libcdecl: Fully remove snprintf requirement from the library.

[cdecl99.git] / src / output.c

diff --git a/src/output.c b/src/output.c
index 4590a5cfc60b2fb9c3d1bdead751da7d37b25d9b..c0438e602753fb0b37c4bdaeaba0be457481b5da 100644 (file)
--- a/src/output.c
+++ b/src/output.c
@@ -22,10 +22,9 @@
 #include "cdecl.h"
 #include "cdecl-internal.h"
 
+#include "parse.h"
 #include "specstr.h"
 
-#define MIN(a, b) ((a) < (b) ? (a) : (b))
-
 size_t cdecl__advance(struct output_state *dst, size_t amount)
 {
        size_t x = MIN(amount, dst->dstlen);
@@ -37,12 +36,60 @@ size_t cdecl__advance(struct output_state *dst, size_t amount)
        return amount;
 }
 
+size_t cdecl__strlcpy(char *dst, const char *src, size_t dstlen)
+{
+       size_t srclen = strlen(src);
+
+       if (dstlen > 0) {
+               memcpy(dst, src, MIN(dstlen, srclen+1));
+               if (dstlen <= srclen)
+                       dst[dstlen-1] = 0;
+       }
+
+       return srclen;
+}
+
 size_t cdecl__emit(struct output_state *dst, const char *src)
 {
-       size_t rc = snprintf(dst->dst, dst->dstlen, "%s", src);
+       size_t rc = cdecl__strlcpy(dst->dst, src, dst->dstlen);
        return cdecl__advance(dst, rc);
 }
 
+/*
+ * 31 decimal digits is enough for values up to 2^102 - 1.
+ * 63 decimal digits is enough for values up to 2^209 - 1.
+ *
+ * We can't portably write numbers this large in preprocessor conditionals,
+ * but since the maximum values of unsigned integer types are always one
+ * less than a power of two, we can use a sequence of small shifts to infer
+ * the bounds.
+ *
+ * All known implementations have 64-bit uintmax_t.  Leave some headroom
+ * to support a possible future implementatons with 128-bit uintmax_t.
+ */
+enum {
+#if (UINTMAX_MAX >> 27 >> 27 >> 26 >> 26) == 0
+       MAX_UINT_DIGITS = 31
+#elif (UINTMAX_MAX >> 27 >> 26 >> 26 >> 26 >> 26 >> 26 >> 26 >> 26) == 0
+       MAX_UINT_DIGITS = 63
+#else
+#      error UINTMAX_MAX is too large, please report a bug.
+#endif
+};
+
+size_t cdecl__emit_uint(struct output_state *dst, uintmax_t val)
+{
+       char buf[MAX_UINT_DIGITS + 1], *p = &buf[sizeof buf];
+
+       *(--p) = 0;
+       while (val > 0) {
+               *(--p) = '0' + val % 10;
+               val /= 10;
+       }
+
+       return cdecl__emit(dst, p);
+}
+
 static void explain_spec(struct output_state *dst, struct cdecl_declspec *s)
 {
        size_t rc;