lxc-user-nic: improve cull_entries

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>

diff --git a/src/lxc/lxc_user_nic.c b/src/lxc/lxc_user_nic.c
index 7d367c1ffc120b7bb1bfc0348c40d86449b0a1a0..7ac30201d3681d64b8d7f192dd3547a2800d9049 100644 (file)
--- a/src/lxc/lxc_user_nic.c
+++ b/src/lxc/lxc_user_nic.c
@@ -622,11 +622,19 @@ static bool get_nic_from_line(char *p, char **nic)
        return true;
 }
 
+struct entry_line {
+       char *start;
+       int len;
+       bool keep;
+};
+
 static bool cull_entries(int fd, char *me, char *t, char *br)
 {
        struct stat sb;
        char *buf, *p, *e, *nic;
        off_t len;
+       struct entry_line *entry_lines = NULL;
+       int i, n = 0;
 
        nic = alloca(100);
 
@@ -643,22 +651,36 @@ static bool cull_entries(int fd, char *me, char *t, char *br)
        p = buf;
        e = buf + len;
        while ((p = find_line(p, e, me, t, br)) != NULL) {
+               struct entry_line *newe = realloc(entry_lines, n+1);
+               if (!newe) {
+                       free(entry_lines);
+                       return false;
+               }
+               entry_lines = newe;
+               entry_lines[n].start = p;
+               entry_lines[n].len = get_eol(p) - entry_lines[n].start;
+               entry_lines[n].keep = true;
+               n++;
                if (!get_nic_from_line(p, &nic))
                        continue;
-               if (nic && !nic_exists(nic)) {
-                       // copy from eol(p)+1..e to p
-                       char *src = get_eol(p) + 1, *dest = p;
-                       int diff = src - p;
-                       while (src < e)
-                               *(dest++) = *(src)++;
-                       e -= diff;
-               } else
-                       p = get_eol(p) + 1;
+               if (nic && !nic_exists(nic))
+                       entry_lines[n-1].keep = false;
+               p += entry_lines[n-1].len + 1;
                if (p >= e)
                        break;
        }
+       p = buf;
+       for (i=0; i<n; i++) {
+               if (!entry_lines[i].keep)
+                       continue;
+               memcpy(p, entry_lines[i].start, entry_lines[i].len);
+               p += entry_lines[i].len;
+               *p = '\n';
+               p++;
+       }
+       free(entry_lines);
        munmap(buf, sb.st_size);
-       if (ftruncate(fd, e-buf))
+       if (ftruncate(fd, p-buf))
                fprintf(stderr, "Failed to set new file size\n");
        return true;
 }