Use SDL_RWops directly on top of PhysFS

This avoids the creation of a temporary buffer containing a complete
file for the sole purpose of wrapping it up in an SDL_RWops.

The necessary wrapper is by Ryan C. Gordon and is included in the
PhysFS repository under 'extras'.

Reviewed-by: Yohann Ferreira

2 files changed, 281 insertions, 0 deletions

diff --git a/src/utils/physfsrwops.c b/src/utils/physfsrwops.c
new file mode 100644
index 00000000..1a5a7137
--- /dev/null
+++ b/src/utils/physfsrwops.c
@@ -0,0 +1,193 @@
+/*
+ * This code provides a glue layer between PhysicsFS and Simple Directmedia
+ *  Layer's (SDL) RWops i/o abstraction.
+ *
+ * License: this code is public domain. I make no warranty that it is useful,
+ *  correct, harmless, or environmentally safe.
+ *
+ * This particular file may be used however you like, including copying it
+ *  verbatim into a closed-source project, exploiting it commercially, and
+ *  removing any trace of my name from the source (although I hope you won't
+ *  do that). I welcome enhancements and corrections to this file, but I do
+ *  not require you to send me patches if you make changes. This code has
+ *  NO WARRANTY.
+ *
+ * Unless otherwise stated, the rest of PhysicsFS falls under the zlib license.
+ *  Please see LICENSE.txt in the root of the source tree.
+ *
+ * SDL falls under the LGPL license. You can get SDL at http://www.libsdl.org/
+ *
+ *  This file was written by Ryan C. Gordon. (icculus@icculus.org).
+ */
+
+#include <stdio.h>  /* used for SEEK_SET, SEEK_CUR, SEEK_END ... */
+#include "physfsrwops.h"
+
+static int physfsrwops_seek(SDL_RWops *rw, int offset, int whence)
+{
+    PHYSFS_File *handle = (PHYSFS_File *) rw->hidden.unknown.data1;
+    int pos = 0;
+
+    if (whence == SEEK_SET)
+    {
+        pos = offset;
+    } /* if */
+
+    else if (whence == SEEK_CUR)
+    {
+        PHYSFS_sint64 current = PHYSFS_tell(handle);
+        if (current == -1)
+        {
+            SDL_SetError("Can't find position in file: %s",
+                          PHYSFS_getLastError());
+            return(-1);
+        } /* if */
+
+        pos = (int) current;
+        if ( ((PHYSFS_sint64) pos) != current )
+        {
+            SDL_SetError("Can't fit current file position in an int!");
+            return(-1);
+        } /* if */
+
+        if (offset == 0)  /* this is a "tell" call. We're done. */
+            return(pos);
+
+        pos += offset;
+    } /* else if */
+
+    else if (whence == SEEK_END)
+    {
+        PHYSFS_sint64 len = PHYSFS_fileLength(handle);
+        if (len == -1)
+        {
+            SDL_SetError("Can't find end of file: %s", PHYSFS_getLastError());
+            return(-1);
+        } /* if */
+
+        pos = (int) len;
+        if ( ((PHYSFS_sint64) pos) != len )
+        {
+            SDL_SetError("Can't fit end-of-file position in an int!");
+            return(-1);
+        } /* if */
+
+        pos += offset;
+    } /* else if */
+
+    else
+    {
+        SDL_SetError("Invalid 'whence' parameter.");
+        return(-1);
+    } /* else */
+
+    if ( pos < 0 )
+    {
+        SDL_SetError("Attempt to seek past start of file.");
+        return(-1);
+    } /* if */
+
+    if (!PHYSFS_seek(handle, (PHYSFS_uint64) pos))
+    {
+        SDL_SetError("PhysicsFS error: %s", PHYSFS_getLastError());
+        return(-1);
+    } /* if */
+
+    return(pos);
+} /* physfsrwops_seek */
+
+
+static int physfsrwops_read(SDL_RWops *rw, void *ptr, int size, int maxnum)
+{
+    PHYSFS_File *handle = (PHYSFS_File *) rw->hidden.unknown.data1;
+    PHYSFS_sint64 rc = PHYSFS_read(handle, ptr, size, maxnum);
+    if (rc != maxnum)
+    {
+        if (!PHYSFS_eof(handle)) /* not EOF? Must be an error. */
+            SDL_SetError("PhysicsFS error: %s", PHYSFS_getLastError());
+    } /* if */
+
+    return((int) rc);
+} /* physfsrwops_read */
+
+
+static int physfsrwops_write(SDL_RWops *rw, const void *ptr, int size, int num)
+{
+    PHYSFS_File *handle = (PHYSFS_File *) rw->hidden.unknown.data1;
+    PHYSFS_sint64 rc = PHYSFS_write(handle, ptr, size, num);
+    if (rc != num)
+        SDL_SetError("PhysicsFS error: %s", PHYSFS_getLastError());
+
+    return((int) rc);
+} /* physfsrwops_write */
+
+
+static int physfsrwops_close(SDL_RWops *rw)
+{
+    PHYSFS_File *handle = (PHYSFS_File *) rw->hidden.unknown.data1;
+    if (!PHYSFS_close(handle))
+    {
+        SDL_SetError("PhysicsFS error: %s", PHYSFS_getLastError());
+        return(-1);
+    } /* if */
+
+    SDL_FreeRW(rw);
+    return(0);
+} /* physfsrwops_close */
+
+
+static SDL_RWops *create_rwops(PHYSFS_File *handle)
+{
+    SDL_RWops *retval = NULL;
+
+    if (handle == NULL)
+        SDL_SetError("PhysicsFS error: %s", PHYSFS_getLastError());
+    else
+    {
+        retval = SDL_AllocRW();
+        if (retval != NULL)
+        {
+            retval->seek  = physfsrwops_seek;
+            retval->read  = physfsrwops_read;
+            retval->write = physfsrwops_write;
+            retval->close = physfsrwops_close;
+            retval->hidden.unknown.data1 = handle;
+        } /* if */
+    } /* else */
+
+    return(retval);
+} /* create_rwops */
+
+
+SDL_RWops *PHYSFSRWOPS_makeRWops(PHYSFS_File *handle)
+{
+    SDL_RWops *retval = NULL;
+    if (handle == NULL)
+        SDL_SetError("NULL pointer passed to PHYSFSRWOPS_makeRWops().");
+    else
+        retval = create_rwops(handle);
+
+    return(retval);
+} /* PHYSFSRWOPS_makeRWops */
+
+
+SDL_RWops *PHYSFSRWOPS_openRead(const char *fname)
+{
+    return(create_rwops(PHYSFS_openRead(fname)));
+} /* PHYSFSRWOPS_openRead */
+
+
+SDL_RWops *PHYSFSRWOPS_openWrite(const char *fname)
+{
+    return(create_rwops(PHYSFS_openWrite(fname)));
+} /* PHYSFSRWOPS_openWrite */
+
+
+SDL_RWops *PHYSFSRWOPS_openAppend(const char *fname)
+{
+    return(create_rwops(PHYSFS_openAppend(fname)));
+} /* PHYSFSRWOPS_openAppend */
+
+
+/* end of physfsrwops.c ... */
+
diff --git a/src/utils/physfsrwops.h b/src/utils/physfsrwops.h
new file mode 100644
index 00000000..406fba6f
--- /dev/null
+++ b/src/utils/physfsrwops.h
@@ -0,0 +1,88 @@
+/*
+ * This code provides a glue layer between PhysicsFS and Simple Directmedia
+ *  Layer's (SDL) RWops i/o abstraction.
+ *
+ * License: this code is public domain. I make no warranty that it is useful,
+ *  correct, harmless, or environmentally safe.
+ *
+ * This particular file may be used however you like, including copying it
+ *  verbatim into a closed-source project, exploiting it commercially, and
+ *  removing any trace of my name from the source (although I hope you won't
+ *  do that). I welcome enhancements and corrections to this file, but I do
+ *  not require you to send me patches if you make changes. This code has
+ *  NO WARRANTY.
+ *
+ * Unless otherwise stated, the rest of PhysicsFS falls under the zlib license.
+ *  Please see LICENSE.txt in the root of the source tree.
+ *
+ * SDL falls under the LGPL license. You can get SDL at http://www.libsdl.org/
+ *
+ *  This file was written by Ryan C. Gordon. (icculus@icculus.org).
+ */
+
+#ifndef _INCLUDE_PHYSFSRWOPS_H_
+#define _INCLUDE_PHYSFSRWOPS_H_
+
+#include "physfs.h"
+#include "SDL.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * Open a platform-independent filename for reading, and make it accessible
+ *  via an SDL_RWops structure. The file will be closed in PhysicsFS when the
+ *  RWops is closed. PhysicsFS should be configured to your liking before
+ *  opening files through this method.
+ *
+ *   @param filename File to open in platform-independent notation.
+ *  @return A valid SDL_RWops structure on success, NULL on error. Specifics
+ *           of the error can be gleaned from PHYSFS_getLastError().
+ */
+__EXPORT__ SDL_RWops *PHYSFSRWOPS_openRead(const char *fname);
+
+/**
+ * Open a platform-independent filename for writing, and make it accessible
+ *  via an SDL_RWops structure. The file will be closed in PhysicsFS when the
+ *  RWops is closed. PhysicsFS should be configured to your liking before
+ *  opening files through this method.
+ *
+ *   @param filename File to open in platform-independent notation.
+ *  @return A valid SDL_RWops structure on success, NULL on error. Specifics
+ *           of the error can be gleaned from PHYSFS_getLastError().
+ */
+__EXPORT__ SDL_RWops *PHYSFSRWOPS_openWrite(const char *fname);
+
+/**
+ * Open a platform-independent filename for appending, and make it accessible
+ *  via an SDL_RWops structure. The file will be closed in PhysicsFS when the
+ *  RWops is closed. PhysicsFS should be configured to your liking before
+ *  opening files through this method.
+ *
+ *   @param filename File to open in platform-independent notation.
+ *  @return A valid SDL_RWops structure on success, NULL on error. Specifics
+ *           of the error can be gleaned from PHYSFS_getLastError().
+ */
+__EXPORT__ SDL_RWops *PHYSFSRWOPS_openAppend(const char *fname);
+
+/**
+ * Make a SDL_RWops from an existing PhysicsFS file handle. You should
+ *  dispose of any references to the handle after successful creation of
+ *  the RWops. The actual PhysicsFS handle will be destroyed when the
+ *  RWops is closed.
+ *
+ *   @param handle a valid PhysicsFS file handle.
+ *  @return A valid SDL_RWops structure on success, NULL on error. Specifics
+ *           of the error can be gleaned from PHYSFS_getLastError().
+ */
+__EXPORT__ SDL_RWops *PHYSFSRWOPS_makeRWops(PHYSFS_File *handle);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* include-once blocker */
+
+/* end of physfsrwops.h ... */
+