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1 | 1 | /* |
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2 | 2 | mpatch.c - efficient binary patching for Mercurial |
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3 | 3 | |
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4 | 4 | This implements a patch algorithm that's O(m + nlog n) where m is the |
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5 | 5 | size of the output and n is the number of patches. |
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6 | 6 | |
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7 | 7 | Given a list of binary patches, it unpacks each into a hunk list, |
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8 | 8 | then combines the hunk lists with a treewise recursion to form a |
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9 | 9 | single hunk list. This hunk list is then applied to the original |
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10 | 10 | text. |
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11 | 11 | |
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12 | 12 | The text (or binary) fragments are copied directly from their source |
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13 | 13 | Python objects into a preallocated output string to avoid the |
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14 | 14 | allocation of intermediate Python objects. Working memory is about 2x |
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15 | 15 | the total number of hunks. |
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16 | 16 | |
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17 | 17 | Copyright 2005, 2006 Matt Mackall <mpm@selenic.com> |
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18 | 18 | |
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19 | 19 | This software may be used and distributed according to the terms |
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20 | 20 | of the GNU General Public License, incorporated herein by reference. |
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21 | 21 | */ |
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22 | 22 | |
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23 | 23 | #define PY_SSIZE_T_CLEAN |
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24 | 24 | #include <Python.h> |
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25 | 25 | #include <stdlib.h> |
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26 | 26 | #include <string.h> |
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27 | 27 | |
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28 | 28 | #include "bitmanipulation.h" |
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29 | 29 | #include "compat.h" |
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30 | 30 | #include "mpatch.h" |
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31 | 31 | #include "util.h" |
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32 | 32 | |
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33 | 33 | static char mpatch_doc[] = "Efficient binary patching."; |
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34 | 34 | static PyObject *mpatch_Error; |
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35 | 35 | |
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36 | 36 | static void setpyerr(int r) |
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37 | 37 | { |
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38 | 38 | switch (r) { |
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39 | 39 | case MPATCH_ERR_NO_MEM: |
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40 | 40 | PyErr_NoMemory(); |
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41 | 41 | break; |
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42 | 42 | case MPATCH_ERR_CANNOT_BE_DECODED: |
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43 | 43 | PyErr_SetString(mpatch_Error, "patch cannot be decoded"); |
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44 | 44 | break; |
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45 | 45 | case MPATCH_ERR_INVALID_PATCH: |
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46 | 46 | PyErr_SetString(mpatch_Error, "invalid patch"); |
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47 | 47 | break; |
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48 | 48 | } |
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49 | 49 | } |
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50 | 50 | |
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51 | 51 | struct mpatch_flist *cpygetitem(void *bins, ssize_t pos) |
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52 | 52 | { |
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53 | 53 | const char *buffer; |
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54 | 54 | struct mpatch_flist *res; |
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55 | 55 | ssize_t blen; |
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56 | 56 | int r; |
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57 | 57 | |
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58 | 58 | PyObject *tmp = PyList_GetItem((PyObject*)bins, pos); |
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59 | 59 | if (!tmp) |
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60 | 60 | return NULL; |
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61 | 61 | if (PyObject_AsCharBuffer(tmp, &buffer, (Py_ssize_t*)&blen)) |
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62 | 62 | return NULL; |
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63 | 63 | if ((r = mpatch_decode(buffer, blen, &res)) < 0) { |
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64 | 64 | if (!PyErr_Occurred()) |
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65 | 65 | setpyerr(r); |
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66 | 66 | return NULL; |
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67 | 67 | } |
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68 | 68 | return res; |
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69 | 69 | } |
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70 | 70 | |
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71 | 71 | static PyObject * |
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72 | 72 | patches(PyObject *self, PyObject *args) |
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73 | 73 | { |
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74 | 74 | PyObject *text, *bins, *result; |
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75 | 75 | struct mpatch_flist *patch; |
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76 | 76 | const char *in; |
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77 | 77 | int r = 0; |
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78 | 78 | char *out; |
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79 | 79 | Py_ssize_t len, outlen, inlen; |
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80 | 80 | |
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81 | 81 | if (!PyArg_ParseTuple(args, "OO:mpatch", &text, &bins)) |
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82 | 82 | return NULL; |
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83 | 83 | |
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84 | 84 | len = PyList_Size(bins); |
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85 | 85 | if (!len) { |
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86 | 86 | /* nothing to do */ |
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87 | 87 | Py_INCREF(text); |
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88 | 88 | return text; |
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89 | 89 | } |
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90 | 90 | |
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91 | 91 | if (PyObject_AsCharBuffer(text, &in, &inlen)) |
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92 | 92 | return NULL; |
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93 | 93 | |
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94 | 94 | patch = mpatch_fold(bins, cpygetitem, 0, len); |
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95 | 95 | if (!patch) { /* error already set or memory error */ |
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96 | 96 | if (!PyErr_Occurred()) |
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97 | 97 | PyErr_NoMemory(); |
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98 | 98 | return NULL; |
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99 | 99 | } |
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100 | 100 | |
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101 | 101 | outlen = mpatch_calcsize(inlen, patch); |
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102 | 102 | if (outlen < 0) { |
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103 | 103 | r = (int)outlen; |
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104 | 104 | result = NULL; |
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105 | 105 | goto cleanup; |
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106 | 106 | } |
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107 | 107 | result = PyBytes_FromStringAndSize(NULL, outlen); |
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108 | 108 | if (!result) { |
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109 | 109 | result = NULL; |
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110 | 110 | goto cleanup; |
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111 | 111 | } |
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112 | 112 | out = PyBytes_AsString(result); |
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113 |
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113 | r = mpatch_apply(out, in, inlen, patch); | |
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114 | if (r < 0) { | |
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114 | 115 | Py_DECREF(result); |
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115 | 116 | result = NULL; |
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116 | 117 | } |
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117 | 118 | cleanup: |
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118 | 119 | mpatch_lfree(patch); |
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119 | 120 | if (!result && !PyErr_Occurred()) |
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120 | 121 | setpyerr(r); |
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121 | 122 | return result; |
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122 | 123 | } |
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123 | 124 | |
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124 | 125 | /* calculate size of a patched file directly */ |
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125 | 126 | static PyObject * |
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126 | 127 | patchedsize(PyObject *self, PyObject *args) |
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127 | 128 | { |
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128 | 129 | long orig, start, end, len, outlen = 0, last = 0, pos = 0; |
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129 | 130 | Py_ssize_t patchlen; |
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130 | 131 | char *bin; |
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131 | 132 | |
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132 | 133 | if (!PyArg_ParseTuple(args, "ls#", &orig, &bin, &patchlen)) |
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133 | 134 | return NULL; |
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134 | 135 | |
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135 | 136 | while (pos >= 0 && pos < patchlen) { |
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136 | 137 | start = getbe32(bin + pos); |
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137 | 138 | end = getbe32(bin + pos + 4); |
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138 | 139 | len = getbe32(bin + pos + 8); |
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139 | 140 | if (start > end) |
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140 | 141 | break; /* sanity check */ |
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141 | 142 | pos += 12 + len; |
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142 | 143 | outlen += start - last; |
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143 | 144 | last = end; |
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144 | 145 | outlen += len; |
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145 | 146 | } |
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146 | 147 | |
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147 | 148 | if (pos != patchlen) { |
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148 | 149 | if (!PyErr_Occurred()) |
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149 | 150 | PyErr_SetString(mpatch_Error, "patch cannot be decoded"); |
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150 | 151 | return NULL; |
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151 | 152 | } |
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152 | 153 | |
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153 | 154 | outlen += orig - last; |
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154 | 155 | return Py_BuildValue("l", outlen); |
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155 | 156 | } |
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156 | 157 | |
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157 | 158 | static PyMethodDef methods[] = { |
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158 | 159 | {"patches", patches, METH_VARARGS, "apply a series of patches\n"}, |
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159 | 160 | {"patchedsize", patchedsize, METH_VARARGS, "calculed patched size\n"}, |
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160 | 161 | {NULL, NULL} |
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161 | 162 | }; |
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162 | 163 | |
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163 | 164 | static const int version = 1; |
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164 | 165 | |
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165 | 166 | #ifdef IS_PY3K |
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166 | 167 | static struct PyModuleDef mpatch_module = { |
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167 | 168 | PyModuleDef_HEAD_INIT, |
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168 | 169 | "mpatch", |
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169 | 170 | mpatch_doc, |
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170 | 171 | -1, |
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171 | 172 | methods |
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172 | 173 | }; |
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173 | 174 | |
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174 | 175 | PyMODINIT_FUNC PyInit_mpatch(void) |
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175 | 176 | { |
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176 | 177 | PyObject *m; |
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177 | 178 | |
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178 | 179 | m = PyModule_Create(&mpatch_module); |
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179 | 180 | if (m == NULL) |
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180 | 181 | return NULL; |
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181 | 182 | |
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182 | 183 | mpatch_Error = PyErr_NewException("mercurial.cext.mpatch.mpatchError", |
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183 | 184 | NULL, NULL); |
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184 | 185 | Py_INCREF(mpatch_Error); |
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185 | 186 | PyModule_AddObject(m, "mpatchError", mpatch_Error); |
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186 | 187 | PyModule_AddIntConstant(m, "version", version); |
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187 | 188 | |
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188 | 189 | return m; |
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189 | 190 | } |
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190 | 191 | #else |
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191 | 192 | PyMODINIT_FUNC |
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192 | 193 | initmpatch(void) |
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193 | 194 | { |
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194 | 195 | PyObject *m; |
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195 | 196 | m = Py_InitModule3("mpatch", methods, mpatch_doc); |
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196 | 197 | mpatch_Error = PyErr_NewException("mercurial.cext.mpatch.mpatchError", |
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197 | 198 | NULL, NULL); |
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198 | 199 | PyModule_AddIntConstant(m, "version", version); |
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199 | 200 | } |
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200 | 201 | #endif |
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