v4.19.13 snapshot.
diff --git a/tools/lib/subcmd/subcmd-util.h b/tools/lib/subcmd/subcmd-util.h
new file mode 100644
index 0000000..794a375
--- /dev/null
+++ b/tools/lib/subcmd/subcmd-util.h
@@ -0,0 +1,83 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __SUBCMD_UTIL_H
+#define __SUBCMD_UTIL_H
+
+#include <stdarg.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#define NORETURN __attribute__((__noreturn__))
+
+static inline void report(const char *prefix, const char *err, va_list params)
+{
+ char msg[1024];
+ vsnprintf(msg, sizeof(msg), err, params);
+ fprintf(stderr, " %s%s\n", prefix, msg);
+}
+
+static NORETURN inline void die(const char *err, ...)
+{
+ va_list params;
+
+ va_start(params, err);
+ report(" Fatal: ", err, params);
+ exit(128);
+ va_end(params);
+}
+
+#define zfree(ptr) ({ free(*ptr); *ptr = NULL; })
+
+#define alloc_nr(x) (((x)+16)*3/2)
+
+/*
+ * Realloc the buffer pointed at by variable 'x' so that it can hold
+ * at least 'nr' entries; the number of entries currently allocated
+ * is 'alloc', using the standard growing factor alloc_nr() macro.
+ *
+ * DO NOT USE any expression with side-effect for 'x' or 'alloc'.
+ */
+#define ALLOC_GROW(x, nr, alloc) \
+ do { \
+ if ((nr) > alloc) { \
+ if (alloc_nr(alloc) < (nr)) \
+ alloc = (nr); \
+ else \
+ alloc = alloc_nr(alloc); \
+ x = xrealloc((x), alloc * sizeof(*(x))); \
+ } \
+ } while(0)
+
+static inline void *xrealloc(void *ptr, size_t size)
+{
+ void *ret = realloc(ptr, size);
+ if (!ret && !size)
+ ret = realloc(ptr, 1);
+ if (!ret) {
+ ret = realloc(ptr, size);
+ if (!ret && !size)
+ ret = realloc(ptr, 1);
+ if (!ret)
+ die("Out of memory, realloc failed");
+ }
+ return ret;
+}
+
+#define astrcatf(out, fmt, ...) \
+({ \
+ char *tmp = *(out); \
+ if (asprintf((out), "%s" fmt, tmp ?: "", ## __VA_ARGS__) == -1) \
+ die("asprintf failed"); \
+ free(tmp); \
+})
+
+static inline void astrcat(char **out, const char *add)
+{
+ char *tmp = *out;
+
+ if (asprintf(out, "%s%s", tmp ?: "", add) == -1)
+ die("asprintf failed");
+
+ free(tmp);
+}
+
+#endif /* __SUBCMD_UTIL_H */