1 files changed, 48 insertions, 0 deletions
diff --git a/c/string_helpers.c b/c/string_helpers.c
new file mode 100644
index 0000000..636bad3
--- /dev/null
+++ b/c/string_helpers.c
@@ -0,0 +1,48 @@
+#include <stdio.h>
+#include <stdarg.h>
+
+static char *sbuild(char *format, ...) {
+    // (1) overapproximate the length of the string. adapted from man va_start
+    unsigned long max_len = 1;
+    char *s;
+    va_list ap;
+    va_start(ap, format);
+    for (char *c = format; *c; c++) {
+        if (*c != '%') {
+            max_len++;
+            continue;
+        }
+
+        switch (*(++c)) {
+        case 's':
+            s = va_arg(ap, char*);
+            max_len += strlen(s);
+            break;
+        case 'l': // not quite accurate
+            va_arg(ap, unsigned long);
+            max_len += 64;
+            break;
+        case 'd':
+            va_arg(ap, int);
+            max_len += 32;
+            break;
+        case 'u':
+            va_arg(ap, unsigned);
+            max_len += 32;
+            break;
+        case 'f':
+            va_arg(ap, double);
+            max_len += 64;
+            break;
+        default: assert(0);
+        }
+    }
+    va_end(ap);
+
+    char *str = calloc(max_len, sizeof(char));
+    va_list ap_;
+    va_start(ap_, format);
+    vsprintf(str, format, ap_);
+    va_end(ap_);
+    return str;
+}