MINOR: tools: make parse_line() provide hints about empty args

In order to help parse_line() callers report the position of empty
args to the user, let's decide that if no error is emitted, then
we'll stuff the errptr with the position of the first empty arg
without affecting the return value.

Co-authored-by: Valentine Krasnobaeva <vkrasnobaeva@haproxy.com>

diff --git a/src/tools.c b/src/tools.c
index 85b958655a0d6acec3af0e9a1f2942e079cae6ca..06b8b201813573b1561a5f2c5514ba6dc65586c3 100644 (file)
--- a/src/tools.c
+++ b/src/tools.c
@@ -6167,7 +6167,9 @@ int is_dir_present(const char *path_fmt, ...)
  * quote/brace is reported in <errptr> if not NULL. When using in-place parsing
  * error reporting might be difficult since zeroes will have been inserted into
  * the string. One solution for the caller may consist in replacing all args
- * delimiters with spaces in this case.
+ * delimiters with spaces in this case. As a convenience, the pointer to the
+ * first empty arg may be reported in errptr if that one was not assigned an
+ * error.
  */
 uint32_t parse_line(char *in, char *out, size_t *outlen, char **args, int *nbargs, uint32_t opts, const char **errptr)
 {
@@ -6179,6 +6181,9 @@ uint32_t parse_line(char *in, char *out, size_t *outlen, char **args, int *nbarg
        int argsmax = *nbargs - 1;
        size_t outpos = 0;
        size_t arg_start = 0; // copy of outpos before EMIT_CHAR().
+       const char *curr_in = in; // <in> at the beginning of the loop
+       const char *begin_new_arg = NULL; // <in> at transition to new arg
+       const char *empty_arg_ptr = NULL; // pos of first empty arg if any (wrt in)
        int squote = 0;
        int dquote = 0;
        int arg = 0;
@@ -6196,6 +6201,7 @@ uint32_t parse_line(char *in, char *out, size_t *outlen, char **args, int *nbarg
        while (1) {
                prev_in_arg = in_arg;
                arg_start = outpos;
+               curr_in = in;
 
                if (*in >= '-' && *in != '\\') {
                        in_arg = 1;
@@ -6426,12 +6432,15 @@ uint32_t parse_line(char *in, char *out, size_t *outlen, char **args, int *nbarg
                                                EMIT_CHAR(*value++);
                                        }
                                        if (!prev_in_arg && in_arg) {
+                                               begin_new_arg = curr_in;
                                                if (arg < argsmax)
                                                        args[arg] = out + arg_start;
                                                else
                                                        err |= PARSE_ERR_TOOMANY;
                                        }
                                        if (prev_in_arg && !in_arg) {
+                                               if (!empty_arg_ptr && args[arg] == out + arg_start)
+                                                       empty_arg_ptr = begin_new_arg;
                                                EMIT_CHAR(0);
                                                arg++;
                                        }
@@ -6464,6 +6473,7 @@ uint32_t parse_line(char *in, char *out, size_t *outlen, char **args, int *nbarg
                }
 
                if (!prev_in_arg && in_arg) {
+                       begin_new_arg = curr_in;
                        if (arg < argsmax)
                                args[arg] = out + arg_start;
                        else
@@ -6471,6 +6481,8 @@ uint32_t parse_line(char *in, char *out, size_t *outlen, char **args, int *nbarg
                }
 
                if (prev_in_arg && !in_arg) {
+                       if (!empty_arg_ptr && args[arg] == out + arg_start)
+                               empty_arg_ptr = begin_new_arg;
                        EMIT_CHAR(0);
                        arg++;
                }
@@ -6478,6 +6490,8 @@ uint32_t parse_line(char *in, char *out, size_t *outlen, char **args, int *nbarg
 
        /* end of output string */
        if (in_arg) {
+               if (!empty_arg_ptr && args[arg] == out + arg_start)
+                       empty_arg_ptr = begin_new_arg;
                EMIT_CHAR(0);
                arg++;
        }
@@ -6502,6 +6516,9 @@ uint32_t parse_line(char *in, char *out, size_t *outlen, char **args, int *nbarg
        while (arg >= 0 && arg <= argsmax)
                args[arg++] = out + outpos - 1;
 
+       /* if no error but an empty arg, report its pointer in errptr for convenience */
+       if (empty_arg_ptr && errptr && !err)
+               *errptr = empty_arg_ptr;
        return err;
 }
 #undef EMIT_CHAR