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| From | Keith Thompson <kst-u@mib.org> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Method other than strlen to check for truncation with fgets? |
| Date | 2015-05-07 12:00 -0700 |
| Organization | None to speak of |
| Message-ID | <878ud0jjri.fsf@kst-u.example.com> (permalink) |
| References | <midqe0$62n$1@dont-email.me> <chine.bleu-B62ADF.11305507052015@news.eternal-september.org> |
Siri Cruz <chine.bleu@yahoo.com> writes:
> In article <midqe0$62n$1@dont-email.me>, mathog <dmathog@gmail.com> wrote:
>> It should work when the input line is truncated. The problem is that,
>> from my reading of the fgets man page, there is no guarantee that the
>> library will not write something beyond the \0 in the buffer. I don't
>> expect that would happen, but also do not see anything saying that it
>> cannot.
>
> If this is critical to you, use fgetline instead.
>
> /*
> Read and return the next line from input.
> The line is mallocked; caller is responsibile for freeing.
> The line ends in \n if the line from the input file did.
> Returns NULL on EOF.
> */
>
> char *fgetline (FILE *input) {
> int c; char *line = NULL; int m = 0, n = 0;
> while ((c=fgetc(input))!=EOF) {
> if (c==0) abort();
> if (n+1>=m) {m = 2*(n+1); line = realloc(line, m);}
> if (!line) abort();
> line[n++] = c;
> if (c=='\n') break;
> }
> if (line) {line = realloc(line, n+1); line[n] = 0;}
> return line;
> }
This doesn't check for allocation failures.
--
Keith Thompson (The_Other_Keith) kst-u@mib.org <http://www.ghoti.net/~kst>
Working, but not speaking, for JetHead Development, Inc.
"We must do something. This is something. Therefore, we must do this."
-- Antony Jay and Jonathan Lynn, "Yes Minister"
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Method other than strlen to check for truncation with fgets? mathog <dmathog@gmail.com> - 2015-05-06 12:35 -0700
Re: Method other than strlen to check for truncation with fgets? Barry Schwarz <schwarzb@dqel.com> - 2015-05-06 15:14 -0700
Re: Method other than strlen to check for truncation with fgets? mathog <dmathog@gmail.com> - 2015-05-06 16:14 -0700
Re: Method other than strlen to check for truncation with fgets? Barry Schwarz <schwarzb@dqel.com> - 2015-05-06 17:51 -0700
Re: Method other than strlen to check for truncation with fgets? Tim Rentsch <txr@alumni.caltech.edu> - 2015-05-06 18:23 -0700
Re: Method other than strlen to check for truncation with fgets? mathog <dmathog@gmail.com> - 2015-05-07 10:07 -0700
Re: Method other than strlen to check for truncation with fgets? Tim Rentsch <txr@alumni.caltech.edu> - 2015-05-07 16:06 -0700
Re: Method other than strlen to check for truncation with fgets? James Kuyper <jameskuyper@verizon.net> - 2015-05-06 22:20 -0400
Re: Method other than strlen to check for truncation with fgets? mathog <dmathog@gmail.com> - 2015-05-07 10:29 -0700
Re: Method other than strlen to check for truncation with fgets? James Kuyper <jameskuyper@verizon.net> - 2015-05-07 14:09 -0400
Re: Method other than strlen to check for truncation with fgets? mathog <dmathog@gmail.com> - 2015-05-07 12:48 -0700
Re: Method other than strlen to check for truncation with fgets? James Kuyper <jameskuyper@verizon.net> - 2015-05-07 17:01 -0400
Re: Method other than strlen to check for truncation with fgets? mathog <dmathog@gmail.com> - 2015-05-08 10:59 -0700
Re: Method other than strlen to check for truncation with fgets? James Kuyper <jameskuyper@verizon.net> - 2015-05-08 14:48 -0400
Re: Method other than strlen to check for truncation with fgets? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-05-08 18:37 +0000
Re: Method other than strlen to check for truncation with fgets? James Kuyper <jameskuyper@verizon.net> - 2015-05-08 15:06 -0400
Re: Method other than strlen to check for truncation with fgets? Lőrinczy Zsigmond <nospam@for.me> - 2015-05-07 07:04 +0200
Re: Method other than strlen to check for truncation with fgets? Richard Heathfield <rjh@cpax.org.uk> - 2015-05-07 06:52 +0100
Re: Method other than strlen to check for truncation with fgets? Lőrinczy Zsigmond <zsiga@nospam.for.me> - 2015-05-07 09:58 +0200
Re: Method other than strlen to check for truncation with fgets? Stephen Sprunk <stephen@sprunk.org> - 2015-05-07 09:12 -0500
Re: Method other than strlen to check for truncation with fgets? Keith Thompson <kst-u@mib.org> - 2015-05-07 08:51 -0700
Re: Method other than strlen to check for truncation with fgets? Lőrinczy Zsigmond <zsiga@nospam.for.me> - 2015-05-07 19:09 +0200
Re: Method other than strlen to check for truncation with fgets? James Kuyper <jameskuyper@verizon.net> - 2015-05-07 14:15 -0400
Re: Method other than strlen to check for truncation with fgets? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-05-07 11:31 +0100
Re: Method other than strlen to check for truncation with fgets? Lőrinczy Zsigmond <zsiga@nospam.for.me> - 2015-05-07 15:41 +0200
Re: Method other than strlen to check for truncation with fgets? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-05-08 02:44 +0100
Re: Method other than strlen to check for truncation with fgets? James Kuyper <jameskuyper@verizon.net> - 2015-05-07 23:24 -0400
Re: Method other than strlen to check for truncation with fgets? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-05-08 04:41 +0100
Re: Method other than strlen to check for truncation with fgets? Keith Thompson <kst-u@mib.org> - 2015-05-07 08:49 -0700
Re: Method other than strlen to check for truncation with fgets? James Kuyper <jameskuyper@verizon.net> - 2015-05-07 12:19 -0400
Re: Method other than strlen to check for truncation with fgets? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-05-07 18:08 +0000
Re: Method other than strlen to check for truncation with fgets? James Kuyper <jameskuyper@verizon.net> - 2015-05-07 12:19 -0400
Re: Method other than strlen to check for truncation with fgets? mathog <dmathog@gmail.com> - 2015-05-07 09:57 -0700
Re: Method other than strlen to check for truncation with fgets? Siri Cruz <chine.bleu@yahoo.com> - 2015-05-07 11:31 -0700
Re: Method other than strlen to check for truncation with fgets? Keith Thompson <kst-u@mib.org> - 2015-05-07 12:00 -0700
Re: Method other than strlen to check for truncation with fgets? Siri Cruz <chine.bleu@yahoo.com> - 2015-05-07 12:44 -0700
Re: Method other than strlen to check for truncation with fgets? Keith Thompson <kst-u@mib.org> - 2015-05-07 14:03 -0700
Re: Method other than strlen to check for truncation with fgets? Siri Cruz <chine.bleu@yahoo.com> - 2015-05-07 15:28 -0700
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