X-Git-Url: https://arthur.barton.de/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=lib%2Fbup%2F_helpers.c;h=59f0fa381558e255a37f8b7059881f09feb73229;hb=534c64edcf41a5f57010aec6447dcf5bcb5d2b57;hp=75d26030545fc9b59041937c5e35a46401bdd0cc;hpb=91efac924a2cd3b2393198c519115951476df042;p=bup.git

diff --git a/lib/bup/_helpers.c b/lib/bup/_helpers.c
index 75d2603..59f0fa3 100644
--- a/lib/bup/_helpers.c
+++ b/lib/bup/_helpers.c
@@ -1,9 +1,362 @@
-#include "bupsplit.h"
+#define _LARGEFILE64_SOURCE 1
+#define PY_SSIZE_T_CLEAN 1
+#undef NDEBUG
+#include "../../config/config.h"
+
+// According to Python, its header has to go first:
+//   http://docs.python.org/2/c-api/intro.html#include-files
 #include <Python.h>
+
 #include <assert.h>
-#include <stdint.h>
+#include <errno.h>
 #include <fcntl.h>
 #include <arpa/inet.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <sys/mman.h>
+
+#ifdef HAVE_SYS_TYPES_H
+#include <sys/types.h>
+#endif
+#ifdef HAVE_SYS_STAT_H
+#include <sys/stat.h>
+#endif
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
+#ifdef HAVE_LINUX_FS_H
+#include <linux/fs.h>
+#endif
+#ifdef HAVE_SYS_IOCTL_H
+#include <sys/ioctl.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;
+
+
+#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
+
+
+#define INTEGRAL_ASSIGNMENT_FITS(dest, src)                             \
+    ({                                                                  \
+        *(dest) = (src);                                                \
+        *(dest) == (src) && (*(dest) < 1) == ((src) < 1);               \
+    })
+
+
+// At the moment any code that calls INTGER_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))
+
+
+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;
+}
+
+
+static int bup_ulong_from_py(unsigned long *x, PyObject *py, const char *name)
+{
+    if (PyInt_Check(py))
+        return bup_ulong_from_pyint(x, py, name);
+
+    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 (PyInt_Check(py))
+    {
+        unsigned long tmp;
+        if (bup_ulong_from_pyint(&tmp, py, name))
+        {
+            *x = tmp;
+            return 1;
+        }
+        return 0;
+    }
+
+    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;
+}
+
+
+// Probably we should use autoconf or something and set HAVE_PY_GETARGCARGV...
+#if __WIN32__ || __CYGWIN__
+
+// There's no 'ps' on win32 anyway, and Py_GetArgcArgv() isn't available.
+static void unpythonize_argv(void) { }
+
+#else // not __WIN32__
+
+// For some reason this isn't declared in Python.h
+extern void Py_GetArgcArgv(int *argc, char ***argv);
+
+static void unpythonize_argv(void)
+{
+    int argc, i;
+    char **argv, *arge;
+    
+    Py_GetArgcArgv(&argc, &argv);
+    
+    for (i = 0; i < argc-1; i++)
+    {
+	if (argv[i] + strlen(argv[i]) + 1 != argv[i+1])
+	{
+	    // The argv block doesn't work the way we expected; it's unsafe
+	    // to mess with it.
+	    return;
+	}
+    }
+    
+    arge = argv[argc-1] + strlen(argv[argc-1]) + 1;
+    
+    if (strstr(argv[0], "python") && argv[1] == argv[0] + strlen(argv[0]) + 1)
+    {
+	char *p;
+	size_t len, diff;
+	p = strrchr(argv[1], '/');
+	if (p)
+	{
+	    p++;
+	    diff = p - argv[0];
+	    len = arge - p;
+	    memmove(argv[0], p, len);
+	    memset(arge - diff, 0, diff);
+	    for (i = 0; i < argc; i++)
+		argv[i] = argv[i+1] ? argv[i+1]-diff : NULL;
+	}
+    }
+}
+
+#endif // not __WIN32__ or __CYGWIN__
+
+
+static unsigned long long count_leading_zeros(const unsigned char * const buf,
+                                              unsigned long long len)
+{
+    const unsigned char *cur = buf;
+    while(len-- && *cur == 0)
+        cur++;
+    return cur - buf;
+}
+
+
+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 *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, "it#OO",
+                          &fd, &buf, &sbuf_len,
+                          &py_min_sparse_len, &py_prev_sparse_len))
+	return NULL;
+    unsigned long long min_sparse_len, prev_sparse_len, buf_len;
+    if (!bup_ullong_from_py(&min_sparse_len, py_min_sparse_len, "min_sparse_len"))
+        return NULL;
+    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");
+
+    // The value of zeros_read indicates the number of zeros read from
+    // buf that haven't been accounted for yet (with respect to cur),
+    // while zeros indicates the total number of pending zeros, which
+    // could be larger in the first iteration if prev_sparse_len
+    // wasn't zero.
+    int rc;
+    unsigned long long unexamined = buf_len;
+    unsigned char *block_start = buf, *cur = buf;
+    unsigned long long zeros, zeros_read = count_leading_zeros(cur, unexamined);
+    assert(zeros_read <= unexamined);
+    unexamined -= zeros_read;
+    if (!uadd(&zeros, prev_sparse_len, zeros_read))
+    {
+        PyObject *err = append_sparse_region(fd, prev_sparse_len);
+        if (err != NULL)
+            return err;
+        zeros = zeros_read;
+    }
+
+    while(unexamined)
+    {
+        if (zeros < min_sparse_len)
+            cur += zeros_read;
+        else
+        {
+            rc = write_all(fd, block_start, cur - block_start);
+            if (rc)
+                return PyErr_SetFromErrno(PyExc_IOError);
+            PyObject *err = append_sparse_region(fd, zeros);
+            if (err != NULL)
+                return err;
+            cur += zeros_read;
+            block_start = cur;
+        }
+        // Pending zeros have ether been made sparse, or are going to
+        // be rolled into the next non-sparse block since we know we
+        // now have at least one unexamined non-zero byte.
+        assert(unexamined && *cur != 0);
+        zeros = zeros_read = 0;
+        while (unexamined && *cur != 0)
+        {
+            cur++; unexamined--;
+        }
+        if (unexamined)
+        {
+            zeros_read = count_leading_zeros(cur, unexamined);
+            assert(zeros_read <= unexamined);
+            unexamined -= zeros_read;
+            zeros = zeros_read;
+        }
+    }
+    rc = write_all(fd, block_start, cur - block_start);
+    if (rc)
+        return PyErr_SetFromErrno(PyExc_IOError);
+    return PyLong_FromUnsignedLongLong(zeros);
+}
+
 
 static PyObject *selftest(PyObject *self, PyObject *args)
 {
@@ -25,11 +378,14 @@ static PyObject *blobbits(PyObject *self, PyObject *args)
 static PyObject *splitbuf(PyObject *self, PyObject *args)
 {
     unsigned char *buf = NULL;
-    int len = 0, out = 0, bits = -1;
+    Py_ssize_t len = 0;
+    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 (out) assert(bits >= BUP_BLOBBITS);
     return Py_BuildValue("ii", out, bits);
 }
 
@@ -37,8 +393,9 @@ static PyObject *splitbuf(PyObject *self, PyObject *args)
 static PyObject *bitmatch(PyObject *self, PyObject *args)
 {
     unsigned char *buf1 = NULL, *buf2 = NULL;
-    int len1 = 0, len2 = 0;
-    int byte, bit;
+    Py_ssize_t len1 = 0, len2 = 0;
+    Py_ssize_t byte;
+    int bit;
 
     if (!PyArg_ParseTuple(args, "t#t#", &buf1, &len1, &buf2, &len2))
 	return NULL;
@@ -56,6 +413,7 @@ static PyObject *bitmatch(PyObject *self, PyObject *args)
 	}
     }
     
+    assert(byte <= (INT_MAX >> 3));
     return Py_BuildValue("i", byte*8 + bit);
 }
 
@@ -63,7 +421,7 @@ static PyObject *bitmatch(PyObject *self, PyObject *args)
 static PyObject *firstword(PyObject *self, PyObject *args)
 {
     unsigned char *buf = NULL;
-    int len = 0;
+    Py_ssize_t len = 0;
     uint32_t v;
 
     if (!PyArg_ParseTuple(args, "t#", &buf, &len))
@@ -73,15 +431,153 @@ static PyObject *firstword(PyObject *self, PyObject *args)
 	return NULL;
     
     v = ntohl(*(uint32_t *)buf);
-    return Py_BuildValue("I", v);
+    return PyLong_FromUnsignedLong(v);
+}
+
+
+#define BLOOM2_HEADERLEN 16
+
+static void to_bloom_address_bitmask4(const unsigned char *buf,
+	const int nbits, uint64_t *v, unsigned char *bitmask)
+{
+    int bit;
+    uint32_t high;
+    uint64_t raw, mask;
+
+    memcpy(&high, buf, 4);
+    mask = (1<<nbits) - 1;
+    raw = (((uint64_t)ntohl(high) << 8) | buf[4]);
+    bit = (raw >> (37-nbits)) & 0x7;
+    *v = (raw >> (40-nbits)) & mask;
+    *bitmask = 1 << bit;
+}
+
+static void to_bloom_address_bitmask5(const unsigned char *buf,
+	const int nbits, uint32_t *v, unsigned char *bitmask)
+{
+    int bit;
+    uint32_t high;
+    uint32_t raw, mask;
+
+    memcpy(&high, buf, 4);
+    mask = (1<<nbits) - 1;
+    raw = ntohl(high);
+    bit = (raw >> (29-nbits)) & 0x7;
+    *v = (raw >> (32-nbits)) & mask;
+    *bitmask = 1 << bit;
+}
+
+#define BLOOM_SET_BIT(name, address, otype) \
+static void name(unsigned char *bloom, const unsigned char *buf, const int nbits)\
+{\
+    unsigned char bitmask;\
+    otype v;\
+    address(buf, nbits, &v, &bitmask);\
+    bloom[BLOOM2_HEADERLEN+v] |= bitmask;\
+}
+BLOOM_SET_BIT(bloom_set_bit4, to_bloom_address_bitmask4, uint64_t)
+BLOOM_SET_BIT(bloom_set_bit5, to_bloom_address_bitmask5, uint32_t)
+
+
+#define BLOOM_GET_BIT(name, address, otype) \
+static int name(const unsigned char *bloom, const unsigned char *buf, const int nbits)\
+{\
+    unsigned char bitmask;\
+    otype v;\
+    address(buf, nbits, &v, &bitmask);\
+    return bloom[BLOOM2_HEADERLEN+v] & bitmask;\
+}
+BLOOM_GET_BIT(bloom_get_bit4, to_bloom_address_bitmask4, uint64_t)
+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;
+    int nbits = 0, k = 0;
+
+    if (!PyArg_ParseTuple(args, "w#s#ii", &bloom, &blen, &sha, &len, &nbits, &k))
+	return NULL;
+
+    if (blen < 16+(1<<nbits) || len % 20 != 0)
+	return NULL;
+
+    if (k == 5)
+    {
+	if (nbits > 29)
+	    return NULL;
+	for (end = sha + len; sha < end; sha += 20/k)
+	    bloom_set_bit5(bloom, sha, 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);
+    }
+    else
+	return NULL;
+
+
+    return Py_BuildValue("n", len/20);
+}
+
+static PyObject *bloom_contains(PyObject *self, PyObject *args)
+{
+    unsigned char *sha = NULL, *bloom = NULL;
+    Py_ssize_t len = 0, blen = 0;
+    int nbits = 0, k = 0;
+    unsigned char *end;
+    int steps;
+
+    if (!PyArg_ParseTuple(args, "t#s#ii", &bloom, &blen, &sha, &len, &nbits, &k))
+	return NULL;
+
+    if (len != 20)
+	return NULL;
+
+    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);
+    }
+    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);
+    }
+    else
+	return NULL;
+
+    return Py_BuildValue("ii", 1, k);
+}
+
+
+static uint32_t _extract_bits(unsigned char *buf, int nbits)
+{
+    uint32_t v, mask;
+
+    mask = (1<<nbits) - 1;
+    v = ntohl(*(uint32_t *)buf);
+    v = (v >> (32-nbits)) & mask;
+    return v;
 }
 
 
 static PyObject *extract_bits(PyObject *self, PyObject *args)
 {
     unsigned char *buf = NULL;
-    int len = 0, nbits = 0;
-    uint32_t v, mask;
+    Py_ssize_t len = 0;
+    int nbits = 0;
 
     if (!PyArg_ParseTuple(args, "t#i", &buf, &len, &nbits))
 	return NULL;
@@ -89,10 +585,241 @@ static PyObject *extract_bits(PyObject *self, PyObject *args)
     if (len < 4)
 	return NULL;
     
-    mask = (1<<nbits) - 1;
-    v = ntohl(*(uint32_t *)buf);
-    v = (v >> (32-nbits)) & mask;
-    return Py_BuildValue("I", v);
+    return PyLong_FromUnsignedLong(_extract_bits(buf, nbits));
+}
+
+
+struct sha {
+    unsigned char bytes[20];
+};
+
+
+struct idx {
+    unsigned char *map;
+    struct sha *cur;
+    struct sha *end;
+    uint32_t *cur_name;
+    Py_ssize_t bytes;
+    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)
+{
+    struct idx *idx;
+    int low, mid, high, c = 0;
+
+    idx = idxs[*last_i];
+    if (idxs[*last_i]->cur >= idxs[*last_i]->end)
+    {
+	idxs[*last_i] = NULL;
+	PyMem_Free(idx);
+	--*last_i;
+	return;
+    }
+    if (*last_i == 0)
+	return;
+
+    low = *last_i-1;
+    mid = *last_i;
+    high = 0;
+    while (low >= high)
+    {
+	mid = (low + high) / 2;
+	c = _cmp_sha(idx->cur, idxs[mid]->cur);
+	if (c < 0)
+	    high = mid + 1;
+	else if (c > 0)
+	    low = mid - 1;
+	else
+	    break;
+    }
+    if (c < 0)
+	++mid;
+    if (mid == *last_i)
+	return;
+    memmove(&idxs[mid+1], &idxs[mid], (*last_i-mid)*sizeof(struct idx *));
+    idxs[mid] = idx;
+}
+
+
+static uint32_t _get_idx_i(struct idx *idx)
+{
+    if (idx->cur_name == NULL)
+	return idx->name_base;
+    return ntohl(*idx->cur_name) + idx->name_base;
+}
+
+#define MIDX4_HEADERLEN 12
+
+static PyObject *merge_into(PyObject *self, PyObject *args)
+{
+    PyObject *py_total, *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;
+    unsigned int total;
+    uint32_t count, prefix;
+    int num_i;
+    int last_i;
+
+    if (!PyArg_ParseTuple(args, "w#iOO",
+                          &fmap, &flen, &bits, &py_total, &ilist))
+	return NULL;
+
+    if (!bup_uint_from_py(&total, py_total, "total"))
+        return NULL;
+
+    num_i = PyList_Size(ilist);
+    idxs = (struct idx **)PyMem_Malloc(num_i * sizeof(struct idx *));
+
+    for (i = 0; i < num_i; i++)
+    {
+	long len, sha_ofs, name_map_ofs;
+	idxs[i] = (struct idx *)PyMem_Malloc(sizeof(struct idx));
+	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))
+	    return NULL;
+	idxs[i]->cur = (struct sha *)&idxs[i]->map[sha_ofs];
+	idxs[i]->end = &idxs[i]->cur[len];
+	if (name_map_ofs)
+	    idxs[i]->cur_name = (uint32_t *)&idxs[i]->map[name_map_ofs];
+	else
+	    idxs[i]->cur_name = NULL;
+    }
+    table_ptr = (uint32_t *)&fmap[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;
+    count = 0;
+    prefix = 0;
+    while (last_i >= 0)
+    {
+	struct idx *idx;
+	uint32_t new_prefix;
+	if (count % 102424 == 0 && istty2)
+	    fprintf(stderr, "midx: writing %.2f%% (%d/%d)\r",
+		    count*100.0/total, count, total);
+	idx = idxs[last_i];
+	new_prefix = _extract_bits((unsigned char *)idx->cur, bits);
+	while (prefix < new_prefix)
+	    table_ptr[prefix++] = htonl(count);
+	memcpy(sha_ptr++, idx->cur, sizeof(struct sha));
+	*name_ptr++ = htonl(_get_idx_i(idx));
+	++idx->cur;
+	if (idx->cur_name != NULL)
+	    ++idx->cur_name;
+	_fix_idx_order(idxs, &last_i);
+	++count;
+    }
+    while (prefix < (1<<bits))
+	table_ptr[prefix++] = htonl(count);
+    assert(count == total);
+    assert(prefix == (1<<bits));
+    assert(sha_ptr == sha_start+count);
+    assert(name_ptr == name_start+count);
+
+    PyMem_Free(idxs);
+    return PyLong_FromUnsignedLong(count);
+}
+
+#define FAN_ENTRIES 256
+
+static PyObject *write_idx(PyObject *self, PyObject *args)
+{
+    char *filename = 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;
+    uint32_t *fan_ptr, *crc_ptr, *ofs_ptr;
+    uint64_t *ofs64_ptr;
+    struct sha *sha_ptr;
+
+    if (!PyArg_ParseTuple(args, "sw#OO",
+                          &filename, &fmap, &flen, &idx, &py_total))
+	return NULL;
+
+    if (!bup_uint_from_py(&total, py_total, "total"))
+        return NULL;
+
+    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);
+
+    const char idx_header[] = "\377tOc\0\0\0\002";
+    memcpy (fmap, idx_header, sizeof(idx_header) - 1);
+
+    fan_ptr = (uint32_t *)&fmap[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];
+    ofs64_ptr = (uint64_t *)&ofs_ptr[total];
+
+    count = 0;
+    ofs64_count = 0;
+    for (i = 0; i < FAN_ENTRIES; ++i)
+    {
+	int plen;
+	part = PyList_GET_ITEM(idx, i);
+	PyList_Sort(part);
+	plen = PyList_GET_SIZE(part);
+	count += plen;
+	*fan_ptr++ = htonl(count);
+	for (j = 0; j < plen; ++j)
+	{
+	    unsigned char *sha = NULL;
+	    Py_ssize_t sha_len = 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#OO",
+				  &sha, &sha_len, &crc_py, &ofs_py))
+		return NULL;
+            if(!bup_uint_from_py(&crc, crc_py, "crc"))
+                return NULL;
+            if(!bup_ullong_from_py(&ofs_ull, ofs_py, "ofs"))
+                return NULL;
+            assert(crc <= UINT32_MAX);
+            assert(ofs_ull <= UINT64_MAX);
+	    ofs = ofs_ull;
+	    if (sha_len != sizeof(struct sha))
+		return NULL;
+	    memcpy(sha_ptr++, sha, sizeof(struct sha));
+	    *crc_ptr++ = htonl(crc);
+	    if (ofs > 0x7fffffff)
+	    {
+                *ofs64_ptr++ = htonll(ofs);
+		ofs = 0x80000000 | ofs64_count++;
+	    }
+	    *ofs_ptr++ = htonl((uint32_t)ofs);
+	}
+    }
+
+    int rc = msync(fmap, flen, MS_ASYNC);
+    if (rc != 0)
+	return PyErr_SetFromErrnoWithFilename(PyExc_IOError, filename);
+
+    return PyLong_FromUnsignedLong(count);
 }
 
 
@@ -105,11 +832,11 @@ static PyObject *extract_bits(PyObject *self, PyObject *args)
 static PyObject *write_random(PyObject *self, PyObject *args)
 {
     uint32_t buf[1024/4];
-    int fd = -1, seed = 0;
+    int fd = -1, seed = 0, verbose = 0;
     ssize_t ret;
     long long len = 0, kbytes = 0, written = 0;
 
-    if (!PyArg_ParseTuple(args, "iLi", &fd, &len, &seed))
+    if (!PyArg_ParseTuple(args, "iLii", &fd, &len, &seed, &verbose))
 	return NULL;
     
     srandom(seed);
@@ -125,7 +852,7 @@ static PyObject *write_random(PyObject *self, PyObject *args)
 	written += ret;
 	if (ret < (int)sizeof(buf))
 	    break;
-	if (kbytes/1024 > 0 && !(kbytes%1024))
+	if (verbose && kbytes/1024 > 0 && !(kbytes%1024))
 	    fprintf(stderr, "Random: %lld Mbytes\r", kbytes/1024);
     }
     
@@ -147,13 +874,33 @@ static PyObject *write_random(PyObject *self, PyObject *args)
 }
 
 
-static PyObject *open_noatime(PyObject *self, PyObject *args)
+static PyObject *random_sha(PyObject *self, PyObject *args)
 {
-    char *filename = NULL;
-    int attrs, attrs_noatime, fd;
-    if (!PyArg_ParseTuple(args, "s", &filename))
+    static int seeded = 0;
+    uint32_t shabuf[20/4];
+    int i;
+    
+    if (!seeded)
+    {
+	assert(sizeof(shabuf) == 20);
+	srandom(time(NULL));
+	seeded = 1;
+    }
+    
+    if (!PyArg_ParseTuple(args, ""))
 	return NULL;
-    attrs = O_RDONLY;
+    
+    memset(shabuf, 0, sizeof(shabuf));
+    for (i=0; i < 20/4; i++)
+	shabuf[i] = random();
+    return Py_BuildValue("s#", shabuf, 20);
+}
+
+
+static int _open_noatime(const char *filename, int attrs)
+{
+    int attrs_noatime, fd;
+    attrs |= O_RDONLY;
 #ifdef O_NOFOLLOW
     attrs |= O_NOFOLLOW;
 #endif
@@ -174,8 +921,19 @@ static PyObject *open_noatime(PyObject *self, PyObject *args)
 	// just harmlessly ignore it, so this branch won't trigger)
 	fd = open(filename, attrs);
     }
+    return fd;
+}
+
+
+static PyObject *open_noatime(PyObject *self, PyObject *args)
+{
+    char *filename = NULL;
+    int fd;
+    if (!PyArg_ParseTuple(args, "s", &filename))
+	return NULL;
+    fd = _open_noatime(filename, 0);
     if (fd < 0)
-	return PyErr_SetFromErrnoWithFilename(PyExc_IOError, filename);
+	return PyErr_SetFromErrnoWithFilename(PyExc_OSError, filename);
     return Py_BuildValue("i", fd);
 }
 
@@ -193,7 +951,355 @@ static PyObject *fadvise_done(PyObject *self, PyObject *args)
 }
 
 
-static PyMethodDef faster_methods[] = {
+// 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 long attr;
+    char *path;
+    int fd;
+
+    if (!PyArg_ParseTuple(args, "s", &path))
+        return NULL;
+
+    fd = _open_noatime(path, O_NONBLOCK);
+    if (fd == -1)
+        return PyErr_SetFromErrnoWithFilename(PyExc_OSError, path);
+
+    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);
+    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 long orig_attr;
+    unsigned int attr;
+    char *path;
+    PyObject *py_attr;
+    int fd;
+
+    if (!PyArg_ParseTuple(args, "sO", &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);
+    if (fd == -1)
+        return PyErr_SetFromErrnoWithFilename(PyExc_OSError, path);
+
+    // Restrict attr to modifiable flags acdeijstuADST -- see
+    // chattr(1) and the e2fsprogs source.  Letter to flag mapping is
+    // in pf.c flags_array[].
+    attr &= FS_APPEND_FL | FS_COMPR_FL | FS_NODUMP_FL | FS_EXTENT_FL
+    | FS_IMMUTABLE_FL | FS_JOURNAL_DATA_FL | FS_SECRM_FL | FS_NOTAIL_FL
+    | FS_UNRM_FL | FS_NOATIME_FL | FS_DIRSYNC_FL | FS_SYNC_FL
+    | 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);
+    assert(orig_attr <= UINT_MAX);  // Kernel type is actually int
+    if (rc == -1)
+    {
+        close(fd);
+        return PyErr_SetFromErrnoWithFilename(PyExc_OSError, path);
+    }
+    attr |= ((unsigned int) orig_attr) & FS_EXTENT_FL;
+
+    rc = ioctl(fd, FS_IOC_SETFLAGS, &attr);
+    if (rc == -1)
+    {
+        close(fd);
+        return PyErr_SetFromErrnoWithFilename(PyExc_OSError, path);
+    }
+
+    close(fd);
+    return Py_BuildValue("O", Py_None);
+}
+#endif /* def BUP_HAVE_FILE_ATTRS */
+
+
+#ifndef HAVE_UTIMENSAT
+#ifndef HAVE_UTIMES
+#error "cannot find utimensat or utimes()"
+#endif
+#ifndef HAVE_LUTIMES
+#error "cannot find utimensat or lutimes()"
+#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;                                                         \
+        })
+
+
+#ifdef HAVE_UTIMENSAT
+
+static PyObject *bup_utimensat(PyObject *self, PyObject *args)
+{
+    int rc;
+    int fd, flag;
+    char *path;
+    PyObject *access_py, *modification_py;
+    struct timespec ts[2];
+
+    if (!PyArg_ParseTuple(args, "is((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))
+    {
+        if (overflow)
+            PyErr_SetString(PyExc_ValueError,
+                            "unable to convert access time seconds for utimensat");
+        return NULL;
+    }
+    if (!ASSIGN_PYLONG_TO_INTEGRAL(&(ts[1].tv_sec), modification_py, &overflow))
+    {
+        if (overflow)
+            PyErr_SetString(PyExc_ValueError,
+                            "unable to convert modification time seconds for utimensat");
+        return NULL;
+    }
+    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, "s((OL)(OL))",
+                          path,
+                          &access_py, &access_us,
+                          &modification_py, &modification_us))
+        return 0;
+
+    int overflow;
+    if (!ASSIGN_PYLONG_TO_INTEGRAL(&(tv[0].tv_sec), access_py, &overflow))
+    {
+        if (overflow)
+            PyErr_SetString(PyExc_ValueError, "unable to convert access time seconds to timeval");
+        return 0;
+    }
+    if (!INTEGRAL_ASSIGNMENT_FITS(&(tv[0].tv_usec), access_us))
+    {
+        PyErr_SetString(PyExc_ValueError, "unable to convert access time nanoseconds to timeval");
+        return 0;
+    }
+    if (!ASSIGN_PYLONG_TO_INTEGRAL(&(tv[1].tv_sec), modification_py, &overflow))
+    {
+        if (overflow)
+            PyErr_SetString(PyExc_ValueError, "unable to convert modification time seconds to timeval");
+        return 0;
+    }
+    if (!INTEGRAL_ASSIGNMENT_FITS(&(tv[1].tv_usec), modification_us))
+    {
+        PyErr_SetString(PyExc_ValueError, "unable to convert modification time nanoseconds to timeval");
+        return 0;
+    }
+    return 1;
+}
+
+#endif /* defined(HAVE_UTIMES) || defined(HAVE_LUTIMES) */
+
+
+#ifdef HAVE_UTIMES
+static PyObject *bup_utimes(PyObject *self, PyObject *args)
+{
+    char *path;
+    struct timeval tv[2];
+    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
+static PyObject *bup_lutimes(PyObject *self, PyObject *args)
+{
+    char *path;
+    struct timeval tv[2];
+    if (!bup_parse_xutimes_args(&path, tv, args))
+        return NULL;
+    int rc = lutimes(path, tv);
+    if (rc != 0)
+        return PyErr_SetFromErrnoWithFilename(PyExc_OSError, path);
+
+    return Py_BuildValue("O", Py_None);
+}
+#endif /* def HAVE_LUTIMES */
+
+
+#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
+# define BUP_STAT_CTIME_NS(st) (st)->st_ctim.tv_nsec
+#elif defined HAVE_STAT_ST_ATIMENSEC
+# define BUP_STAT_ATIME_NS(st) (st)->st_atimespec.tv_nsec
+# define BUP_STAT_MTIME_NS(st) (st)->st_mtimespec.tv_nsec
+# define BUP_STAT_CTIME_NS(st) (st)->st_ctimespec.tv_nsec
+#else
+# define BUP_STAT_ATIME_NS(st) 0
+# define BUP_STAT_MTIME_NS(st) 0
+# define BUP_STAT_CTIME_NS(st) 0
+#endif
+
+
+#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)
+{
+    // 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().  Assumes ns values will fit in a
+    // long.
+    return Py_BuildValue("OKOOOOOL(Ol)(Ol)(Ol)",
+                         INTEGER_TO_PY(st->st_mode),
+                         (unsigned PY_LONG_LONG) st->st_ino,
+                         INTEGER_TO_PY(st->st_dev),
+                         INTEGER_TO_PY(st->st_nlink),
+                         INTEGER_TO_PY(st->st_uid),
+                         INTEGER_TO_PY(st->st_gid),
+                         INTEGER_TO_PY(st->st_rdev),
+                         (PY_LONG_LONG) st->st_size,
+                         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))
+        return NULL;
+
+    struct stat st;
+    rc = stat(filename, &st);
+    if (rc != 0)
+        return PyErr_SetFromErrnoWithFilename(PyExc_OSError, filename);
+    return stat_struct_to_py(&st, filename, 0);
+}
+
+
+static PyObject *bup_lstat(PyObject *self, PyObject *args)
+{
+    int rc;
+    char *filename;
+
+    if (!PyArg_ParseTuple(args, "s", &filename))
+        return NULL;
+
+    struct stat st;
+    rc = lstat(filename, &st);
+    if (rc != 0)
+        return PyErr_SetFromErrnoWithFilename(PyExc_OSError, filename);
+    return stat_struct_to_py(&st, filename, 0);
+}
+
+
+static PyObject *bup_fstat(PyObject *self, PyObject *args)
+{
+    int rc, fd;
+
+    if (!PyArg_ParseTuple(args, "i", &fd))
+        return NULL;
+
+    struct stat st;
+    rc = fstat(fd, &st);
+    if (rc != 0)
+        return PyErr_SetFromErrno(PyExc_OSError);
+    return stat_struct_to_py(&st, NULL, fd);
+}
+
+
+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,
@@ -204,18 +1310,111 @@ static PyMethodDef faster_methods[] = {
 	"Count the number of matching prefix bits between two strings." },
     { "firstword", firstword, METH_VARARGS,
         "Return an int corresponding to the first 32 bits of buf." },
+    { "bloom_contains", bloom_contains, METH_VARARGS,
+	"Check if a bloom filter of 2^nbits bytes contains an object" },
+    { "bloom_add", bloom_add, METH_VARARGS,
+	"Add an object to a bloom filter of 2^nbits bytes" },
     { "extract_bits", extract_bits, METH_VARARGS,
 	"Take the first 'nbits' bits from 'buf' and return them as an int." },
+    { "merge_into", merge_into, METH_VARARGS,
+	"Merges a bunch of idx and midx files into a single midx." },
+    { "write_idx", write_idx, METH_VARARGS,
+	"Write a PackIdxV2 file from an idx list of lists of tuples" },
     { "write_random", write_random, METH_VARARGS,
 	"Write random bytes to the given file descriptor" },
+    { "random_sha", random_sha, METH_VARARGS,
+        "Return a random 20-byte string" },
     { "open_noatime", open_noatime, METH_VARARGS,
 	"open() the given filename for read with O_NOATIME if possible" },
     { "fadvise_done", fadvise_done, METH_VARARGS,
 	"Inform the kernel that we're finished with earlier parts of a file" },
+#ifdef BUP_HAVE_FILE_ATTRS
+    { "get_linux_file_attr", bup_get_linux_file_attr, METH_VARARGS,
+      "Return the Linux attributes for the given file." },
+#endif
+#ifdef BUP_HAVE_FILE_ATTRS
+    { "set_linux_file_attr", bup_set_linux_file_attr, METH_VARARGS,
+      "Set the Linux attributes for the given file." },
+#endif
+#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 HAVE_LUTIMES
+    { "bup_lutimes", bup_lutimes, METH_VARARGS,
+      "Change path timestamps with microsecond precision;"
+      " don't follow symlinks." },
+#endif
+    { "stat", bup_stat, METH_VARARGS,
+      "Extended version of stat." },
+    { "lstat", bup_lstat, METH_VARARGS,
+      "Extended version of lstat." },
+    { "fstat", bup_fstat, METH_VARARGS,
+      "Extended version of fstat." },
     { NULL, NULL, 0, NULL },  // sentinel
 };
 
+
 PyMODINIT_FUNC init_helpers(void)
 {
-    Py_InitModule("_helpers", faster_methods);
+    // 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.
+    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));
+
+    if (sizeof(off_t) < sizeof(int))
+    {
+        // Originally required by append_sparse_region().
+        fprintf(stderr, "sizeof(off_t) < sizeof(int); please report.\n");
+        exit(1);
+    }
+
+    char *e;
+    PyObject *m = Py_InitModule("_helpers", helper_methods);
+    if (m == NULL)
+        return;
+
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wtautological-compare" // For INTEGER_TO_PY().
+#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
+    {
+        PyObject *value;
+        const long arg_max = sysconf(_SC_ARG_MAX);
+        if (arg_max == -1)
+        {
+            fprintf(stderr, "Cannot find SC_ARG_MAX, please report a bug.\n");
+            exit(1);
+        }
+        value = INTEGER_TO_PY(arg_max);
+        PyObject_SetAttrString(m, "SC_ARG_MAX", value);
+        Py_DECREF(value);
+    }
+#pragma clang diagnostic pop  // ignored "-Wtautological-compare"
+
+    e = getenv("BUP_FORCE_TTY");
+    istty2 = isatty(2) || (atoi(e ? e : "0") & 2);
+    unpythonize_argv();
 }