Fix calculations in clone_update_unexp_hooks()

Changes v3:
(1) Fix typo (q --> p).

(1) This commit fixes the calculations when updating paths in lxc.hooks.*
    entries. We now also update conf->unexpandend_alloced which hasn't been
done prior to this commit.

(2) Also we use the stricter check:

    	if (p >= lend)
    		continue;

    This should deal better with invalid config files.

(3) Insert some spaces between operators to increase readability.

(4) Use gotos to simplify function and increase readability.

Signed-off-by: Christian Brauner <christianvanbrauner@gmail.com>
Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>

diff --git a/src/lxc/confile.c b/src/lxc/confile.c
index d5849643469ac1f0f780554f8cc731f11d43589d..c2eaaa6ce2d6f14f19e9d092fafccadfdf183513 100644 (file)
--- a/src/lxc/confile.c
+++ b/src/lxc/confile.c
@@ -2695,7 +2695,8 @@ next:
 }
 
 bool clone_update_unexp_hooks(struct lxc_conf *conf, const char *oldpath,
-       const char *newpath, const char *oldname, const char *newname)
+                             const char *newpath, const char *oldname,
+                             const char *newname)
 {
        const char *key = "lxc.hook";
        int ret;
@@ -2705,13 +2706,13 @@ bool clone_update_unexp_hooks(struct lxc_conf *conf, const char *oldpath,
        char *olddir = alloca(olddirlen + 1);
        char *newdir = alloca(newdirlen + 1);
 
-       ret = snprintf(olddir, olddirlen+1, "%s/%s", oldpath, oldname);
-       if (ret < 0 || ret >= olddirlen+1) {
+       ret = snprintf(olddir, olddirlen + 1, "%s/%s", oldpath, oldname);
+       if (ret < 0 || ret >= olddirlen + 1) {
                ERROR("Bug in %s", __func__);
                return false;
        }
-       ret = snprintf(newdir, newdirlen+1, "%s/%s", newpath, newname);
-       if (ret < 0 || ret >= newdirlen+1) {
+       ret = snprintf(newdir, newdirlen + 1, "%s/%s", newpath, newname);
+       if (ret < 0 || ret >= newdirlen + 1) {
                ERROR("Bug in %s", __func__);
                return false;
        }
@@ -2723,56 +2724,53 @@ bool clone_update_unexp_hooks(struct lxc_conf *conf, const char *oldpath,
                        lend = lstart + strlen(lstart);
                else
                        lend++;
-               if (strncmp(lstart, key, strlen(key)) != 0) {
-                       lstart = lend;
-                       continue;
-               }
-               p = strchr(lstart+strlen(key), '=');
-               if (!p) {
-                       lstart = lend;
-                       continue;
-               }
+               if (strncmp(lstart, key, strlen(key)) != 0)
+                        goto next;
+               p = strchr(lstart + strlen(key), '=');
+               if (!p)
+                        goto next;
                p++;
                while (isblank(*p))
                        p++;
-               if (!*p)
-                       return true;
-               if (strncmp(p, olddir, strlen(olddir)) != 0) {
-                       lstart = lend;
-                       continue;
-               }
+                if (p >= lend)
+                        goto next;
+               if (strncmp(p, olddir, strlen(olddir)) != 0)
+                        goto next;
                /* replace the olddir with newdir */
                if (olddirlen >= newdirlen) {
                        size_t diff = olddirlen - newdirlen;
                        memcpy(p, newdir, newdirlen);
                        if (olddirlen != newdirlen) {
-                               memmove(lend-diff, lend, strlen(lend)+1);
+                               memmove(p + newdirlen, p + newdirlen + diff,
+                                       strlen(p) - newdirlen - diff + 1);
                                lend -= diff;
                                conf->unexpanded_len -= diff;
                        }
-                       lstart = lend;
                } else {
                        char *new;
                        size_t diff = newdirlen - olddirlen;
                        size_t oldlen = conf->unexpanded_len;
                        size_t newlen = oldlen + diff;
                        size_t poffset = p - conf->unexpanded_config;
-                       new = realloc(conf->unexpanded_config, newlen);
+                       new = realloc(conf->unexpanded_config, newlen + 1);
                        if (!new) {
                                ERROR("Out of memory");
                                return false;
                        }
                        conf->unexpanded_len = newlen;
-                       new[newlen-1] = '\0';
+                       conf->unexpanded_alloced = newlen + 1;
+                       new[newlen - 1] = '\0';
                        lend = new + (lend - conf->unexpanded_config);
-                       /* move over the remainder, /$hookname\n$rest */
-                       memmove(new+poffset+newdirlen,
-                                       new+poffset+olddirlen,
-                                       oldlen-poffset-olddirlen);
+                       /* move over the remainder to make room for the newdir */
+                       memmove(new + poffset + newdirlen,
+                               new + poffset + olddirlen,
+                               oldlen - poffset - olddirlen + 1);
                        conf->unexpanded_config = new;
-                       memcpy(new+poffset, newdir, newdirlen);
-                       lstart = lend + diff;
+                       memcpy(new + poffset, newdir, newdirlen);
+                       lend += diff;
                }
+next:
+                       lstart = lend;
        }
        return true;
 }