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hurd: Disable O_TRUNC and FS_RETRY_MAGICAL in rtld

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hurd/lookup-retry.c is compiled into rtld, the dynamic linker/loader. To
avoid pulling in file_set_size, file_utimens, tty/ctty stuff, more
string/memory code (memmove, strncpy, strcpy), and more strtoul/itoa
code, compile out support for O_TRUNC and FS_RETRY_MAGICAL when building
hurd/lookup-retry.c for rtld. None of that functionality is useful to
rtld during startup anyway. Keep support for FS_RETRY_MAGICAL("/"),
since that does not pull in much, and is required for following absolute
symlinks.

The large number of extra code being pulled into rtld was noticed by
reviewing librtld.map & elf/librtld.os.map in the build tree.

It is worth noting that once libc.so is loaded, the real __open, __stat,
etc. replace the minimal versions used initially by rtld -- this is
especially important in the Hurd port, where the minimal rtld versions
do not use the dtable and just pass real Mach port names as fds. Thus,
once libc.so is loaded, rtld will gain access to the full
__hurd_file_name_lookup_retry () version, complete with FS_RETRY_MAGICAL
support, which is important in case the program decides to
dlopen ("/proc/self/fd/...") or some such.

Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
Message-Id: <20230319151017.531737-9-bugaevc@gmail.com>
This commit is contained in:
Sergey Bugaev 2023-03-19 18:09:51 +03:00 • committed by Samuel Thibault
parent 6a73ea505b
commit 543f0cfc9a
1 changed files with 5 additions and 2 deletions
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7
hurd/lookup-retry.c
View file

@ -177,7 +177,7 @@ __hurd_file_name_lookup_retry (error_t (*use_init_port)
/* We got a successful translation. Now apply any open-time
action flags we were passed. */
#if !IS_IN (rtld)
if (!err && (flags & O_TRUNC))
{
/* Asked to truncate the file. */
@ -189,6 +189,7 @@ __hurd_file_name_lookup_retry (error_t (*use_init_port)
__file_utimens (*result, atime, mtime);
}
}
#endif
if (err)
__mach_port_deallocate (__mach_task_self (), *result);
@ -214,6 +215,7 @@ __hurd_file_name_lookup_retry (error_t (*use_init_port)
file_name = &retryname[1];
break;
#if !IS_IN (rtld)
case 'f':
if (retryname[1] == 'd' && retryname[2] == '/')
{
@ -358,8 +360,9 @@ __hurd_file_name_lookup_retry (error_t (*use_init_port)
goto bad_magic;
break;
default:
bad_magic:
#endif /* !IS_IN (rtld) */
default:
err = EGRATUITOUS;
goto out;
}