raco dist: unbreak ELF size update

racket/collects/compiler/distribute.rkt

@@ -338,6 +338,11 @@
 
   (define (patch-stub-exe-paths b exe shared-lib-dir)
     ;; Adjust paths to executable and DLL that is embedded in the executable
+    (define rx:rackprog #rx#"^[.]rackprog\0")
+    (define section-offset+size (get-racket-section-offset+size b rx:rackprog))
+    (define section-offset (if section-offset+size
+			       (car section-offset+size)
+			       0))
     (let-values ([(config-pos all-start start end prog-len dll-len rest)
 		  (with-input-from-file b
 		    (lambda ()
@@ -351,7 +356,7 @@
 			(read-one-int i) ; start of program
 			(let ([start (read-one-int i)] ; start of data
 			      [end (read-one-int i)]) ; end of data
-			  (file-position i start)
+			  (file-position i (+ start section-offset))
 			  (let ([prog-len (next-bytes-length i)]
 				[dll-len (next-bytes-length i)])
 			    (values (+ (cdar m) 1) ; position after "cOnFiG:[" tag
@@ -375,7 +380,7 @@
                 (file-position o (+ config-pos 12)) ; update the end of the program data
                 (write-one-int (- end delta) o)
                 (flush-output o)
-                (file-position o start)
+                (file-position o (+ start section-offset))
                 (write-bytes exe-bytes o)
                 (write-bytes #"\0" o)
                 (write-bytes shared-lib-bytes o)
@@ -385,7 +390,7 @@
           ;; May need to fix the size of the ELF section:
           (adjust-racket-section-size
            b
-           #rx#"^[.]rack(?:cmdl|prog)\0"
+           rx:rackprog
            (- (- end all-start) delta))))))
 
   (define (copy-and-patch-binaries copy? magic

racket/collects/compiler/private/elf.rkt

@@ -1,6 +1,7 @@
 #lang racket/base
 
 (provide add-racket-section
+         get-racket-section-offset+size
          adjust-racket-section-size
          get-rpath
          set-rpath)
@@ -504,6 +505,24 @@
             ;; Any final writes:
             (finish out adjust adjust*))))))))
 
+(define (get-racket-section-offset+size src-file name-regexp)
+  (call-with-input-file*
+   src-file
+   (lambda (in)
+     (read-elf
+      in
+      (lambda () #f)
+      (lambda (elf sections programs str-section strs)
+        (and elf
+             (for/or ([s (in-list sections)]
+                      [i (in-naturals)])
+               (and (regexp-match? name-regexp
+                                   strs
+                                   (min (section-name-offset s)
+                                        (bytes-length strs)))
+                    (cons (section-offset s)
+                          (section-size s))))))))))
+
 (define (adjust-racket-section-size src-file name-regexp new-size)
   (define fixup
     (call-with-input-file*

racket/src/start/ustart.c

@@ -308,7 +308,7 @@ int main(int argc, char **argv)
   {
     int expected_length = end - prog_end;
     if (expected_length != read(fd, data, expected_length)) {
-      printf("read failed to read all %i bytes from file %s\n", expected_length, embedding_me);
+      printf("read failed to read all %i bytes from file %s at offset %d\n", expected_length, embedding_me, prog_end);
       abort();
     }
   }