MINOR: tools: make csv_enc_append() always start at the first byte of the chunk

csv_enc_append() returns a pointer to the beginning of the encoded
string, which makes it convenient to use in printf(). However it's not
convenient for use in chunks as it may leave an unused byte at the
beginning depending on the automatic quoting. Let's modify it to work
in two passes. First it looks for a character that requires escaping
using strpbrk(), and second it encodes the string. This way it
guarantees to always start at the first available byte of the chunk.
Additionally it made the code quite simpler.

diff --git a/src/standard.c b/src/standard.c
index adbffd4c498d079835b9dc0b8a5fc586bab6177c..1b158e2e3f58ae514f74e1361be0d86a80d341d1 100644 (file)
--- a/src/standard.c
+++ b/src/standard.c
@@ -1443,8 +1443,8 @@ char *encode_chunk(char *start, char *stop,
  *
  *    printf("..., \"%s\", ...\r\n", csv_enc(str, 0, &trash));
  *
- * If <quote> is 1, the converter puts the quotes only if any character is
- * escaped. If <quote> is 2, the converter always puts the quotes.
+ * If <quote> is 1, the converter puts the quotes only if any reserved character
+ * is present. If <quote> is 2, the converter always puts the quotes.
  *
  * <output> is a struct chunk used for storing the output string.
  *
@@ -1455,20 +1455,29 @@ char *encode_chunk(char *start, char *stop,
  * If the output buffer is too short to contain the input string, the result
  * is truncated.
  *
- * This function appends the encoding to the existing output chunk. Please
- * use csv_enc() instead if you want to replace the output chunk.
+ * This function appends the encoding to the existing output chunk, and it
+ * guarantees that it starts immediately at the first available character of
+ * the chunk. Please use csv_enc() instead if you want to replace the output
+ * chunk.
  */
 const char *csv_enc_append(const char *str, int quote, struct chunk *output)
 {
        char *end = output->str + output->size;
-       char *out = output->str + output->len + 1; /* +1 for reserving space for a first <"> */
+       char *out = output->str + output->len;
        char *ptr = out;
 
+       if (quote == 1) {
+               /* automatic quoting: first verify if we'll have to quote the string */
+               if (!strpbrk(str, "\n\r,\""))
+                       quote = 0;
+       }
+
+       if (quote)
+               *ptr++ = '"';
+
        while (*str && ptr < end - 2) { /* -2 for reserving space for <"> and \0. */
                *ptr = *str;
                if (*str == '"') {
-                       if (quote == 1)
-                               quote = 2;
                        ptr++;
                        if (ptr >= end - 2) {
                                ptr--;
@@ -1476,21 +1485,13 @@ const char *csv_enc_append(const char *str, int quote, struct chunk *output)
                        }
                        *ptr = '"';
                }
-               if (quote == 1 && ( *str == '\r' || *str == '\n' || *str == ',') )
-                       quote = 2;
                ptr++;
                str++;
        }
 
-       if (quote < 2) {
-               *ptr = '\0';
-               output->len = ptr - output->str;
-               return out;
-       }
+       if (quote)
+               *ptr++ = '"';
 
-       /* quote == 2 : add quotes */
-       *--out = '"';
-       *++ptr = '"';
        *ptr = '\0';
        output->len = ptr - output->str;
        return out;