ref: 567d60c3af74d0ac4d9d2ed91d0f548963ce9693
parent: 4d213b31b890011f120146f0d760d7ffd70f75b9
author: Natanael Copa <ncopa@alpinelinux.org>
date: Thu Oct 8 12:00:10 CDT 2015
nlplug-findfs: save stackspace while recursing dir tree avoid allocate PATH_MAX on stack for every dir. Instead reuse the path buffer.
--- a/nlplug-findfs.c
+++ b/nlplug-findfs.c
@@ -264,9 +264,10 @@
void *userdata;
};
-void recurse_dir(const char *dir, struct recurse_opts *opts)
+/* pathbuf needs hold PATH_MAX chars */
+void recurse_dir(char *pathbuf, struct recurse_opts *opts)
{- DIR *d = opendir(dir);
+ DIR *d = opendir(pathbuf);
struct dirent *entry;
if (d == NULL)
@@ -273,29 +274,39 @@
return;
while ((entry = readdir(d)) != NULL) {- char path[PATH_MAX];
struct stat st;
+ size_t pathlen = strlen(pathbuf);
+ size_t namelen = strlen(entry->d_name);
/* d_type is not supported by all filesystems so we need
lstat */
- snprintf(path, sizeof(path), "%s/%s", dir, entry->d_name);
- if (lstat(path, &st) < 0) {- dbg("%s: %s", path, strerror(errno));+ if (pathlen + 2 + namelen > PATH_MAX) {+ dbg("path length overflow");continue;
}
+ pathbuf[pathlen] = '/';
+ strcpy(&pathbuf[pathlen+1], entry->d_name);
+
+ if (lstat(pathbuf, &st) < 0) {+ dbg("%s: %s", pathbuf, strerror(errno));+ goto next;
+ }
+
if (S_ISDIR(st.st_mode)) {if (entry->d_name[0] == '.')
- continue;
+ goto next;
} else if (opts->searchname
&& strcmp(entry->d_name, opts->searchname) != 0) {- continue;
+ goto next;
}
if (S_ISDIR(st.st_mode))
- recurse_dir(path, opts);
+ recurse_dir(pathbuf, opts);
else
- opts->callback(path, opts->userdata);
+ opts->callback(pathbuf, opts->userdata);
+next:
+ pathbuf[pathlen] = '\0';
}
closedir(d);
}
@@ -570,8 +581,11 @@
.callback = trigger_uevent_cb,
.userdata = NULL,
};
- recurse_dir("/sys/bus", &opts);- recurse_dir("/sys/devices", &opts);+ char path[PATH_MAX] = "/sys/bus";
+
+ recurse_dir(path, &opts);
+ strcpy(path, "/sys/devices");
+ recurse_dir(path, &opts);
write(fd, &ok, sizeof(ok));
return NULL;
}