]> arthur.barton.de Git - bup.git/blobdiff - lib/bup/_helpers.c
Remove vestigial and inappropriate isnan()/isinf() timestamp tests.
[bup.git] / lib / bup / _helpers.c
index f58243017f029f9ba821a8e0205c4f7fca9cbbc1..0fd20cc233db19fc0152f1a98aa692abdffbb6c4 100644 (file)
@@ -1,8 +1,12 @@
 #define _LARGEFILE64_SOURCE 1
+#define PY_SSIZE_T_CLEAN 1
 #undef NDEBUG
 #include "../../config/config.h"
-#include "bupsplit.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 <errno.h>
 #include <fcntl.h>
@@ -10,6 +14,7 @@
 #include <stdint.h>
 #include <stdlib.h>
 #include <stdio.h>
+#include <sys/mman.h>
 
 #ifdef HAVE_SYS_TYPES_H
 #include <sys/types.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
+
+#ifndef FS_NOCOW_FL
+// Of course, this assumes it's a bitfield value.
+#define FS_NOCOW_FL 0
+#endif
+
 static int istty2 = 0;
 
 // Probably we should use autoconf or something and set HAVE_PY_GETARGCARGV...
@@ -101,10 +117,12 @@ 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);
@@ -114,8 +132,9 @@ 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;
@@ -133,6 +152,7 @@ static PyObject *bitmatch(PyObject *self, PyObject *args)
        }
     }
     
+    assert(byte <= (INT_MAX >> 3));
     return Py_BuildValue("i", byte*8 + bit);
 }
 
@@ -140,7 +160,7 @@ 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))
@@ -156,66 +176,66 @@ static PyObject *firstword(PyObject *self, PyObject *args)
 
 #define BLOOM2_HEADERLEN 16
 
-typedef struct {
-    uint32_t high;
-    unsigned char low;
-} bits40_t;
-
-static void to_bloom_address_bitmask4(const bits40_t *buf,
+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(buf->high)) << 8) | buf->low;
+    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 uint32_t *buf,
+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(*buf);
+    raw = ntohl(high);
     bit = (raw >> (29-nbits)) & 0x7;
     *v = (raw >> (32-nbits)) & mask;
     *bitmask = 1 << bit;
 }
 
-#define BLOOM_SET_BIT(name, address, itype, otype) \
-static void name(unsigned char *bloom, const void *buf, const int nbits)\
+#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((itype *)buf, nbits, &v, &bitmask);\
+    address(buf, nbits, &v, &bitmask);\
     bloom[BLOOM2_HEADERLEN+v] |= bitmask;\
 }
-BLOOM_SET_BIT(bloom_set_bit4, to_bloom_address_bitmask4, bits40_t, uint64_t)
-BLOOM_SET_BIT(bloom_set_bit5, to_bloom_address_bitmask5, uint32_t, uint32_t)
+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, itype, otype) \
-static int name(const unsigned char *bloom, const void *buf, const int nbits)\
+#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((itype *)buf, nbits, &v, &bitmask);\
+    address(buf, nbits, &v, &bitmask);\
     return bloom[BLOOM2_HEADERLEN+v] & bitmask;\
 }
-BLOOM_GET_BIT(bloom_get_bit4, to_bloom_address_bitmask4, bits40_t, uint64_t)
-BLOOM_GET_BIT(bloom_get_bit5, to_bloom_address_bitmask5, uint32_t, uint32_t)
+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;
-    int len = 0, blen = 0, nbits = 0, k = 0;
+    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;
@@ -241,13 +261,14 @@ static PyObject *bloom_add(PyObject *self, PyObject *args)
        return NULL;
 
 
-    return Py_BuildValue("i", len/20);
+    return Py_BuildValue("n", len/20);
 }
 
 static PyObject *bloom_contains(PyObject *self, PyObject *args)
 {
     unsigned char *sha = NULL, *bloom = NULL;
-    int len = 0, blen = 0, nbits = 0, k = 0;
+    Py_ssize_t len = 0, blen = 0;
+    int nbits = 0, k = 0;
     unsigned char *end;
     int steps;
 
@@ -289,10 +310,13 @@ static uint32_t _extract_bits(unsigned char *buf, int nbits)
     v = (v >> (32-nbits)) & mask;
     return v;
 }
+
+
 static PyObject *extract_bits(PyObject *self, PyObject *args)
 {
     unsigned char *buf = NULL;
-    int len = 0, nbits = 0;
+    Py_ssize_t len = 0;
+    int nbits = 0;
 
     if (!PyArg_ParseTuple(args, "t#i", &buf, &len, &nbits))
        return NULL;
@@ -307,12 +331,14 @@ static PyObject *extract_bits(PyObject *self, PyObject *args)
 struct sha {
     unsigned char bytes[20];
 };
+
+
 struct idx {
     unsigned char *map;
     struct sha *cur;
     struct sha *end;
     uint32_t *cur_name;
-    long bytes;
+    Py_ssize_t bytes;
     int name_base;
 };
 
@@ -382,8 +408,10 @@ static PyObject *merge_into(PyObject *self, PyObject *args)
     struct sha *sha_ptr, *sha_start = NULL;
     uint32_t *table_ptr, *name_ptr, *name_start;
     struct idx **idxs = NULL;
-    int flen = 0, bits = 0, i;
-    uint32_t total, count, prefix;
+    Py_ssize_t flen = 0;
+    int bits = 0, i;
+    unsigned int total;
+    uint32_t count, prefix;
     int num_i;
     int last_i;
 
@@ -457,30 +485,37 @@ static uint64_t htonll(uint64_t value)
     return value; // already in network byte order MSB-LSB
 }
 
-#define PACK_IDX_V2_HEADERLEN 8
 #define FAN_ENTRIES 256
 
 static PyObject *write_idx(PyObject *self, PyObject *args)
 {
-    PyObject *pf = NULL, *idx = NULL;
+    char *filename = NULL;
+    PyObject *idx = NULL;
     PyObject *part;
-    FILE *f;
     unsigned char *fmap = NULL;
-    int flen = 0;
-    uint32_t total = 0;
+    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, "Ow#OI", &pf, &fmap, &flen, &idx, &total))
+    if (!PyArg_ParseTuple(args, "sw#OI", &filename, &fmap, &flen, &idx, &total))
        return NULL;
 
-    fan_ptr = (uint32_t *)&fmap[PACK_IDX_V2_HEADERLEN];
+    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];
-    f = PyFile_AsFile(pf);
+    ofs64_ptr = (uint64_t *)&ofs_ptr[total];
 
     count = 0;
     ofs64_count = 0;
@@ -495,26 +530,33 @@ static PyObject *write_idx(PyObject *self, PyObject *args)
        for (j = 0; j < plen; ++j)
        {
            unsigned char *sha = NULL;
-           int sha_len = 0;
-           uint32_t crc = 0;
-           uint64_t ofs = 0;
+           Py_ssize_t sha_len = 0;
+           unsigned int crc = 0;
+            unsigned PY_LONG_LONG ofs_py = 0;
+           uint64_t ofs;
            if (!PyArg_ParseTuple(PyList_GET_ITEM(part, j), "t#IK",
-                                 &sha, &sha_len, &crc, &ofs))
+                                 &sha, &sha_len, &crc, &ofs_py))
                return NULL;
+            assert(crc <= UINT32_MAX);
+            assert(ofs_py <= UINT64_MAX);
+           ofs = ofs_py;
            if (sha_len != sizeof(struct sha))
                return NULL;
            memcpy(sha_ptr++, sha, sizeof(struct sha));
            *crc_ptr++ = htonl(crc);
            if (ofs > 0x7fffffff)
            {
-               uint64_t nofs = htonll(ofs);
-               if (fwrite(&nofs, sizeof(uint64_t), 1, f) != 1)
-                   return PyErr_SetFromErrno(PyExc_OSError);
+                *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);
 }
 
@@ -593,13 +635,10 @@ static PyObject *random_sha(PyObject *self, PyObject *args)
 }
 
 
-static PyObject *open_noatime(PyObject *self, PyObject *args)
+static int _open_noatime(const char *filename, int attrs)
 {
-    char *filename = NULL;
-    int attrs, attrs_noatime, fd;
-    if (!PyArg_ParseTuple(args, "s", &filename))
-       return NULL;
-    attrs = O_RDONLY;
+    int attrs_noatime, fd;
+    attrs |= O_RDONLY;
 #ifdef O_NOFOLLOW
     attrs |= O_NOFOLLOW;
 #endif
@@ -620,6 +659,17 @@ 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_OSError, filename);
     return Py_BuildValue("i", fd);
@@ -639,18 +689,18 @@ static PyObject *fadvise_done(PyObject *self, PyObject *args)
 }
 
 
-#ifdef FS_IOC_GETFLAGS
+#ifdef BUP_HAVE_FILE_ATTRS
 static PyObject *bup_get_linux_file_attr(PyObject *self, PyObject *args)
 {
     int rc;
-    unsigned long attr;
+    unsigned int attr;
     char *path;
     int fd;
 
     if (!PyArg_ParseTuple(args, "s", &path))
         return NULL;
 
-    fd = open(path, O_RDONLY | O_NONBLOCK | O_LARGEFILE | O_NOFOLLOW);
+    fd = _open_noatime(path, O_NONBLOCK);
     if (fd == -1)
         return PyErr_SetFromErrnoWithFilename(PyExc_OSError, path);
 
@@ -663,26 +713,43 @@ static PyObject *bup_get_linux_file_attr(PyObject *self, PyObject *args)
     }
 
     close(fd);
-    return Py_BuildValue("k", attr);
+    return Py_BuildValue("I", attr);
 }
-#endif /* def FS_IOC_GETFLAGS */
+#endif /* def BUP_HAVE_FILE_ATTRS */
 
 
-#ifdef FS_IOC_SETFLAGS
+#ifdef BUP_HAVE_FILE_ATTRS
 static PyObject *bup_set_linux_file_attr(PyObject *self, PyObject *args)
 {
     int rc;
-    unsigned long attr;
+    unsigned int orig_attr, attr;
     char *path;
     int fd;
 
-    if (!PyArg_ParseTuple(args, "sk", &path, &attr))
+    if (!PyArg_ParseTuple(args, "sI", &path, &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).
+    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);
+
     rc = ioctl(fd, FS_IOC_SETFLAGS, &attr);
     if (rc == -1)
     {
@@ -693,7 +760,17 @@ static PyObject *bup_set_linux_file_attr(PyObject *self, PyObject *args)
     close(fd);
     return Py_BuildValue("O", Py_None);
 }
-#endif /* def FS_IOC_SETFLAGS */
+#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
 
 
 #if defined(HAVE_UTIMENSAT) || defined(HAVE_FUTIMES) || defined(HAVE_LUTIMES)
@@ -710,49 +787,6 @@ static int bup_parse_xutime_args(char **path,
                           access, access_ns,
                           modification, modification_ns))
         return 0;
-
-    if (isnan(*access))
-    {
-        PyErr_SetString(PyExc_ValueError, "access time is NaN");
-        return 0;
-    }
-    else if (isinf(*access))
-    {
-        PyErr_SetString(PyExc_ValueError, "access time is infinite");
-        return 0;
-    }
-    else if (isnan(*modification))
-    {
-        PyErr_SetString(PyExc_ValueError, "modification time is NaN");
-        return 0;
-    }
-    else if (isinf(*modification))
-    {
-        PyErr_SetString(PyExc_ValueError, "modification time is infinite");
-        return 0;
-    }
-
-    if (isnan(*access_ns))
-    {
-        PyErr_SetString(PyExc_ValueError, "access time ns is NaN");
-        return 0;
-    }
-    else if (isinf(*access_ns))
-    {
-        PyErr_SetString(PyExc_ValueError, "access time ns is infinite");
-        return 0;
-    }
-    else if (isnan(*modification_ns))
-    {
-        PyErr_SetString(PyExc_ValueError, "modification time ns is NaN");
-        return 0;
-    }
-    else if (isinf(*modification_ns))
-    {
-        PyErr_SetString(PyExc_ValueError, "modification time ns is infinite");
-        return 0;
-    }
-
     return 1;
 }
 
@@ -760,49 +794,89 @@ static int bup_parse_xutime_args(char **path,
           || defined(HAVE_LUTIMES) */
 
 
+#define INTEGRAL_ASSIGNMENT_FITS(dest, src)                             \
+    ({                                                                  \
+        *(dest) = (src);                                                \
+        *(dest) == (src) && (*(dest) < 1) == ((src) < 1);               \
+    })
+
+
+#define ASSIGN_PYLONG_TO_INTEGRAL(dest, pylong, overflow) \
+    ({                                                     \
+        int result = 0;                                                 \
+        *(overflow) = 0;                                                \
+        const long long ltmp = PyLong_AsLongLong(pylong);               \
+        if (ltmp == -1 && PyErr_Occurred())                             \
+        {                                                               \
+            if (PyErr_ExceptionMatches(PyExc_OverflowError))            \
+            {                                                           \
+                const unsigned long ultmp = PyLong_AsUnsignedLongLong(pylong); \
+                if (ultmp == (unsigned long long) -1 && PyErr_Occurred()) \
+                {                                                       \
+                    if (PyErr_ExceptionMatches(PyExc_OverflowError))    \
+                    {                                                   \
+                        PyErr_Clear();                                  \
+                        *(overflow) = 1;                                \
+                    }                                                   \
+                }                                                       \
+                if (INTEGRAL_ASSIGNMENT_FITS((dest), ultmp))            \
+                    result = 1;                                         \
+                else                                                    \
+                    *(overflow) = 1;                                    \
+            }                                                           \
+        }                                                               \
+        else                                                            \
+        {                                                               \
+            if (INTEGRAL_ASSIGNMENT_FITS((dest), ltmp))                 \
+                result = 1;                                             \
+            else                                                        \
+                *(overflow) = 1;                                        \
+        }                                                               \
+        result;                                                         \
+        })
+
+
 #ifdef HAVE_UTIMENSAT
 
-static PyObject *bup_xutime_ns(PyObject *self, PyObject *args,
-                               int follow_symlinks)
+static PyObject *bup_utimensat(PyObject *self, PyObject *args)
 {
     int rc;
+    int fd, flag;
     char *path;
-    long access, access_ns, modification, modification_ns;
+    PyObject *access_py, *modification_py;
     struct timespec ts[2];
 
-    if (!bup_parse_xutime_args(&path, &access, &access_ns,
-                               &modification, &modification_ns,
-                               self, args))
-       return NULL;
+    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;
 
-    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);
+    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);
 }
 
-
-#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 /* def HAVE_UTIMENSAT */
 
 
 #ifdef HAVE_UTIMES
@@ -859,9 +933,6 @@ 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
@@ -877,43 +948,87 @@ static PyObject *bup_lutime_ns(PyObject *self, PyObject *args)
 #endif
 
 
-static PyObject *stat_struct_to_py(const struct stat *st)
+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))
+
+
+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);
 
-    /* Enforce the current timespec nanosecond range expectations. */
-    if (atime_ns < 0 || atime_ns > 999999999)
-    {
-        PyErr_SetString(PyExc_ValueError, "invalid atime timespec nanoseconds");
+    if (!normalize_timespec_values("atime", &atime, &atime_ns, filename, fd))
         return NULL;
-    }
-    if (mtime_ns < 0 || mtime_ns > 999999999)
-    {
-        PyErr_SetString(PyExc_ValueError, "invalid mtime timespec nanoseconds");
+    if (!normalize_timespec_values("mtime", &mtime, &mtime_ns, filename, fd))
         return NULL;
-    }
-    if (ctime_ns < 0 || ctime_ns > 999999999)
-    {
-        PyErr_SetString(PyExc_ValueError, "invalid ctime timespec nanoseconds");
+    if (!normalize_timespec_values("ctime", &ctime, &ctime_ns, filename, fd))
         return NULL;
-    }
 
-    return Py_BuildValue("kkkkkkkk(Ll)(Ll)(Ll)",
-                         (unsigned long) st->st_mode,
-                         (unsigned long) st->st_ino,
-                         (unsigned long) st->st_dev,
-                         (unsigned long) st->st_nlink,
-                         (unsigned long) st->st_uid,
-                         (unsigned long) st->st_gid,
-                         (unsigned long) st->st_rdev,
-                         (unsigned long) st->st_size,
-                         (long long) st->st_atime,
+    // 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)",
+                         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,
+                         (PY_LONG_LONG) atime,
                          (long) atime_ns,
-                         (long long) st->st_mtime,
+                         (PY_LONG_LONG) mtime,
                          (long) mtime_ns,
-                         (long long) st->st_ctime,
+                         (PY_LONG_LONG) ctime,
                          (long) ctime_ns);
 }
 
@@ -930,7 +1045,7 @@ static PyObject *bup_stat(PyObject *self, PyObject *args)
     rc = stat(filename, &st);
     if (rc != 0)
         return PyErr_SetFromErrnoWithFilename(PyExc_OSError, filename);
-    return stat_struct_to_py(&st);
+    return stat_struct_to_py(&st, filename, 0);
 }
 
 
@@ -946,7 +1061,7 @@ static PyObject *bup_lstat(PyObject *self, PyObject *args)
     rc = lstat(filename, &st);
     if (rc != 0)
         return PyErr_SetFromErrnoWithFilename(PyExc_OSError, filename);
-    return stat_struct_to_py(&st);
+    return stat_struct_to_py(&st, filename, 0);
 }
 
 
@@ -961,7 +1076,7 @@ static PyObject *bup_fstat(PyObject *self, PyObject *args)
     rc = fstat(fd, &st);
     if (rc != 0)
         return PyErr_SetFromErrno(PyExc_OSError);
-    return stat_struct_to_py(&st);
+    return stat_struct_to_py(&st, NULL, fd);
 }
 
 
@@ -994,14 +1109,18 @@ static PyMethodDef helper_methods[] = {
        "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 FS_IOC_GETFLAGS
+#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 FS_IOC_SETFLAGS
+#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 BUP_HAVE_BUP_UTIME_NS
     { "bup_utime_ns", bup_utime_ns, METH_VARARGS,
       "Change path timestamps with up to nanosecond precision." },
@@ -1023,10 +1142,36 @@ static PyMethodDef helper_methods[] = {
 
 PyMODINIT_FUNC init_helpers(void)
 {
+    // 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));
+
     char *e;
     PyObject *m = Py_InitModule("_helpers", helper_methods);
     if (m == NULL)
         return;
+
+#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
+
     e = getenv("BUP_FORCE_TTY");
     istty2 = isatty(2) || (atoi(e ? e : "0") & 2);
     unpythonize_argv();