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When looking for a device match, do a breadth-first search instead

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of depth-first.  We already special case /dev/pts/ so chances are
good that if it is not a pseudo-tty it is in the base of /dev/.
Also avoid a stat(2) when possible if struct dirent has d_type.
This commit is contained in:
Todd C. Miller
2012-04-13 16:00:32 -04:00
parent 5f969cc12a
commit 48d3b5aad1
1 changed files with 34 additions and 14 deletions
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48
src/ttyname.c
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@@ -154,7 +154,7 @@ sudo_ttyname_dev(dev_t tdev)
}
#else
/*
* Devices to search before doing a depth-first scan.
* Devices to search before doing a breadth-first scan.
* XXX - use /etc/ttysrch too (for Solaris).
* XXX - add tty* w/ wildcards?
*/
@@ -177,14 +177,14 @@ static char *ignore_devs[] = {
};
/*
* Do a depth-first scan of dir looking for the specified device.
* Do a breadth-first scan of dir looking for the specified device.
*/
static
char *sudo_ttyname_scan(const char *dir, dev_t rdev, bool builtin)
{
DIR *d;
char pathbuf[PATH_MAX], *devname = NULL;
size_t sdlen, d_len, len;
char pathbuf[PATH_MAX], **subdirs = NULL, *devname = NULL;
size_t sdlen, d_len, len, num_subdirs = 0, max_subdirs = 0;
struct dirent *dp;
struct stat sb;
int i;
@@ -237,21 +237,41 @@ char *sudo_ttyname_scan(const char *dir, dev_t rdev, bool builtin)
if (search_devs[i] != NULL)
continue;
}
if (stat(pathbuf, &sb) == 0) {
if (S_ISDIR(sb.st_mode)) {
if (!builtin)
devname = sudo_ttyname_scan(pathbuf, rdev, builtin);
continue;
}
if (S_ISCHR(sb.st_mode) && sb.st_rdev == rdev) {
devname = estrdup(pathbuf);
break;
# if defined(HAVE_STRUCT_DIRENT_D_TYPE) && defined(DTTOIF)
/* Use d_type to avoid a stat() if possible. */
/* Convert d_type to stat-style type bits but follow links. */
if (dp->d_type != DT_LNK && dp->d_type != DT_CHR)
sb.st_mode = DTTOIF(dp->d_type);
else
# endif
if (stat(pathbuf, &sb) == -1)
continue;
if (S_ISDIR(sb.st_mode)) {
if (!builtin) {
/* Add to list of subdirs to search. */
if (num_subdirs + 1 > max_subdirs) {
max_subdirs += 64;
subdirs = erealloc3(subdirs, max_subdirs, sizeof(char *));
}
subdirs[num_subdirs++] = estrdup(pathbuf);
}
continue;
}
if (S_ISCHR(sb.st_mode) && sb.st_rdev == rdev) {
devname = estrdup(pathbuf);
break;
}
}
closedir(d);
/* Search subdirs if we didn't find it in the root level. */
for (i = 0; devname == NULL && i < num_subdirs; i++)
devname = sudo_ttyname_scan(subdirs[i], rdev, false);
done:
for (i = 0; i < num_subdirs; i++)
efree(subdirs[i]);
efree(subdirs);
debug_return_str(devname);
}
@@ -299,7 +319,7 @@ sudo_ttyname_dev(dev_t rdev)
}
/*
* Not found? Do a depth-first traversal of /dev/.
* Not found? Do a breadth-first traversal of /dev/.
*/
if (tty == NULL)
tty = sudo_ttyname_scan(_PATH_DEV, rdev, false);