Description: Allow the build timestamp to be externally set
 In order to make Ghostscript output reproducible, we need a way to
 set the build timestamp to other values than the current time.
 We now consistently use gp_get_realtime() instead of directly calling
 time() or gp_get_usertime() and make gp_get_realtime() use the value
 found in the SOURCE_DATE_EPOCH environment variable if set. Also,
 environment timezone is fixed to UTC if SOURCE_DATE_EPOCH is used to
 avoid variations.
Author: Eduard Sanou <dhole@openmailbox.org>
Author: Peter De Wachter <pdewacht@gmail.com>
Bug-Debian: https://bugs.debian.org/794004
Forwarded: not-needed
Last-Update: 2023-09-13
---
This patch header follows DEP-3: https://dep.debian.net/deps/dep3/
--- a/base/gp_unix.c
+++ b/base/gp_unix.c
@@ -19,6 +19,7 @@
 #ifdef __MINGW32__
 #  include "windows_.h"
 #endif
+#include "errno_.h"
 #include "pipe_.h"
 #include "string_.h"
 #include "time_.h"
@@ -149,6 +150,7 @@
 gp_get_realtime(long *pdt)
 {
     struct timeval tp;
+    const char *env;
 
 #if gettimeofday_no_timezone    /* older versions of SVR4 */
     {
@@ -168,6 +170,26 @@
     }
 #endif
 
+    env = getenv("SOURCE_DATE_EPOCH");
+    if (env) {
+        char *end;
+        long timestamp;
+
+        errno = 0;
+        timestamp = strtol(env, &end, 10);
+        if (env == end || *end || errno != 0) {
+            lprintf("Ghostscript: SOURCE_DATE_EPOCH is not a number!\n");
+            timestamp = 0;
+        }
+
+        tp.tv_sec = timestamp;
+        tp.tv_usec = 0;
+
+        /* We need to fix the environment timezone to get reproducible */
+        /* results when parsing the result of gp_get_realtime. */
+        setenv("TZ", "UTC", 1);
+    }
+
     /* tp.tv_sec is #secs since Jan 1, 1970 */
     pdt[0] = tp.tv_sec;
 
--- a/devices/vector/gdevpdf.c
+++ b/devices/vector/gdevpdf.c
@@ -437,6 +437,7 @@
     if (!pdev->OmitInfoDate)
     {
         struct tm tms;
+        long secs_ns[2];
         time_t t;
         char buf[1+2+4+2+2+2+2+2+1+2+1+2+1+1+1]; /* (D:yyyymmddhhmmssZhh'mm')\0 */
         int timeoffset;
@@ -448,7 +449,8 @@
         timesign = 'Z';
         timeoffset = 0;
 #else
-        time(&t);
+        gp_get_realtime(secs_ns);
+        t = secs_ns[0];
         tms = *gmtime(&t);
         tms.tm_isdst = -1;
         timeoffset = (int)difftime(t, mktime(&tms)); /* tz+dst in seconds */
--- a/devices/vector/gdevpdfe.c
+++ b/devices/vector/gdevpdfe.c
@@ -216,6 +216,7 @@
 {
     /* We don't write a day time because we don't have a time zone. */
     struct tm tms;
+    long secs_ns[2];
     time_t t;
     char buf1[4+1+2+1+2+1]; /* yyyy-mm-dd\0 */
 
@@ -223,7 +224,8 @@
     memset(&t, 0, sizeof(t));
     memset(&tms, 0, sizeof(tms));
 #else
-    time(&t);
+    gp_get_realtime(secs_ns);
+    t = secs_ns[0];
     tms = *localtime(&t);
 #endif
     gs_snprintf(buf1, sizeof(buf1),
--- a/devices/vector/gdevpsu.c
+++ b/devices/vector/gdevpsu.c
@@ -187,6 +187,7 @@
             dev->dname);
 #endif
     {
+        long secs_ns[2];
         time_t t;
         struct tm tms;
 
@@ -194,7 +195,8 @@
         memset(&t, 0, sizeof(t));
         memset(&tms, 0, sizeof(tms));
 #else
-        time(&t);
+        gp_get_realtime(secs_ns);
+        t = secs_ns[0];
         tms = *localtime(&t);
 #endif
         fprintf(f, "%%%%CreationDate: %d/%02d/%02d %02d:%02d:%02d\n",