From 7b9f57f207b51132f188f750161953b7baf32154 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Thu, 8 Oct 2015 22:03:53 +0000 Subject: fix open_[w]memstream behavior when no writes take place the specification for these functions requires that the buffer/size exposed to the caller be valid after any successful call to fflush or fclose on the stream. the implementation's approach is to update them only at flush time, but that misses the case where fflush or fclose is called without any writes having taken place, in which case the write flushing callback will not be called. to fix both the observable bug and the desired invariant, setup empty buffers at open time and fail the open operation if no memory is available. --- src/stdio/open_memstream.c | 11 +++++++++-- src/stdio/open_wmemstream.c | 11 +++++++++-- 2 files changed, 18 insertions(+), 4 deletions(-) diff --git a/src/stdio/open_memstream.c b/src/stdio/open_memstream.c index 58504c9f..eab024da 100644 --- a/src/stdio/open_memstream.c +++ b/src/stdio/open_memstream.c @@ -59,14 +59,21 @@ FILE *open_memstream(char **bufp, size_t *sizep) { FILE *f; struct cookie *c; + char *buf; + if (!(f=malloc(sizeof *f + sizeof *c + BUFSIZ))) return 0; + if (!(buf=malloc(sizeof *buf))) { + free(f); + return 0; + } memset(f, 0, sizeof *f + sizeof *c); f->cookie = c = (void *)(f+1); c->bufp = bufp; c->sizep = sizep; - c->pos = c->len = c->space = 0; - c->buf = 0; + c->pos = c->len = c->space = *sizep = 0; + c->buf = *bufp = buf; + *buf = 0; f->flags = F_NORD; f->fd = -1; diff --git a/src/stdio/open_wmemstream.c b/src/stdio/open_wmemstream.c index 7ab2c643..4d90cd97 100644 --- a/src/stdio/open_wmemstream.c +++ b/src/stdio/open_wmemstream.c @@ -61,14 +61,21 @@ FILE *open_wmemstream(wchar_t **bufp, size_t *sizep) { FILE *f; struct cookie *c; + wchar_t *buf; + if (!(f=malloc(sizeof *f + sizeof *c))) return 0; + if (!(buf=malloc(sizeof *buf))) { + free(f); + return 0; + } memset(f, 0, sizeof *f + sizeof *c); f->cookie = c = (void *)(f+1); c->bufp = bufp; c->sizep = sizep; - c->pos = c->len = c->space = 0; - c->buf = 0; + c->pos = c->len = c->space = *sizep = 0; + c->buf = *bufp = buf; + *buf = 0; f->flags = F_NORD; f->fd = -1; -- cgit v1.2.1