correct usage help string for git-hash-object

diff --git a/interpolate.c b/interpolate.c
index 00826778fc3d760a9b001423cd9c26e7972c126f..7f03bd99c5b66afa6cc7fa11a2430301a3042656 100644 (file)
--- a/interpolate.c
+++ b/interpolate.c
@@ -11,8 +11,7 @@ void interp_set_entry(struct interp *table, int slot, const char *value)
        char *oldval = table[slot].value;
        char *newval = NULL;
 
-       if (oldval)
-               free(oldval);
+       free(oldval);
 
        if (value)
                newval = xstrdup(value);
@@ -44,9 +43,8 @@ void interp_clear_table(struct interp *table, int ninterps)
  *        { "%%", "%"},
  *    }
  *
- * Returns 0 on a successful substitution pass that fits in result,
- * Returns a number of bytes needed to hold the full substituted
- * string otherwise.
+ * Returns the length of the substituted string (not including the final \0).
+ * Like with snprintf, if the result is >= reslen, then it overflowed.
  */
 
 unsigned long interpolate(char *result, unsigned long reslen,
@@ -61,8 +59,6 @@ unsigned long interpolate(char *result, unsigned long reslen,
        int i;
        char c;
 
-        memset(result, 0, reslen);
-
        while ((c = *src)) {
                if (c == '%') {
                        /* Try to match an interpolation string. */
@@ -76,11 +72,15 @@ unsigned long interpolate(char *result, unsigned long reslen,
                        /* Check for valid interpolation. */
                        if (i < ninterps) {
                                value = interps[i].value;
-                               valuelen = strlen(value);
+                               if (!value) {
+                                       src += namelen;
+                                       continue;
+                               }
 
-                               if (newlen + valuelen + 1 < reslen) {
+                               valuelen = strlen(value);
+                               if (newlen + valuelen < reslen) {
                                        /* Substitute. */
-                                       strncpy(dest, value, valuelen);
+                                       memcpy(dest, value, valuelen);
                                        dest += valuelen;
                                }
                                newlen += valuelen;
@@ -95,8 +95,9 @@ unsigned long interpolate(char *result, unsigned long reslen,
                newlen++;
        }
 
-       if (newlen + 1 < reslen)
-               return 0;
-       else
-               return newlen + 2;
+       /* XXX: the previous loop always keep room for the ending NUL,
+          we just need to check if there was room for a NUL in the first place */
+       if (reslen > 0)
+               *dest = '\0';
+       return newlen;
 }