config: handle allocation failure explicitly

xmalloc.c

@@ -0,0 +1,78 @@
+#include <errno.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include "xmalloc.h"
+
+static NORETURN COLD void
+fatal_error(const char *msg, int err)
+{
+    errno = err;
+    perror(msg);
+    abort();
+}
+
+static void *
+check_alloc(void *alloc)
+{
+    if (unlikely(alloc == NULL)) {
+        fatal_error(__func__, ENOMEM);
+    }
+    return alloc;
+}
+
+void *
+xmalloc(size_t size)
+{
+    if (unlikely(size == 0)) {
+        size = 1;
+    }
+    return check_alloc(malloc(size));
+}
+
+void *
+xcalloc(size_t nmemb, size_t size)
+{
+    if (unlikely(nmemb == 0 || size == 0)) {
+        size = 1;
+    }
+    return check_alloc(calloc(nmemb, size));
+}
+
+char *
+xstrdup(const char *str)
+{
+    return check_alloc(strdup(str));
+}
+
+static VPRINTF(2) int
+xvasprintf_(char **strp, const char *format, va_list ap)
+{
+    va_list ap2;
+    va_copy(ap2, ap);
+    int n = vsnprintf(NULL, 0, format, ap2);
+    if (unlikely(n < 0)) {
+        fatal_error("vsnprintf", EILSEQ);
+    }
+    va_end(ap2);
+    *strp = xmalloc(n + 1);
+    return vsnprintf(*strp, n + 1, format, ap);
+}
+
+static VPRINTF(1) char *
+xvasprintf(const char *format, va_list ap)
+{
+    char *str;
+    xvasprintf_(&str, format, ap);
+    return str;
+}
+
+char *
+xasprintf(const char *format, ...)
+{
+    va_list ap;
+    va_start(ap, format);
+    char *str = xvasprintf(format, ap);
+    va_end(ap);
+    return str;
+}