avoid asking ?alloc() for zero bytes.

Avoid asking for zero bytes when that change simplifies overall
logic.  Later we would change the wrapper to ask for 1 byte on
platforms that return NULL for zero byte request.

Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/diff.c b/diff.c
index c815918..bfc864d 100644 (file)
--- a/diff.c
+++ b/diff.c
@@ -504,9 +504,9 @@ static void prepare_temp_file(const char *name,
                }
                if (S_ISLNK(st.st_mode)) {
                        int ret;
-                       char *buf, buf_[1024];
-                       buf = ((sizeof(buf_) < st.st_size) ?
-                              xmalloc(st.st_size) : buf_);
+                       char buf[PATH_MAX + 1]; /* ought to be SYMLINK_MAX */
+                       if (sizeof(buf) <= st.st_size)
+                               die("symlink too long: %s", name);
                        ret = readlink(name, buf, st.st_size);
                        if (ret < 0)
                                die("readlink(%s)", name);

diff --git a/diffcore-order.c b/diffcore-order.c
index b381223..0bc2b22 100644 (file)
--- a/diffcore-order.c
+++ b/diffcore-order.c
@@ -105,9 +105,13 @@ static int compare_pair_order(const void *a_, const void *b_)
 void diffcore_order(const char *orderfile)
 {
        struct diff_queue_struct *q = &diff_queued_diff;
-       struct pair_order *o = xmalloc(sizeof(*o) * q->nr);
+       struct pair_order *o;
        int i;
 
+       if (!q->nr)
+               return;
+
+       o = xmalloc(sizeof(*o) * q->nr);
        prepare_order(orderfile);
        for (i = 0; i < q->nr; i++) {
                o[i].pair = q->queue[i];

diff --git a/diffcore-pathspec.c b/diffcore-pathspec.c
index 68fe009..139fe88 100644 (file)
--- a/diffcore-pathspec.c
+++ b/diffcore-pathspec.c
@@ -48,6 +48,9 @@ void diffcore_pathspec(const char **pathspec)
        for (i = 0; pathspec[i]; i++)
                ;
        speccnt = i;
+       if (!speccnt)
+               return;
+
        spec = xmalloc(sizeof(*spec) * speccnt);
        for (i = 0; pathspec[i]; i++) {
                spec[i].spec = pathspec[i];

diff --git a/index-pack.c b/index-pack.c
index d4ce3af..541d7bc 100644 (file)
--- a/index-pack.c
+++ b/index-pack.c
@@ -352,18 +352,24 @@ static int sha1_compare(const void *_a, const void *_b)
 static void write_index_file(const char *index_name, unsigned char *sha1)
 {
        struct sha1file *f;
-       struct object_entry **sorted_by_sha =
-               xcalloc(nr_objects, sizeof(struct object_entry *));
-       struct object_entry **list = sorted_by_sha;
-       struct object_entry **last = sorted_by_sha + nr_objects;
+       struct object_entry **sorted_by_sha, **list, **last;
        unsigned int array[256];
        int i;
        SHA_CTX ctx;
 
-       for (i = 0; i < nr_objects; ++i)
-               sorted_by_sha[i] = &objects[i];
-       qsort(sorted_by_sha, nr_objects, sizeof(sorted_by_sha[0]),
-             sha1_compare);
+       if (nr_objects) {
+               sorted_by_sha =
+                       xcalloc(nr_objects, sizeof(struct object_entry *));
+               list = sorted_by_sha;
+               last = sorted_by_sha + nr_objects;
+               for (i = 0; i < nr_objects; ++i)
+                       sorted_by_sha[i] = &objects[i];
+               qsort(sorted_by_sha, nr_objects, sizeof(sorted_by_sha[0]),
+                     sha1_compare);
+
+       }
+       else
+               sorted_by_sha = list = last = NULL;
 
        unlink(index_name);
        f = sha1create("%s", index_name);

diff --git a/read-tree.c b/read-tree.c
index e3b9c0d..a46c6fe 100644 (file)
--- a/read-tree.c
+++ b/read-tree.c
@@ -294,17 +294,20 @@ static int unpack_trees(merge_fn_t fn)
 {
        int indpos = 0;
        unsigned len = object_list_length(trees);
-       struct tree_entry_list **posns = 
-               xmalloc(len * sizeof(struct tree_entry_list *));
+       struct tree_entry_list **posns;
        int i;
        struct object_list *posn = trees;
        merge_size = len;
-       for (i = 0; i < len; i++) {
-               posns[i] = ((struct tree *) posn->item)->entries;
-               posn = posn->next;
+
+       if (len) {
+               posns = xmalloc(len * sizeof(struct tree_entry_list *));
+               for (i = 0; i < len; i++) {
+                       posns[i] = ((struct tree *) posn->item)->entries;
+                       posn = posn->next;
+               }
+               if (unpack_trees_rec(posns, len, "", fn, &indpos))
+                       return -1;
        }
-       if (unpack_trees_rec(posns, len, "", fn, &indpos))
-               return -1;
 
        if (trivial_merges_only && nontrivial_merge)
                die("Merge requires file-level merging");

diff --git a/tree-diff.c b/tree-diff.c
index 0ef06a9..382092b 100644 (file)
--- a/tree-diff.c
+++ b/tree-diff.c
@@ -263,6 +263,10 @@ void diff_tree_setup_paths(const char **p)
 
                paths = p;
                nr_paths = count_paths(paths);
+               if (nr_paths == 0) {
+                       pathlens = NULL;
+                       return;
+               }
                pathlens = xmalloc(nr_paths * sizeof(int));
                for (i=0; i<nr_paths; i++)
                        pathlens[i] = strlen(paths[i]);