binsub.c: attempt to handle read-only files.

    Some files may be r--r--r-- (0444), which
    would have failed in the previous version.

    Also fixed a subtle bug where the 'fopen'
    was being called with "rb+" instead of "rb"
    which caused a premature failure.

bootstrap: ensure string offsets remain consistent.

    This has been thoroughly analyzed and tested
    in the discussion in #26, but a mechanistic
    understanding of the root cause has not yet
    been realized. That would still be worth doing.

Fixes: #26.

2 files changed, 48 insertions, 19 deletions

diff --git a/binsub.c b/binsub.c
index c66148c..892646e 100644
--- a/binsub.c
+++ b/binsub.c
@@ -1,7 +1,7 @@
 /**
- * binsub.c / 2022-12-09
+ * binsub.c / 2025-02-23
  *
- * (C) 2022 Zach van Rijn <me@zv.io>
+ * (C) 2022-2025 Zach van Rijn <me@zv.io>
  *
  * MIT License
  *
@@ -18,6 +18,8 @@
 #include <stdio.h>
 #include <string.h>
 #include <stdlib.h>
+#include <sys/types.h>
+#include <sys/stat.h>
 
 /**
  * Basic memory structure.
@@ -145,17 +147,40 @@ scanner (const char *file, const char *find, const char *repl)
     FILE   *fp = NULL;
     size_t  nb = 0;
 
+    struct stat st;
+    mode_t pold, pnew;
+
     struct buffer buf;
     memset(&buf, 0, sizeof(struct buffer));
 
-    fp = fopen(file, "rb+");
+    if (stat(file, &st) == -1)
+    {
+        fprintf(stderr,
+            "E: Could not stat FILE '%s' at all!\n",
+            file
+        );
+        return;
+    }
+
+    pold = st.st_mode;          /* don't want to modify this  */
+    pnew = pold | S_IWUSR;      /* could be read-only file    */
+
+    if (chmod(file, pnew) == -1)
+    {
+        fprintf(stderr,
+            "E: Could not chmod FILE '%s' for writing!\n",
+            file
+        );
+    }
+
+    fp = fopen(file, "rb");
     if (!fp)
     {
         fprintf(stderr,
             "E: Could not open FILE '%s' for reading!\n",
             file
         );
-        return;
+        goto restore;
     }
 
     fseek(fp, 0, SEEK_END);
@@ -175,7 +200,7 @@ scanner (const char *file, const char *find, const char *repl)
             buf.len,
             file
         );
-        return;
+        goto restore;
     }
     buf.data[buf.len] = 0;      /* extra byte needs to be nil */
     
@@ -191,7 +216,7 @@ scanner (const char *file, const char *find, const char *repl)
             buf.len,
             file
         );
-        return;
+        goto restore;
     }
     fclose(fp);
 
@@ -205,7 +230,7 @@ scanner (const char *file, const char *find, const char *repl)
             "E: Could not open FILE '%s' for writing!\n",
             file
         );
-        return;
+        goto restore;
     }
 
     nb = fwrite(buf.data, 1, buf.len, fp);
@@ -220,11 +245,20 @@ scanner (const char *file, const char *find, const char *repl)
             buf.len,
             file
         );
-        return;
+        goto restore;
     }
     fclose(fp);
 
     free(buf.data);
+
+restore:
+    if (chmod(file, pold) == -1)
+    {
+        fprintf(stderr,
+            "E: Could not restore FILE '%s' permissions!\n",
+            file
+        );
+    }
 }
 
 
diff --git a/bootstrap b/bootstrap
index 0171ad9..d2344f2 100755
--- a/bootstrap
+++ b/bootstrap
@@ -5,7 +5,7 @@
 # Purpose  : Bootstraps Adélie from source for any architecture.
 # Authors  : Zach van Rijn <me@zv.io>
 # License  : MIT
-# Revision : 20250222
+# Revision : 20250223
 #===============================================================
 
 #===============================================================
@@ -783,19 +783,14 @@ if ! test -f rootfs-${TARGET}-patched.tgz; then
         ;
 
     ##
-    # Replace needle with the empty string.
+    # Maintain needle length but canonically replace with '/'.
+    # Length requirement only seems to affect 'perl'; truncating
+    # appears to be sufficient for all other binaries and files.
+    # Please refer to #26 for more information.
     #
     x="${BASE}"/mcmtools-${TARGET}/sys;
     grep -rl "${x}" ${t} | while read k; do
-        # exceptions
-
-        case "${k}" in
-            "${t}"/bin/perl) continue; ;; # @INC fuckery
-        esac
-
-        # delete needle
-        ./binsub ${k} "${x}"; # alternatively use "/"
-
+        ./binsub ${k} "${x}" $(printf "%${#x}s" | tr ' ' '/');
     done
 
     ##