* doprnt.c (doprnt): Truncate multibyte char correctly.

Without this change, doprnt (buf, 2, "%s", FORMAT_END, AP)
would mishandle a string argument "Xc" if X was a multibyte
character of length 2: it would truncate after X's first byte
rather than including all of X.

2 files changed, 21 insertions, 9 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index 7ea9ad8f3e3..3acf12e4483 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,11 @@
+2012-06-07  Paul Eggert  <eggert@cs.ucla.edu>
+
+        * doprnt.c (doprnt): Truncate multibyte char correctly.
+        Without this change, doprnt (buf, 2, "%s", FORMAT_END, AP)
+        would mishandle a string argument "Xc" if X was a multibyte
+        character of length 2: it would truncate after X's first byte
+        rather than including all of X.
+
 2012-06-06  Chong Yidong  <cyd@gnu.org>
 
         * buffer.c (word_wrap): Doc fix.
diff --git a/src/doprnt.c b/src/doprnt.c
index df9ebc11f9c..b106ffb1938 100644
--- a/src/doprnt.c
+++ b/src/doprnt.c
@@ -392,15 +392,19 @@ doprnt (char *buffer, ptrdiff_t bufsize, const char *format,
                 {
                   /* Truncate the string at character boundary.  */
                   tem = bufsize;
-                  while (!CHAR_HEAD_P (string[tem - 1])) tem--;
-                  /* If the multibyte sequence of this character is
-                     too long for the space we have left in the
-                     buffer, truncate before it.  */
-                  if (tem > 0
-                      && BYTES_BY_CHAR_HEAD (string[tem - 1]) > bufsize)
-                    tem--;
-                  if (tem > 0)
-                    memcpy (bufptr, string, tem);
+                  do
+                    {
+                      tem--;
+                      if (CHAR_HEAD_P (string[tem]))
+                        {
+                          if (BYTES_BY_CHAR_HEAD (string[tem]) <= bufsize - tem)
+                            tem = bufsize;
+                          break;
+                        }
+                    }
+                  while (tem != 0);
+
+                  memcpy (bufptr, string, tem);
                   bufptr[tem] = 0;
                   /* Trigger exit from the loop, but make sure we
                      return to the caller a value which will indicate