[PATCH v1 1/1] ldconfig: add --install option

[DJ Delorie]

Add --install option, which copies a pre-built ld.so.cache into place,
honoring the cache and root options and defaults.  This gives the user
a canonical "correct" way to install a pre-built cache.
---
 elf/ldconfig.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 53 insertions(+), 2 deletions(-)

diff --git a/elf/ldconfig.c b/elf/ldconfig.c
index 070e933df6..dcd885449a 100644
--- a/elf/ldconfig.c
+++ b/elf/ldconfig.c
@@ -104,6 +104,9 @@ static int opt_manual_link;
 /* Should we ignore an old auxiliary cache file?  */
 static int opt_ignore_aux_cache;
 
+/* Install a pre-existing cache file instead of generating a new one.  */
+static int opt_install;
+
 /* Cache file to use.  */
 static char *cache_file;
 
@@ -132,6 +135,7 @@ static const struct argp_option options[] =
   { NULL, 'l', NULL, 0, N_("Manually link individual libraries."), 0},
   { "format", 'c', N_("FORMAT"), 0, N_("Format to use: new (default), old, or compat"), 0},
   { "ignore-aux-cache", 'i', NULL, 0, N_("Ignore auxiliary cache file"), 0},
+  { "install", 'I', NULL, 0, N_("install pre-existing cache file"), 0},
   { NULL, 0, NULL, 0, NULL, 0 }
 };
 
@@ -197,6 +201,9 @@ parse_opt (int key, char *arg, struct argp_state *state)
       else if (strcmp (arg, "new") == 0)
 	opt_format = opt_format_new;
       break;
+    case 'I':
+      opt_install = 1;
+      break;
     default:
       return ARGP_ERR_UNKNOWN;
     }
@@ -1045,8 +1052,8 @@ main (int argc, char **argv)
   argp_parse (&argp, argc, argv, 0, &remaining, NULL);
 
   /* Remaining arguments are additional directories if opt_manual_link
-     is not set.  */
-  if (remaining != argc && !opt_manual_link)
+     and opt_install are not set.  */
+  if (remaining != argc && !opt_manual_link && !opt_install)
     {
       int i;
       for (i = remaining; i < argc; ++i)
@@ -1139,6 +1146,50 @@ main (int argc, char **argv)
       exit (0);
     }
 
+  if (opt_install)
+    {
+      if (argv[remaining] == NULL)
+	error (EXIT_FAILURE, 0, _("Missing source file name"));
+
+      char *source = (opt_chroot
+		      ? chroot_canon (opt_chroot, argv[remaining])
+		      : argv[remaining]);
+      if (source == NULL)
+	error (EXIT_FAILURE, errno, _("Can't find %s"), argv[remaining]);
+
+      int src_fd = open (source, O_RDONLY);
+      if (src_fd < 0)
+	error (EXIT_FAILURE, errno, _("Can't open %s"), source);
+
+      char *dest = xmalloc (strlen (cache_file) + 6 + 1);
+
+      sprintf(dest, "%sXXXXXX", cache_file);
+      int dest_fd = mkstemp (dest);
+      if (dest_fd < 0)
+	error (EXIT_FAILURE, errno, _("Can't create %s"), dest);
+
+      struct stat st;
+      if (fstat (src_fd, &st) < 0)
+	error (EXIT_FAILURE, errno, _("Can't stat %s"), source);
+
+      if (copy_file_range (src_fd, NULL, dest_fd, NULL, st.st_size, 0)
+	  < st.st_size)
+	error (EXIT_FAILURE, errno, _("Can't copy to %s"), dest);
+
+      /* Make sure user can always read cache file */
+      if (chmod (dest, S_IROTH|S_IRGRP|S_IRUSR|S_IWUSR))
+	error (EXIT_FAILURE, errno,
+	       _("Changing access rights of %s to %#o failed"), dest,
+	       S_IROTH|S_IRGRP|S_IRUSR|S_IWUSR);
+
+      fsync (dest_fd);
+      if (rename (dest, cache_file) < 0)
+	error (EXIT_FAILURE, errno, _("Can't rename %s to %s"), dest, cache_file);
+
+      close (src_fd);
+      close (dest_fd);
+      exit (0);
+    }
 
   if (opt_build_cache)
     init_cache ();
-- 
2.47.3