Fix for STR#3421: Fl_SVG_Image crashes if passed an svg file that is a static const char* string

git-svn-id: file:///fltk/svn/fltk/branches/branch-1.4@12536 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

FL/Fl_SVG_Image.H

@@ -43,6 +43,64 @@ struct NSVGimage;
  
  The FLTK library can optionally be built without SVG support; in that case, 
  class Fl_SVG_Image is unavailable.
+
+ Example of displaying a hard-coded svg file:
+ \code
+ #include <FL/Fl.H>
+ #include <FL/Fl_Window.H>
+ #include <FL/Fl_Box.H>
+ #include <FL/Fl_SVG_Image.H>
+
+ // A black rotated rectangle
+ const char *svg_data = "<svg viewBox=\"0 0 200 200\" version = \"1.1\">\n"
+                        "<rect x=\"25\" y=\"50\" width=\"150\" height=\"100\" fill=\"black\" "
+                        "transform=\"rotate(45 100 100)\"> </svg>\n";
+
+ int main(int argc, char **argv) {
+     Fl_SVG_Image *svg = new Fl_SVG_Image(0, svg_data);       // create SVG object
+     Fl_Window    *win = new Fl_Window(720, 486, "svg test");
+     Fl_Box       *box = new Fl_Box(0,0,win->w(),win->h());
+     box->image(svg);  // assign svg object to Fl_Box
+     win->end();
+     win->show(argc,argv);
+     return(Fl::run());
+ }
+ \endcode
+
+ Example of displaying an svg image from a file:
+ \code
+ #include <errno.h>   // errno
+ #include <string.h>  // strerror
+ #include <FL/Fl.H>
+ #include <FL/Fl_Window.H>
+ #include <FL/Fl_Box.H>
+ #include <FL/Fl_SVG_Image.H>
+ #include <FL/fl_message.H>
+ int main(int argc, char **argv) {
+     Fl_Window *win = new Fl_Window(720, 486, "svg test");
+     Fl_Box    *box = new Fl_Box(0,0,win->w(),win->h());
+ 
+     // Load svg image from disk, assign to a box
+     const char *svgpath = "/var/tmp/simple.svg";
+     Fl_SVG_Image *svg = new Fl_SVG_Image(svgpath);  // load SVG object from disk
+     switch ( svg->fail() ) {
+         case Fl_Image::ERR_FILE_ACCESS:
+            // File couldn't load? show path + os error to user
+            fl_alert("%s: %s", svgpath, strerror(errno));
+            return 1;
+         case Fl_Image::ERR_FORMAT:
+            // Parsing error
+            fl_alert("%s: couldn't decode image", svgpath);
+            return 1;
+     }
+     box->image(svg);  // assign svg object to box
+ 
+     win->end();
+     win->show(argc,argv);
+     return(Fl::run());
+ }
+ \endcode
+
  */
 class FL_EXPORT Fl_SVG_Image : public Fl_RGB_Image {
 private:
@@ -58,7 +116,7 @@ private:
   float average_weight_;
   float svg_scaling_(int W, int H);
   void rasterize_(int W, int H);
-  void init_(const char *filename, char *filedata, Fl_SVG_Image *copy_source);
+  void init_(const char *filename, const char *filedata, Fl_SVG_Image *copy_source);
   Fl_SVG_Image(Fl_SVG_Image *source);
 protected:
   virtual int draw_scaled(int X, int Y, int W, int H);
@@ -66,7 +124,7 @@ public:
   /** Set this to \c false to allow image re-scaling that alters the image aspect ratio.
    Upon object creation, \c proportional is set to \c true, and the aspect ratio is kept constant.*/
   bool proportional;
-  Fl_SVG_Image(const char *filename, char *filedata = NULL);
+  Fl_SVG_Image(const char *filename, const char *filedata = NULL);
   virtual ~Fl_SVG_Image();
   virtual Fl_Image *copy(int W, int H);
   void resize(int width, int height);

examples/howto-simple-svg.cxx

@@ -59,7 +59,7 @@ int main(int argc, char **argv) {
     fl_message("You need to build fltk with --enable-nanosvg to use this example.");
     return(1);
 #else
-    Fl_SVG_Image *svg = new Fl_SVG_Image(NULL, (char*)strdup(svg_logo)); // XXX: strdup() shouldn't be needed -- see STR #3421
+    Fl_SVG_Image *svg = new Fl_SVG_Image(NULL, svg_logo);
     Fl_Window    *win = new Fl_Window(720, 486, "svg test");
     Fl_Box       *box = new Fl_Box(10,10,720-20,486-20);
     box->image(svg);

src/Fl_SVG_Image.cxx

@@ -48,9 +48,9 @@ static double strtoll(const char *str, char **endptr, int base) {
  \param filename A full path and name pointing to a .svg or .svgz file, or NULL.
  \param filedata A pointer to the memory location of the SVG image data.
  This parameter allows to load an SVG image from in-memory data, and is used when \p filename is NULL.
- \note In-memory SVG data is modified by the object constructor and is no longer used after construction.
+ \note In-memory SVG data is parsed by the object constructor and is no longer used after construction.
  */
-Fl_SVG_Image::Fl_SVG_Image(const char *filename, char *filedata) : Fl_RGB_Image(NULL, 0, 0, 4) {
+Fl_SVG_Image::Fl_SVG_Image(const char *filename, const char *filedata) : Fl_RGB_Image(NULL, 0, 0, 4) {
   init_(filename, filedata, NULL);
 }
 
@@ -113,9 +113,9 @@ static char *svg_inflate(const char *fname) {
 }
 #endif
 
-void Fl_SVG_Image::init_(const char *filename, char *filedata, Fl_SVG_Image *copy_source) {
+void Fl_SVG_Image::init_(const char *filename, const char *in_filedata, Fl_SVG_Image *copy_source) {
   if (copy_source) {
-    filename = filedata = NULL;
+    filename = in_filedata = NULL;
     counted_svg_image_ = copy_source->counted_svg_image_;
     counted_svg_image_->ref_count++;
   } else {
@@ -123,6 +123,7 @@ void Fl_SVG_Image::init_(const char *filename, char *filedata, Fl_SVG_Image *cop
     counted_svg_image_->svg_image = NULL;
     counted_svg_image_->ref_count = 1;
   }
+  char *filedata = NULL;
   to_desaturate_ = false;
   average_weight_ = 1;
   proportional = true;
@@ -130,7 +131,6 @@ void Fl_SVG_Image::init_(const char *filename, char *filedata, Fl_SVG_Image *cop
 #if defined(HAVE_LIBZ)
     filedata = svg_inflate(filename);
 #else
-    filedata = NULL;
     FILE *fp = fl_fopen(filename, "rb");
     if (fp) {
       fseek(fp, 0, SEEK_END);
@@ -140,8 +140,7 @@ void Fl_SVG_Image::init_(const char *filename, char *filedata, Fl_SVG_Image *cop
       if (filedata) {
         if (fread(filedata, 1, size, fp) == size) {
           filedata[size] = '\0';
-        }
+        } else {
-        else {
           free(filedata);
           filedata = NULL;
         }
@@ -150,10 +149,13 @@ void Fl_SVG_Image::init_(const char *filename, char *filedata, Fl_SVG_Image *cop
     }
 #endif // HAVE_LIBZ
     if (!filedata) ld(ERR_FILE_ACCESS);
+  } else {
+    // XXX: Make internal copy -- nsvgParse() modifies filedata during parsing (!)
+    filedata = in_filedata ? strdup(in_filedata) : NULL;
   }
   if (filedata) {
     counted_svg_image_->svg_image = nsvgParse(filedata, "px", 96);
-    if (filename) free(filedata);
+    free(filedata);	// made with svg_inflate|malloc|strdup
     if (counted_svg_image_->svg_image->width == 0 || counted_svg_image_->svg_image->height == 0) {
       d(-1);
       ld(ERR_FORMAT);