On 11/24/2015 09:34 AM, marcandre.lur...@redhat.com wrote: > From: Marc-André Lureau <marcandre.lur...@redhat.com>
In the subject: s/implicitely/implicitly/ if you are fixing the typo, or s/implicitely/explicitly/ if you are trying to make it match what the patch actually does. No 0/2 cover letter? ALL multi-patch series should include a cover letter, as it is easier on tooling to be able to base series-wide conversations on the cover letter. > > According to the specification: > http://pubs.opengroup.org/onlinepubs/9699919799/functions/fopen.html > > "the application shall ensure that output is not directly followed by > input without an intervening call to fflush() or to a file positioning > function (fseek(), fsetpos(), or rewind()), and input is not directly > followed by output without an intervening call to a file positioning > function, unless the input operation encounters end-of-file." > > Without this change, a write() followed by a read() may lose the > previously written content, as shown in the following test. > > Fixes: > https://bugzilla.redhat.com/show_bug.cgi?id=1210246 > > Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com> > --- > qga/commands-posix.c | 22 ++++++++++++++++++++++ > 1 file changed, 22 insertions(+) > > diff --git a/qga/commands-posix.c b/qga/commands-posix.c > index 0ebd473..3c86a4e 100644 > --- a/qga/commands-posix.c > +++ b/qga/commands-posix.c > @@ -219,6 +219,7 @@ void qmp_guest_set_time(bool has_time, int64_t time_ns, > Error **errp) > typedef struct GuestFileHandle { > uint64_t id; > FILE *fh; > + bool writing; > QTAILQ_ENTRY(GuestFileHandle) next; > } GuestFileHandle; > > @@ -460,6 +461,17 @@ struct GuestFileRead *qmp_guest_file_read(int64_t > handle, bool has_count, > } > > fh = gfh->fh; > + > + /* implicitely flush when switching from writing to reading */ Again, s/implicitely/explicitly/ > + if (gfh->writing) { > + int ret = fflush(fh); > + if (ret == EOF) { > + error_setg_errno(errp, errno, "failed to flush file"); > + return NULL; > + } > + gfh->writing = false; > + } > + > buf = g_malloc0(count+1); > read_count = fread(buf, 1, count, fh); > if (ferror(fh)) { > @@ -496,6 +508,16 @@ GuestFileWrite *qmp_guest_file_write(int64_t handle, > const char *buf_b64, > } > > fh = gfh->fh; > + > + if (!gfh->writing) { > + int ret = fseek(fh, 0, SEEK_CUR); Seems a bit odd to use fflush() in one place and fseek() in the other, but the net result is the same either way. > + if (ret == -1) { > + error_setg_errno(errp, errno, "failed to seek file"); > + return NULL; > + } > + gfh->writing = true; > + } > + With typos fixed, Reviewed-by: Eric Blake <ebl...@redhat.com> > buf = g_base64_decode(buf_b64, &buf_len); > > if (!has_count) { > -- Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org
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