Lift 16kB limit of log message output

Traditionally we had 16kB limit when formatting log messages for
output, because it was easier to arrange for the caller to have
a reasonably big buffer and pass it down without ever worrying
about reallocating.

This changes the calling convention of pretty_print_commit() to
lift this limit.  Instead of the buffer and remaining length, it
now takes a pointer to the pointer that points at the allocated
buffer, and another pointer to the location that stores the
allocated length, and reallocates the buffer as necessary.

To support the user format, the error return of interpolate()
needed to be changed.  It used to return a bool telling "Ok the
result fits", or "Sorry, I had to truncate it".  Now it returns
0 on success, and returns the size of the buffer it wants in
order to fit the whole result.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 21 insertions, 25 deletions

diff --git a/interpolate.c b/interpolate.c
index fb30694f47..00826778fc 100644
--- a/interpolate.c
+++ b/interpolate.c
@@ -44,33 +44,33 @@ void interp_clear_table(struct interp *table, int ninterps)
  *        { "%%", "%"},
  *    }
  *
- * Returns 1 on a successful substitution pass that fits in result,
- * Returns 0 on a failed or overflowing substitution pass.
+ * Returns 0 on a successful substitution pass that fits in result,
+ * Returns a number of bytes needed to hold the full substituted
+ * string otherwise.
  */
 
-int interpolate(char *result, int reslen,
+unsigned long interpolate(char *result, unsigned long reslen,
 		const char *orig,
 		const struct interp *interps, int ninterps)
 {
 	const char *src = orig;
 	char *dest = result;
-	int newlen = 0;
+	unsigned long newlen = 0;
 	const char *name, *value;
-	int namelen, valuelen;
+	unsigned long namelen, valuelen;
 	int i;
 	char c;
 
         memset(result, 0, reslen);
 
-	while ((c = *src) && newlen < reslen - 1) {
+	while ((c = *src)) {
 		if (c == '%') {
 			/* Try to match an interpolation string. */
 			for (i = 0; i < ninterps; i++) {
 				name = interps[i].name;
 				namelen = strlen(name);
-				if (strncmp(src, name, namelen) == 0) {
+				if (strncmp(src, name, namelen) == 0)
 					break;
-				}
 			}
 
 			/* Check for valid interpolation. */
@@ -78,29 +78,25 @@ int interpolate(char *result, int reslen,
 				value = interps[i].value;
 				valuelen = strlen(value);
 
-				if (newlen + valuelen < reslen - 1) {
+				if (newlen + valuelen + 1 < reslen) {
 					/* Substitute. */
 					strncpy(dest, value, valuelen);
-					newlen += valuelen;
 					dest += valuelen;
-					src += namelen;
-				} else {
-					/* Something's not fitting. */
-					return 0;
 				}
-
-			} else {
-				/* Skip bogus interpolation. */
-				*dest++ = *src++;
-				newlen++;
+				newlen += valuelen;
+				src += namelen;
+				continue;
 			}
-
-		} else {
-			/* Straight copy one non-interpolation character. */
-			*dest++ = *src++;
-			newlen++;
 		}
+		/* Straight copy one non-interpolation character. */
+		if (newlen + 1 < reslen)
+			*dest++ = *src;
+		src++;
+		newlen++;
 	}
 
-	return newlen < reslen - 1;
+	if (newlen + 1 < reslen)
+		return 0;
+	else
+		return newlen + 2;
 }