--- a/ST80FormReader.st	Mon Apr 21 18:57:34 1997 +0200
+++ b/ST80FormReader.st	Mon Apr 21 19:50:12 1997 +0200
@@ -78,7 +78,7 @@
 isValidImageFile:aFileName
     "return true, if aFileName contains an st80-bitmap-file image"
 
-    |code inStream ok|
+    |code inStream ok w h|
 
     inStream := self streamReadingFile:aFileName.
     inStream isNil ifTrue:[^ false].
@@ -86,8 +86,17 @@
     inStream binary.
     code := inStream nextWord.
     ok := (code == 1).
+
+    w := inStream nextWord.
+    h := inStream nextWord.
+    ((w == 0) or:[h == 0]) ifTrue:[
+        ok := false
+    ].
+
     inStream close.
     ^ ok
+
+    "Modified: 21.4.1997 / 19:48:56 / cg"
 ! !
 
 !ST80FormReader methodsFor:'reading from file'!
@@ -104,9 +113,17 @@
     code isNil ifTrue:[
         ^ nil
     ].
+    code ~~ 1 ifTrue:[
+        'ST80FormReader [warning]: expected magic 1' errorPrintCR.
+        ^ nil
+    ].
 
     width := aStream nextWord.
     height := aStream nextWord.
+    ((width == 0) or:[height == 0]) ifTrue:[
+        'ST80FormReader [warning]: zero width/height' errorPrintCR.
+        ^ nil
+    ].
     offsetX := aStream nextWord.
     offsetY := aStream nextWord.
 
@@ -118,7 +135,9 @@
     samplesPerPixel := 1.
     bitsPerSample := #(1)
 
-    "ST80FormReader fromFile:''" 
+    "ST80FormReader fromFile:''"
+
+    "Modified: 21.4.1997 / 19:47:43 / cg"
 ! !
 
 !ST80FormReader methodsFor:'writing to file'!
@@ -171,6 +190,6 @@
 !ST80FormReader class methodsFor:'documentation'!
 
 version
-    ^ '$Header: /cvs/stx/stx/libview2/ST80FormReader.st,v 1.17 1997-02-27 11:50:58 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libview2/ST80FormReader.st,v 1.18 1997-04-21 17:50:12 cg Exp $'
 ! !
 ST80FormReader initialize!

--- a/STFormRdr.st	Mon Apr 21 18:57:34 1997 +0200
+++ b/STFormRdr.st	Mon Apr 21 19:50:12 1997 +0200
@@ -78,7 +78,7 @@
 isValidImageFile:aFileName
     "return true, if aFileName contains an st80-bitmap-file image"
 
-    |code inStream ok|
+    |code inStream ok w h|
 
     inStream := self streamReadingFile:aFileName.
     inStream isNil ifTrue:[^ false].
@@ -86,8 +86,17 @@
     inStream binary.
     code := inStream nextWord.
     ok := (code == 1).
+
+    w := inStream nextWord.
+    h := inStream nextWord.
+    ((w == 0) or:[h == 0]) ifTrue:[
+        ok := false
+    ].
+
     inStream close.
     ^ ok
+
+    "Modified: 21.4.1997 / 19:48:56 / cg"
 ! !
 
 !ST80FormReader methodsFor:'reading from file'!
@@ -104,9 +113,17 @@
     code isNil ifTrue:[
         ^ nil
     ].
+    code ~~ 1 ifTrue:[
+        'ST80FormReader [warning]: expected magic 1' errorPrintCR.
+        ^ nil
+    ].
 
     width := aStream nextWord.
     height := aStream nextWord.
+    ((width == 0) or:[height == 0]) ifTrue:[
+        'ST80FormReader [warning]: zero width/height' errorPrintCR.
+        ^ nil
+    ].
     offsetX := aStream nextWord.
     offsetY := aStream nextWord.
 
@@ -118,7 +135,9 @@
     samplesPerPixel := 1.
     bitsPerSample := #(1)
 
-    "ST80FormReader fromFile:''" 
+    "ST80FormReader fromFile:''"
+
+    "Modified: 21.4.1997 / 19:47:43 / cg"
 ! !
 
 !ST80FormReader methodsFor:'writing to file'!
@@ -171,6 +190,6 @@
 !ST80FormReader class methodsFor:'documentation'!
 
 version
-    ^ '$Header: /cvs/stx/stx/libview2/Attic/STFormRdr.st,v 1.17 1997-02-27 11:50:58 cg Exp $'
+    ^ '$Header: /cvs/stx/stx/libview2/Attic/STFormRdr.st,v 1.18 1997-04-21 17:50:12 cg Exp $'
 ! !
 ST80FormReader initialize!