From dfa085603d6e04b40d00de385040b58e78310ec5 Mon Sep 17 00:00:00 2001
From: Iustin Pop <iustin@k1024.org>
Date: Sat, 5 Jun 2021 03:46:48 +0200
Subject: [PATCH] Remove auto-detection of optimal buffer size

Since we don't pass zero anymore, this code is never called. Replace
it with 'zero means hardcoded initial value', since that hardcoded
value is what we were already passing, and change all the callers to
pass in zero (as 'auto-compute' again) instead, for simplicity.
---
 xattr.c | 37 +++++++++++++------------------------
 1 file changed, 13 insertions(+), 24 deletions(-)

diff --git a/xattr.c b/xattr.c
index e118f79..ab21fac 100644
--- a/xattr.c
+++ b/xattr.c
@@ -311,13 +311,11 @@ static int _remove_obj(target_t *tgt, const char *name) {
  * - buffer: pointer to either an already allocated memory area (in
  *   which case size contains its current size), or NULL to
  *   allocate. In all cases (success or failure), the caller should
- *   deallocate the buffer, using PyMem_Free(). Note that if size is
- *   zero but buffer already points to allocate memory, it will be
- *   ignored/leaked.
+ *   deallocate the buffer, using PyMem_Free().
  * - size: either size of current buffer (if non-NULL), or size for
- *   initial allocation (if non-zero), or a zero value which means
- *   auto-allocate buffer with automatically queried size. Value will
- *   be updated upon return with the current buffer size.
+ *   initial allocation; zero means use a hardcoded initial buffer
+ *   size (ESTIMATE_ATTR_SIZE). The value will be updated upon return
+ *   with the current buffer size.
  * - io_errno: if non-NULL, the actual errno will be recorded here; if
  *   zero, the call was successful and the output/size/nval are valid.
  *
@@ -354,18 +352,9 @@ static ssize_t _generic_get(buf_getter getter, target_t *tgt,
   }
 
   /* Initialize the buffer, if needed. */
-  if (*size == 0 || *buffer == NULL) {
-    if (*size == 0) {
-      ssize_t nalloc;
-      if ((nalloc = getter(tgt, name, NULL, 0)) == -1) {
-        EXIT_IOERROR();
-      }
-      if (nalloc == 0) {
-        /* Empty, so no need to retrieve it. */
-        return 0;
-      }
-      *size = nalloc;
-    }
+  if (*buffer == NULL) {
+    if (*size == 0)
+      *size = ESTIMATE_ATTR_SIZE;
     if((*buffer = PyMem_Malloc(*size)) == NULL) {
       PyErr_NoMemory();
       return -1;
@@ -443,7 +432,7 @@ pygetxattr(PyObject *self, PyObject *args)
     char *attrname = NULL;
     char *buf = NULL;
     ssize_t nret;
-    size_t nalloc = ESTIMATE_ATTR_SIZE;
+    size_t nalloc = 0;
     PyObject *res;
 
     /* Parse the arguments */
@@ -507,7 +496,7 @@ xattr_get(PyObject *self, PyObject *args, PyObject *keywds)
     char *buf = NULL;
     const char *ns = NULL;
     ssize_t nret;
-    size_t nalloc = ESTIMATE_ATTR_SIZE;
+    size_t nalloc = 0;
     PyObject *res = NULL;
     static char *kwlist[] = {"item", "name", "nofollow", "namespace", NULL};
 
@@ -591,7 +580,7 @@ get_all(PyObject *self, PyObject *args, PyObject *keywds)
     const char *ns = NULL;
     char *buf_list = NULL, *buf_val = NULL;
     const char *s;
-    size_t nalloc = ESTIMATE_ATTR_SIZE;
+    size_t nalloc = 0;
     ssize_t nlist, nval;
     PyObject *mylist;
     target_t tgt;
@@ -621,7 +610,7 @@ get_all(PyObject *self, PyObject *args, PyObject *keywds)
       goto free_buf_list;
     }
 
-    nalloc = ESTIMATE_ATTR_SIZE;
+    nalloc = 0;
     /* Create and insert the attributes as strings in the list */
     for(s = buf_list; s - buf_list < nlist; s += strlen(s) + 1) {
         PyObject *my_tuple;
@@ -970,7 +959,7 @@ pylistxattr(PyObject *self, PyObject *args)
     char *buf = NULL;
     int nofollow = 0;
     ssize_t nret;
-    size_t nalloc = ESTIMATE_ATTR_SIZE;
+    size_t nalloc = 0;
     PyObject *myarg;
     PyObject *mylist;
     Py_ssize_t nattrs;
@@ -1053,7 +1042,7 @@ xattr_list(PyObject *self, PyObject *args, PyObject *keywds)
     char *buf = NULL;
     int nofollow = 0;
     ssize_t nret;
-    size_t nalloc = ESTIMATE_ATTR_SIZE;
+    size_t nalloc = 0;
     PyObject *myarg;
     PyObject *res;
     const char *ns = NULL;
-- 
2.39.2