The file compiles (I've tried a few compiler options) and "gdb run" yields
Program received signal SIGSEGV, Segmentation fault.
0x00007ffff783eea5 in _int_malloc (av=0x7ffff7b6a620 <main_arena>,
bytes=16) at malloc.c:3790
The frames 0-3 involve allocation functions that are not particular to my
file. Frame 4 says:
#4 __patsfun_28__28__14 (arg0=<optimized out>, env1=0x605540, env0=10
'\n') at csv_lexer_dats.c:9023
9023 ATSINSmove_con1_new(tmpret63__14, postiats_tysum_7) ;
My not-so-educated guess is that this refers to making a cons-cell of a
stream.
But: How can my function do just fine when manually fed
cons('a', cons( ';', sing('b'))): stream_vt(char),
but segfault when I use [streamize_fileref_char] to construct the very same
stream from the string "a;b" in a file? Where is the room for an infinite
recursion in that?
Thank you,
August
Den torsdag 2 mars 2017 kl. 23:04:35 UTC+1 skrev August Alm:
>
> Hi!
>
> I'm in over my head and tried writing a CSV-parser using linear lazy
> streams. My code thus far is 600 lines and almost to my own surprise I get
> it to compile! However, there is something fishy because I get a segfault
> when applying my program to an actual CSV-file. I've been trying to debug
> using gdb but the fault eludes me. Since I don't expect anyone to mull
> through 600 lines of code, I am hoping these code snippets are enough for
> one of you guys to give me some advice.
>
> This code executes just fine:
>
> implement main0 () = {
>
> val test = stream_vt_make_cons(
> 'a', stream_vt_make_cons(
> ';',
> stream_vt_make_sing('b'))) (* the stream ('a', ';', 'b') *)
> val lexed = lex_csv(true, ';', test)
> val h = (lexed.head())
> val- CSV_Field(r) = h
> val a = r.csvFieldContent
> val () = println!(a)
>
> }
>
> Here [lex_csv] is my 600-line alogrithm. It reads a [stream_vt(char)] and
> gives back a [stream_vt(CSVEntry)], where [CSVEntry] is a record type, one
> of whose fields is [CSVFieldContent]. When executing the program I get "a"
> printed to the console.
>
> This code results in a segfault:
>
> implement main0 () = {
>
> val inp = fileref_open_exn("small.csv", file_mode_r)
> val ins = streamize_fileref_char(inp)
> val lexed = lex_csv(true, ';', ins)
> val () = fileref_close(inp)
> val h = (lexed.head())
> val- CSV_Field(r) = h
> val a = r.csvFieldContent
> val () = println!(a)
>
> }
>
> The file "small.csv" only contains the string "a;b". Hence I would expect
> this code to give the result as the previous one! But, it doesn't just
> return something else, it segfaults.
>
> gdb indicates there is a malloc problem having to do with
> "GC_clear_stack_inner", in case that's helpful. (I'm a mathematician who
> recently left academia after postdoc and decided to teach myself
> programming to become more useful outside of academia; hence I understand
> type systems and the like--the mathy stuff--a lot better than I understand
> memory allocation and other stuff that most programmers are supposed to be
> confident with.)
>
> What could be the problem here?
>
> Best wishes,
> August
>
>
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