[PATCH 23/35] perf tools: Add reallocarray_as_needed()

Adrian Hunter
2022-07-11T10:13:25Z

Add helper reallocarray_as_needed() to reallocate an array to a larger
size and initialize the extra entries to an arbitrary value.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
tools/perf/util/util.c | 33 +++++++++++++++++++++++++++++++++
tools/perf/util/util.h | 15 +++++++++++++++
2 files changed, 48 insertions(+)

diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
index 9b02edf9311d..391c1e928bd7 100644
--- a/tools/perf/util/util.c
+++ b/tools/perf/util/util.c
@@ -18,6 +18,7 @@
#include <linux/kernel.h>
#include <linux/log2.h>
#include <linux/time64.h>
+#include <linux/overflow.h>
#include <unistd.h>
#include "cap.h"
#include "strlist.h"
@@ -500,3 +501,35 @@ char *filename_with_chroot(int pid, const char *filename)

return new_name;
}
+
+/*
+ * Reallocate an array *arr of size *arr_sz so that it is big enough to contain
+ * x elements of size msz, initializing new entries to *init_val or zero if
+ * init_val is NULL
+ */
+int do_realloc_array_as_needed(void **arr, size_t *arr_sz, size_t x, size_t msz, const void *init_val)
+{
+ size_t new_sz = *arr_sz;
+ void *new_arr;
+ size_t i;
+
+ if (!new_sz)
+ new_sz = msz >= 64 ? 1 : roundup(64, msz); /* Start with at least 64 bytes */
+ while (x >= new_sz) {
+ if (check_mul_overflow(new_sz, (size_t)2, &new_sz))
+ return -ENOMEM;
+ }
+ if (new_sz == *arr_sz)
+ return 0;
+ new_arr = calloc(new_sz, msz);
+ if (!new_arr)
+ return -ENOMEM;
+ memcpy(new_arr, *arr, *arr_sz * msz);
+ if (init_val) {
+ for (i = *arr_sz; i < new_sz; i++)
+ memcpy(new_arr + (i * msz), init_val, msz);
+ }
+ *arr = new_arr;
+ *arr_sz = new_sz;
+ return 0;
+}
diff --git a/tools/perf/util/util.h b/tools/perf/util/util.h
index 0f78f1e7782d..c1f2d423a9ec 100644
--- a/tools/perf/util/util.h
+++ b/tools/perf/util/util.h
@@ -79,4 +79,19 @@ struct perf_debuginfod {
void perf_debuginfod_setup(struct perf_debuginfod *di);

char *filename_with_chroot(int pid, const char *filename);
+
+int do_realloc_array_as_needed(void **arr, size_t *arr_sz, size_t x,
+ size_t msz, const void *init_val);
+
+#define realloc_array_as_needed(a, n, x, v) ({ \
+ typeof(x) __x = (x); \
+ __x >= (n) ? \
+ do_realloc_array_as_needed((void **)&(a), \
+ &(n), \
+ __x, \
+ sizeof(*(a)), \
+ (const void *)(v)) : \
+ 0; \
+ })
+
#endif /* GIT_COMPAT_UTIL_H */
--
2.25.1