]> arthur.barton.de Git - bup.git/blobdiff - lib/bup/_helpers.c
hashsplit: replace join_bytes with cat_bytes
[bup.git] / lib / bup / _helpers.c
index 9634b1e6d0643fcec76ab128023c75a5626f0f5b..5f13d6a1c4f932792cc05e2fdb1e3960e2136bdb 100644 (file)
 #include <errno.h>
 #include <fcntl.h>
 #include <arpa/inet.h>
+#include <stddef.h>
 #include <stdint.h>
 #include <stdlib.h>
 #include <stdio.h>
-#include <sys/mman.h>
+#include <string.h>
 
+#ifdef HAVE_SYS_MMAN_H
+#include <sys/mman.h>
+#endif
 #ifdef HAVE_SYS_TYPES_H
 #include <sys/types.h>
 #endif
@@ -25,6 +29,9 @@
 #ifdef HAVE_UNISTD_H
 #include <unistd.h>
 #endif
+#ifdef HAVE_SYS_TIME_H
+#include <sys/time.h>
+#endif
 
 #ifdef HAVE_LINUX_FS_H
 #include <linux/fs.h>
 #include <sys/ioctl.h>
 #endif
 
+#ifdef HAVE_TM_TM_GMTOFF
+#include <time.h>
+#endif
+
 #include "bupsplit.h"
 
 #if defined(FS_IOC_GETFLAGS) && defined(FS_IOC_SETFLAGS)
 #define BUP_HAVE_FILE_ATTRS 1
 #endif
 
+/*
+ * Check for incomplete UTIMENSAT support (NetBSD 6), and if so,
+ * pretend we don't have it.
+ */
+#if !defined(AT_FDCWD) || !defined(AT_SYMLINK_NOFOLLOW)
+#undef HAVE_UTIMENSAT
+#endif
+
 #ifndef FS_NOCOW_FL
 // Of course, this assumes it's a bitfield value.
 #define FS_NOCOW_FL 0
 #endif
 
-static int istty2 = 0;
+
+typedef unsigned char byte;
+
+
+typedef struct {
+    int istty2;
+} state_t;
+
+// cstr_argf: for byte vectors without null characters (e.g. paths)
+// rbuf_argf: for read-only byte vectors
+// wbuf_argf: for mutable byte vectors
+
+#if PY_MAJOR_VERSION < 3
+static state_t state;
+#  define get_state(x) (&state)
+#  define cstr_argf "s"
+#  define rbuf_argf "s#"
+#  define wbuf_argf "s*"
+#else
+#  define get_state(x) ((state_t *) PyModule_GetState(x))
+#  define cstr_argf "y"
+#  define rbuf_argf "y#"
+#  define wbuf_argf "y*"
+#endif // PY_MAJOR_VERSION >= 3
+
+
+static void *checked_malloc(size_t n, size_t size)
+{
+    size_t total;
+    if (__builtin_mul_overflow(n, size, &total))
+    {
+        PyErr_Format(PyExc_OverflowError,
+                     "request to allocate %lu items of size %lu is too large",
+                     n, size);
+        return NULL;
+    }
+    void *result = malloc(total);
+    if (!result)
+        return PyErr_NoMemory();
+    return result;
+}
+
+static void *checked_calloc(size_t n, size_t size)
+{
+    void *result = calloc(n, size);
+    if (!result)
+        PyErr_NoMemory();
+    return result;
+}
+
+
+#ifndef htonll
+// This function should technically be macro'd out if it's going to be used
+// more than ocasionally.  As of this writing, it'll actually never be called
+// in real world bup scenarios (because our packs are < MAX_INT bytes).
+static uint64_t htonll(uint64_t value)
+{
+    static const int endian_test = 42;
+
+    if (*(char *)&endian_test == endian_test) // LSB-MSB
+       return ((uint64_t)htonl(value & 0xFFFFFFFF) << 32) | htonl(value >> 32);
+    return value; // already in network byte order MSB-LSB
+}
+#endif
+
+
+// Disabling sign-compare here should be fine since we're explicitly
+// checking for a sign mismatch, i.e. if the signs don't match, then
+// it doesn't matter what the value comparison says.
+// FIXME: ... so should we reverse the order?
+#define INTEGRAL_ASSIGNMENT_FITS(dest, src)                             \
+    ({                                                                  \
+        _Pragma("GCC diagnostic push");                                 \
+        _Pragma("GCC diagnostic ignored \"-Wsign-compare\"");           \
+        *(dest) = (src);                                                \
+        int result = *(dest) == (src) && (*(dest) < 1) == ((src) < 1);  \
+        _Pragma("GCC diagnostic pop");                                  \
+        result;                                                         \
+    })
+
+
+// At the moment any code that calls INTEGER_TO_PY() will have to
+// disable -Wtautological-compare for clang.  See below.
+
+#define INTEGER_TO_PY(x) \
+    (((x) >= 0) ? PyLong_FromUnsignedLongLong(x) : PyLong_FromLongLong(x))
+
+
+
+#if PY_MAJOR_VERSION < 3
+static int bup_ulong_from_pyint(unsigned long *x, PyObject *py,
+                                const char *name)
+{
+    const long tmp = PyInt_AsLong(py);
+    if (tmp == -1 && PyErr_Occurred())
+    {
+        if (PyErr_ExceptionMatches(PyExc_OverflowError))
+            PyErr_Format(PyExc_OverflowError, "%s too big for unsigned long",
+                         name);
+        return 0;
+    }
+    if (tmp < 0)
+    {
+        PyErr_Format(PyExc_OverflowError,
+                     "negative %s cannot be converted to unsigned long", name);
+        return 0;
+    }
+    *x = tmp;
+    return 1;
+}
+#endif
+
+
+static int bup_ulong_from_py(unsigned long *x, PyObject *py, const char *name)
+{
+#if PY_MAJOR_VERSION < 3
+    if (PyInt_Check(py))
+        return bup_ulong_from_pyint(x, py, name);
+#endif
+
+    if (!PyLong_Check(py))
+    {
+        PyErr_Format(PyExc_TypeError, "expected integer %s", name);
+        return 0;
+    }
+
+    const unsigned long tmp = PyLong_AsUnsignedLong(py);
+    if (PyErr_Occurred())
+    {
+        if (PyErr_ExceptionMatches(PyExc_OverflowError))
+            PyErr_Format(PyExc_OverflowError, "%s too big for unsigned long",
+                         name);
+        return 0;
+    }
+    *x = tmp;
+    return 1;
+}
+
+
+static int bup_uint_from_py(unsigned int *x, PyObject *py, const char *name)
+{
+    unsigned long tmp;
+    if (!bup_ulong_from_py(&tmp, py, name))
+        return 0;
+
+    if (tmp > UINT_MAX)
+    {
+        PyErr_Format(PyExc_OverflowError, "%s too big for unsigned int", name);
+        return 0;
+    }
+    *x = tmp;
+    return 1;
+}
+
+static int bup_ullong_from_py(unsigned PY_LONG_LONG *x, PyObject *py,
+                              const char *name)
+{
+#if PY_MAJOR_VERSION < 3
+    if (PyInt_Check(py))
+    {
+        unsigned long tmp;
+        if (bup_ulong_from_pyint(&tmp, py, name))
+        {
+            *x = tmp;
+            return 1;
+        }
+        return 0;
+    }
+#endif
+
+    if (!PyLong_Check(py))
+    {
+        PyErr_Format(PyExc_TypeError, "integer argument expected for %s", name);
+        return 0;
+    }
+
+    const unsigned PY_LONG_LONG tmp = PyLong_AsUnsignedLongLong(py);
+    if (tmp == (unsigned long long) -1 && PyErr_Occurred())
+    {
+        if (PyErr_ExceptionMatches(PyExc_OverflowError))
+            PyErr_Format(PyExc_OverflowError,
+                         "%s too big for unsigned long long", name);
+        return 0;
+    }
+    *x = tmp;
+    return 1;
+}
+
+
+static PyObject *bup_bytescmp(PyObject *self, PyObject *args)
+{
+    PyObject *py_s1, *py_s2;  // This is really a PyBytes/PyString
+    if (!PyArg_ParseTuple(args, "SS", &py_s1, &py_s2))
+       return NULL;
+    char *s1, *s2;
+    Py_ssize_t s1_len, s2_len;
+    if (PyBytes_AsStringAndSize(py_s1, &s1, &s1_len) == -1)
+        return NULL;
+    if (PyBytes_AsStringAndSize(py_s2, &s2, &s2_len) == -1)
+        return NULL;
+    const Py_ssize_t n = (s1_len < s2_len) ? s1_len : s2_len;
+    const int cmp = memcmp(s1, s2, n);
+    if (cmp != 0)
+        return PyLong_FromLong(cmp);
+    if (s1_len == s2_len)
+        return PyLong_FromLong(0);;
+    return PyLong_FromLong((s1_len < s2_len) ? -1 : 1);
+}
+
+
+static PyObject *bup_cat_bytes(PyObject *self, PyObject *args)
+{
+    unsigned char *bufx = NULL, *bufy = NULL;
+    Py_ssize_t bufx_len, bufx_ofs, bufx_n;
+    Py_ssize_t bufy_len, bufy_ofs, bufy_n;
+    if (!PyArg_ParseTuple(args,
+                          rbuf_argf "nn"
+                          rbuf_argf "nn",
+                          &bufx, &bufx_len, &bufx_ofs, &bufx_n,
+                          &bufy, &bufy_len, &bufy_ofs, &bufy_n))
+       return NULL;
+    if (bufx_ofs < 0)
+        return PyErr_Format(PyExc_ValueError, "negative x offset");
+    if (bufx_n < 0)
+        return PyErr_Format(PyExc_ValueError, "negative x extent");
+    if (bufx_ofs > bufx_len)
+        return PyErr_Format(PyExc_ValueError, "x offset greater than length");
+    if (bufx_n > bufx_len - bufx_ofs)
+        return PyErr_Format(PyExc_ValueError, "x extent past end of buffer");
+
+    if (bufy_ofs < 0)
+        return PyErr_Format(PyExc_ValueError, "negative y offset");
+    if (bufy_n < 0)
+        return PyErr_Format(PyExc_ValueError, "negative y extent");
+    if (bufy_ofs > bufy_len)
+        return PyErr_Format(PyExc_ValueError, "y offset greater than length");
+    if (bufy_n > bufy_len - bufy_ofs)
+        return PyErr_Format(PyExc_ValueError, "y extent past end of buffer");
+
+    if (bufy_n > PY_SSIZE_T_MAX - bufx_n)
+        return PyErr_Format(PyExc_OverflowError, "result length too long");
+
+    PyObject *result = PyBytes_FromStringAndSize(NULL, bufx_n + bufy_n);
+    if (!result)
+        return PyErr_NoMemory();
+    char *buf = PyBytes_AS_STRING(result);
+    memcpy(buf, bufx + bufx_ofs, bufx_n);
+    memcpy(buf + bufx_n, bufy + bufy_ofs, bufy_n);
+    return result;
+}
+
+
 
 // Probably we should use autoconf or something and set HAVE_PY_GETARGCARGV...
 #if __WIN32__ || __CYGWIN__
@@ -97,6 +367,236 @@ static void unpythonize_argv(void)
 #endif // not __WIN32__ or __CYGWIN__
 
 
+static int write_all(int fd, const void *buf, const size_t count)
+{
+    size_t written = 0;
+    while (written < count)
+    {
+        const ssize_t rc = write(fd, buf + written, count - written);
+        if (rc == -1)
+            return -1;
+        written += rc;
+    }
+    return 0;
+}
+
+
+static int uadd(unsigned long long *dest,
+                const unsigned long long x,
+                const unsigned long long y)
+{
+    const unsigned long long result = x + y;
+    if (result < x || result < y)
+        return 0;
+    *dest = result;
+    return 1;
+}
+
+
+static PyObject *append_sparse_region(const int fd, unsigned long long n)
+{
+    while (n)
+    {
+        off_t new_off;
+        if (!INTEGRAL_ASSIGNMENT_FITS(&new_off, n))
+            new_off = INT_MAX;
+        const off_t off = lseek(fd, new_off, SEEK_CUR);
+        if (off == (off_t) -1)
+            return PyErr_SetFromErrno(PyExc_IOError);
+        n -= new_off;
+    }
+    return NULL;
+}
+
+
+static PyObject *record_sparse_zeros(unsigned long long *new_pending,
+                                     const int fd,
+                                     unsigned long long prev_pending,
+                                     const unsigned long long count)
+{
+    // Add count additional sparse zeros to prev_pending and store the
+    // result in new_pending, or if the total won't fit in
+    // new_pending, write some of the zeros to fd sparsely, and store
+    // the remaining sum in new_pending.
+    if (!uadd(new_pending, prev_pending, count))
+    {
+        PyObject *err = append_sparse_region(fd, prev_pending);
+        if (err != NULL)
+            return err;
+        *new_pending = count;
+    }
+    return NULL;
+}
+
+
+static byte* find_not_zero(const byte * const start, const byte * const end)
+{
+    // Return a pointer to first non-zero byte between start and end,
+    // or end if there isn't one.
+    assert(start <= end);
+    const unsigned char *cur = start;
+    while (cur < end && *cur == 0)
+        cur++;
+    return (byte *) cur;
+}
+
+
+static byte* find_trailing_zeros(const byte * const start,
+                                 const byte * const end)
+{
+    // Return a pointer to the start of any trailing run of zeros, or
+    // end if there isn't one.
+    assert(start <= end);
+    if (start == end)
+        return (byte *) end;
+    const byte * cur = end;
+    while (cur > start && *--cur == 0) {}
+    if (*cur == 0)
+        return (byte *) cur;
+    else
+        return (byte *) (cur + 1);
+}
+
+
+static byte *find_non_sparse_end(const byte * const start,
+                                 const byte * const end,
+                                 const ptrdiff_t min_len)
+{
+    // Return the first pointer to a min_len sparse block in [start,
+    // end) if there is one, otherwise a pointer to the start of any
+    // trailing run of zeros.  If there are no trailing zeros, return
+    // end.
+    if (start == end)
+        return (byte *) end;
+    assert(start < end);
+    assert(min_len);
+    // Probe in min_len jumps, searching backward from the jump
+    // destination for a non-zero byte.  If such a byte is found, move
+    // just past it and try again.
+    const byte *candidate = start;
+    // End of any run of zeros, starting at candidate, that we've already seen
+    const byte *end_of_known_zeros = candidate;
+    while (end - candidate >= min_len) // Handle all min_len candidate blocks
+    {
+        const byte * const probe_end = candidate + min_len;
+        const byte * const trailing_zeros =
+            find_trailing_zeros(end_of_known_zeros, probe_end);
+        if (trailing_zeros == probe_end)
+            end_of_known_zeros = candidate = probe_end;
+        else if (trailing_zeros == end_of_known_zeros)
+        {
+            assert(candidate >= start);
+            assert(candidate <= end);
+            assert(*candidate == 0);
+            return (byte *) candidate;
+        }
+        else
+        {
+            candidate = trailing_zeros;
+            end_of_known_zeros = probe_end;
+        }
+    }
+
+    if (candidate == end)
+        return (byte *) end;
+
+    // No min_len sparse run found, search backward from end
+    const byte * const trailing_zeros = find_trailing_zeros(end_of_known_zeros,
+                                                            end);
+
+    if (trailing_zeros == end_of_known_zeros)
+    {
+        assert(candidate >= start);
+        assert(candidate < end);
+        assert(*candidate == 0);
+        assert(end - candidate < min_len);
+        return (byte *) candidate;
+    }
+
+    if (trailing_zeros == end)
+    {
+        assert(*(end - 1) != 0);
+        return (byte *) end;
+    }
+
+    assert(end - trailing_zeros < min_len);
+    assert(trailing_zeros >= start);
+    assert(trailing_zeros < end);
+    assert(*trailing_zeros == 0);
+    return (byte *) trailing_zeros;
+}
+
+
+static PyObject *bup_write_sparsely(PyObject *self, PyObject *args)
+{
+    int fd;
+    unsigned char *buf = NULL;
+    Py_ssize_t sbuf_len;
+    PyObject *py_min_sparse_len, *py_prev_sparse_len;
+    if (!PyArg_ParseTuple(args, "i" rbuf_argf "OO",
+                          &fd, &buf, &sbuf_len,
+                          &py_min_sparse_len, &py_prev_sparse_len))
+       return NULL;
+    ptrdiff_t min_sparse_len;
+    unsigned long long prev_sparse_len, buf_len, ul_min_sparse_len;
+    if (!bup_ullong_from_py(&ul_min_sparse_len, py_min_sparse_len, "min_sparse_len"))
+        return NULL;
+    if (!INTEGRAL_ASSIGNMENT_FITS(&min_sparse_len, ul_min_sparse_len))
+        return PyErr_Format(PyExc_OverflowError, "min_sparse_len too large");
+    if (!bup_ullong_from_py(&prev_sparse_len, py_prev_sparse_len, "prev_sparse_len"))
+        return NULL;
+    if (sbuf_len < 0)
+        return PyErr_Format(PyExc_ValueError, "negative bufer length");
+    if (!INTEGRAL_ASSIGNMENT_FITS(&buf_len, sbuf_len))
+        return PyErr_Format(PyExc_OverflowError, "buffer length too large");
+
+    const byte * block = buf; // Start of pending block
+    const byte * const end = buf + buf_len;
+    unsigned long long zeros = prev_sparse_len;
+    while (1)
+    {
+        assert(block <= end);
+        if (block == end)
+            return PyLong_FromUnsignedLongLong(zeros);
+
+        if (*block != 0)
+        {
+            // Look for the end of block, i.e. the next sparse run of
+            // at least min_sparse_len zeros, or the end of the
+            // buffer.
+            const byte * const probe = find_non_sparse_end(block + 1, end,
+                                                           min_sparse_len);
+            // Either at end of block, or end of non-sparse; write pending data
+            PyObject *err = append_sparse_region(fd, zeros);
+            if (err != NULL)
+                return err;
+            int rc = write_all(fd, block, probe - block);
+            if (rc)
+                return PyErr_SetFromErrno(PyExc_IOError);
+
+            if (end - probe < min_sparse_len)
+                zeros = end - probe;
+            else
+                zeros = min_sparse_len;
+            block = probe + zeros;
+        }
+        else // *block == 0
+        {
+            // Should be in the first loop iteration, a sparse run of
+            // zeros, or nearly at the end of the block (within
+            // min_sparse_len).
+            const byte * const zeros_end = find_not_zero(block, end);
+            PyObject *err = record_sparse_zeros(&zeros, fd,
+                                                zeros, zeros_end - block);
+            if (err != NULL)
+                return err;
+            assert(block <= zeros_end);
+            block = zeros_end;
+        }
+    }
+}
+
+
 static PyObject *selftest(PyObject *self, PyObject *args)
 {
     if (!PyArg_ParseTuple(args, ""))
@@ -116,14 +616,29 @@ static PyObject *blobbits(PyObject *self, PyObject *args)
 
 static PyObject *splitbuf(PyObject *self, PyObject *args)
 {
-    unsigned char *buf = NULL;
-    Py_ssize_t len = 0;
+    // We stick to buffers in python 2 because they appear to be
+    // substantially smaller than memoryviews, and because
+    // zlib.compress() in python 2 can't accept a memoryview
+    // (cf. hashsplit.py).
     int out = 0, bits = -1;
-
-    if (!PyArg_ParseTuple(args, "t#", &buf, &len))
-       return NULL;
-    assert(len <= INT_MAX);
-    out = bupsplit_find_ofs(buf, len, &bits);
+    if (PY_MAJOR_VERSION > 2)
+    {
+        Py_buffer buf;
+        if (!PyArg_ParseTuple(args, "y*", &buf))
+            return NULL;
+        assert(buf.len <= INT_MAX);
+        out = bupsplit_find_ofs(buf.buf, buf.len, &bits);
+        PyBuffer_Release(&buf);
+    }
+    else
+    {
+        unsigned char *buf = NULL;
+        Py_ssize_t len = 0;
+        if (!PyArg_ParseTuple(args, "t#", &buf, &len))
+            return NULL;
+        assert(len <= INT_MAX);
+        out = bupsplit_find_ofs(buf, len, &bits);
+    }
     if (out) assert(bits >= BUP_BLOBBITS);
     return Py_BuildValue("ii", out, bits);
 }
@@ -136,7 +651,7 @@ static PyObject *bitmatch(PyObject *self, PyObject *args)
     Py_ssize_t byte;
     int bit;
 
-    if (!PyArg_ParseTuple(args, "t#t#", &buf1, &len1, &buf2, &len2))
+    if (!PyArg_ParseTuple(args, rbuf_argf rbuf_argf, &buf1, &len1, &buf2, &len2))
        return NULL;
     
     bit = 0;
@@ -163,7 +678,7 @@ static PyObject *firstword(PyObject *self, PyObject *args)
     Py_ssize_t len = 0;
     uint32_t v;
 
-    if (!PyArg_ParseTuple(args, "t#", &buf, &len))
+    if (!PyArg_ParseTuple(args, rbuf_argf, &buf, &len))
        return NULL;
     
     if (len < 4)
@@ -232,72 +747,95 @@ BLOOM_GET_BIT(bloom_get_bit5, to_bloom_address_bitmask5, uint32_t)
 
 static PyObject *bloom_add(PyObject *self, PyObject *args)
 {
-    unsigned char *sha = NULL, *bloom = NULL;
-    unsigned char *end;
-    Py_ssize_t len = 0, blen = 0;
+    Py_buffer bloom, sha;
     int nbits = 0, k = 0;
+    if (!PyArg_ParseTuple(args, wbuf_argf wbuf_argf "ii",
+                          &bloom, &sha, &nbits, &k))
+        return NULL;
 
-    if (!PyArg_ParseTuple(args, "w#s#ii", &bloom, &blen, &sha, &len, &nbits, &k))
-       return NULL;
+    PyObject *result = NULL;
 
-    if (blen < 16+(1<<nbits) || len % 20 != 0)
-       return NULL;
+    if (bloom.len < 16+(1<<nbits) || sha.len % 20 != 0)
+        goto clean_and_return;
 
     if (k == 5)
     {
-       if (nbits > 29)
-           return NULL;
-       for (end = sha + len; sha < end; sha += 20/k)
-           bloom_set_bit5(bloom, sha, nbits);
+        if (nbits > 29)
+            goto clean_and_return;
+        unsigned char *cur = sha.buf;
+        unsigned char *end;
+        for (end = cur + sha.len; cur < end; cur += 20/k)
+            bloom_set_bit5(bloom.buf, cur, nbits);
     }
     else if (k == 4)
     {
-       if (nbits > 37)
-           return NULL;
-       for (end = sha + len; sha < end; sha += 20/k)
-           bloom_set_bit4(bloom, sha, nbits);
+        if (nbits > 37)
+            goto clean_and_return;
+        unsigned char *cur = sha.buf;
+        unsigned char *end = cur + sha.len;
+        for (; cur < end; cur += 20/k)
+            bloom_set_bit4(bloom.buf, cur, nbits);
     }
     else
-       return NULL;
+        goto clean_and_return;
 
+    result = Py_BuildValue("n", sha.len / 20);
 
-    return Py_BuildValue("n", len/20);
+ clean_and_return:
+    PyBuffer_Release(&bloom);
+    PyBuffer_Release(&sha);
+    return result;
 }
 
 static PyObject *bloom_contains(PyObject *self, PyObject *args)
 {
-    unsigned char *sha = NULL, *bloom = NULL;
-    Py_ssize_t len = 0, blen = 0;
+    Py_buffer bloom;
+    unsigned char *sha = NULL;
+    Py_ssize_t len = 0;
     int nbits = 0, k = 0;
-    unsigned char *end;
-    int steps;
+    if (!PyArg_ParseTuple(args, wbuf_argf rbuf_argf "ii",
+                          &bloom, &sha, &len, &nbits, &k))
+        return NULL;
 
-    if (!PyArg_ParseTuple(args, "t#s#ii", &bloom, &blen, &sha, &len, &nbits, &k))
-       return NULL;
+    PyObject *result = NULL;
 
     if (len != 20)
-       return NULL;
+        goto clean_and_return;
 
     if (k == 5)
     {
-       if (nbits > 29)
-           return NULL;
-       for (steps = 1, end = sha + 20; sha < end; sha += 20/k, steps++)
-           if (!bloom_get_bit5(bloom, sha, nbits))
-               return Py_BuildValue("Oi", Py_None, steps);
+        if (nbits > 29)
+            goto clean_and_return;
+        int steps;
+        unsigned char *end;
+        for (steps = 1, end = sha + 20; sha < end; sha += 20/k, steps++)
+            if (!bloom_get_bit5(bloom.buf, sha, nbits))
+            {
+                result = Py_BuildValue("Oi", Py_None, steps);
+                goto clean_and_return;
+            }
     }
     else if (k == 4)
     {
-       if (nbits > 37)
-           return NULL;
-       for (steps = 1, end = sha + 20; sha < end; sha += 20/k, steps++)
-           if (!bloom_get_bit4(bloom, sha, nbits))
-               return Py_BuildValue("Oi", Py_None, steps);
+        if (nbits > 37)
+            goto clean_and_return;
+        int steps;
+        unsigned char *end;
+        for (steps = 1, end = sha + 20; sha < end; sha += 20/k, steps++)
+            if (!bloom_get_bit4(bloom.buf, sha, nbits))
+            {
+                result = Py_BuildValue("Oi", Py_None, steps);
+                goto clean_and_return;
+            }
     }
     else
-       return NULL;
+        goto clean_and_return;
+
+    result = Py_BuildValue("ii", 1, k);
 
-    return Py_BuildValue("ii", 1, k);
+ clean_and_return:
+    PyBuffer_Release(&bloom);
+    return result;
 }
 
 
@@ -318,7 +856,7 @@ static PyObject *extract_bits(PyObject *self, PyObject *args)
     Py_ssize_t len = 0;
     int nbits = 0;
 
-    if (!PyArg_ParseTuple(args, "t#i", &buf, &len, &nbits))
+    if (!PyArg_ParseTuple(args, rbuf_argf "i", &buf, &len, &nbits))
        return NULL;
     
     if (len < 4)
@@ -332,6 +870,11 @@ struct sha {
     unsigned char bytes[20];
 };
 
+static inline int _cmp_sha(const struct sha *sha1, const struct sha *sha2)
+{
+    return memcmp(sha1->bytes, sha2->bytes, sizeof(sha1->bytes));
+}
+
 
 struct idx {
     unsigned char *map;
@@ -342,18 +885,7 @@ struct idx {
     int name_base;
 };
 
-
-static int _cmp_sha(const struct sha *sha1, const struct sha *sha2)
-{
-    int i;
-    for (i = 0; i < sizeof(struct sha); i++)
-       if (sha1->bytes[i] != sha2->bytes[i])
-           return sha1->bytes[i] - sha2->bytes[i];
-    return 0;
-}
-
-
-static void _fix_idx_order(struct idx **idxs, int *last_i)
+static void _fix_idx_order(struct idx **idxs, Py_ssize_t *last_i)
 {
     struct idx *idx;
     int low, mid, high, c = 0;
@@ -403,32 +935,51 @@ static uint32_t _get_idx_i(struct idx *idx)
 
 static PyObject *merge_into(PyObject *self, PyObject *args)
 {
-    PyObject *ilist = NULL;
-    unsigned char *fmap = NULL;
     struct sha *sha_ptr, *sha_start = NULL;
     uint32_t *table_ptr, *name_ptr, *name_start;
-    struct idx **idxs = NULL;
-    Py_ssize_t flen = 0;
-    int bits = 0, i;
+    int i;
     unsigned int total;
     uint32_t count, prefix;
-    int num_i;
-    int last_i;
 
-    if (!PyArg_ParseTuple(args, "w#iIO", &fmap, &flen, &bits, &total, &ilist))
+
+    Py_buffer fmap;
+    int bits;;
+    PyObject *py_total, *ilist = NULL;
+    if (!PyArg_ParseTuple(args, wbuf_argf "iOO",
+                          &fmap, &bits, &py_total, &ilist))
        return NULL;
 
+    PyObject *result = NULL;
+    struct idx **idxs = NULL;
+    Py_ssize_t num_i = 0;
+    int *idx_buf_init = NULL;
+    Py_buffer *idx_buf = NULL;
+
+    if (!bup_uint_from_py(&total, py_total, "total"))
+        goto clean_and_return;
+
     num_i = PyList_Size(ilist);
-    idxs = (struct idx **)PyMem_Malloc(num_i * sizeof(struct idx *));
+
+    if (!(idxs = checked_malloc(num_i, sizeof(struct idx *))))
+        goto clean_and_return;
+    if (!(idx_buf_init = checked_calloc(num_i, sizeof(int))))
+        goto clean_and_return;
+    if (!(idx_buf = checked_malloc(num_i, sizeof(Py_buffer))))
+        goto clean_and_return;
 
     for (i = 0; i < num_i; i++)
     {
        long len, sha_ofs, name_map_ofs;
-       idxs[i] = (struct idx *)PyMem_Malloc(sizeof(struct idx));
+       if (!(idxs[i] = checked_malloc(1, sizeof(struct idx))))
+            goto clean_and_return;
        PyObject *itup = PyList_GetItem(ilist, i);
-       if (!PyArg_ParseTuple(itup, "t#llli", &idxs[i]->map, &idxs[i]->bytes,
-                   &len, &sha_ofs, &name_map_ofs, &idxs[i]->name_base))
+       if (!PyArg_ParseTuple(itup, wbuf_argf "llli",
+                              &(idx_buf[i]), &len, &sha_ofs, &name_map_ofs,
+                              &idxs[i]->name_base))
            return NULL;
+        idx_buf_init[i] = 1;
+        idxs[i]->map = idx_buf[i].buf;
+        idxs[i]->bytes = idx_buf[i].len;
        idxs[i]->cur = (struct sha *)&idxs[i]->map[sha_ofs];
        idxs[i]->end = &idxs[i]->cur[len];
        if (name_map_ofs)
@@ -436,18 +987,18 @@ static PyObject *merge_into(PyObject *self, PyObject *args)
        else
            idxs[i]->cur_name = NULL;
     }
-    table_ptr = (uint32_t *)&fmap[MIDX4_HEADERLEN];
+    table_ptr = (uint32_t *) &((unsigned char *) fmap.buf)[MIDX4_HEADERLEN];
     sha_start = sha_ptr = (struct sha *)&table_ptr[1<<bits];
     name_start = name_ptr = (uint32_t *)&sha_ptr[total];
 
-    last_i = num_i-1;
+    Py_ssize_t last_i = num_i - 1;
     count = 0;
     prefix = 0;
     while (last_i >= 0)
     {
        struct idx *idx;
        uint32_t new_prefix;
-       if (count % 102424 == 0 && istty2)
+       if (count % 102424 == 0 && get_state(self)->istty2)
            fprintf(stderr, "midx: writing %.2f%% (%d/%d)\r",
                    count*100.0/total, count, total);
        idx = idxs[last_i];
@@ -462,27 +1013,32 @@ static PyObject *merge_into(PyObject *self, PyObject *args)
        _fix_idx_order(idxs, &last_i);
        ++count;
     }
-    while (prefix < (1<<bits))
+    while (prefix < ((uint32_t) 1 << bits))
        table_ptr[prefix++] = htonl(count);
     assert(count == total);
-    assert(prefix == (1<<bits));
+    assert(prefix == ((uint32_t) 1 << bits));
     assert(sha_ptr == sha_start+count);
     assert(name_ptr == name_start+count);
 
-    PyMem_Free(idxs);
-    return PyLong_FromUnsignedLong(count);
-}
+    result = PyLong_FromUnsignedLong(count);
 
-// This function should technically be macro'd out if it's going to be used
-// more than ocasionally.  As of this writing, it'll actually never be called
-// in real world bup scenarios (because our packs are < MAX_INT bytes).
-static uint64_t htonll(uint64_t value)
-{
-    static const int endian_test = 42;
-
-    if (*(char *)&endian_test == endian_test) // LSB-MSB
-       return ((uint64_t)htonl(value & 0xFFFFFFFF) << 32) | htonl(value >> 32);
-    return value; // already in network byte order MSB-LSB
+ clean_and_return:
+    if (idx_buf_init)
+    {
+        for (i = 0; i < num_i; i++)
+            if (idx_buf_init[i])
+                PyBuffer_Release(&(idx_buf[i]));
+        free(idx_buf_init);
+        free(idx_buf);
+    }
+    if (idxs)
+    {
+        for (i = 0; i < num_i; i++)
+            free(idxs[i]);
+        free(idxs);
+    }
+    PyBuffer_Release(&fmap);
+    return result;
 }
 
 #define FAN_ENTRIES 256
@@ -490,10 +1046,8 @@ static uint64_t htonll(uint64_t value)
 static PyObject *write_idx(PyObject *self, PyObject *args)
 {
     char *filename = NULL;
-    PyObject *idx = NULL;
+    PyObject *py_total, *idx = NULL;
     PyObject *part;
-    unsigned char *fmap = NULL;
-    Py_ssize_t flen = 0;
     unsigned int total = 0;
     uint32_t count;
     int i, j, ofs64_count;
@@ -501,17 +1055,27 @@ static PyObject *write_idx(PyObject *self, PyObject *args)
     uint64_t *ofs64_ptr;
     struct sha *sha_ptr;
 
-    if (!PyArg_ParseTuple(args, "sw#OI", &filename, &fmap, &flen, &idx, &total))
+    Py_buffer fmap;
+    if (!PyArg_ParseTuple(args, cstr_argf wbuf_argf "OO",
+                          &filename, &fmap, &idx, &py_total))
        return NULL;
 
+    PyObject *result = NULL;
+
+    if (!bup_uint_from_py(&total, py_total, "total"))
+        goto clean_and_return;
+
     if (PyList_Size (idx) != FAN_ENTRIES) // Check for list of the right length.
-        return PyErr_Format (PyExc_TypeError, "idx must contain %d entries",
-                             FAN_ENTRIES);
+    {
+        result = PyErr_Format (PyExc_TypeError, "idx must contain %d entries",
+                               FAN_ENTRIES);
+        goto clean_and_return;
+    }
 
     const char idx_header[] = "\377tOc\0\0\0\002";
-    memcpy (fmap, idx_header, sizeof(idx_header) - 1);
+    memcpy (fmap.buf, idx_header, sizeof(idx_header) - 1);
 
-    fan_ptr = (uint32_t *)&fmap[sizeof(idx_header) - 1];
+    fan_ptr = (uint32_t *)&((unsigned char *)fmap.buf)[sizeof(idx_header) - 1];
     sha_ptr = (struct sha *)&fan_ptr[FAN_ENTRIES];
     crc_ptr = (uint32_t *)&sha_ptr[total];
     ofs_ptr = (uint32_t *)&crc_ptr[total];
@@ -531,17 +1095,22 @@ static PyObject *write_idx(PyObject *self, PyObject *args)
        {
            unsigned char *sha = NULL;
            Py_ssize_t sha_len = 0;
-           unsigned int crc = 0;
-            unsigned PY_LONG_LONG ofs_py = 0;
+            PyObject *crc_py, *ofs_py;
+           unsigned int crc;
+            unsigned PY_LONG_LONG ofs_ull;
            uint64_t ofs;
-           if (!PyArg_ParseTuple(PyList_GET_ITEM(part, j), "t#IK",
-                                 &sha, &sha_len, &crc, &ofs_py))
-               return NULL;
+           if (!PyArg_ParseTuple(PyList_GET_ITEM(part, j), rbuf_argf "OO",
+                                 &sha, &sha_len, &crc_py, &ofs_py))
+                goto clean_and_return;
+            if(!bup_uint_from_py(&crc, crc_py, "crc"))
+                goto clean_and_return;
+            if(!bup_ullong_from_py(&ofs_ull, ofs_py, "ofs"))
+                goto clean_and_return;
             assert(crc <= UINT32_MAX);
-            assert(ofs_py <= UINT64_MAX);
-           ofs = ofs_py;
+            assert(ofs_ull <= UINT64_MAX);
+           ofs = ofs_ull;
            if (sha_len != sizeof(struct sha))
-               return NULL;
+                goto clean_and_return;
            memcpy(sha_ptr++, sha, sizeof(struct sha));
            *crc_ptr++ = htonl(crc);
            if (ofs > 0x7fffffff)
@@ -553,11 +1122,18 @@ static PyObject *write_idx(PyObject *self, PyObject *args)
        }
     }
 
-    int rc = msync(fmap, flen, MS_ASYNC);
+    int rc = msync(fmap.buf, fmap.len, MS_ASYNC);
     if (rc != 0)
-       return PyErr_SetFromErrnoWithFilename(PyExc_IOError, filename);
+    {
+        result = PyErr_SetFromErrnoWithFilename(PyExc_IOError, filename);
+        goto clean_and_return;
+    }
 
-    return PyLong_FromUnsignedLong(count);
+    result = PyLong_FromUnsignedLong(count);
+
+ clean_and_return:
+    PyBuffer_Release(&fmap);
+    return result;
 }
 
 
@@ -631,7 +1207,7 @@ static PyObject *random_sha(PyObject *self, PyObject *args)
     memset(shabuf, 0, sizeof(shabuf));
     for (i=0; i < 20/4; i++)
        shabuf[i] = random();
-    return Py_BuildValue("s#", shabuf, 20);
+    return Py_BuildValue(rbuf_argf, shabuf, 20);
 }
 
 
@@ -667,7 +1243,7 @@ static PyObject *open_noatime(PyObject *self, PyObject *args)
 {
     char *filename = NULL;
     int fd;
-    if (!PyArg_ParseTuple(args, "s", &filename))
+    if (!PyArg_ParseTuple(args, cstr_argf, &filename))
        return NULL;
     fd = _open_noatime(filename, 0);
     if (fd < 0)
@@ -679,54 +1255,77 @@ static PyObject *open_noatime(PyObject *self, PyObject *args)
 static PyObject *fadvise_done(PyObject *self, PyObject *args)
 {
     int fd = -1;
-    long long ofs = 0;
-    if (!PyArg_ParseTuple(args, "iL", &fd, &ofs))
+    long long llofs, lllen = 0;
+    if (!PyArg_ParseTuple(args, "iLL", &fd, &llofs, &lllen))
        return NULL;
+    off_t ofs, len;
+    if (!INTEGRAL_ASSIGNMENT_FITS(&ofs, llofs))
+        return PyErr_Format(PyExc_OverflowError,
+                            "fadvise offset overflows off_t");
+    if (!INTEGRAL_ASSIGNMENT_FITS(&len, lllen))
+        return PyErr_Format(PyExc_OverflowError,
+                            "fadvise length overflows off_t");
 #ifdef POSIX_FADV_DONTNEED
-    posix_fadvise(fd, 0, ofs, POSIX_FADV_DONTNEED);
+    posix_fadvise(fd, ofs, len, POSIX_FADV_DONTNEED);
 #endif    
     return Py_BuildValue("");
 }
 
 
+// Currently the Linux kernel and FUSE disagree over the type for
+// FS_IOC_GETFLAGS and FS_IOC_SETFLAGS.  The kernel actually uses int,
+// but FUSE chose long (matching the declaration in linux/fs.h).  So
+// if you use int, and then traverse a FUSE filesystem, you may
+// corrupt the stack.  But if you use long, then you may get invalid
+// results on big-endian systems.
+//
+// For now, we just use long, and then disable Linux attrs entirely
+// (with a warning) in helpers.py on systems that are affected.
+
 #ifdef BUP_HAVE_FILE_ATTRS
 static PyObject *bup_get_linux_file_attr(PyObject *self, PyObject *args)
 {
     int rc;
-    unsigned int attr;
+    unsigned long attr;
     char *path;
     int fd;
 
-    if (!PyArg_ParseTuple(args, "s", &path))
+    if (!PyArg_ParseTuple(args, cstr_argf, &path))
         return NULL;
 
     fd = _open_noatime(path, O_NONBLOCK);
     if (fd == -1)
         return PyErr_SetFromErrnoWithFilename(PyExc_OSError, path);
 
-    attr = 0;
+    attr = 0;  // Handle int/long mismatch (see above)
     rc = ioctl(fd, FS_IOC_GETFLAGS, &attr);
     if (rc == -1)
     {
         close(fd);
         return PyErr_SetFromErrnoWithFilename(PyExc_OSError, path);
     }
-
     close(fd);
-    return Py_BuildValue("I", attr);
+    assert(attr <= UINT_MAX);  // Kernel type is actually int
+    return PyLong_FromUnsignedLong(attr);
 }
 #endif /* def BUP_HAVE_FILE_ATTRS */
 
 
+
 #ifdef BUP_HAVE_FILE_ATTRS
 static PyObject *bup_set_linux_file_attr(PyObject *self, PyObject *args)
 {
     int rc;
-    unsigned int orig_attr, attr;
+    unsigned long orig_attr;
+    unsigned int attr;
     char *path;
+    PyObject *py_attr;
     int fd;
 
-    if (!PyArg_ParseTuple(args, "sI", &path, &attr))
+    if (!PyArg_ParseTuple(args, cstr_argf "O", &path, &py_attr))
+        return NULL;
+
+    if (!bup_uint_from_py(&attr, py_attr, "attr"))
         return NULL;
 
     fd = open(path, O_RDONLY | O_NONBLOCK | O_LARGEFILE | O_NOFOLLOW);
@@ -742,13 +1341,15 @@ static PyObject *bup_set_linux_file_attr(PyObject *self, PyObject *args)
     | FS_TOPDIR_FL | FS_NOCOW_FL;
 
     // The extents flag can't be removed, so don't (see chattr(1) and chattr.c).
+    orig_attr = 0; // Handle int/long mismatch (see above)
     rc = ioctl(fd, FS_IOC_GETFLAGS, &orig_attr);
     if (rc == -1)
     {
         close(fd);
         return PyErr_SetFromErrnoWithFilename(PyExc_OSError, path);
     }
-    attr |= (orig_attr & FS_EXTENT_FL);
+    assert(orig_attr <= UINT_MAX);  // Kernel type is actually int
+    attr |= ((unsigned int) orig_attr) & FS_EXTENT_FL;
 
     rc = ioctl(fd, FS_IOC_SETFLAGS, &attr);
     if (rc == -1)
@@ -772,162 +1373,151 @@ static PyObject *bup_set_linux_file_attr(PyObject *self, PyObject *args)
 #endif
 #endif
 
+#define ASSIGN_PYLONG_TO_INTEGRAL(dest, pylong, overflow) \
+    ({                                                     \
+        int result = 0;                                                 \
+        *(overflow) = 0;                                                \
+        const long long lltmp = PyLong_AsLongLong(pylong);              \
+        if (lltmp == -1 && PyErr_Occurred())                            \
+        {                                                               \
+            if (PyErr_ExceptionMatches(PyExc_OverflowError))            \
+            {                                                           \
+                const unsigned long long ulltmp = PyLong_AsUnsignedLongLong(pylong); \
+                if (ulltmp == (unsigned long long) -1 && PyErr_Occurred()) \
+                {                                                       \
+                    if (PyErr_ExceptionMatches(PyExc_OverflowError))    \
+                    {                                                   \
+                        PyErr_Clear();                                  \
+                        *(overflow) = 1;                                \
+                    }                                                   \
+                }                                                       \
+                if (INTEGRAL_ASSIGNMENT_FITS((dest), ulltmp))           \
+                    result = 1;                                         \
+                else                                                    \
+                    *(overflow) = 1;                                    \
+            }                                                           \
+        }                                                               \
+        else                                                            \
+        {                                                               \
+            if (INTEGRAL_ASSIGNMENT_FITS((dest), lltmp))                \
+                result = 1;                                             \
+            else                                                        \
+                *(overflow) = 1;                                        \
+        }                                                               \
+        result;                                                         \
+        })
 
-#if defined(HAVE_UTIMENSAT) || defined(HAVE_FUTIMES) || defined(HAVE_LUTIMES)
 
-static int bup_parse_xutime_args(char **path,
-                                 long *access,
-                                 long *access_ns,
-                                 long *modification,
-                                 long *modification_ns,
-                                 PyObject *self, PyObject *args)
+#ifdef HAVE_UTIMENSAT
+
+static PyObject *bup_utimensat(PyObject *self, PyObject *args)
 {
-    if (!PyArg_ParseTuple(args, "s((ll)(ll))",
-                          path,
-                          access, access_ns,
-                          modification, modification_ns))
-        return 0;
+    int rc;
+    int fd, flag;
+    char *path;
+    PyObject *access_py, *modification_py;
+    struct timespec ts[2];
 
-    if (isnan(*access))
-    {
-        PyErr_SetString(PyExc_ValueError, "access time is NaN");
-        return 0;
-    }
-    else if (isinf(*access))
+    if (!PyArg_ParseTuple(args, "i" cstr_argf "((Ol)(Ol))i",
+                          &fd,
+                          &path,
+                          &access_py, &(ts[0].tv_nsec),
+                          &modification_py, &(ts[1].tv_nsec),
+                          &flag))
+        return NULL;
+
+    int overflow;
+    if (!ASSIGN_PYLONG_TO_INTEGRAL(&(ts[0].tv_sec), access_py, &overflow))
     {
-        PyErr_SetString(PyExc_ValueError, "access time is infinite");
-        return 0;
+        if (overflow)
+            PyErr_SetString(PyExc_ValueError,
+                            "unable to convert access time seconds for utimensat");
+        return NULL;
     }
-    else if (isnan(*modification))
+    if (!ASSIGN_PYLONG_TO_INTEGRAL(&(ts[1].tv_sec), modification_py, &overflow))
     {
-        PyErr_SetString(PyExc_ValueError, "modification time is NaN");
-        return 0;
+        if (overflow)
+            PyErr_SetString(PyExc_ValueError,
+                            "unable to convert modification time seconds for utimensat");
+        return NULL;
     }
-    else if (isinf(*modification))
-    {
-        PyErr_SetString(PyExc_ValueError, "modification time is infinite");
+    rc = utimensat(fd, path, ts, flag);
+    if (rc != 0)
+        return PyErr_SetFromErrnoWithFilename(PyExc_OSError, path);
+
+    return Py_BuildValue("O", Py_None);
+}
+
+#endif /* def HAVE_UTIMENSAT */
+
+
+#if defined(HAVE_UTIMES) || defined(HAVE_LUTIMES)
+
+static int bup_parse_xutimes_args(char **path,
+                                  struct timeval tv[2],
+                                  PyObject *args)
+{
+    PyObject *access_py, *modification_py;
+    long long access_us, modification_us; // POSIX guarantees tv_usec is signed.
+
+    if (!PyArg_ParseTuple(args, cstr_argf "((OL)(OL))",
+                          path,
+                          &access_py, &access_us,
+                          &modification_py, &modification_us))
         return 0;
-    }
 
-    if (isnan(*access_ns))
+    int overflow;
+    if (!ASSIGN_PYLONG_TO_INTEGRAL(&(tv[0].tv_sec), access_py, &overflow))
     {
-        PyErr_SetString(PyExc_ValueError, "access time ns is NaN");
+        if (overflow)
+            PyErr_SetString(PyExc_ValueError, "unable to convert access time seconds to timeval");
         return 0;
     }
-    else if (isinf(*access_ns))
+    if (!INTEGRAL_ASSIGNMENT_FITS(&(tv[0].tv_usec), access_us))
     {
-        PyErr_SetString(PyExc_ValueError, "access time ns is infinite");
+        PyErr_SetString(PyExc_ValueError, "unable to convert access time nanoseconds to timeval");
         return 0;
     }
-    else if (isnan(*modification_ns))
+    if (!ASSIGN_PYLONG_TO_INTEGRAL(&(tv[1].tv_sec), modification_py, &overflow))
     {
-        PyErr_SetString(PyExc_ValueError, "modification time ns is NaN");
+        if (overflow)
+            PyErr_SetString(PyExc_ValueError, "unable to convert modification time seconds to timeval");
         return 0;
     }
-    else if (isinf(*modification_ns))
+    if (!INTEGRAL_ASSIGNMENT_FITS(&(tv[1].tv_usec), modification_us))
     {
-        PyErr_SetString(PyExc_ValueError, "modification time ns is infinite");
+        PyErr_SetString(PyExc_ValueError, "unable to convert modification time nanoseconds to timeval");
         return 0;
     }
-
     return 1;
 }
 
-#endif /* defined(HAVE_UTIMENSAT) || defined(HAVE_FUTIMES)
-          || defined(HAVE_LUTIMES) */
-
-
-#ifdef HAVE_UTIMENSAT
-
-static PyObject *bup_xutime_ns(PyObject *self, PyObject *args,
-                               int follow_symlinks)
-{
-    int rc;
-    char *path;
-    long access, access_ns, modification, modification_ns;
-    struct timespec ts[2];
-
-    if (!bup_parse_xutime_args(&path, &access, &access_ns,
-                               &modification, &modification_ns,
-                               self, args))
-       return NULL;
-
-    ts[0].tv_sec = access;
-    ts[0].tv_nsec = access_ns;
-    ts[1].tv_sec = modification;
-    ts[1].tv_nsec = modification_ns;
-    rc = utimensat(AT_FDCWD, path, ts,
-                   follow_symlinks ? 0 : AT_SYMLINK_NOFOLLOW);
-    if (rc != 0)
-        return PyErr_SetFromErrnoWithFilename(PyExc_OSError, path);
-
-    return Py_BuildValue("O", Py_None);
-}
-
-
-#define BUP_HAVE_BUP_UTIME_NS 1
-static PyObject *bup_utime_ns(PyObject *self, PyObject *args)
-{
-    return bup_xutime_ns(self, args, 1);
-}
-
-
-#define BUP_HAVE_BUP_LUTIME_NS 1
-static PyObject *bup_lutime_ns(PyObject *self, PyObject *args)
-{
-    return bup_xutime_ns(self, args, 0);
-}
-
-
-#else /* not defined(HAVE_UTIMENSAT) */
+#endif /* defined(HAVE_UTIMES) || defined(HAVE_LUTIMES) */
 
 
 #ifdef HAVE_UTIMES
-#define BUP_HAVE_BUP_UTIME_NS 1
-static PyObject *bup_utime_ns(PyObject *self, PyObject *args)
+static PyObject *bup_utimes(PyObject *self, PyObject *args)
 {
-    int rc;
     char *path;
-    long access, access_ns, modification, modification_ns;
     struct timeval tv[2];
-
-    if (!bup_parse_xutime_args(&path, &access, &access_ns,
-                               &modification, &modification_ns,
-                               self, args))
-       return NULL;
-
-    tv[0].tv_sec = access;
-    tv[0].tv_usec = access_ns / 1000;
-    tv[1].tv_sec = modification;
-    tv[1].tv_usec = modification_ns / 1000;
-    rc = utimes(path, tv);
+    if (!bup_parse_xutimes_args(&path, tv, args))
+        return NULL;
+    int rc = utimes(path, tv);
     if (rc != 0)
         return PyErr_SetFromErrnoWithFilename(PyExc_OSError, path);
-
     return Py_BuildValue("O", Py_None);
 }
 #endif /* def HAVE_UTIMES */
 
 
 #ifdef HAVE_LUTIMES
-#define BUP_HAVE_BUP_LUTIME_NS 1
-static PyObject *bup_lutime_ns(PyObject *self, PyObject *args)
+static PyObject *bup_lutimes(PyObject *self, PyObject *args)
 {
-    int rc;
     char *path;
-    long access, access_ns, modification, modification_ns;
     struct timeval tv[2];
-
-    if (!bup_parse_xutime_args(&path, &access, &access_ns,
-                               &modification, &modification_ns,
-                               self, args))
-       return NULL;
-
-    tv[0].tv_sec = access;
-    tv[0].tv_usec = access_ns / 1000;
-    tv[1].tv_sec = modification;
-    tv[1].tv_usec = modification_ns / 1000;
-    rc = lutimes(path, tv);
+    if (!bup_parse_xutimes_args(&path, tv, args))
+        return NULL;
+    int rc = lutimes(path, tv);
     if (rc != 0)
         return PyErr_SetFromErrnoWithFilename(PyExc_OSError, path);
 
@@ -936,9 +1526,6 @@ static PyObject *bup_lutime_ns(PyObject *self, PyObject *args)
 #endif /* def HAVE_LUTIMES */
 
 
-#endif /* not defined(HAVE_UTIMENSAT) */
-
-
 #ifdef HAVE_STAT_ST_ATIM
 # define BUP_STAT_ATIME_NS(st) (st)->st_atim.tv_nsec
 # define BUP_STAT_MTIME_NS(st) (st)->st_mtim.tv_nsec
@@ -954,74 +1541,18 @@ static PyObject *bup_lutime_ns(PyObject *self, PyObject *args)
 #endif
 
 
-static void set_invalid_timespec_msg(const char *field,
-                                     const long long sec,
-                                     const long nsec,
-                                     const char *filename,
-                                     int fd)
-{
-    if (filename != NULL)
-        PyErr_Format(PyExc_ValueError,
-                     "invalid %s timespec (%lld %ld) for file \"%s\"",
-                     field, sec, nsec, filename);
-    else
-        PyErr_Format(PyExc_ValueError,
-                     "invalid %s timespec (%lld %ld) for file descriptor %d",
-                     field, sec, nsec, fd);
-}
-
-
-static int normalize_timespec_values(const char *name,
-                                     long long *sec,
-                                     long *nsec,
-                                     const char *filename,
-                                     int fd)
-{
-    if (*nsec < -999999999 || *nsec > 999999999)
-    {
-        set_invalid_timespec_msg(name, *sec, *nsec, filename, fd);
-        return 0;
-    }
-    if (*nsec < 0)
-    {
-        if (*sec == LONG_MIN)
-        {
-            set_invalid_timespec_msg(name, *sec, *nsec, filename, fd);
-            return 0;
-        }
-        *nsec += 1000000000;
-        *sec -= 1;
-    }
-    return 1;
-}
-
-
-#define INTEGER_TO_PY(x) \
-    (((x) >= 0) ? PyLong_FromUnsignedLongLong(x) : PyLong_FromLongLong(x))
-
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wtautological-compare" // For INTEGER_TO_PY().
 
 static PyObject *stat_struct_to_py(const struct stat *st,
                                    const char *filename,
                                    int fd)
 {
-    long long atime = st->st_atime;
-    long long mtime = st->st_mtime;
-    long long ctime = st->st_ctime;
-    long atime_ns = BUP_STAT_ATIME_NS(st);
-    long mtime_ns = BUP_STAT_MTIME_NS(st);
-    long ctime_ns = BUP_STAT_CTIME_NS(st);
-
-    if (!normalize_timespec_values("atime", &atime, &atime_ns, filename, fd))
-        return NULL;
-    if (!normalize_timespec_values("mtime", &mtime, &mtime_ns, filename, fd))
-        return NULL;
-    if (!normalize_timespec_values("ctime", &ctime, &ctime_ns, filename, fd))
-        return NULL;
-
     // We can check the known (via POSIX) signed and unsigned types at
     // compile time, but not (easily) the unspecified types, so handle
-    // those via INTEGER_TO_PY().
-    return Py_BuildValue("OKOOOOOL(Ll)(Ll)(Ll)",
+    // those via INTEGER_TO_PY().  Assumes ns values will fit in a
+    // long.
+    return Py_BuildValue("NKNNNNNL(Nl)(Nl)(Nl)",
                          INTEGER_TO_PY(st->st_mode),
                          (unsigned PY_LONG_LONG) st->st_ino,
                          INTEGER_TO_PY(st->st_dev),
@@ -1030,21 +1561,22 @@ static PyObject *stat_struct_to_py(const struct stat *st,
                          INTEGER_TO_PY(st->st_gid),
                          INTEGER_TO_PY(st->st_rdev),
                          (PY_LONG_LONG) st->st_size,
-                         (PY_LONG_LONG) atime,
-                         (long) atime_ns,
-                         (PY_LONG_LONG) mtime,
-                         (long) mtime_ns,
-                         (PY_LONG_LONG) ctime,
-                         (long) ctime_ns);
+                         INTEGER_TO_PY(st->st_atime),
+                         (long) BUP_STAT_ATIME_NS(st),
+                         INTEGER_TO_PY(st->st_mtime),
+                         (long) BUP_STAT_MTIME_NS(st),
+                         INTEGER_TO_PY(st->st_ctime),
+                         (long) BUP_STAT_CTIME_NS(st));
 }
 
+#pragma clang diagnostic pop  // ignored "-Wtautological-compare"
 
 static PyObject *bup_stat(PyObject *self, PyObject *args)
 {
     int rc;
     char *filename;
 
-    if (!PyArg_ParseTuple(args, "s", &filename))
+    if (!PyArg_ParseTuple(args, cstr_argf, &filename))
         return NULL;
 
     struct stat st;
@@ -1060,7 +1592,7 @@ static PyObject *bup_lstat(PyObject *self, PyObject *args)
     int rc;
     char *filename;
 
-    if (!PyArg_ParseTuple(args, "s", &filename))
+    if (!PyArg_ParseTuple(args, cstr_argf, &filename))
         return NULL;
 
     struct stat st;
@@ -1086,7 +1618,95 @@ static PyObject *bup_fstat(PyObject *self, PyObject *args)
 }
 
 
+#ifdef HAVE_TM_TM_GMTOFF
+static PyObject *bup_localtime(PyObject *self, PyObject *args)
+{
+    long long lltime;
+    time_t ttime;
+    if (!PyArg_ParseTuple(args, "L", &lltime))
+       return NULL;
+    if (!INTEGRAL_ASSIGNMENT_FITS(&ttime, lltime))
+        return PyErr_Format(PyExc_OverflowError, "time value too large");
+
+    struct tm tm;
+    tzset();
+    if(localtime_r(&ttime, &tm) == NULL)
+        return PyErr_SetFromErrno(PyExc_OSError);
+
+    // Match the Python struct_time values.
+    return Py_BuildValue("[i,i,i,i,i,i,i,i,i,i,s]",
+                         1900 + tm.tm_year, tm.tm_mon + 1, tm.tm_mday,
+                         tm.tm_hour, tm.tm_min, tm.tm_sec,
+                         tm.tm_wday, tm.tm_yday + 1,
+                         tm.tm_isdst, tm.tm_gmtoff, tm.tm_zone);
+}
+#endif /* def HAVE_TM_TM_GMTOFF */
+
+
+#ifdef BUP_MINCORE_BUF_TYPE
+static PyObject *bup_mincore(PyObject *self, PyObject *args)
+{
+    Py_buffer src, dest;
+    PyObject *py_src_n, *py_src_off, *py_dest_off;
+
+    if (!PyArg_ParseTuple(args, cstr_argf "*OOw*O",
+                          &src, &py_src_n, &py_src_off,
+                          &dest, &py_dest_off))
+       return NULL;
+
+    PyObject *result = NULL;
+
+    unsigned long long src_n, src_off, dest_off;
+    if (!(bup_ullong_from_py(&src_n, py_src_n, "src_n")
+          && bup_ullong_from_py(&src_off, py_src_off, "src_off")
+          && bup_ullong_from_py(&dest_off, py_dest_off, "dest_off")))
+        goto clean_and_return;
+
+    unsigned long long src_region_end;
+    if (!uadd(&src_region_end, src_off, src_n)) {
+        result = PyErr_Format(PyExc_OverflowError, "(src_off + src_n) too large");
+        goto clean_and_return;
+    }
+    assert(src.len >= 0);
+    if (src_region_end > (unsigned long long) src.len) {
+        result = PyErr_Format(PyExc_OverflowError, "region runs off end of src");
+        goto clean_and_return;
+    }
+
+    unsigned long long dest_size;
+    if (!INTEGRAL_ASSIGNMENT_FITS(&dest_size, dest.len)) {
+        result = PyErr_Format(PyExc_OverflowError, "invalid dest size");
+        goto clean_and_return;
+    }
+    if (dest_off > dest_size) {
+        result = PyErr_Format(PyExc_OverflowError, "region runs off end of dest");
+        goto clean_and_return;
+    }
+
+    size_t length;
+    if (!INTEGRAL_ASSIGNMENT_FITS(&length, src_n)) {
+        result = PyErr_Format(PyExc_OverflowError, "src_n overflows size_t");
+        goto clean_and_return;
+    }
+    int rc = mincore((void *)(src.buf + src_off), src_n,
+                     (BUP_MINCORE_BUF_TYPE *) (dest.buf + dest_off));
+    if (rc != 0) {
+        result = PyErr_SetFromErrno(PyExc_OSError);
+        goto clean_and_return;
+    }
+    result = Py_BuildValue("O", Py_None);
+
+ clean_and_return:
+    PyBuffer_Release(&src);
+    PyBuffer_Release(&dest);
+    return result;
+}
+#endif /* def BUP_MINCORE_BUF_TYPE */
+
+
 static PyMethodDef helper_methods[] = {
+    { "write_sparsely", bup_write_sparsely, METH_VARARGS,
+      "Write buf excepting zeros at the end. Return trailing zero count." },
     { "selftest", selftest, METH_VARARGS,
        "Check that the rolling checksum rolls correctly (for unit tests)." },
     { "blobbits", blobbits, METH_VARARGS,
@@ -1123,13 +1743,17 @@ static PyMethodDef helper_methods[] = {
     { "set_linux_file_attr", bup_set_linux_file_attr, METH_VARARGS,
       "Set the Linux attributes for the given file." },
 #endif
-#ifdef BUP_HAVE_BUP_UTIME_NS
-    { "bup_utime_ns", bup_utime_ns, METH_VARARGS,
-      "Change path timestamps with up to nanosecond precision." },
+#ifdef HAVE_UTIMENSAT
+    { "bup_utimensat", bup_utimensat, METH_VARARGS,
+      "Change path timestamps with nanosecond precision (POSIX)." },
+#endif
+#ifdef HAVE_UTIMES
+    { "bup_utimes", bup_utimes, METH_VARARGS,
+      "Change path timestamps with microsecond precision." },
 #endif
-#ifdef BUP_HAVE_BUP_LUTIME_NS
-    { "bup_lutime_ns", bup_lutime_ns, METH_VARARGS,
-      "Change path timestamps with up to nanosecond precision;"
+#ifdef HAVE_LUTIMES
+    { "bup_lutimes", bup_lutimes, METH_VARARGS,
+      "Change path timestamps with microsecond precision;"
       " don't follow symlinks." },
 #endif
     { "stat", bup_stat, METH_VARARGS,
@@ -1138,27 +1762,160 @@ static PyMethodDef helper_methods[] = {
       "Extended version of lstat." },
     { "fstat", bup_fstat, METH_VARARGS,
       "Extended version of fstat." },
+#ifdef HAVE_TM_TM_GMTOFF
+    { "localtime", bup_localtime, METH_VARARGS,
+      "Return struct_time elements plus the timezone offset and name." },
+#endif
+    { "bytescmp", bup_bytescmp, METH_VARARGS,
+      "Return a negative value if x < y, zero if equal, positive otherwise."},
+    { "cat_bytes", bup_cat_bytes, METH_VARARGS,
+      "For (x_bytes, x_ofs, x_n, y_bytes, y_ofs, y_n) arguments, return their concatenation."},
+#ifdef BUP_MINCORE_BUF_TYPE
+    { "mincore", bup_mincore, METH_VARARGS,
+      "For mincore(src, src_n, src_off, dest, dest_off)"
+      " call the system mincore(src + src_off, src_n, &dest[dest_off])." },
+#endif
     { NULL, NULL, 0, NULL },  // sentinel
 };
 
+static void test_integral_assignment_fits(void)
+{
+    assert(sizeof(signed short) == sizeof(unsigned short));
+    assert(sizeof(signed short) < sizeof(signed long long));
+    assert(sizeof(signed short) < sizeof(unsigned long long));
+    assert(sizeof(unsigned short) < sizeof(signed long long));
+    assert(sizeof(unsigned short) < sizeof(unsigned long long));
+    assert(sizeof(Py_ssize_t) <= sizeof(size_t));
+    {
+        signed short ss, ssmin = SHRT_MIN, ssmax = SHRT_MAX;
+        unsigned short us, usmax = USHRT_MAX;
+        signed long long sllmin = LLONG_MIN, sllmax = LLONG_MAX;
+        unsigned long long ullmax = ULLONG_MAX;
+
+        assert(INTEGRAL_ASSIGNMENT_FITS(&ss, ssmax));
+        assert(INTEGRAL_ASSIGNMENT_FITS(&ss, ssmin));
+        assert(!INTEGRAL_ASSIGNMENT_FITS(&ss, usmax));
+        assert(!INTEGRAL_ASSIGNMENT_FITS(&ss, sllmin));
+        assert(!INTEGRAL_ASSIGNMENT_FITS(&ss, sllmax));
+        assert(!INTEGRAL_ASSIGNMENT_FITS(&ss, ullmax));
+
+        assert(INTEGRAL_ASSIGNMENT_FITS(&us, usmax));
+        assert(!INTEGRAL_ASSIGNMENT_FITS(&us, ssmin));
+        assert(!INTEGRAL_ASSIGNMENT_FITS(&us, sllmin));
+        assert(!INTEGRAL_ASSIGNMENT_FITS(&us, sllmax));
+        assert(!INTEGRAL_ASSIGNMENT_FITS(&us, ullmax));
+    }
+}
 
-PyMODINIT_FUNC init_helpers(void)
+static int setup_module(PyObject *m)
 {
-    // FIXME: migrate these tests to configure.  Check against the
-    // type we're going to use when passing to python.  Other stat
-    // types are tested at runtime.
+    // FIXME: migrate these tests to configure, or at least don't
+    // possibly crash the whole application.  Check against the type
+    // we're going to use when passing to python.  Other stat types
+    // are tested at runtime.
     assert(sizeof(ino_t) <= sizeof(unsigned PY_LONG_LONG));
     assert(sizeof(off_t) <= sizeof(PY_LONG_LONG));
     assert(sizeof(blksize_t) <= sizeof(PY_LONG_LONG));
     assert(sizeof(blkcnt_t) <= sizeof(PY_LONG_LONG));
     // Just be sure (relevant when passing timestamps back to Python above).
     assert(sizeof(PY_LONG_LONG) <= sizeof(long long));
+    assert(sizeof(unsigned PY_LONG_LONG) <= sizeof(unsigned long long));
+
+    test_integral_assignment_fits();
+
+    // Originally required by append_sparse_region()
+    {
+        off_t probe;
+        if (!INTEGRAL_ASSIGNMENT_FITS(&probe, INT_MAX))
+        {
+            fprintf(stderr, "off_t can't hold INT_MAX; please report.\n");
+            exit(1);
+        }
+    }
 
     char *e;
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wtautological-compare" // For INTEGER_TO_PY().
+    {
+        PyObject *value;
+        value = INTEGER_TO_PY(INT_MAX);
+        PyObject_SetAttrString(m, "INT_MAX", value);
+        Py_DECREF(value);
+        value = INTEGER_TO_PY(UINT_MAX);
+        PyObject_SetAttrString(m, "UINT_MAX", value);
+        Py_DECREF(value);
+    }
+#ifdef HAVE_UTIMENSAT
+    {
+        PyObject *value;
+        value = INTEGER_TO_PY(AT_FDCWD);
+        PyObject_SetAttrString(m, "AT_FDCWD", value);
+        Py_DECREF(value);
+        value = INTEGER_TO_PY(AT_SYMLINK_NOFOLLOW);
+        PyObject_SetAttrString(m, "AT_SYMLINK_NOFOLLOW", value);
+        Py_DECREF(value);
+        value = INTEGER_TO_PY(UTIME_NOW);
+        PyObject_SetAttrString(m, "UTIME_NOW", value);
+        Py_DECREF(value);
+    }
+#endif
+#ifdef BUP_HAVE_MINCORE_INCORE
+    {
+        PyObject *value;
+        value = INTEGER_TO_PY(MINCORE_INCORE);
+        PyObject_SetAttrString(m, "MINCORE_INCORE", value);
+        Py_DECREF(value);
+    }
+#endif
+#pragma clang diagnostic pop  // ignored "-Wtautological-compare"
+
+    e = getenv("BUP_FORCE_TTY");
+    get_state(m)->istty2 = isatty(2) || (atoi(e ? e : "0") & 2);
+    unpythonize_argv();
+    return 1;
+}
+
+
+#if PY_MAJOR_VERSION < 3
+
+PyMODINIT_FUNC init_helpers(void)
+{
     PyObject *m = Py_InitModule("_helpers", helper_methods);
     if (m == NULL)
         return;
-    e = getenv("BUP_FORCE_TTY");
-    istty2 = isatty(2) || (atoi(e ? e : "0") & 2);
-    unpythonize_argv();
+
+    if (!setup_module(m))
+    {
+        Py_DECREF(m);
+        return;
+    }
 }
+
+# else // PY_MAJOR_VERSION >= 3
+
+static struct PyModuleDef helpers_def = {
+    PyModuleDef_HEAD_INIT,
+    "_helpers",
+    NULL,
+    sizeof(state_t),
+    helper_methods,
+    NULL,
+    NULL, // helpers_traverse,
+    NULL, // helpers_clear,
+    NULL
+};
+
+PyMODINIT_FUNC PyInit__helpers(void)
+{
+    PyObject *module = PyModule_Create(&helpers_def);
+    if (module == NULL)
+        return NULL;
+    if (!setup_module(module))
+    {
+        Py_DECREF(module);
+        return NULL;
+    }
+    return module;
+}
+
+#endif // PY_MAJOR_VERSION >= 3