With this patch, jq run-time errors printed to stderr will contain the
filename and line of the offending input.
But note that the JSON text parser does (yet) print the input filename
on parse error. A jq run-time error is a jq program error, not
including syntax errors nor JSON text input format errors.
Examples:
With stdin and multiple lines:
$ printf '{"a":43}\n{"a":{"b":66}}\n' | ./jq '.a+1'
44
jq: error (at stdin:2): object and number cannot be added
With multiple files:
$ printf '{"a":43}' > 1.json
$ printf '{"a":"hello"}\n' > 2.json
$ printf '{"a":{"b":66}}\n' > 3.json
$ ./jq '[.a]|@tsv' 1.json 2.json 3.json
"43"
"hello"
jq: error (at 3.json:1): object is not valid in a csv row
With very long lines (spanning multiple `fgets` calls):
$ ( printf '{"a":43}\n' ;
printf '{"a":{"b":[' ; seq 10000 | paste -d, -s | tr -d '\n' ;
printf ']}}\n' ;
printf '{"a":"hello"}\n' ) | ./jq '[.a] | @tsv'
"43"
jq: error (at stdin:2): object is not valid in a csv row
"hello"
With raw input:
$ seq 1000 | ./jq --raw-input 'select(.=="700") | . + 10'
jq: error (at stdin:700): string and number cannot be added
Caveat:
The reported line will be the last line of the (valid) parsed JSON data.
Example:
$ printf '{\n"a":\n"hello"\n\n\n}\n' | ./jq '.a+4'
jq: error (at stdin:6): string and number cannot be added
We can't know how many bytes fgets() read when we reach EOF and fgets()
didn't see a newline; we can only assume that at least strlen(buf) bytes
were read. This is quite obnoxious if one wants to use NULs in raw
input, but at least we can make reading "a\0b\0c\0" with no newline
yield "a\0b\0c", losing only the final sequence of NULs.
We can't use getline() either, since it will want to allocate a buffer
big enough for an entire line, and we might not have any newlines in our
input. A complete fix will have to use getc() or read(), preferably the
latter.
