)
 
 exit:
   unshield_reader_destroy(reader);
-  FCLOSE(output);
+  FCLOSE(unshield, output);
   FREE(input_buffer);
   FREE(output_buffer);
   return success;

lib/helper.c

@@ -11,8 +11,6 @@
 #include <unistd.h>
 
 #ifdef _WIN32
-  #define fseek _fseeki64
-  #define ftell _ftelli64
   #define realpath(N,R) _fullpath((R),(N),_MAX_PATH)
   #include <direct.h>
   #ifndef PATH_MAX
@@ -103,11 +101,12 @@ FILE* unshield_fopen_for_reading(Unshield* unshield, int index, const char* suff
     else
       q=filename;
 
-    sourcedir = opendir(dirname);
+    sourcedir = unshield->io_callbacks->opendir(dirname, unshield->io_userdata);
     /* Search for the File case independent */
     if (sourcedir)
     {
-      for (dent=readdir(sourcedir);dent;dent=readdir(sourcedir))
+      for (dent=unshield->io_callbacks->readdir(sourcedir, unshield->io_userdata);dent;
+           dent=unshield->io_callbacks->readdir(sourcedir, unshield->io_userdata))
       {
         if (!(strcasecmp(q, dent->d_name)))
         {
@@ -134,11 +133,11 @@ FILE* unshield_fopen_for_reading(Unshield* unshield, int index, const char* suff
 #if VERBOSE
     unshield_trace("Opening file '%s'", filename);
 #endif
-    result = fopen(filename, "rb");
+    result = unshield->io_callbacks->fopen(filename, "rb", unshield->io_userdata);
 
 exit:
     if (sourcedir)
-      closedir(sourcedir);
+      unshield->io_callbacks->closedir(sourcedir, unshield->io_userdata);
     free(filename);
     free(dirname);
     return result;
@@ -147,13 +146,13 @@ FILE* unshield_fopen_for_reading(Unshield* unshield, int index, const char* suff
   return NULL;
 }
 
-long long unshield_fsize(FILE* file)
+long long unshield_fsize(Unshield* unshield, FILE* file)
 {
   long long result;
-  long long previous = ftell(file);
-  fseek(file, 0L, SEEK_END);
-  result = ftell(file);
-  fseek(file, previous, SEEK_SET);
+  long long previous = unshield->io_callbacks->ftell(file, unshield->io_userdata);
+  unshield->io_callbacks->fseek(file, 0L, SEEK_END, unshield->io_userdata);
+  result = unshield->io_callbacks->ftell(file, unshield->io_userdata);
+  unshield->io_callbacks->fseek(file, previous, SEEK_SET, unshield->io_userdata);
   return result;
 }
 

lib/internal.h

@@ -52,6 +52,8 @@ struct _Unshield
 {
   Header* header_list;
   char* filename_pattern;
+  const UnshieldIoCallbacks* io_callbacks;
+  void* io_userdata;
 };
 
 /*
@@ -77,7 +79,7 @@ void unshield_file_group_destroy(UnshieldFileGroup* self);
 char *unshield_get_base_directory_name(Unshield *unshield);
 long int unshield_get_path_max(Unshield* unshield);
 FILE* unshield_fopen_for_reading(Unshield* unshield, int index, const char* suffix);
-long long unshield_fsize(FILE* file);
+long long unshield_fsize(Unshield* unshield, FILE* file);
 bool unshield_read_common_header(uint8_t** buffer, CommonHeader* common);
 
 const char* unshield_get_utf8_string(Header* header, const void* buffer);
@@ -100,8 +102,8 @@ uint8_t* unshield_header_get_buffer(Header* header, uint32_t offset);
 #define STRDUP(str)     ((str) ? strdup(str) : NULL)
 #define NEW(type, count)      ((type*)calloc(count, sizeof(type)))
 #define NEW1(type)      ((type*)calloc(1, sizeof(type)))
-#define FCLOSE(file)    if (file) { fclose(file); (file) = NULL; }
-#define FSIZE(file)     ((file) ? unshield_fsize(file) : 0)
+#define FCLOSE(unshield, file) if (file) { unshield->io_callbacks->fclose(file, unshield->io_userdata); (file) = NULL; }
+#define FSIZE(unshield, file)     ((file) ? unshield_fsize(unshield, file) : 0)
 #define STREQ(s1,s2)    (0 == strcmp(s1,s2))
 
 static inline uint16_t get_unaligned_le16(const uint8_t *p)

lib/libunshield.c

@@ -6,6 +6,73 @@
 #include <ctype.h>
 #include <stdlib.h>
 #include <string.h>
+#include <dirent.h>
+
+#ifdef _WIN32
+  #define unshield_native_fseek _fseeki64
+  #define unshield_native_ftell _ftelli64
+#else
+  #define unshield_native_fseek fseek
+  #define unshield_native_ftell ftell
+#endif
+
+
+void *unshield_default_fopen(const char *filename, const char *modes, void *userdata)
+{
+  return fopen(filename, modes);
+}
+
+int unshield_default_fseek(void *file, long int offset, int whence, void *userdata)
+{
+  return unshield_native_fseek(file, offset, whence);
+}
+
+long int unshield_default_ftell(void *file, void *userdata)
+{
+  return unshield_native_ftell(file);
+}
+
+size_t unshield_default_fread(void *ptr, size_t size, size_t n, void *file, void *userdata)
+{
+  return fread(ptr, size, n, file);
+}
+
+size_t unshield_default_fwrite(const void *ptr, size_t size, size_t n, void *file, void *userdata)
+{
+  return fwrite(ptr, size, n, file);
+}
+
+int unshield_default_fclose(void *ptr, void *userdata)
+{
+  return fclose(ptr);
+}
+
+void *unshield_default_opendir(const char *name, void *userdata)
+{
+  return opendir(name);
+}
+
+int unshield_default_closedir(void *dir, void *userdata)
+{
+  return closedir(dir);
+}
+
+struct dirent* unshield_default_readdir(void *dir, void *userdata)
+{
+  return readdir(dir);
+}
+
+static UnshieldIoCallbacks unshield_default_io_callbacks = {
+  .fopen = unshield_default_fopen,
+  .fseek = unshield_default_fseek,
+  .ftell = unshield_default_ftell,
+  .fread = unshield_default_fread,
+  .fwrite = unshield_default_fwrite,
+  .fclose = unshield_default_fclose,
+  .opendir = unshield_default_opendir,
+  .closedir = unshield_default_closedir,
+  .readdir = unshield_default_readdir,
+};
 
 /**
   Create filename pattern used by unshield_fopen_for_reading()
@@ -239,7 +306,7 @@ static bool unshield_read_headers(Unshield* unshield, int version)/*{{{*/
       Header* header = NEW1(Header);
       header->index = i;
 
-      header->size = FSIZE(file);
+      header->size = FSIZE(unshield, file);
       if (header->size < 4)
       {
         unshield_error("Header file %i too small", i);
@@ -253,8 +320,8 @@ static bool unshield_read_headers(Unshield* unshield, int version)/*{{{*/
         goto error;
       }
 
-      bytes_read = fread(header->data, 1, header->size, file);
-      FCLOSE(file);
+      bytes_read = unshield->io_callbacks->fread(header->data, 1, header->size, file, unshield->io_userdata);
+      FCLOSE(unshield, file);
 
       if (bytes_read != header->size)
       {
@@ -344,6 +411,16 @@ Unshield* unshield_open(const char* filename)/*{{{*/
 }/*}}}*/
 
 Unshield* unshield_open_force_version(const char* filename, int version)/*{{{*/
+{
+  return unshield_open2_force_version(filename, version, NULL, NULL);
+}/*}}}*/
+
+Unshield* unshield_open2(const char* filename, const UnshieldIoCallbacks* callbacks, void* userdata)/*{{{*/
+{
+  return unshield_open2_force_version(filename, -1, callbacks, userdata);
+}/*}}}*/
+
+Unshield* unshield_open2_force_version(const char* filename, int version, const UnshieldIoCallbacks* callbacks, void* userdata)/*{{{*/
 {
   Unshield* unshield = NEW1(Unshield);
   if (!unshield)
@@ -352,6 +429,9 @@ Unshield* unshield_open_force_version(const char* filename, int version)/*{{{*/
     goto error;
   }
 
+  unshield->io_callbacks = callbacks == NULL ? &unshield_default_io_callbacks : callbacks;
+  unshield->io_userdata = userdata;
+
   if (!unshield_create_filename_pattern(unshield, filename))
   {
     unshield_error("Failed to create filename pattern");

lib/libunshield.h

@@ -35,6 +35,22 @@ Unshield* unshield_open(const char* filename);
 Unshield* unshield_open_force_version(const char* filename, int version);
 void unshield_close(Unshield* unshield);
 
+typedef struct
+{
+    void *(*fopen)(const char *filename, const char *modes, void *userdata);
+    int (*fseek)(void *file, long int offset, int whence, void *userdata);
+    long int (*ftell)(void *file, void *userdata);
+    size_t (*fread)(void *ptr, size_t size, size_t n, void *file, void *userdata);
+    size_t (*fwrite)(const void *ptr, size_t size, size_t n, void *file, void *userdata);
+    int (*fclose)(void *ptr, void *userdata);
+    void *(*opendir)(const char *name, void *userdata);
+    int (*closedir)(void *dir, void *userdata);
+    struct dirent* (*readdir)(void *dir, void *userdata);
+} UnshieldIoCallbacks;
+
+Unshield* unshield_open2(const char* filename, const UnshieldIoCallbacks* callbacks, void* userdata);
+Unshield* unshield_open2_force_version(const char* filename, int version, const UnshieldIoCallbacks* callbacks, void* userdata);
+
 /*
    Component functions
  */