From 023ff226423c77b8b6072217eef0215f94b229b2 Mon Sep 17 00:00:00 2001
From: Glenn Randers-Pehrson <glennrp at users.sourceforge.net>
Date: Thu, 6 Nov 2014 07:56:34 -0600
Subject: [PATCH] [libpng15] Only mark text chunks as written after
 successfully writing them.

---
 example.c  |  2 +-
 pngtest.c  |  2 +-
 pngwrite.c | 26 ++++++++++++++------------
 3 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/example.c b/example.c
index ae4b7d5a4..e30ab5497 100644
--- a/example.c
+++ b/example.c
@@ -750,7 +750,7 @@ void write_png(char *file_name /* , ... other image information ... */)
     */
 
    /* Once we write out the header, the compression type on the text
-    * chunks gets changed to PNG_TEXT_COMPRESSION_NONE_WR or
+    * chunk gets changed to PNG_TEXT_COMPRESSION_NONE_WR or
     * PNG_TEXT_COMPRESSION_zTXt_WR, so it doesn't get written out again
     * at the end.
     */
diff --git a/pngtest.c b/pngtest.c
index dd9aa28ec..00d6dc3ba 100644
--- a/pngtest.c
+++ b/pngtest.c
@@ -646,7 +646,7 @@ set_location(png_structp png_ptr, struct user_chunk_data *data, int what)
    if ((data->location[0] & what) || (data->location[1] & what))
       return 0; /* already have one of these */
 
-   /* Find where we are (the code below zeros info_ptr to indicate that the
+   /* Find where we are (the code below zeroes info_ptr to indicate that the
     * chunks before the first IDAT have been read.)
     */
    if (data->info_ptr == NULL) /* after IDAT */
diff --git a/pngwrite.c b/pngwrite.c
index 5781bd1da..a0f6bf99d 100644
--- a/pngwrite.c
+++ b/pngwrite.c
@@ -223,11 +223,14 @@ png_write_info(png_structp png_ptr, png_infop info_ptr)
              info_ptr->text[i].lang,
              info_ptr->text[i].lang_key,
              info_ptr->text[i].text);
+         /* Mark this chunk as written */
+         if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
+            info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
+         else
+            info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
 #else
-          png_warning(png_ptr, "Unable to write international text");
+         png_warning(png_ptr, "Unable to write international text");
 #endif
-          /* Mark this chunk as written */
-          info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
       }
 
       /* If we want a compressed text chunk */
@@ -238,11 +241,11 @@ png_write_info(png_structp png_ptr, png_infop info_ptr)
          png_write_zTXt(png_ptr, info_ptr->text[i].key,
              info_ptr->text[i].text, 0,
              info_ptr->text[i].compression);
+         /* Mark this chunk as written */
+         info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
 #else
          png_warning(png_ptr, "Unable to write compressed text");
 #endif
-         /* Mark this chunk as written */
-         info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
       }
 
       else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
@@ -340,11 +343,11 @@ png_write_end(png_structp png_ptr, png_infop info_ptr)
                 info_ptr->text[i].lang,
                 info_ptr->text[i].lang_key,
                 info_ptr->text[i].text);
+            /* Mark this chunk as written */
+            info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
 #else
             png_warning(png_ptr, "Unable to write international text");
 #endif
-            /* Mark this chunk as written */
-            info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
          }
 
          else if (info_ptr->text[i].compression >= PNG_TEXT_COMPRESSION_zTXt)
@@ -354,11 +357,11 @@ png_write_end(png_structp png_ptr, png_infop info_ptr)
             png_write_zTXt(png_ptr, info_ptr->text[i].key,
                 info_ptr->text[i].text, 0,
                 info_ptr->text[i].compression);
+            /* Mark this chunk as written */
+            info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
 #else
             png_warning(png_ptr, "Unable to write compressed text");
 #endif
-            /* Mark this chunk as written */
-            info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_zTXt_WR;
          }
 
          else if (info_ptr->text[i].compression == PNG_TEXT_COMPRESSION_NONE)
@@ -367,12 +370,11 @@ png_write_end(png_structp png_ptr, png_infop info_ptr)
             /* Write uncompressed chunk */
             png_write_tEXt(png_ptr, info_ptr->text[i].key,
                 info_ptr->text[i].text, 0);
+            /* Mark this chunk as written */
+            info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
 #else
             png_warning(png_ptr, "Unable to write uncompressed text");
 #endif
-
-            /* Mark this chunk as written */
-            info_ptr->text[i].compression = PNG_TEXT_COMPRESSION_NONE_WR;
          }
       }
 #endif