bug#27563: [PATCH v4 3/3] gnu: ghostscript: Make "/CreationDate", "/ModDate" optoinal, depending on environment variable.

[Danny Milosavljevic]

* gnu/packages/patches/ghostscript-no-header-creationdate.patch: New file.
* gnu/local.mk (dist_patch_DATA): Add it.
* gnu/packages/ghostscript.scm (ghostscript): Use it.
---
 gnu/local.mk                                             |  1 +
 gnu/packages/ghostscript.scm                             | 10 ++--------
 .../patches/ghostscript-no-header-creationdate.patch     | 16 ++++++++++++++++
 3 files changed, 19 insertions(+), 8 deletions(-)
 create mode 100644 
gnu/packages/patches/ghostscript-no-header-creationdate.patch

diff --git a/gnu/local.mk b/gnu/local.mk
index 9cf4648aa..0880de038 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -621,6 +621,7 @@ dist_patch_DATA =                                           
\
   %D%/packages/patches/ghostscript-CVE-2017-8291.patch         \
   %D%/packages/patches/ghostscript-no-header-id.patch          \
   %D%/packages/patches/ghostscript-no-header-uuid.patch                \
+  %D%/packages/patches/ghostscript-no-header-creationdate.patch \
   %D%/packages/patches/ghostscript-runpath.patch               \
   %D%/packages/patches/glib-networking-ssl-cert-file.patch     \
   %D%/packages/patches/glib-tests-timer.patch                  \
diff --git a/gnu/packages/ghostscript.scm b/gnu/packages/ghostscript.scm
index 3a84db3e4..b15b032a7 100644
--- a/gnu/packages/ghostscript.scm
+++ b/gnu/packages/ghostscript.scm
@@ -144,6 +144,7 @@ printing, and psresize, for adjusting page sizes.")
           "0lyhjcrkmd5fcmh8h56bs4xr9k4jasmikv5vsix1hd4ai0ad1q9b"))
         (patches (search-patches "ghostscript-runpath.patch"
                                  "ghostscript-CVE-2017-8291.patch"
+                                 "ghostscript-no-header-creationdate.patch"
                                  "ghostscript-no-header-id.patch"
                                  "ghostscript-no-header-uuid.patch"))
         (modules '((guix build utils)))
@@ -154,14 +155,7 @@ printing, and psresize, for adjusting page sizes.")
          '(begin
             (for-each delete-file-recursively '("freetype" "jbig2dec" "jpeg"
                                                 "lcms2" "libpng"
-                                                "tiff" "zlib"))
-            ;; Get rid of timestamps (remove /CreationDate and /ModDate).
-            (substitute* "devices/vector/gdevpdf.c"
-             ((", but we do the same")
-              (string-append "*/ "
-                             "if (!getenv(\"GS_GENERATE_UUIDS\") || "
-                             "(strcmp(getenv(\"GS_GENERATE_UUIDS\"), \"0\") != 
0 && "
-                             "strcmp(getenv(\"GS_GENERATE_UUIDS\"), \"no\") != 
0)) /*")))))))
+                                                "tiff" "zlib"))))))
     (build-system gnu-build-system)
     (outputs '("out" "doc"))                  ;19 MiB of HTML/PS doc + examples
     (arguments
diff --git a/gnu/packages/patches/ghostscript-no-header-creationdate.patch 
b/gnu/packages/patches/ghostscript-no-header-creationdate.patch
new file mode 100644
index 000000000..2601938b7
--- /dev/null
+++ b/gnu/packages/patches/ghostscript-no-header-creationdate.patch
@@ -0,0 +1,16 @@
+This patch makes emission of /CreationDate and /ModDate headers optional.
+
+diff --git a/orig/gnu-ghostscript-9.14.0/devices/vector/gdevpdf.c 
b/bb/gnu-ghostscript-9.14.0/devices/vector/gdevpdf.c
+index 0fb067e..b342e2c 100644
+--- orig/gnu-ghostscript-9.14.0/devices/vector/gdevpdf.c
++++ gnu-ghostscript-9.14.0/devices/vector/gdevpdf.c
+@@ -305,6 +305,9 @@ pdf_initialize_ids(gx_device_pdf * pdev)
+      * date and time, rather than (for example) %%CreationDate from the
+      * PostScript file.  We think this is wrong, but we do the same.
+      */
++    if (!getenv("GS_GENERATE_UUIDS") ||
++        (strcmp(getenv("GS_GENERATE_UUIDS"), "0") != 0 &&
++         strcmp(getenv("GS_GENERATE_UUIDS"), "no") != 0))
+     {
+         struct tm tms;
+         time_t t;