stage1: Move the symlink creation from stage1 to init.

In order to run stage1 we now need to do things a little differently,
namely that we move the symlinking fixups into 'init' itself which we will
actually call as a kind of fake switch_root implementation to avoid
hacking dracut too much[1]. As we run stage1 during dracut's 'mount' phase
we should not do the symlink hacks so early otherwise it will mess up
the rest of the dracut initqueue processing.

Currently, the initrd's /usr is nuked and then symlinked, but to
allow for easier debugging I now just bind mount the stage2 /usr over
the top which allows us to unmount it again easily enough if we want to
go back.

We no longer touch the /bin, /sbin or /lib[64] symlinks as these are
relative and simply bind mounting /usr is enough to fix all of them.

1. This scheme will have to change if we eventually swtich to a
systemd based dracut invocation.

1 files changed, 86 insertions, 6 deletions

diff --git a/mdk-stage1/init.c b/mdk-stage1/init.c
index 3f912c2ac..6d571a62a 100644
--- a/mdk-stage1/init.c
+++ b/mdk-stage1/init.c
@@ -22,6 +22,7 @@
 #include <stdlib.h>
 #include <unistd.h>
 #include <stdio.h>
+#include <dirent.h>
 #include <string.h>
 #include <sys/types.h>
 #include <sys/socket.h>
@@ -378,7 +379,86 @@ int in_reboot(void)
         return 0;
 }
 
-int exit_value_proceed = 66;
+int recursive_remove(char *file);
+int recursive_remove(char *file)
+{
+	struct stat sb;
+
+	if (lstat(file, &sb) != 0) {
+		printf("failed to stat %s: %d\n", file, errno);
+		return -1;
+	}
+
+	/* only descend into subdirectories if device is same as dir */
+	if (S_ISDIR(sb.st_mode)) {
+		char * strBuf = alloca(strlen(file) + 1024);
+		DIR * dir;
+		struct dirent * d;
+
+		if (!(dir = opendir(file))) {
+			printf("error opening %s: %d\n", file, errno);
+			return -1;
+		}
+		while ((d = readdir(dir))) {
+			if (!strcmp(d->d_name, ".") || !strcmp(d->d_name, ".."))
+				continue;
+
+			strcpy(strBuf, file);
+			strcat(strBuf, "/");
+			strcat(strBuf, d->d_name);
+
+			if (recursive_remove(strBuf) != 0) {
+				closedir(dir);
+				return -1;
+			}
+		}
+		closedir(dir);
+
+		if (rmdir(file)) {
+			printf("failed to rmdir %s: %d\n", file, errno);
+			return -1;
+		}
+	} else {
+		if (unlink(file) != 0) {
+			printf("failed to remove %s: %d\n", file, errno);
+			return -1;
+		}
+	}
+	return 0;
+}
+
+
+int create_initial_fs_symlinks(char* symlinks)
+{
+        FILE *f;
+        char buf[5000];
+
+        if (!(f = fopen(symlinks, "rb"))) {
+                printf("Error opening symlink definitions file '%s'\n", symlinks);
+                return -1;
+        }
+        while (fgets(buf, sizeof(buf), f)) {
+                char oldpath[500], newpath[500];
+                struct stat sb;
+
+                buf[strlen(buf)-1] = '\0';  // trim \n
+                if (sscanf(buf, "%s %s", oldpath, newpath) != 2) {
+                        sprintf(oldpath, "%s%s", STAGE2_LOCATION, buf);
+                        sprintf(newpath, "%s", buf);
+                }
+                if (lstat(newpath, &sb) == 0)
+                        recursive_remove(newpath);
+                printf("Creating symlink %s -> %s\n", oldpath, newpath);
+                if (symlink(oldpath, newpath)) {
+                        printf("Error creating symlink\n");
+                        return -1;
+                }
+        }
+        fclose(f);
+        return 0;
+}
+
+
 int exit_value_restart = 0x35;
 
 int main(int argc, char **argv)
@@ -454,12 +534,12 @@ int main(int argc, char **argv)
 	if (!testing) 
 		doklog();
 
-	/* Go into normal init mode - keep going, and then do a orderly shutdown
-	   when:
+	if (create_initial_fs_symlinks(STAGE2_LOCATION "/usr/share/symlinks") != 0)
+		fatal_error("Fatal error finishing initialization (could not create symlinks).");
+
+	if (mount(STAGE2_LOCATION "/usr", "/usr", "none", MS_BIND|MS_RDONLY, NULL))
+		fatal_error("Unable to bind mount /usr filesystem from rescue or installer stage2");
 
-	   1) install exits
-	   2) we receive a SIGHUP 
-	*/
 
         do {
 		if (counter == 1) {