Messages in this thread | | | Date | Thu, 19 Aug 2004 16:12:47 +0200 | From | Martin Zwickel <> | Subject | Re: problem with fwrite |
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On Thu, 19 Aug 2004 09:42:41 -0400 Lei Yang <leiyang@nec-labs.com> bubbled:
> Hi all, > > This is not really a kernel issue, apologize if anyone thinks that > this is not the right place to post it. But I am writing a kernel > module and got stuck on fwrite, really hope someone could point out > what stupid mistake I've made. I wrote a very simple code to test the > idea, what I really want to do in fred() is to read from 'dest' and > write to 'src'. It seems that upon running , fgetc doesn't get > anything from in_stream, so the first char it gets is an EOF and it > breaks. Just why fwrite didn't write anything to in_stream? > > If this is not the right way to do it, what is ? > > Appreciate any comments, even harsh ones.
First: Wrong place!!!
> > TIA > Lei > > // in test.c > > #include <stdio.h> > > fred(char *dest, size_t *destlen, char *src, size_t size) > { > FILE *in_stream = tmpfile(); > FILE *out_stream = tmpfile(); > fwrite(src, 1, size, in_stream);
Seek in_stream to 0 (rewind)! like: rewind(in_stream);
> > int c, i; > for(i = 0;;i++) > { > c = fgetc(in_stream); > fprintf(stderr, "get char %c\n", c);
the fprintf of the read char should be after the EOF check!
> if ( c == EOF) break; > fputc(c, out_stream); > } > > *destlen = i; > > fseek(out_stream, 0, SEEK_SET); //rewind > fread(dest, 1, *destlen, out_stream); > fclose(in_stream); > fclose(out_stream); > fprintf(stderr, "buf = `%s', size = %d\n", dest, *destlen); > } > > int main(void) > { > static char source[] = "really hope this works "; > > char *bp = malloc (2048); > size_t destlen; > > fred(bp, &destlen, source, strlen(source)); > > fprintf(stderr, "buf = `%s', size = %d\n", bp, destlen); > return 0; > } > - > To unsubscribe from this list: send the line "unsubscribe > linux-kernel" in the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
-- MyExcuse: Traffic jam on the Information Superhighway.
Martin Zwickel <martin.zwickel@technotrend.de> Research & Development
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