From f9123b5003e62b6e54996076e860f23aee9a0593 Mon Sep 17 00:00:00 2001 From: Adhemerval Zanella Date: Tue, 26 Apr 2016 17:40:25 -0300 Subject: libio: Update internal fmemopen position after write (BZ #20005) Current GLIBC fmemopen fails with a simple testcase: char buffer[500] = "x"; FILE *stream; stream = fmemopen(buffer, 500, "r+"); fwrite("fish",sizeof(char),5,stream); printf("pos-1:%ld\n",ftell(stream)); fflush(stream); printf("pos-2:%ld\n",ftell(stream)); It returns: pos-1:5 pos-2:0 Where it should return: pos-1:5 pos-2:5 This is due the internal write function does not correctly update the internal object position state and then the seek operation returns a wrong value. This patch fixes it. It fixes both BZ #20005 and BZ #19230 (marked as duplicated). A new test is added to check for such case. Tested on x86_64 and i686. * libio/fmemopen.c (fmemopen_write): Update internal position after write. * stdio-common/Makefile (tests): Add tst-fmemopen4.c. * stdio-common/tst-fmemopen4.c: New file.. --- libio/fmemopen.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'libio') diff --git a/libio/fmemopen.c b/libio/fmemopen.c index 23b5c5f..9264b72 100644 --- a/libio/fmemopen.c +++ b/libio/fmemopen.c @@ -86,10 +86,10 @@ fmemopen_write (void *cookie, const char *b, size_t s) memcpy (&(c->buffer[pos]), b, s); - pos += s; - if ((size_t) pos > c->maxpos) + c->pos += s; + if ((size_t) c->pos > c->maxpos) { - c->maxpos = pos; + c->maxpos = c->pos; if (addnullc) c->buffer[c->maxpos] = '\0'; } -- cgit v1.1