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authorRich Felker <dalias@aerifal.cx>2015-10-08 22:03:53 +0000
committerRich Felker <dalias@aerifal.cx>2015-10-08 22:10:09 +0000
commit7b9f57f207b51132f188f750161953b7baf32154 (patch)
tree38055088e85f9428998dd1d37381c18c6f1339ff
parentdc97951402b499023ce877dd2438bce0840b2c26 (diff)
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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.
-rw-r--r--src/stdio/open_memstream.c11
-rw-r--r--src/stdio/open_wmemstream.c11
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;