From 28383cf083afa2b38d5c10605e4d3c9f9847c3e5 Mon Sep 17 00:00:00 2001
From: Moritz Bunkus <moritz@bunkus.org>
Date: Wed, 24 Sep 2003 19:10:16 +0000
Subject: [PATCH] Implemented a more compatible method of getting the required
 buffer size for a sprintf/vsprintf.

---
 src/chapter_parser_xml.cpp | 10 +++++-----
 src/chapters.cpp           |  4 ++--
 src/common.cpp             | 31 +++++++++++++++++++++++++++++++
 src/common.h               |  3 +++
 src/mkvmerge.cpp           |  6 ------
 5 files changed, 41 insertions(+), 13 deletions(-)

diff --git a/src/chapter_parser_xml.cpp b/src/chapter_parser_xml.cpp
index ed860d555..f01417ef8 100644
--- a/src/chapter_parser_xml.cpp
+++ b/src/chapter_parser_xml.cpp
@@ -69,12 +69,12 @@ static void cperror(parser_data_t *pdata, const char *fmt, ...) {
   int len;
 
   fix_format(fmt, new_fmt);
-  len = snprintf(NULL, 0, "Error: Chapter parser failed for '%s', line %d, "
-                 "column %d: ", pdata->file_name,
-                 XML_GetCurrentLineNumber(pdata->parser),
-                 XML_GetCurrentColumnNumber(pdata->parser));
+  len = get_arg_len("Error: Chapter parser failed for '%s', line %d, "
+                    "column %d: ", pdata->file_name,
+                    XML_GetCurrentLineNumber(pdata->parser),
+                    XML_GetCurrentColumnNumber(pdata->parser));
   va_start(ap, fmt);
-  len += vsnprintf(NULL, 0, new_fmt.c_str(), ap);
+  len += get_varg_len(new_fmt.c_str(), ap);
   new_string = (char *)safemalloc(len + 2);
   sprintf(new_string, "Error: Chapter parser failed for '%s', line %d, "
           "column %d: ", pdata->file_name,
diff --git a/src/chapters.cpp b/src/chapters.cpp
index 3e34f772f..9dee08947 100644
--- a/src/chapters.cpp
+++ b/src/chapters.cpp
@@ -67,10 +67,10 @@ static void chapter_error(const char *fmt, ...) {
   char *new_error;
   int len;
 
-  len = snprintf(NULL, 0, "Error: Simple chapter parser: ");
+  len = strlen("Error: Simple chapter parser: ");
   va_start(ap, fmt);
   fix_format(fmt, new_fmt);
-  len += vsnprintf(NULL, 0, new_fmt.c_str(), ap);
+  len += get_varg_len(new_fmt.c_str(), ap);
   new_error = (char *)safemalloc(len + 2);
   strcpy(new_error, "Error: Simple chapter parser: ");
   vsprintf(&new_error[strlen(new_error)], new_fmt.c_str(), ap);
diff --git a/src/common.cpp b/src/common.cpp
index d4a8b62ea..11e0d64cf 100644
--- a/src/common.cpp
+++ b/src/common.cpp
@@ -1319,3 +1319,34 @@ void mxexit(int code) {
 
   exit(0);
 }
+
+int get_arg_len(const char *fmt, ...) {
+  int size;
+  va_list ap;
+
+  va_start(ap, fmt);
+  size = get_varg_len(fmt, ap);
+  va_end(ap);
+
+  return size;
+}
+
+int get_varg_len(const char *fmt, va_list ap) {
+  int size, result;
+  char *dst;
+
+  size = 1024;
+  dst = (char *)safemalloc(size);
+  while (1) {
+    result = vsnprintf(dst, size - 1, fmt, ap);
+    if (result >= 0) {
+      safefree(dst);
+      return result;
+    }
+    size += 1024;
+    dst = (char *)saferealloc(dst, size);
+  }
+  safefree(dst);
+
+  return -1;
+}
diff --git a/src/common.h b/src/common.h
index 5003f826f..3485af745 100644
--- a/src/common.h
+++ b/src/common.h
@@ -142,6 +142,9 @@ bool parse_int(const char *s, int64_t &value);
 bool parse_int(const char *s, int &value);
 string to_string(int64_t i);
 
+int get_arg_len(const char *fmt, ...);
+int get_varg_len(const char *fmt, va_list ap);
+
 extern int verbose;
 
 class bit_cursor_c {
diff --git a/src/mkvmerge.cpp b/src/mkvmerge.cpp
index 541fd4e4a..73cb84fc2 100644
--- a/src/mkvmerge.cpp
+++ b/src/mkvmerge.cpp
@@ -1689,12 +1689,6 @@ static void handle_args(int argc, char **argv) {
 // {{{ global setup and cleanup functions
 
 static void setup() {
-  if ((snprintf(NULL, 0, "hallo") != 5) ||
-      (vsnprintf(NULL, 0, "hallo", NULL) != 5))
-    mxerror("Your system does not return proper values for the snprintf() "
-            "and vsnprintf functions. mkvmerge cannot run securely on this "
-            "system.\n");
-
 #if ! defined(COMP_MSC)
   if (setlocale(LC_CTYPE, "") == NULL)
     mxerror("Could not set the locale properly. Check the "