Don't break help with gcc -O2

libDtHelp is unable to read SDL help files
with -ftree-store-ccp optimization which
is enabled by -O2 on gcc 4.2.1.

GifUtils.c and decompress.c didn't work
properly with -ftree-store-ccp enabled.

GifUtils.c was repaired by fixing
those warnings:

GifUtils.c: In function 'create_pixmap':
GifUtils.c:1093: warning: return makes integer from pointer without a cast
GifUtils.c:1110: warning: return makes integer from pointer without a cast
GifUtils.c:1215: warning: return makes integer from pointer without a cast
GifUtils.c: In function 'gif_to_pixmap':
GifUtils.c:1242: warning: return makes integer from pointer without a cast

decompress.c didn't generate warnings, but the
only effect of the -ftree-store-cpp was to introduce
this change:

        addq    $1, %rax
        movq    %rax, (%rbx)
 .L90:
-       cmpl    $157, %edx
+       cmpl    $-99, %edx
        jne     .L86
        movl    8(%rbx), %eax
        subl    $1, %eax

Which corresponds to this source code:

bufioI.h

     57 #define BufFileGet(f)   ((f)->left-- ? *(f)->bufp++ : (*(f)->io) (f))

     42     int     (*io)(/* BufFilePtr f */);

decompress.c
     53 #ifdef NO_UCHAR
     54  typedef char   char_type;
     55 #else
     56  typedef        unsigned char   char_type;
     57 #endif /* UCHAR */
     58
     59 static  char_type magic_header[] = { "\037\235" };      /* 1F 9D */

    131     if ((BufFileGet(f) != (magic_header[0] & 0xFF)) ||
    132         (BufFileGet(f) != (magic_header[1] & 0xFF)))
    133     {
    134         return 0;
    135     }

BufFileGet() returns (int), so the (unsigned char) constants
got promoted to (int) with sign extension; therefore constant
157 decimal (0x9D) became -99 decimal, sign extended
(0xffffff9D), and the comparison was always false.

Tested using:
$ gcc -v
Using built-in specs.
Target: amd64-undermydesk-freebsd
Configured with: FreeBSD/amd64 system compiler
Thread model: posix
gcc version 4.2.1 20070831 patched [FreeBSD]

Running on:
FreeBSD 10.0-CURRENT (r240948M)
built Wed Sep 26 23:33:08 CEST 2012

diff --git a/cde/lib/DtHelp/GifUtils.c b/cde/lib/DtHelp/GifUtils.c
index f0a78c44ba3ef1f874dd845666db516c65cee673..d21f869e813a5cd5acb402c87c017a2449a6ed58 100644 (file)
--- a/cde/lib/DtHelp/GifUtils.c
+++ b/cde/lib/DtHelp/GifUtils.c
@@ -1090,7 +1090,7 @@ create_pixmap( GifObj *g, pixel **image, int width, int height, Pixel fg, Pixel
 
   if (!ximData) {
     fprintf(stderr, "Could not allocate ximage data\n");
-    return NULL;
+    return None;
   }
 
   /* Monochrome */
@@ -1107,7 +1107,7 @@ create_pixmap( GifObj *g, pixel **image, int width, int height, Pixel fg, Pixel
 
   if (!g->f_ximage) {
     fprintf(stderr, "XCreateImage failed\n");
-    return NULL;
+    return None;
   }
 
 
@@ -1212,7 +1212,7 @@ else
 
   if (!pm) {
     fprintf(stderr, "could not create pixmap\n");
-    return NULL;
+    return None;
   }
 
   _XmPutScaledImage (g->f_dpy,pm,g->f_gc,g->f_ximage,
@@ -1239,7 +1239,7 @@ gif_to_pixmap(GifObj *g, byte *inbuf, unsigned int buflen, Dimension *w, Dimensi
 
   /* Create raw image from compress GIF data */
   raw_image = create_raw_image (inbuf, buflen, &width, &height, 1);
-  if (!raw_image) return NULL;
+  if (!raw_image) return None;
 
   /* Create X pixmap from raw image data */
   pixmap = create_pixmap(g, raw_image, width, height, fg, bg, ratio);

diff --git a/cde/lib/DtHelp/decompress.c b/cde/lib/DtHelp/decompress.c
index b96be4f5a7a774787f43e9541825243ac1c0dc55..c21d80877657147a3f0c797a5fafcb6b912ba2aa 100644 (file)
--- a/cde/lib/DtHelp/decompress.c
+++ b/cde/lib/DtHelp/decompress.c
@@ -56,7 +56,7 @@ typedef long int        count_int;
  typedef       unsigned char   char_type;
 #endif /* UCHAR */
 
-static char_type magic_header[] = { "\037\235" };      /* 1F 9D */
+static int magic_header[] = { 0x1F, 0x9D };
 
 /* Defines for third byte of header */
 #define BIT_MASK       0x1f
@@ -128,8 +128,8 @@ _DtHelpCeBufFilePushZ (BufFilePtr f)
     CompressedFile  *file;
     int                    extra;
 
-    if ((BufFileGet(f) != (magic_header[0] & 0xFF)) ||
-       (BufFileGet(f) != (magic_header[1] & 0xFF)))
+    if ((BufFileGet(f) != magic_header[0]) ||
+       (BufFileGet(f) != magic_header[1]))
     {
        return 0;
     }