Avoid splitting a multi-byte character when trimming a name.

Fixes bug 7816.  Also makes the get_tmpname() code and comments
more like the master.

diff --git a/receiver.c b/receiver.c
index 878ed00418ae273023fc2936477f6e19fefa51a4..202b678c16d812a2790284e474ee264cc3dca1d3 100644 (file)
--- a/receiver.c
+++ b/receiver.c
@@ -64,31 +64,29 @@ static flist_ndx_list batch_redo_list;
 /* We're either updating the basis file or an identical copy: */
 static int updating_basis_or_equiv;
 
-/*
- * get_tmpname() - create a tmp filename for a given filename
+#define TMPNAME_SUFFIX ".XXXXXX"
+#define TMPNAME_SUFFIX_LEN ((int)sizeof TMPNAME_SUFFIX - 1)
+
+/* get_tmpname() - create a tmp filename for a given filename
  *
- *   If a tmpdir is defined, use that as the directory to
- *   put it in.  Otherwise, the tmp filename is in the same
- *   directory as the given name.  Note that there may be no
- *   directory at all in the given name!
+ * If a tmpdir is defined, use that as the directory to put it in.  Otherwise,
+ * the tmp filename is in the same directory as the given name.  Note that
+ * there may be no directory at all in the given name!
  *
- *   The tmp filename is basically the given filename with a
- *   dot prepended, and .XXXXXX appended (for mkstemp() to
- *   put its unique gunk in).  Take care to not exceed
- *   either the MAXPATHLEN or NAME_MAX, esp. the last, as
- *   the basename basically becomes 8 chars longer. In that
- *   case, the original name is shortened sufficiently to
- *   make it all fit.
+ * The tmp filename is basically the given filename with a dot prepended, and
+ * .XXXXXX appended (for mkstemp() to put its unique gunk in).  We take care
+ * to not exceed either the MAXPATHLEN or NAME_MAX, especially the last, as
+ * the basename basically becomes 8 characters longer.  In such a case, the
+ * original name is shortened sufficiently to make it all fit.
  *
- *   Of course, there's no real reason for the tmp name to
- *   look like the original, except to satisfy us humans.
- *   As long as it's unique, rsync will work.
- */
-
+ * Of course, the only reason the file is based on the original name is to
+ * make it easier to figure out what purpose a temp file is serving when a
+ * transfer is in progress. */
 int get_tmpname(char *fnametmp, const char *fname)
 {
        int maxname, added, length = 0;
        const char *f;
+       char *suf;
 
        if (tmpdir) {
                /* Note: this can't overflow, so the return value is safe */
@@ -108,8 +106,9 @@ int get_tmpname(char *fnametmp, const char *fname)
        fnametmp[length++] = '.';
 
        /* The maxname value is bufsize, and includes space for the '\0'.
-        * (Note that NAME_MAX get -8 for the leading '.' above.) */
-       maxname = MIN(MAXPATHLEN - 7 - length, NAME_MAX - 8);
+        * NAME_MAX needs an extra -1 for the name's leading dot. */
+       maxname = MIN(MAXPATHLEN - length - TMPNAME_SUFFIX_LEN,
+                     NAME_MAX - 1 - TMPNAME_SUFFIX_LEN);
 
        if (maxname < 1) {
                rprintf(FERROR_XFER, "temporary filename too long: %s\n", fname);
@@ -120,7 +119,17 @@ int get_tmpname(char *fnametmp, const char *fname)
        added = strlcpy(fnametmp + length, f, maxname);
        if (added >= maxname)
                added = maxname - 1;
-       memcpy(fnametmp + length + added, ".XXXXXX", 8);
+       suf = fnametmp + length + added;
+
+       /* Trim any dangling high-bit chars if the first-trimmed char (if any) is
+        * also a high-bit char, just in case we cut into a multi-byte sequence.
+        * We are guaranteed to stop because of the leading '.' we added. */
+       if ((int)f[added] & 0x80) {
+               while ((int)suf[-1] & 0x80)
+                       suf--;
+       }
+
+       memcpy(suf, TMPNAME_SUFFIX, TMPNAME_SUFFIX_LEN+1);
 
        return 1;
 }