1 | /* $Id: get_file.c,v 1.21 2009-05-04 20:49:13 zacheiss Exp $ |
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2 | * |
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3 | * Copyright (C) 1988-1998 by the Massachusetts Institute of Technology. |
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4 | * For copying and distribution information, please see the file |
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5 | * <mit-copyright.h>. |
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6 | */ |
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7 | |
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8 | #include <mit-copyright.h> |
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9 | #include <moira.h> |
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10 | #include "update_server.h" |
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11 | #include "update.h" |
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12 | |
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13 | #include <errno.h> |
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14 | #include <fcntl.h> |
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15 | #include <stdio.h> |
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16 | #include <stdlib.h> |
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17 | #include <string.h> |
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18 | #include <unistd.h> |
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19 | |
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20 | #ifdef HAVE_KRB4 |
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21 | #include <des.h> |
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22 | #endif |
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23 | |
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24 | RCSID("$Header: /afs/athena.mit.edu/astaff/project/moiradev/repository/moira/update/get_file.c,v 1.21 2009-05-04 20:49:13 zacheiss Exp $"); |
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25 | |
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26 | #ifndef MIN |
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27 | #define MIN(a, b) (((a) < (b)) ? (a) : (b)) |
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28 | #endif /* MIN */ |
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29 | |
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30 | #ifdef HAVE_KRB4 |
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31 | static des_key_schedule sched; |
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32 | static des_cblock ivec; |
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33 | extern des_cblock session; |
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34 | #endif |
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35 | |
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36 | static int get_block(int conn, int fd, int max_size, int encrypt); |
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37 | |
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38 | /* |
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39 | * get_file() |
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40 | * |
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41 | * arguments: |
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42 | * char *pathname |
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43 | * file to receive |
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44 | * int file_size |
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45 | * number of bytes |
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46 | * int checksum |
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47 | * linear checksum of bytes |
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48 | * |
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49 | * syntax: |
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50 | * (initial protocol already done) |
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51 | * <<< (int)code (can we accept the file?) |
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52 | * >>> (STRING)data |
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53 | * <<< (int)code |
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54 | * >>> (STRING)data |
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55 | * <<< (int)code |
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56 | * ... |
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57 | * >>> (STRING)data (last data block) |
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58 | * <<< (int)code (from read, write, checksum verify) |
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59 | * |
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60 | * returns: |
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61 | * int |
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62 | * 0 for success, 1 for failure |
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63 | * |
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64 | * function: |
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65 | * perform initial preparations and receive file as |
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66 | * a single string, storing it into <pathname> |
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67 | * |
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68 | */ |
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69 | |
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70 | int get_file(int conn, char *pathname, int file_size, int checksum, |
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71 | int mode, int encrypt) |
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72 | { |
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73 | int fd, n_written, code; |
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74 | int found_checksum; |
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75 | char buf[BUFSIZ]; |
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76 | |
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77 | memset(buf, '\0', sizeof(buf)); |
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78 | |
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79 | if (!have_authorization) |
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80 | { |
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81 | send_int(conn, MR_PERM); |
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82 | return 1; |
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83 | } |
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84 | if (setuid(uid) < 0) |
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85 | { |
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86 | com_err(whoami, errno, "Unable to setuid to %d\n", uid); |
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87 | exit(1); |
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88 | } |
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89 | |
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90 | /* unlink old file */ |
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91 | if (!config_lookup("noclobber")) |
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92 | unlink(pathname); |
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93 | /* open file descriptor */ |
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94 | fd = open(pathname, O_CREAT|O_EXCL|O_WRONLY, mode); |
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95 | if (fd == -1) |
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96 | { |
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97 | code = errno; |
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98 | com_err(whoami, errno, "creating file %s (get_file)", pathname); |
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99 | send_int(conn, code); |
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100 | return 1; |
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101 | } |
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102 | |
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103 | /* check to see if we've got the disk space */ |
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104 | n_written = 0; |
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105 | while (n_written < file_size) |
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106 | { |
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107 | int n_wrote; |
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108 | n_wrote = write(fd, buf, sizeof(buf)); |
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109 | if (n_wrote == -1) |
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110 | { |
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111 | code = errno; |
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112 | com_err(whoami, code, "verifying free disk space for %s (get_file)", |
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113 | pathname); |
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114 | send_int(conn, code); |
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115 | |
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116 | /* do all we can to free the space */ |
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117 | unlink(pathname); |
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118 | ftruncate(fd, 0); |
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119 | close(fd); |
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120 | return 1; |
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121 | } |
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122 | n_written += n_wrote; |
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123 | } |
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124 | |
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125 | lseek(fd, 0, SEEK_SET); |
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126 | send_ok(conn); |
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127 | |
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128 | if (encrypt) |
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129 | { |
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130 | #ifdef HAVE_KRB4 |
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131 | des_key_sched(session, sched); |
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132 | memcpy(ivec, session, sizeof(ivec)); |
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133 | #else |
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134 | /* The session key only gets stored if auth happens in krb4 to |
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135 | begin with. If you don't have krb4, you can't possibly be |
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136 | coming up with a valid session key. */ |
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137 | return MR_NO_KRB4; |
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138 | #endif |
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139 | } |
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140 | |
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141 | n_written = 0; |
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142 | while (n_written < file_size) |
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143 | { |
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144 | int n_got = get_block(conn, fd, file_size - n_written, encrypt); |
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145 | |
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146 | if (n_got == -1) |
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147 | { |
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148 | /* get_block has already printed a message */ |
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149 | unlink(pathname); |
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150 | return 1; |
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151 | } |
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152 | n_written += n_got; |
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153 | if (n_written != file_size) |
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154 | send_ok(conn); |
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155 | } |
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156 | |
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157 | fsync(fd); |
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158 | ftruncate(fd, file_size); |
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159 | fsync(fd); |
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160 | close(fd); |
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161 | |
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162 | /* validate checksum */ |
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163 | found_checksum = checksum_file(pathname); |
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164 | if (checksum != found_checksum) |
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165 | { |
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166 | code = MR_MISSINGFILE; |
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167 | com_err(whoami, code, ": expected = %d, found = %d", |
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168 | checksum, found_checksum); |
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169 | send_int(conn, code); |
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170 | return 1; |
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171 | } |
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172 | |
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173 | send_ok(conn); |
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174 | return 0; |
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175 | } |
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176 | |
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177 | static int get_block(int conn, int fd, int max_size, int encrypt) |
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178 | { |
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179 | char *data; |
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180 | size_t len; |
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181 | int n_read, n, i, code; |
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182 | |
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183 | recv_string(conn, &data, &len); |
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184 | |
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185 | if (encrypt) |
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186 | { |
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187 | #ifdef HAVE_KRB4 |
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188 | char *unenc = malloc(len); |
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189 | |
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190 | if (!unenc) |
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191 | { |
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192 | send_int(conn, ENOMEM); |
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193 | return -1; |
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194 | } |
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195 | |
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196 | des_pcbc_encrypt(data, unenc, len, sched, ivec, 1); |
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197 | for (i = 0; i < 8; i++) |
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198 | ivec[i] = data[len - 8 + i] ^ unenc[len - 8 + i]; |
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199 | free(data); |
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200 | data = unenc; |
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201 | #endif |
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202 | } |
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203 | |
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204 | n_read = MIN(len, max_size); |
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205 | n = 0; |
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206 | while (n < n_read) |
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207 | { |
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208 | int n_wrote; |
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209 | n_wrote = write(fd, data + n, n_read - n); |
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210 | if (n_wrote == -1) |
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211 | { |
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212 | code = errno; |
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213 | com_err(whoami, errno, "writing file (get_file)"); |
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214 | send_int(conn, code); |
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215 | free(data); |
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216 | close(fd); |
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217 | return -1; |
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218 | } |
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219 | n += n_wrote; |
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220 | } |
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221 | free(data); |
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222 | return n; |
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223 | } |
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