Merge branch 'tf/diff-whitespace-incomplete-line'

[git.git] / compat / snprintf.c

diff --git a/compat/snprintf.c b/compat/snprintf.c
index dbfc2d6b6e2bc115e9976c231ae9d8fef7b2e086..4d07087abd4f956b4dbe209236e6abafd459b1e4 100644 (file)
--- a/compat/snprintf.c
+++ b/compat/snprintf.c
@@ -1,12 +1,32 @@
 #include "../git-compat-util.h"
 
+/*
+ * The size parameter specifies the available space, i.e. includes
+ * the trailing NUL byte; but Windows's vsnprintf expects the
+ * number of characters to write, and does not necessarily write the
+ * trailing NUL.
+ */
+#ifndef SNPRINTF_SIZE_CORR
+#if defined(__MINGW32__) && defined(__GNUC__) && __GNUC__ < 4
+#define SNPRINTF_SIZE_CORR 1
+#else
+#define SNPRINTF_SIZE_CORR 0
+#endif
+#endif
+
 #undef vsnprintf
 int git_vsnprintf(char *str, size_t maxsize, const char *format, va_list ap)
 {
        char *s;
-       int ret;
-
-       ret = vsnprintf(str, maxsize, format, ap);
+       int ret = -1;
+
+       if (maxsize > 0) {
+               ret = vsnprintf(str, maxsize-SNPRINTF_SIZE_CORR, format, ap);
+               if (ret == maxsize-1)
+                       ret = -1;
+               /* Windows does not NUL-terminate if result fills buffer */
+               str[maxsize-1] = 0;
+       }
        if (ret != -1)
                return ret;
 
@@ -20,7 +40,9 @@ int git_vsnprintf(char *str, size_t maxsize, const char *format, va_list ap)
                if (! str)
                        break;
                s = str;
-               ret = vsnprintf(str, maxsize, format, ap);
+               ret = vsnprintf(str, maxsize-SNPRINTF_SIZE_CORR, format, ap);
+               if (ret == maxsize-1)
+                       ret = -1;
        }
        free(s);
        return ret;