Emile: Reduce ERR logs on invalid JPEG images

When reading the head of a file, we may get the error that it is
not a JPEG image (which is normal), so we should not print any ERR.

The JPEG header read function can indeed be called to test whether a
file can be opened by the JPEG loader or not (any file).

Note that JPEG files don't have reliable magic numbers, so we
don't check them, but rely on libjpeg instead.

Fixes T2290

1 files changed, 9 insertions, 2 deletions

diff --git a/src/lib/emile/emile_image.c b/src/lib/emile/emile_image.c
index 9ea45396b7..dc8af2c196 100644
--- a/src/lib/emile/emile_image.c
+++ b/src/lib/emile/emile_image.c
@@ -23,6 +23,7 @@
 #include <stdio.h>
 #include <setjmp.h>
 #include <jpeglib.h>
+#include <jerror.h>
 
 #ifdef HAVE_EVIL
 #include <Evil.h>
@@ -673,8 +674,12 @@ _emile_image_jpeg_error_exit_cb(j_common_ptr cinfo)
    char buffer[JMSG_LENGTH_MAX];
    emptr errmgr;
 
-   (*cinfo->err->format_message)(cinfo, buffer);
-   ERR("%s", buffer);
+   // Avoid message "Not a JPEG file: starts with 0x%02x 0x%02x"
+   if (cinfo->client_data || (cinfo->err->msg_code != JERR_NO_SOI))
+     {
+        (*cinfo->err->format_message)(cinfo, buffer);
+        ERR("%s", buffer);
+     }
    errmgr = (emptr)cinfo->err;
    longjmp(errmgr->setjmp_buffer, 1);
 }
@@ -1352,6 +1357,7 @@ _emile_jpeg_head(Emile_Image *image,
 
    memset(&cinfo, 0, sizeof(cinfo));
    cinfo.err = jpeg_std_error(&(jerr.pub));
+   cinfo.client_data = NULL;
    jerr.pub.error_exit = _emile_image_jpeg_error_exit_cb;
    jerr.pub.emit_message = _emile_image_jpeg_emit_message_cb;
    jerr.pub.output_message = _emile_image_jpeg_output_message_cb;
@@ -1610,6 +1616,7 @@ _emile_jpeg_data(Emile_Image *image,
      }
 
    cinfo.err = jpeg_std_error(&(jerr.pub));
+   cinfo.client_data = (void *)(intptr_t) 0x1;
    jerr.pub.error_exit = _emile_image_jpeg_error_exit_cb;
    jerr.pub.emit_message = _emile_image_jpeg_emit_message_cb;
    jerr.pub.output_message = _emile_image_jpeg_output_message_cb;