From: Christoph Mallon <christoph.mallon@gmx.de>
Date: Tue, 4 May 2010 11:53:26 +0000 (+0000)
Subject: Fix obstack_printf() (slightly broken in r27474).
X-Git-Url: http://nsz.repo.hu/git/?a=commitdiff_plain;h=53c740e61018fc1172d2c290a486251efd4e906b;p=libfirm

Fix obstack_printf() (slightly broken in r27474).

[r27476]
---

diff --git a/ir/obstack/obstack_printf.c b/ir/obstack/obstack_printf.c
index 1b432e2ec..ab494bb99 100644
--- a/ir/obstack/obstack_printf.c
+++ b/ir/obstack/obstack_printf.c
@@ -9,42 +9,40 @@
 
 int obstack_printf(struct obstack *obst, const char *fmt, ...)
 {
-	char  buf[128];
-	char *buffer = buf;
+	char    buf[128];
+	char   *buffer = buf;
+	size_t  size   = lengthof(buf);
 	va_list ap;
-	int len;
+	int     len;
 
-	va_start(ap, fmt);
-	len = vsnprintf(buffer, sizeof(buffer), fmt, ap);
-	va_end(ap);
-	if (len < 0 || len >= (int) sizeof(buffer)) {
-		size_t size   = len >= 0 ? (size_t) len : sizeof(buffer) * 2;
-		char  *buffer = malloc(size);
-		do {
-			if (buffer == NULL)
-				return -1;
-
-			va_start(ap, fmt);
-			len = vsnprintf(buffer, size, fmt, ap);
-			va_end(ap);
+	for (;;) {
+		va_start(ap, fmt);
+		len = vsnprintf(buffer, sizeof(buffer), fmt, ap);
+		va_end(ap);
 
-			/* snprintf should return -1 only in the error case, but older
-			 * glibcs and probably other systems are buggy in this respect and
-			 * return -1 if the buffer was too small. We only abort for LARGE
-			 * unrealistic buffer sizes here */
-			if (len < 0) {
-				if (size > 65536)
-					return -1;
-				size *= 2;
-				buffer = realloc(buffer, size);
-			} else if (len >= (int) size) {
-				/* this should not happen if snprintf works correctly */
-				abort();
-			}
-		} while (len < 0);
-		free(buffer);
+		/* snprintf should return -1 only in the error case, but older glibcs
+		 * and probably other systems are buggy in this respect and return -1 if
+		 * the buffer was too small. We only abort for LARGE unrealistic buffer
+		 * sizes here */
+		if (len < 0) {
+			if (buffer != buf)
+				free(buffer);
+			if (size > 65536)
+				return -1;
+			size *= 2;
+		} else if ((size_t)len >= size) {
+			/* If we come here more than once, vsnprintf() returned garbage */
+			assert(buffer == buf);
+			size = (size_t)len + 1;
+		} else {
+			break;
+		}
+		buffer = malloc(buffer, size);
 	}
+
 	obstack_grow(obst, buffer, len);
+	if (buffer != buf)
+		free(buffer);
 
 	return len;
 }