[glibc] hurd: Fix FS_RETRY_MAGICAL "machtype" handling

[Samuel Thibault <sthibaul@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=f56ad6174c62aa38f7edf68167d620482b776dc9

commit f56ad6174c62aa38f7edf68167d620482b776dc9
Author: Sergey Bugaev <bugaevc@gmail.com>
Date:   Sat Apr 29 16:13:54 2023 +0300

    hurd: Fix FS_RETRY_MAGICAL "machtype" handling
    
    We need to set file_name, not update retryname. This is what the other
    branches do.
    
    Before this change, any attempt to access such a file would segfault due
    to file_name being unset:
    
    $ settrans -ac /tmp/my-machtype /hurd/magic machtype
    $ cat /tmp/my-machtype
    Segmentation fault
    
    Checked on i686-gnu.
    
    Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
    Message-Id: <20230429131354.2507443-7-bugaevc@gmail.com>

Diff:
---
 hurd/lookup-retry.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/hurd/lookup-retry.c b/hurd/lookup-retry.c
index 99c981046f..62f94bbc92 100644
--- a/hurd/lookup-retry.c
+++ b/hurd/lookup-retry.c
@@ -277,7 +277,6 @@ __hurd_file_name_lookup_retry (error_t (*use_init_port)
 		  error_t err;
 		  struct host_basic_info hostinfo;
 		  mach_msg_type_number_t hostinfocnt = HOST_BASIC_INFO_COUNT;
-		  char *p;
 		  /* XXX want client's host */
 		  if (err = __host_info (__mach_host_self (), HOST_BASIC_INFO,
 					 (integer_t *) &hostinfo,
@@ -288,13 +287,11 @@ __hurd_file_name_lookup_retry (error_t (*use_init_port)
 		      err = EGRATUITOUS;
 		      goto out;
 		    }
-		  p = _itoa (hostinfo.cpu_subtype, &retryname[8], 10, 0);
-		  *--p = '/';
-		  p = _itoa (hostinfo.cpu_type, &retryname[8], 10, 0);
-		  if (p < retryname)
+		  file_name = _itoa (hostinfo.cpu_subtype, &retryname[8], 10, 0);
+		  *--file_name = '/';
+		  file_name = _itoa (hostinfo.cpu_type, file_name, 10, 0);
+		  if (file_name < retryname)
 		    abort ();	/* XXX write this right if this ever happens */
-		  if (p > retryname)
-		    memmove (retryname, p, strlen(p) + 1);
 		  startdir = *result;
 		}
 	      else