blockdev-util: add correct API for detecting if block device has partition scanning...

[thirdparty/systemd.git] / src / basic / alloc-util.c

diff --git a/src/basic/alloc-util.c b/src/basic/alloc-util.c
index ab7a42c4e20116a9cff540bb1e559943546cf796..5951e8c3d590c91f325364454d44aa08087889bd 100644 (file)
--- a/src/basic/alloc-util.c
+++ b/src/basic/alloc-util.c
@@ -1,11 +1,12 @@
 /* SPDX-License-Identifier: LGPL-2.1+ */
 
+#include <malloc.h>
 #include <stdint.h>
 #include <string.h>
 
 #include "alloc-util.h"
 #include "macro.h"
-#include "util.h"
+#include "memory-util.h"
 
 void* memdup(const void *p, size_t l) {
         void *ret;
@@ -27,6 +28,9 @@ void* memdup_suffix0(const void *p, size_t l) {
 
         /* The same as memdup() but place a safety NUL byte after the allocated memory */
 
+        if (_unlikely_(l == SIZE_MAX)) /* prevent overflow */
+                return NULL;
+
         ret = malloc(l + 1);
         if (!ret)
                 return NULL;
@@ -45,17 +49,44 @@ void* greedy_realloc(void **p, size_t *allocated, size_t need, size_t size) {
         if (*allocated >= need)
                 return *p;
 
-        newalloc = MAX(need * 2, 64u / size);
-        a = newalloc * size;
+        if (_unlikely_(need > SIZE_MAX/2)) /* Overflow check */
+                return NULL;
 
-        /* check for overflows */
-        if (a < size * need)
+        newalloc = need * 2;
+        if (size_multiply_overflow(newalloc, size))
                 return NULL;
 
+        a = newalloc * size;
+        if (a < 64) /* Allocate at least 64 bytes */
+                a = 64;
+
         q = realloc(*p, a);
         if (!q)
                 return NULL;
 
+        if (size > 0) {
+                size_t bn;
+
+                /* Adjust for the 64 byte minimum */
+                newalloc = a / size;
+
+                bn = malloc_usable_size(q) / size;
+                if (bn > newalloc) {
+                        void *qq;
+
+                        /* The actual size allocated is larger than what we asked for. Let's call realloc() again to
+                         * take possession of the extra space. This should be cheap, since libc doesn't have to move
+                         * the memory for this. */
+
+                        qq = reallocarray(q, bn, size);
+                        if (_likely_(qq)) {
+                                *p = qq;
+                                *allocated = bn;
+                                return qq;
+                        }
+                }
+        }
+
         *p = q;
         *allocated = newalloc;
         return q;