Add escaping printf specifier

[~andy/ct] / lib.c

diff --git a/lib.c b/lib.c
new file mode 100644 (file)
index 0000000..7b46a05
--- /dev/null
+++ b/lib.c
@@ -0,0 +1,43 @@
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <printf.h>
+
+static int printf_markup(FILE *stream,
+               const struct printf_info *info,
+               const void *const *args)
+{
+       int len = 0;
+       const char *str = *(const char **)args[0];
+       for (int i = 0; str[i]; i++)
+               switch (str[i]) {
+               case '"':  len += fputs("&#39;",  stream); break;
+               case '\'': len += fputs("&quot;", stream); break;
+               case '&':  len += fputs("&amp;",  stream); break;
+               case '<':  len += fputs("&lt;",   stream); break;
+               case '>':  len += fputs("&gt;",   stream); break;
+               default:   len += fputc(str[i],   stream); break;
+               }
+       return len;
+}
+
+static int printf_markup_arginfo(const struct printf_info *info,
+               size_t n, int *argtypes, int *size)
+{
+       argtypes[0] = PA_STRING;
+       return 1;
+}
+
+void ct_use_escape()
+{
+       register_printf_specifier('M', printf_markup, printf_markup_arginfo);
+}
+
+int main(void)
+{
+       ct_use_escape();
+       printf("%M\n", "<Hello, World>");
+       printf("%M\n", "<Hello, World>");
+       printf("%M\n", "<Hello, World>");
+       return 0;
+}