Use fstat to work out the lease file size and read in one go rather than

use a loop with a small growing buffer.

diff --git a/src/dhcp-common.c b/src/dhcp-common.c
index 2aec0d914dbb3767fd55051e62ac800bbaaee6b7..91aed334f1dddfc853ac7bfa2038381f0c483a16 100644 (file)
--- a/src/dhcp-common.c
+++ b/src/dhcp-common.c
@@ -25,6 +25,7 @@
  * SUCH DAMAGE.
  */
 
+#include <sys/stat.h>
 #include <sys/utsname.h>
 
 #include <ctype.h>
@@ -1060,34 +1061,32 @@ dhcp_zero_index(struct dhcp_opt *opt)
 size_t
 dhcp_read_lease_fd(int fd, void **lease)
 {
-       uint8_t *buf, *nbuf;
-       size_t len, new_len;
-       ssize_t bytes;
-
-       if ((buf = malloc(BUFSIZ)) == NULL)
+       struct stat st;
+       size_t sz;
+       void *buf;
+       ssize_t len;
+       
+       if (fstat(fd, &st) != 0)
+               goto out;
+       if (!S_ISREG(st.st_mode)) {
+               errno = EINVAL;
                goto out;
+       }
+       if (st.st_size > UINT32_MAX) {
+               errno = E2BIG;
+               goto out;
+       }
 
-       len = 0;
-       for (;;) {
-               bytes = read(fd, buf + len, BUFSIZ);
-               if (bytes == -1)
-                       break;
-               if (bytes < BUFSIZ) {
-                       *lease = buf;
-                       return len + (size_t)bytes;
-               }
-               new_len = len + (BUFSIZ * 2);
-               if (new_len > UINT32_MAX || new_len < len) {
-                       errno = E2BIG;
-                       break;
-               }
-               if ((nbuf = realloc(buf, new_len)) == NULL)
-                       break;
-               buf = nbuf;
-               len += BUFSIZ;
+       sz = (size_t)st.st_size;
+       if ((buf = malloc(sz)) == NULL)
+               goto out;
+       if ((len = read(fd, buf, sz)) == -1) {
+               free(buf);
+               goto out;
        }
+       *lease = buf;
+       return (size_t)len;
 
-       free(buf);
 out:
        *lease = NULL;
        return 0;