This patch to Andreas Dilger's XV PNG patch 1.2d addresses the following
bugs, buglets and typos:
- fixes a core-dump triggered by an unfortunate "feature" in libpng 0.97
and later (i.e., libpng frees text buffers it didn't allocate)
- fixes an infinite-loop bug in text-comment processing (from TenThumbs,
tenthumbs@cybernex.net, 5 August 1998)
- forces text comments inherited from GIF or elsewhere to be in proper
PNG format (i.e., Unix-style "LF" line-endings); inherited PNG comments
are still assumed to be in proper format
- corrects argument types for png_xv_error() and png_xv_warning() to
match what png_create_write_struct() and png_create_read_struct()
expect
- changes default ">>" increment on compression dial from 2 to 3 so that
maximum compression (level 9) is one click away from default (level 6)
- fixes some comment typos and removes overlooked debug code
This code has been tested with various versions of libpng, most recently
version 1.0.2, with no apparent problems.
Greg Roelofs, newt@pobox.com
9 August 1998
--- xvpng.c.stock Thu Jun 13 16:42:11 1996
+++ xvpng.c Sun Aug 9 13:08:43 1998
@@ -49,6 +50,9 @@
#define BUTTH 24
+#define LF 10 /* a.k.a. '\n' on ASCII machines */
+#define CR 13 /* a.k.a. '\r' on ASCII machines */
+
/*** local functions ***/
static void drawPD PARM((int, int, int, int));
static void clickPD PARM((int, int));
@@ -57,8 +61,10 @@
static int WritePNG PARM((FILE *, byte *, int, int, int,
byte *, byte *, byte *, int));
-static void png_xv_error PARM((png_struct *png_ptr, char *message));
-static void png_xv_warning PARM((png_struct *png_ptr, char *message));
+static void png_xv_error PARM((png_structp png_ptr,
+ png_const_charp message));
+static void png_xv_warning PARM((png_structp png_ptr,
+ png_const_charp message));
/*** local variables ***/
static char *filename;
@@ -87,7 +93,7 @@
XSelectInput(theDisp, pngW, ExposureMask | ButtonPressMask | KeyPressMask);
DCreate(&cDial, pngW, 12, 25, DWIDE, DHIGH, (double)Z_NO_COMPRESSION,
- (double)Z_BEST_COMPRESSION, COMPRESSION, 1.0, 2.0,
+ (double)Z_BEST_COMPRESSION, COMPRESSION, 1.0, 3.0,
infofg, infobg, hicol, locol, "Compression", NULL);
DCreate(&gDial, pngW, DWIDE+27, 25, DWIDE, DHIGH, 1.0, 3.5,DISPLAY_GAMMA,0.01,0.2,
@@ -594,14 +607,13 @@
int j;
p = pic;
for(j = 0; j < h; j++) {
- fflush(stdout);
if(info_ptr->color_type == PNG_COLOR_TYPE_GRAY) {
int k;
for(k = 0; k < w; k++)
png_line[k] = ptype==PIC24 ? MONO(p[k*3], p[k*3+1], p[k*3+2]) :
remap[p[k]];
png_write_row(png_ptr, png_line);
- } else /* rbg or palette */
+ } else /* RGB or palette */
png_write_row(png_ptr, p);
if((j & 0x1f) == 0) WaitCursor();
p += linesize;
@@ -642,6 +654,7 @@
}
/* See if it looks like a PNG keyword from LoadPNG */
+ /* GRR: should test for strictly < 80, right? (key = 1-79 chars only) */
if(comment && comment[1] == ':' && comment - key <= 80) {
*(comment++) = '\0';
*(comment++) = '\0';
@@ -661,9 +674,9 @@
/* We have to find the end of this comment, and the next keyword
if there is one */
- do {
- key = comment = strchr(comment, ':');
- } while (key && key[1] != ':');
+ for (; NULL != (key = comment = strchr(comment, ':')); comment++)
+ if (key[1] == ':')
+ break;
/* It looks like another keyword, go backward to the beginning */
if (key) {
@@ -690,11 +703,25 @@
tp++;
}
}
- /* It is just a generic comment */
+ /* Just a generic comment: make sure line-endings are valid for PNG */
else {
+ char *p=key, *q=key; /* only deleting chars, not adding any */
+
+ while (*p) {
+ if (*p == CR) { /* lone CR or CR/LF: EOL either way */
+ *q++ = LF; /* LF is the only allowed PNG line-ending */
+ if (p[1] == LF) /* get rid of any original LF */
+ ++p;
+ } else if (*p == LF) /* lone LF */
+ *q++ = LF;
+ else
+ *q++ = *p;
+ ++p;
+ }
+ *q = '\0'; /* unnecessary...but what the heck */
tp->key = "Comment";
tp->text = key;
- tp->text_length = strlen(tp->text);
+ tp->text_length = q - key;
tp->compression = tp->text_length > 750 ? 0 : -1;
info_ptr->num_text++;
key = NULL;
@@ -712,15 +739,22 @@
info_ptr->valid |= PNG_INFO_tIME;
png_write_end(png_ptr, info_ptr);
- png_destroy_write_struct(&png_ptr, &info_ptr);
+ fflush(fp); /* just in case we core-dump before finishing... */
if (text)
{
free(text);
+ /* must do this or png_destroy_write_struct() 0.97+ will free text again: */
+ info_ptr->text = (png_textp)NULL;
if (savecmnt)
+ {
free(savecmnt);
+ savecmnt = (char *)NULL;
+ }
}
+ png_destroy_write_struct(&png_ptr, &info_ptr);
+
return 0;
}
@@ -941,8 +1001,8 @@
/*******************************************/
static void
png_xv_error(png_ptr, message)
- png_struct *png_ptr;
- char *message;
+ png_structp png_ptr;
+ png_const_charp message;
{
SetISTR(ISTR_WARNING,"%s: libpng error: %s", fbasename, message);
@@ -953,8 +1013,8 @@
/*******************************************/
static void
png_xv_warning(png_ptr, message)
- png_struct *png_ptr;
- char *message;
+ png_structp png_ptr;
+ png_const_charp message;
{
if (!png_ptr)
return;