Python 3.7 Support

[sscherfke]

The latest PR #7 compiles with Python 3.7 but when I import base92 I get a segfault.

I have not yet digged deeper into yet.

[sscherfke]

>>> import faulthandler
>>> faulthandler.enable()
>>> import base92
Fatal Python error: Segmentation fault

Current thread 0x00007fc11e5f6740 (most recent call first):
  File "<frozen importlib._bootstrap>", line 219 in _call_with_frames_removed
  File "<frozen importlib._bootstrap_external>", line 1043 in create_module
  File "<frozen importlib._bootstrap>", line 583 in module_from_spec
  File "<frozen importlib._bootstrap>", line 670 in _load_unlocked
  File "<frozen importlib._bootstrap>", line 967 in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 983 in _find_and_load
  File "/opt/emsconda/conda-bld/base92_1531909595061/_test_env_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placeold_placehold_pla
cehold_placehold_placehold_/lib/python3.7/site-packages/base92/cbase92.py", line 38 in <module>
  File "<frozen importlib._bootstrap>", line 219 in _call_with_frames_removed
  File "<frozen importlib._bootstrap_external>", line 728 in exec_module
  File "<frozen importlib._bootstrap>", line 677 in _load_unlocked
  File "<frozen importlib._bootstrap>", line 967 in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 983 in _find_and_load
  File "<frozen importlib._bootstrap>", line 219 in _call_with_frames_removed
  File "<frozen importlib._bootstrap>", line 1035 in _handle_fromlist
  File "/opt/emsconda/conda-bld/base92_1531909595061/_test_env_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_/lib/python3.7/site-packages/base92/__init__.py", line 17 in <module>
  File "<frozen importlib._bootstrap>", line 219 in _call_with_frames_removed
  File "<frozen importlib._bootstrap_external>", line 728 in exec_module
  File "<frozen importlib._bootstrap>", line 677 in _load_unlocked
  File "<frozen importlib._bootstrap>", line 967 in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 983 in _find_and_load
  File "<stdin>", line 1 in <module>
Segmentation fault (core dumped)

[sscherfke]

If I compile the c-lib with gcc -c -Wall -Werror -fpic -shared -o $PREFIX/lib/libbase92.so -Ic/src c/src/base92.c I get some more errors:

c/src/base92.c: In function ‘base92encode’:
c/src/base92.c:84:17: error: pointer targets in return differ in signedness [-Werror=pointer-sign]
                 return "~";
                 ^
c/src/base92.c: In function ‘base92decode’:
c/src/base92.c:162:9: error: pointer targets in passing argument 1 of ‘strlen’ differ in signedness [-Werror=pointer-s
ign]
         size = strlen(str);
         ^
In file included from c/src/base92.h:12:0,
                 from c/src/base92.c:7:
/usr/include/string.h:395:15: note: expected ‘const char *’ but argument is of type ‘unsigned char *’
 extern size_t strlen (const char *__s)
               ^
c/src/base92.c:164:9: error: pointer targets in passing argument 1 of ‘strcmp’ differ in signedness [-Werror=pointer-s
ign]
         if (strcmp(str, "~") == 0 || size == 0) {
         ^
In file included from c/src/base92.h:12:0,
                 from c/src/base92.c:7:
/usr/include/string.h:140:12: note: expected ‘const char *’ but argument is of type ‘unsigned char *’
 extern int strcmp (const char *__s1, const char *__s2)
            ^
cc1: all warnings being treated as errors

Maybe this helps.

[sscherfke]

The following patch solves the problem:

diff --git a/c/src/base92.c b/c/src/base92.c
index e0208b0..d5c50f7 100644
--- a/c/src/base92.c
+++ b/c/src/base92.c
@@ -79,9 +79,9 @@ unsigned char* base92encode(unsigned char* str, int len) {
         int tmp;
         unsigned char c;
         unsigned char *res;
-
+
         if (len == 0) {
-                return "~";
+                return (unsigned char*)"~";
         }
         // precalculate how much space we need to malloc
         size = (len * 8) % 13;
@@ -159,9 +159,9 @@ unsigned char* base92decode(unsigned char* str, int* len) {
         unsigned char* res;
         unsigned long workspace;
         unsigned short wssize;
-        size = strlen(str);
+        size = strlen((char*)str);
         // handle small cases first
-        if (strcmp(str, "~") == 0 || size == 0) {
+        if (strcmp((char*)str, "~") == 0 || size == 0) {
                 res = (unsigned char*)malloc(sizeof(char) * 1);
                 res[0] = 0;
                 return res;
diff --git a/python/base92/base92_extension.c b/python/base92/base92_extension.c
index 57907cf..a9687bc 100644
--- a/python/base92/base92_extension.c
+++ b/python/base92/base92_extension.c
@@ -289,6 +289,7 @@ static PyMethodDef base92_methods[] =
 {
     {"encode", (PyCFunction)PyBase92_encode, METH_VARARGS, encode__doc__},
     {"decode", (PyCFunction)PyBase92_decode, METH_VARARGS, decode__doc__},
+    {NULL, NULL, 0, NULL}        /* Sentinel */
 };


@@ -315,17 +316,11 @@ static struct PyModuleDef base92_def = {
     "base92_extension",
     NULL,
     -1,
-    base92_methods,
-    NULL,
-    NULL,
-    NULL,
-    NULL
+    base92_methods
 };

 PyMODINIT_FUNC
 PyInit_base92_extension(void) {
-    PyObject *m = PyModule_Create(&base92_def);
-
-    return m;
+    return PyModule_Create(&base92_def);
 }
 #endif

[backbord]

Hi @sscherfke, looks good. If you'll open a PR for my fork, I'll gladly merge it.