Allow the low level COPY routines to read arbitrary numbers of fields.

This doesn't involve any user-visible change in behavior, but will be
useful when the COPY routines are exposed to allow their use by Foreign
Data Wrapper routines, which will be able to use these routines to read
irregular CSV files, for example.

diff --git a/src/backend/commands/copy.c b/src/backend/commands/copy.c
index 3ffd10b..40632b0 100644 (file)
--- a/src/backend/commands/copy.c
+++ b/src/backend/commands/copy.c
@@ -141,6 +141,11 @@ typedef struct CopyStateData
         */
        StringInfoData attribute_buf;
 
+       /* field raw data pointers found by COPY FROM */
+
+       int max_fields;
+       char ** raw_fields;
+
        /*
         * Similarly, line_buf holds the whole input line being processed. The
         * input cycle is first to read the whole line into line_buf, convert it
@@ -250,10 +255,8 @@ static void CopyOneRowTo(CopyState cstate, Oid tupleOid,
 static void CopyFrom(CopyState cstate);
 static bool CopyReadLine(CopyState cstate);
 static bool CopyReadLineText(CopyState cstate);
-static int CopyReadAttributesText(CopyState cstate, int maxfields,
-                                          char **fieldvals);
-static int CopyReadAttributesCSV(CopyState cstate, int maxfields,
-                                         char **fieldvals);
+static int CopyReadAttributesText(CopyState cstate);
+static int CopyReadAttributesCSV(CopyState cstate);
 static Datum CopyReadBinaryAttribute(CopyState cstate,
                                                int column_no, FmgrInfo *flinfo,
                                                Oid typioparam, int32 typmod,
@@ -1921,7 +1924,11 @@ CopyFrom(CopyState cstate)
 
        /* create workspace for CopyReadAttributes results */
        nfields = file_has_oids ? (attr_count + 1) : attr_count;
-       field_strings = (char **) palloc(nfields * sizeof(char *));
+       if (! cstate->binary)
+       {
+               cstate->max_fields = nfields;
+               cstate->raw_fields = (char **) palloc(nfields * sizeof(char *));
+       }
 
        /* Initialize state variables */
        cstate->fe_eof = false;
@@ -1985,10 +1992,18 @@ CopyFrom(CopyState cstate)
 
                        /* Parse the line into de-escaped field values */
                        if (cstate->csv_mode)
-                               fldct = CopyReadAttributesCSV(cstate, nfields, field_strings);
+                               fldct = CopyReadAttributesCSV(cstate);
                        else
-                               fldct = CopyReadAttributesText(cstate, nfields, field_strings);
+                               fldct = CopyReadAttributesText(cstate);
+
+                       /* check for overflowing fields */
+                       if (nfields > 0 && fldct > nfields)
+                               ereport(ERROR,
+                                               (errcode(ERRCODE_BAD_COPY_FILE_FORMAT),
+                                                errmsg("extra data after last expected column")));
+
                        fieldno = 0;
+                       field_strings = cstate->raw_fields;
 
                        /* Read the OID field if present */
                        if (file_has_oids)
@@ -2218,7 +2233,8 @@ CopyFrom(CopyState cstate)
 
        pfree(values);
        pfree(nulls);
-       pfree(field_strings);
+       if (! cstate->binary)
+               pfree(cstate->raw_fields);
 
        pfree(in_functions);
        pfree(typioparams);
@@ -2717,21 +2733,22 @@ GetDecimalFromHex(char hex)
  * performing de-escaping as needed.
  *
  * The input is in line_buf.  We use attribute_buf to hold the result
- * strings.  fieldvals[k] is set to point to the k'th attribute string,
- * or NULL when the input matches the null marker string.  (Note that the
- * caller cannot check for nulls since the returned string would be the
- * post-de-escaping equivalent, which may look the same as some valid data
- * string.)
+ * strings.  cstate->raw_fields[k] is set to point to the k'th attribute 
+ * string, or NULL when the input matches the null marker string.  
+ * This array is expanded as necessary.
+ *
+ * (Note that the caller cannot check for nulls since the returned 
+ * string would be the post-de-escaping equivalent, which may look 
+ * the same as some valid data string.)
  *
  * delim is the column delimiter string (must be just one byte for now).
  * null_print is the null marker string.  Note that this is compared to
  * the pre-de-escaped input string.
  *
- * The return value is the number of fields actually read.     (We error out
- * if this would exceed maxfields, which is the length of fieldvals[].)
+ * The return value is the number of fields actually read.
  */
 static int
-CopyReadAttributesText(CopyState cstate, int maxfields, char **fieldvals)
+CopyReadAttributesText(CopyState cstate)
 {
        char            delimc = cstate->delim[0];
        int                     fieldno;
@@ -2743,7 +2760,7 @@ CopyReadAttributesText(CopyState cstate, int maxfields, char **fieldvals)
         * We need a special case for zero-column tables: check that the input
         * line is empty, and return.
         */
-       if (maxfields <= 0)
+       if (cstate->max_fields <= 0)
        {
                if (cstate->line_buf.len != 0)
                        ereport(ERROR,
@@ -2759,7 +2776,7 @@ CopyReadAttributesText(CopyState cstate, int maxfields, char **fieldvals)
         * data line, so we can just force attribute_buf to be large enough and
         * then transfer data without any checks for enough space.      We need to do
         * it this way because enlarging attribute_buf mid-stream would invalidate
-        * pointers already stored into fieldvals[].
+        * pointers already stored into cstate->raw_fields[].
         */
        if (cstate->attribute_buf.maxlen <= cstate->line_buf.len)
                enlargeStringInfo(&cstate->attribute_buf, cstate->line_buf.len);
@@ -2779,15 +2796,17 @@ CopyReadAttributesText(CopyState cstate, int maxfields, char **fieldvals)
                int                     input_len;
                bool            saw_non_ascii = false;
 
-               /* Make sure space remains in fieldvals[] */
-               if (fieldno >= maxfields)
-                       ereport(ERROR,
-                                       (errcode(ERRCODE_BAD_COPY_FILE_FORMAT),
-                                        errmsg("extra data after last expected column")));
+               /* Make sure there is enough space for the next value */
+               if (fieldno >= cstate->max_fields)
+               {
+                       cstate->max_fields *= 2;
+                       cstate->raw_fields = 
+                               repalloc(cstate->raw_fields, cstate->max_fields*sizeof(char *));
+               }
 
                /* Remember start of field on both input and output sides */
                start_ptr = cur_ptr;
-               fieldvals[fieldno] = output_ptr;
+               cstate->raw_fields[fieldno] = output_ptr;
 
                /* Scan data for field */
                for (;;)
@@ -2912,7 +2931,7 @@ CopyReadAttributesText(CopyState cstate, int maxfields, char **fieldvals)
                 */
                if (saw_non_ascii)
                {
-                       char       *fld = fieldvals[fieldno];
+                       char       *fld = cstate->raw_fields[fieldno];
 
                        pg_verifymbstr(fld, output_ptr - (fld + 1), false);
                }
@@ -2921,7 +2940,7 @@ CopyReadAttributesText(CopyState cstate, int maxfields, char **fieldvals)
                input_len = end_ptr - start_ptr;
                if (input_len == cstate->null_print_len &&
                        strncmp(start_ptr, cstate->null_print, input_len) == 0)
-                       fieldvals[fieldno] = NULL;
+                       cstate->raw_fields[fieldno] = NULL;
 
                fieldno++;
                /* Done if we hit EOL instead of a delim */
@@ -2944,7 +2963,7 @@ CopyReadAttributesText(CopyState cstate, int maxfields, char **fieldvals)
  * "standard" (i.e. common) CSV usage.
  */
 static int
-CopyReadAttributesCSV(CopyState cstate, int maxfields, char **fieldvals)
+CopyReadAttributesCSV(CopyState cstate)
 {
        char            delimc = cstate->delim[0];
        char            quotec = cstate->quote[0];
@@ -2958,7 +2977,7 @@ CopyReadAttributesCSV(CopyState cstate, int maxfields, char **fieldvals)
         * We need a special case for zero-column tables: check that the input
         * line is empty, and return.
         */
-       if (maxfields <= 0)
+       if (cstate->max_fields <= 0)
        {
                if (cstate->line_buf.len != 0)
                        ereport(ERROR,
@@ -2974,7 +2993,7 @@ CopyReadAttributesCSV(CopyState cstate, int maxfields, char **fieldvals)
         * data line, so we can just force attribute_buf to be large enough and
         * then transfer data without any checks for enough space.      We need to do
         * it this way because enlarging attribute_buf mid-stream would invalidate
-        * pointers already stored into fieldvals[].
+        * pointers already stored into cstate->raw_fields[].
         */
        if (cstate->attribute_buf.maxlen <= cstate->line_buf.len)
                enlargeStringInfo(&cstate->attribute_buf, cstate->line_buf.len);
@@ -2994,15 +3013,17 @@ CopyReadAttributesCSV(CopyState cstate, int maxfields, char **fieldvals)
                char       *end_ptr;
                int                     input_len;
 
-               /* Make sure space remains in fieldvals[] */
-               if (fieldno >= maxfields)
-                       ereport(ERROR,
-                                       (errcode(ERRCODE_BAD_COPY_FILE_FORMAT),
-                                        errmsg("extra data after last expected column")));
+               /* Make sure there is enough space for the next value */
+               if (fieldno >= cstate->max_fields)
+               {
+                       cstate->max_fields *= 2;
+                       cstate->raw_fields = 
+                               repalloc(cstate->raw_fields, cstate->max_fields*sizeof(char *));
+               }
 
                /* Remember start of field on both input and output sides */
                start_ptr = cur_ptr;
-               fieldvals[fieldno] = output_ptr;
+               cstate->raw_fields[fieldno] = output_ptr;
 
                /*
                 * Scan data for field,
@@ -3090,7 +3111,7 @@ endfield:
                input_len = end_ptr - start_ptr;
                if (!saw_quote && input_len == cstate->null_print_len &&
                        strncmp(start_ptr, cstate->null_print, input_len) == 0)
-                       fieldvals[fieldno] = NULL;
+                       cstate->raw_fields[fieldno] = NULL;
 
                fieldno++;
                /* Done if we hit EOL instead of a delim */