sys-file-reader: Ignore duplicate value labels written by ReadStat.

The ReadStat software writes duplicate value labels due to a
misunderstanding of string widths.  This change make PSPP ignore these
duplicates.

diff --git a/doc/dev/system-file-format.texi b/doc/dev/system-file-format.texi
index e52b9571166a25b477a8f6263f34d0960b9f0423..484fbb43f1eca08fc089bd0f5ec171215f279403 100644 (file)
--- a/doc/dev/system-file-format.texi
+++ b/doc/dev/system-file-format.texi
@@ -222,6 +222,12 @@ pspp 0.1.4 - sparc-sun-solaris2.5.2}.  The string is truncated if it
 would be longer than 60 characters; otherwise it is padded on the right
 with spaces.
 
+The product name field allow readers to behave differently based on
+quirks in the way that particular software writes system files.
+@xref{Value Labels Records}, for the detail of the quirk that the PSPP
+system file reader tolerates in files written by ReadStat, which has
+@code{https://github.com/WizardMac/ReadStat} in @code{prod_name}.
+
 @anchor{layout_code}
 @item int32 layout_code;
 Normally set to 2, although a few system files have been spotted in
@@ -524,6 +530,14 @@ numeric and short string variables only.  Long string variables may
 have value labels, but their value labels are recorded using a
 different record type (@pxref{Long String Value Labels Record}).
 
+ReadStat (@pxref{File Header Record}) writes value labels that label a
+single value more than once.  In more detail, it emits value labels
+whose values are longer than string variables' widths, that are
+identical in the actual width of the variable, e.g.@: labels for
+values @code{ABC123} and @code{ABC456} for a string variable with
+width 3.  For files written by this software, PSPP ignores such
+labels.
+
 The value label record has the following format:
 
 @example
@@ -606,9 +620,7 @@ Record type.  Always set to 6.
 
 @item int32 n_lines;
 Number of lines of documents present.  This should be greater than
-zero, but the system file writer that identifies itself as
-@url{https://github.com/WizardMac/ReadStat} writes document records
-with zero @code{n_lines}.
+zero, but ReadStats writes system files with zero @code{n_lines}.
 
 @item char lines[][80];
 Document lines.  The number of elements is defined by @code{n_lines}.

diff --git a/src/data/sys-file-reader.c b/src/data/sys-file-reader.c
index 5e5dc8b144f33c81d2b275be66504e62d833b762..9d7e392d01ca1b23c51e50d8ccc60ce214c44917 100644 (file)
--- a/src/data/sys-file-reader.c
+++ b/src/data/sys-file-reader.c
@@ -203,6 +203,7 @@ struct sfm_reader
     size_t sfm_var_cnt;         /* Number of variables. */
     int case_cnt;               /* Number of cases */
     const char *encoding;       /* String encoding. */
+    bool written_by_readstat; /* From https://github.com/WizardMac/ReadStat? */
 
     /* Decompression. */
     enum any_compression compression;
@@ -967,6 +968,8 @@ read_header (struct sfm_reader *r, struct any_read_info *info,
   if (!read_string (r, header->magic, sizeof header->magic)
       || !read_string (r, header->eye_catcher, sizeof header->eye_catcher))
     return false;
+  r->written_by_readstat = strstr (header->eye_catcher,
+                                   "https://github.com/WizardMac/ReadStat");
 
   if (!strcmp (ASCII_MAGIC, header->magic)
       || !strcmp (EBCDIC_MAGIC, header->magic))
@@ -2228,7 +2231,15 @@ parse_value_labels (struct sfm_reader *r, struct dictionary *dict,
 
           if (!var_add_value_label (var, &value, utf8_labels[j]))
             {
-              if (var_is_numeric (var))
+              if (r->written_by_readstat)
+                {
+                  /* Ignore the problem.  ReadStat is buggy and emits value
+                     labels whose values are longer than string variables'
+                     widths, that are identical in the actual width of the
+                     variable, e.g. both values "ABC123" and "ABC456" for a
+                     string variable with width 3. */
+                }
+              else if (var_is_numeric (var))
                 sys_warn (r, record->pos,
                           _("Duplicate value label for %g on %s."),
                           value.f, var_get_name (var));