From 0b365b7fb7a8623dd6d46ac25fc432f1d0cffc89 Mon Sep 17 00:00:00 2001
From: Tony Cook <tony@develop-help.com>
Date: Thu, 14 Feb 2019 19:01:47 +1100
Subject: [PATCH] correct the type of the im_decode_exif() data parameter

const foo * and foo* have the same representation so this doesn't
break the ABI.

const unsigned char * will accept all parameter types it did previously.

The only issue is if someone makes a copy of the pointer, but I don't
support that.
---
 imexif.c     | 8 ++++----
 imexif.h     | 2 +-
 imexttypes.h | 2 +-
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/imexif.c b/imexif.c
index 4bdf386a..30a89896 100644
--- a/imexif.c
+++ b/imexif.c
@@ -213,7 +213,7 @@ typedef struct {
 /* in memory tiff structure */
 typedef struct {
   /* the data we use as a tiff */
-  unsigned char *base;
+  const unsigned char *base;
   size_t size;
 
   /* intel or motorola byte order */
@@ -228,7 +228,7 @@ typedef struct {
   unsigned long next_ifd;
 } imtiff;
 
-static int tiff_init(imtiff *tiff, unsigned char *base, size_t length);
+static int tiff_init(imtiff *tiff, const unsigned char *base, size_t length);
 static int tiff_load_ifd(imtiff *tiff, unsigned long offset);
 static void tiff_final(imtiff *tiff);
 static void tiff_clear_ifd(imtiff *tiff);
@@ -286,7 +286,7 @@ Returns true if an EXIF header was seen.
 */
 
 int
-im_decode_exif(i_img *im, unsigned char *data, size_t length) {
+im_decode_exif(i_img *im, const unsigned char *data, size_t length) {
   imtiff tiff;
   unsigned long exif_ifd_offset = 0;
   unsigned long gps_ifd_offset = 0;
@@ -840,7 +840,7 @@ the first IFD (IFD0 in EXIF) in first_ifd_offset.
 */
 
 static int
-tiff_init(imtiff *tiff, unsigned char *data, size_t length) {
+tiff_init(imtiff *tiff, const unsigned char *data, size_t length) {
   int version;
 
   tiff->base = data;
diff --git a/imexif.h b/imexif.h
index 2e02d1d2..67b674c6 100644
--- a/imexif.h
+++ b/imexif.h
@@ -5,6 +5,6 @@
 #include <stddef.h>
 #include "imdatatypes.h"
 
-extern int im_decode_exif(i_img *im, unsigned char *data, size_t length);
+extern int im_decode_exif(i_img *im, const unsigned char *data, size_t length);
 
 #endif /* ifndef IMAGER_IMEXIF_H */
diff --git a/imexttypes.h b/imexttypes.h
index 62e325ba..0d25c5ef 100644
--- a/imexttypes.h
+++ b/imexttypes.h
@@ -271,7 +271,7 @@ typedef struct {
   int (*f_i_img_color_channels)(i_img *im);
 
   /* IMAGER_API_LEVEL 10 functions will be added here */
-  int (*f_im_decode_exif)(i_img *im, unsigned char *data, size_t length);
+  int (*f_im_decode_exif)(i_img *im, const unsigned char *data, size_t length);
 
   /* IMAGER_API_LEVEL 11 functions will be added here */
 } im_ext_funcs;
-- 
2.39.5