Issue #13645: pyc files now contain the size of the corresponding source
code, to avoid timestamp collisions (especially on filesystems with a low
timestamp resolution) when checking for freshness of the bytecode.
diff --git a/Python/import.c b/Python/import.c
index c754131..4efc369 100644
--- a/Python/import.c
+++ b/Python/import.c
@@ -104,6 +104,7 @@
Python 3.2a2 3180 (add DELETE_DEREF)
Python 3.3a0 3190 __class__ super closure changed
Python 3.3a0 3200 (__qualname__ added)
+ 3210 (added size modulo 2**32 to the pyc header)
*/
/* MAGIC must change whenever the bytecode emitted by the compiler may no
@@ -116,7 +117,7 @@
#define STRIFY(name) QUOTE(name)
#define MAJOR STRIFY(PY_MAJOR_VERSION)
#define MINOR STRIFY(PY_MINOR_VERSION)
-#define MAGIC (3200 | ((long)'\r'<<16) | ((long)'\n'<<24))
+#define MAGIC (3210 | ((long)'\r'<<16) | ((long)'\n'<<24))
#define TAG "cpython-" MAJOR MINOR;
#define CACHEDIR "__pycache__"
/* Current magic word and string tag as globals. */
@@ -1071,11 +1072,12 @@
Doesn't set an exception. */
static FILE *
-check_compiled_module(PyObject *pathname, time_t mtime, PyObject *cpathname)
+check_compiled_module(PyObject *pathname, struct stat *srcstat, PyObject *cpathname)
{
FILE *fp;
long magic;
long pyc_mtime;
+ long pyc_size;
fp = _Py_fopen(cpathname, "rb");
if (fp == NULL)
@@ -1088,12 +1090,19 @@
return NULL;
}
pyc_mtime = PyMarshal_ReadLongFromFile(fp);
- if (pyc_mtime != mtime) {
+ if (pyc_mtime != srcstat->st_mtime) {
if (Py_VerboseFlag)
PySys_FormatStderr("# %R has bad mtime\n", cpathname);
fclose(fp);
return NULL;
}
+ pyc_size = PyMarshal_ReadLongFromFile(fp);
+ if (pyc_size != (srcstat->st_size & 0xFFFFFFFF)) {
+ if (Py_VerboseFlag)
+ PySys_FormatStderr("# %R has bad size\n", cpathname);
+ fclose(fp);
+ return NULL;
+ }
if (Py_VerboseFlag)
PySys_FormatStderr("# %R matches %R\n", cpathname, pathname);
return fp;
@@ -1136,6 +1145,8 @@
"Bad magic number in %R", cpathname);
return NULL;
}
+ /* Skip mtime and size */
+ (void) PyMarshal_ReadLongFromFile(fp);
(void) PyMarshal_ReadLongFromFile(fp);
co = read_compiled_module(cpathname, fp);
if (co == NULL)
@@ -1196,6 +1207,7 @@
Py_UCS4 *cpathname_ucs4;
FILE *fp;
time_t mtime = srcstat->st_mtime;
+ long size = srcstat->st_size & 0xFFFFFFFF;
PyObject *cpathname_tmp;
#ifdef MS_WINDOWS /* since Windows uses different permissions */
mode_t mode = srcstat->st_mode & ~S_IEXEC;
@@ -1326,14 +1338,16 @@
return;
}
PyMarshal_WriteLongToFile(pyc_magic, fp, Py_MARSHAL_VERSION);
- /* First write a 0 for mtime */
+ /* First write a 0 for mtime and size */
+ PyMarshal_WriteLongToFile(0L, fp, Py_MARSHAL_VERSION);
PyMarshal_WriteLongToFile(0L, fp, Py_MARSHAL_VERSION);
PyMarshal_WriteObjectToFile((PyObject *)co, fp, Py_MARSHAL_VERSION);
fflush(fp);
- /* Now write the true mtime */
+ /* Now write the true mtime and size */
fseek(fp, 4L, 0);
assert(mtime < LONG_MAX);
PyMarshal_WriteLongToFile((long)mtime, fp, Py_MARSHAL_VERSION);
+ PyMarshal_WriteLongToFile(size, fp, Py_MARSHAL_VERSION);
if (fflush(fp) != 0 || ferror(fp)) {
if (Py_VerboseFlag)
PySys_FormatStderr("# can't write %R\n", cpathname);
@@ -1478,7 +1492,7 @@
cpathname = make_compiled_pathname(pathname, !Py_OptimizeFlag);
if (cpathname != NULL)
- fpc = check_compiled_module(pathname, st.st_mtime, cpathname);
+ fpc = check_compiled_module(pathname, &st, cpathname);
else
fpc = NULL;