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annotate lib/mgetgroups.c @ 40231:9b3c79fdfe0b

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strtod: fix clash with strtold Problem reported for RHEL 5 by Jesse Caldwell (Bug#34817). * lib/strtod.c (compute_minus_zero, minus_zero): Simplify by remving the macro / external variable, and having just a function. User changed. This avoids the need for an external variable that might clash.
author Paul Eggert <eggert@cs.ucla.edu>
date Mon, 11 Mar 2019 16:40:29 -0700
parents b06060465f09
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
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1 /* mgetgroups.c -- return a list of the groups a user or current process is in
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2
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3 Copyright (C) 2007-2019 Free Software Foundation, Inc.
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4
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5 This program is free software: you can redistribute it and/or modify
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6 it under the terms of the GNU General Public License as published by
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7 the Free Software Foundation, either version 3 of the License, or
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8 (at your option) any later version.
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9
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10 This program is distributed in the hope that it will be useful,
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11 but WITHOUT ANY WARRANTY; without even the implied warranty of
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12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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13 GNU General Public License for more details.
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14
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15 You should have received a copy of the GNU General Public License
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16 along with this program. If not, see <https://www.gnu.org/licenses/>. */
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17
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18 /* Extracted from coreutils' src/id.c. */
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19
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20 #include <config.h>
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21
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22 #include "mgetgroups.h"
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23
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24 #include <stdlib.h>
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25 #include <unistd.h>
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26 #include <stdint.h>
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27 #include <string.h>
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28 #include <errno.h>
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29 #if HAVE_GETGROUPLIST
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30 # include <grp.h>
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31 #endif
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32
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33 #include "getugroups.h"
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34 #include "xalloc-oversized.h"
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35
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36 /* Work around an incompatibility of OS X 10.11: getgrouplist
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37 accepts int *, not gid_t *, and int and gid_t differ in sign. */
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38 #if 4 < __GNUC__ + (3 <= __GNUC_MINOR__)
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39 # pragma GCC diagnostic ignored "-Wpointer-sign"
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40 #endif
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41
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42 static gid_t *
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43 realloc_groupbuf (gid_t *g, size_t num)
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44 {
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45 if (xalloc_oversized (num, sizeof *g))
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46 {
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47 errno = ENOMEM;
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48 return NULL;
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49 }
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50
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51 return realloc (g, num * sizeof *g);
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52 }
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53
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54 /* Like getugroups, but store the result in malloc'd storage.
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55 Set *GROUPS to the malloc'd list of all group IDs of which USERNAME
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56 is a member. If GID is not -1, store it first. GID should be the
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57 group ID (pw_gid) obtained from getpwuid, in case USERNAME is not
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58 listed in the groups database (e.g., /etc/groups). If USERNAME is
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59 NULL, store the supplementary groups of the current process, and GID
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60 should be -1 or the effective group ID (getegid). Upon failure,
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61 don't modify *GROUPS, set errno, and return -1. Otherwise, return
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62 the number of groups. The resulting list may contain duplicates,
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63 but adjacent members will be distinct. */
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64
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65 int
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66 mgetgroups (char const *username, gid_t gid, gid_t **groups)
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67 {
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68 int max_n_groups;
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69 int ng;
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70 gid_t *g;
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71
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72 #if HAVE_GETGROUPLIST
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73 /* We prefer to use getgrouplist if available, because it has better
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74 performance characteristics.
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75
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76 In glibc 2.3.2, getgrouplist is buggy. If you pass a zero as the
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77 length of the output buffer, getgrouplist will still write to the
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78 buffer. Contrary to what some versions of the getgrouplist
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79 manpage say, this doesn't happen with nonzero buffer sizes.
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80 Therefore our usage here just avoids a zero sized buffer. */
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81 if (username)
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82 {
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83 enum { N_GROUPS_INIT = 10 };
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84 max_n_groups = N_GROUPS_INIT;
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85
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86 g = realloc_groupbuf (NULL, max_n_groups);
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87 if (g == NULL)
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88 return -1;
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89
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90 while (1)
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91 {
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92 gid_t *h;
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93 int last_n_groups = max_n_groups;
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94
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95 /* getgrouplist updates max_n_groups to num required. */
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96 ng = getgrouplist (username, gid, g, &max_n_groups);
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97
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98 /* Some systems (like Darwin) have a bug where they
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99 never increase max_n_groups. */
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100 if (ng < 0 && last_n_groups == max_n_groups)
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101 max_n_groups *= 2;
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102
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103 if ((h = realloc_groupbuf (g, max_n_groups)) == NULL)
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104 {
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105 int saved_errno = errno;
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106 free (g);
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107 errno = saved_errno;
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108 return -1;
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109 }
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110 g = h;
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111
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112 if (0 <= ng)
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113 {
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114 *groups = g;
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115 /* On success some systems just return 0 from getgrouplist,
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116 so return max_n_groups rather than ng. */
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117 return max_n_groups;
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118 }
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119 }
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120 }
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121 /* else no username, so fall through and use getgroups. */
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122 #endif
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123
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124 max_n_groups = (username
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125 ? getugroups (0, NULL, username, gid)
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126 : getgroups (0, NULL));
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127
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128 /* If we failed to count groups because there is no supplemental
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129 group support, then return an array containing just GID.
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130 Otherwise, we fail for the same reason. */
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131 if (max_n_groups < 0)
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132 {
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133 if (errno == ENOSYS && (g = realloc_groupbuf (NULL, 1)))
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134 {
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135 *groups = g;
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136 *g = gid;
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137 return gid != (gid_t) -1;
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138 }
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139 return -1;
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140 }
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141
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142 if (max_n_groups == 0 || (!username && gid != (gid_t) -1))
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143 max_n_groups++;
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144 g = realloc_groupbuf (NULL, max_n_groups);
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145 if (g == NULL)
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146 return -1;
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147
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148 ng = (username
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149 ? getugroups (max_n_groups, g, username, gid)
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150 : getgroups (max_n_groups - (gid != (gid_t) -1),
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parents: 12411
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151 g + (gid != (gid_t) -1)));
12281
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152
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153 if (ng < 0)
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154 {
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642c575d5700 mgetgroups: add xgetgroups, and avoid ENOSYS failures
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parents: 12381
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155 /* Failure is unexpected, but handle it anyway. */
12281
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156 int saved_errno = errno;
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157 free (g);
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158 errno = saved_errno;
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159 return -1;
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160 }
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parents:
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161
12381
e63e3a5265e5 mgetgroups: avoid argument promotion issues with -1
Eric Blake <ebb9@byu.net>
parents: 12281
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162 if (!username && gid != (gid_t) -1)
12281
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163 {
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164 *g = gid;
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165 ng++;
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166 }
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parents:
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167 *groups = g;
12397
799c920db2a5 mgetgroups: reduce duplicate listings
Eric Blake <ebb9@byu.net>
parents: 12382
diff changeset
168
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Eric Blake <ebb9@byu.net>
parents: 12382
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169 /* Reduce the number of duplicates. On some systems, getgroups
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parents: 12382
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170 returns the effective gid twice: once as the first element, and
799c920db2a5 mgetgroups: reduce duplicate listings
Eric Blake <ebb9@byu.net>
parents: 12382
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171 once in its position within the supplementary groups. On other
799c920db2a5 mgetgroups: reduce duplicate listings
Eric Blake <ebb9@byu.net>
parents: 12382
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172 systems, getgroups does not return the effective gid at all,
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Eric Blake <ebb9@byu.net>
parents: 12382
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173 which is why we provide a GID argument. Meanwhile, the GID
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Eric Blake <ebb9@byu.net>
parents: 12382
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174 argument, if provided, is typically any member of the
799c920db2a5 mgetgroups: reduce duplicate listings
Eric Blake <ebb9@byu.net>
parents: 12382
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175 supplementary groups, and not necessarily the effective gid. So,
799c920db2a5 mgetgroups: reduce duplicate listings
Eric Blake <ebb9@byu.net>
parents: 12382
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176 the most likely duplicates are the first element with an
799c920db2a5 mgetgroups: reduce duplicate listings
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parents: 12382
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177 arbitrary other element, or pair-wise duplication between the
799c920db2a5 mgetgroups: reduce duplicate listings
Eric Blake <ebb9@byu.net>
parents: 12382
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178 first and second elements returned by getgroups. It is possible
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parents: 12382
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179 that this O(n) pass will not remove all duplicates, but it is not
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Eric Blake <ebb9@byu.net>
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180 worth the effort to slow down to an O(n log n) algorithm that
799c920db2a5 mgetgroups: reduce duplicate listings
Eric Blake <ebb9@byu.net>
parents: 12382
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181 sorts the array in place, nor the extra memory needed for
799c920db2a5 mgetgroups: reduce duplicate listings
Eric Blake <ebb9@byu.net>
parents: 12382
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182 duplicate removal via an O(n) hash-table. Hence, this function
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183 is only documented as guaranteeing no pair-wise duplicates,
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Eric Blake <ebb9@byu.net>
parents: 12382
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184 rather than returning the minimal set. */
12411
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Bruno Haible <bruno@clisp.org>
parents: 12397
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185 if (1 < ng)
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186 {
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187 gid_t first = *g;
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188 gid_t *next;
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189 gid_t *groups_end = g + ng;
12397
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190
12411
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diff changeset
191 for (next = g + 1; next < groups_end; next++)
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192 {
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diff changeset
193 if (*next == first || *next == *g)
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194 ng--;
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195 else
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diff changeset
196 *++g = *next;
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197 }
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198 }
12397
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199
12281
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200 return ng;
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201 }