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Issue #15381: Fixed a bug in BytesIO.write(). 

It was expected that string_size == PyBytes_GET_SIZE(buf) if the buffer is
shared, but truncate() and __setstate__() can set string_size without
unsharing the buffer.
This commit is contained in:
Serhiy Storchaka 2015-02-03 18:51:58 +02:00
parent 06bb1226d1
commit 38c30e6c8e
1 changed files with 10 additions and 9 deletions
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19
Modules/_io/bytesio.c
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@ -19,7 +19,7 @@ typedef struct {
/* The bytesio object can be in three states: /* The bytesio object can be in three states:
* Py_REFCNT(buf) == 1, exports == 0. * Py_REFCNT(buf) == 1, exports == 0.
* Py_REFCNT(buf) > 1. exports == 0, string_size == PyBytes_GET_SIZE(buf), * Py_REFCNT(buf) > 1. exports == 0,
first modification or export causes the internal buffer copying. first modification or export causes the internal buffer copying.
* exports > 0. Py_REFCNT(buf) == 1, any modifications are forbidden. * exports > 0. Py_REFCNT(buf) == 1, any modifications are forbidden.
*/ */
@ -38,8 +38,7 @@ typedef struct {
return NULL; \ return NULL; \
} }
#define SHARED_BUF(self) (Py_REFCNT((self)->buf) > 1 || \ #define SHARED_BUF(self) (Py_REFCNT((self)->buf) > 1)
PyBytes_GET_SIZE((self)->buf) <= 1)
/* Internal routine to get a line from the buffer of a BytesIO /* Internal routine to get a line from the buffer of a BytesIO
@ -152,16 +151,18 @@ resize_buffer(bytesio *self, size_t size)
static Py_ssize_t static Py_ssize_t
write_bytes(bytesio *self, const char *bytes, Py_ssize_t len) write_bytes(bytesio *self, const char *bytes, Py_ssize_t len)
{ {
size_t endpos;
assert(self->buf != NULL); assert(self->buf != NULL);
assert(self->pos >= 0); assert(self->pos >= 0);
assert(len >= 0); assert(len >= 0);
if ((size_t)self->pos + len > (size_t)PyBytes_GET_SIZE(self->buf)) { endpos = (size_t)self->pos + len;
if (resize_buffer(self, (size_t)self->pos + len) < 0) if (endpos > (size_t)PyBytes_GET_SIZE(self->buf)) {
if (resize_buffer(self, endpos) < 0)
return -1; return -1;
} }
else if (SHARED_BUF(self)) { else if (SHARED_BUF(self)) {
if (unshare_buffer(self, self->string_size) < 0) if (unshare_buffer(self, Py_MAX(endpos, (size_t)self->string_size)) < 0)
return -1; return -1;
} }
@ -181,11 +182,11 @@ write_bytes(bytesio *self, const char *bytes, Py_ssize_t len)
/* Copy the data to the internal buffer, overwriting some of the existing /* Copy the data to the internal buffer, overwriting some of the existing
data if self->pos < self->string_size. */ data if self->pos < self->string_size. */
memcpy(PyBytes_AS_STRING(self->buf) + self->pos, bytes, len); memcpy(PyBytes_AS_STRING(self->buf) + self->pos, bytes, len);
self->pos += len; self->pos = endpos;
/* Set the new length of the internal string if it has changed. */ /* Set the new length of the internal string if it has changed. */
if (self->string_size < self->pos) { if ((size_t)self->string_size < endpos) {
self->string_size = self->pos; self->string_size = endpos;
} }
return len; return len;