term.c: add term_snprint function

Add function for printing terms to buffers.

Signed-off-by: Davide Bettio <[email protected]>

Author: bettio

src/libAtomVM/term.c

@@ -44,6 +44,13 @@ struct FprintfFun
     FILE *stream;
 };
 
+struct SnprintfFun
+{
+    PrinterFun base;
+    int size;
+    char *buf;
+};
+
 const term empty_tuple = 0;
 
 int fprintf_printer(PrinterFun *fun, const char *fmt, ...)
@@ -61,6 +68,23 @@ int fprintf_printer(PrinterFun *fun, const char *fmt, ...)
     return ret;
 }
 
+int snprintf_printer(PrinterFun *fun, const char *fmt, ...)
+{
+    int ret;
+
+    va_list args;
+    va_start(args, fmt);
+
+    struct SnprintfFun *snpf = CONTAINER_OF(fun, struct SnprintfFun, base);
+    ret = vsnprintf(snpf->buf, snpf->size, fmt, args);
+    snpf->buf += ret;
+    snpf->size -= ret;
+
+    va_end(args);
+
+    return ret;
+}
+
 void term_display(FILE *fd, term t, const Context *ctx)
 {
     term_fprint(fd, t, ctx->global);
@@ -78,6 +102,19 @@ int term_fprint(FILE *stream, term t, const GlobalContext *global)
     return term_funprint(&fprintf_fun.base, t, global);
 }
 
+int term_snprint(char *buf, size_t size, term t, const GlobalContext *global)
+{
+    struct SnprintfFun snprintf_fun = {
+        .base = {
+            .print = snprintf_printer
+        },
+        .buf = buf,
+        .size = size
+    };
+
+    return term_funprint(&snprintf_fun.base, t, global);
+}
+
 int term_funprint(PrinterFun *fun, term t, const GlobalContext *global)
 {
     if (term_is_atom(t)) {

src/libAtomVM/term.h

@@ -1435,6 +1435,18 @@ int term_funprint(PrinterFun *pf, term t, const GlobalContext *global);
  */
 int term_fprint(FILE *fd, term t, const GlobalContext *global);
 
+/**
+ * @brief Write a term to a string as text
+ *
+ * @details Print any given term to the given buffer.
+ * @param buf the buffer where the term will be printed.
+ * @param size the buffer size.
+ * @param t the term that will be printed.
+ * @param global the \c GlobalContext.
+ * @returns the number of printed characters.
+ */
+int term_snprint(char *buf, size_t size, term t, const GlobalContext *global);
+
 /**
  * @brief Checks if a term is a string (i.e., a list of characters)
  *