hurd: Refactor readlinkat()

Make the code flow more linear using early returns where possible. This
makes it so much easier to reason about what runs on error / successful
code paths.

Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
Message-Id: <20230212111044.610942-2-bugaevc@gmail.com>
This commit is contained in:
Sergey Bugaev 2023-02-12 14:10:32 +03:00 committed by Samuel Thibault
parent e42ec82219
commit 8a86e7b6a6

View File

@ -31,38 +31,47 @@ __readlinkat (int fd, const char *file_name, char *buf, size_t len)
error_t err;
file_t file_stat;
struct stat64 st;
enum retry_type doretry;
char retryname[1024];
file_t file;
char *rbuf = buf;
file_stat = __file_name_lookup_at (fd, 0, file_name, O_NOLINK, 0);
if (file_stat == MACH_PORT_NULL)
return -1;
err = __io_stat (file_stat, &st);
if (! err)
if (S_ISLNK (st.st_mode))
{
enum retry_type doretry;
char retryname[1024];
file_t file;
char *rbuf = buf;
err = __dir_lookup (file_stat, "", O_READ | O_NOLINK, 0, &doretry, retryname, &file);
if (! err && (doretry != FS_RETRY_NORMAL || retryname[0] != '\0'))
err = EGRATUITOUS;
if (! err)
{
err = __io_read (file, &rbuf, &len, 0, len);
if (!err && rbuf != buf)
{
memcpy (buf, rbuf, len);
__vm_deallocate (__mach_task_self (), (vm_address_t)rbuf, len);
}
__mach_port_deallocate (__mach_task_self (), file);
}
}
else
if (err)
goto out;
if (!S_ISLNK (st.st_mode))
{
err = EINVAL;
goto out;
}
err = __dir_lookup (file_stat, "", O_READ | O_NOLINK,
0, &doretry, retryname, &file);
if (err)
goto out;
if (doretry != FS_RETRY_NORMAL || retryname[0] != '\0')
{
err = EGRATUITOUS;
goto out;
}
err = __io_read (file, &rbuf, &len, 0, len);
__mach_port_deallocate (__mach_task_self (), file);
if (err)
goto out;
if (rbuf != buf)
{
memcpy (buf, rbuf, len);
__vm_deallocate (__mach_task_self (), (vm_address_t) rbuf, len);
}
out:
__mach_port_deallocate (__mach_task_self (), file_stat);
return err ? __hurd_fail (err) : len;