src: error reporting with -f and read from stdin

Reading from stdin requires to store the ruleset in a buffer so error
reporting works accordingly, eg.

 # cat ruleset.nft | nft -f -
 /dev/stdin:3:13-13: Error: unknown identifier 'x'
                 ip saddr $x
                           ^

The error reporting infrastructure performs a fseek() on the file
descriptor which does not work in this case since the data from the
descriptor has been already consumed.

This patch adds a new stdin input descriptor to perform this special
handling which consists on re-routing this request through the buffer
functions.

Fixes: 935f82e7dd49 ("Support 'nft -f -' to read from stdin")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 7 insertions, 1 deletions

diff --git a/src/erec.c b/src/erec.c
index 7c9165c2..32fb079f 100644
--- a/src/erec.c
+++ b/src/erec.c
@@ -101,10 +101,11 @@ void print_location(FILE *f, const struct input_descriptor *indesc,
 			iloc = &tmp->location;
 		}
 	}
-	if (indesc->name != NULL)
+	if (indesc->type != INDESC_BUFFER && indesc->name) {
 		fprintf(f, "%s:%u:%u-%u: ", indesc->name,
 			loc->first_line, loc->first_column,
 			loc->last_column);
+	}
 }
 
 const char *line_location(const struct input_descriptor *indesc,
@@ -145,6 +146,11 @@ void erec_print(struct output_ctx *octx, const struct error_record *erec,
 		line = indesc->data;
 		*strchrnul(line, '\n') = '\0';
 		break;
+	case INDESC_STDIN:
+		line = indesc->data;
+		line += loc->line_offset;
+		*strchrnul(line, '\n') = '\0';
+		break;
 	case INDESC_FILE:
 		line = line_location(indesc, loc, buf, sizeof(buf));
 		break;