Cleanup, make pnmtopng.c compile with libpng 1.4 beta, split out pngx.c

git-svn-id: http://svn.code.sf.net/p/netpbm/code/trunk@968 9d0c8265-081b-0410-96cb-a4ca84ce46f8

1 files changed, 95 insertions, 0 deletions

diff --git a/converter/other/pngx.c b/converter/other/pngx.c
new file mode 100644
index 00000000..6d79bcfe
--- /dev/null
+++ b/converter/other/pngx.c
@@ -0,0 +1,95 @@
+#include <png.h>
+#include "pm_c_util.h"
+#include "mallocvar.h"
+#include "pm.h"
+#include "pngx.h"
+
+
+static void
+errorHandler(png_structp     const png_ptr,
+             png_const_charp const msg) {
+
+    jmp_buf * jmpbufP;
+
+    /* this function, aside from the extra step of retrieving the "error
+       pointer" (below) and the fact that it exists within the application
+       rather than within libpng, is essentially identical to libpng's
+       default error handler.  The second point is critical:  since both
+       setjmp() and longjmp() are called from the same code, they are
+       guaranteed to have compatible notions of how big a jmp_buf is,
+       regardless of whether _BSD_SOURCE or anything else has (or has not)
+       been defined.
+    */
+
+    pm_message("fatal libpng error: %s", msg);
+
+    jmpbufP = png_get_error_ptr(png_ptr);
+
+    if (!jmpbufP) {
+        /* we are completely hosed now */
+        pm_error("EXTREMELY fatal error: jmpbuf unrecoverable; terminating.");
+    }
+
+    longjmp(*jmpbufP, 1);
+}
+
+
+
+void
+pngx_create(struct pngx ** const pngxPP,
+            pngx_rw        const rw,
+            jmp_buf *      const jmpbufP) {
+
+    struct pngx * pngxP;
+
+    MALLOCVAR(pngxP);
+
+    if (!pngxP)
+        pm_error("Failed to allocate memory for PNG object");
+    else {
+        switch(rw) {
+        case PNGX_READ:
+            pngxP->png_ptr = png_create_write_struct(
+                PNG_LIBPNG_VER_STRING,
+                jmpbufP, errorHandler, NULL);
+            break;
+        case PNGX_WRITE:
+            pngxP->png_ptr = png_create_write_struct(
+                PNG_LIBPNG_VER_STRING,
+                jmpbufP, errorHandler, NULL);
+            break;
+        }
+        if (!pngxP->png_ptr)
+            pm_error("cannot allocate main libpng structure (png_ptr)");
+        else {
+            pngxP->info_ptr = png_create_info_struct(pngxP->png_ptr);
+
+            if (!pngxP->info_ptr)
+                pm_error("cannot allocate libpng info structure (info_ptr)");
+            else
+                *pngxPP = pngxP;
+        }
+    }
+}
+
+
+
+void
+pngx_destroy(struct pngx * const pngxP) {
+
+    png_destroy_write_struct(&pngxP->png_ptr, &pngxP->info_ptr);
+
+    free(pngxP);
+}
+
+
+
+bool
+pngx_chunkIsPresent(struct pngx * const pngxP,
+                    uint32_t      const chunkType) {
+
+    return png_get_valid(pngxP->png_ptr, pngxP->info_ptr, chunkType);
+}
+
+
+