1 | /* getpwent(), getpwuid(), getpwnam() - password file routines
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2 | *
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3 | * Author: Kees J. Bot
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4 | * 31 Jan 1994
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5 | */
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6 | #define nil 0
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7 | #define open _open
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8 | #define fcntl _fcntl
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9 | #define read _read
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10 | #define close _close
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11 | #include <sys/types.h>
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12 | #include <pwd.h>
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13 | #include <string.h>
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14 | #include <stdlib.h>
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15 | #include <unistd.h>
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16 | #include <fcntl.h>
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17 |
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18 | #define arraysize(a) (sizeof(a) / sizeof((a)[0]))
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19 | #define arraylimit(a) ((a) + arraysize(a))
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20 |
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21 | static char PASSWD[]= "/etc/passwd"; /* The password file. */
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22 | static const char *pwfile; /* Current password file. */
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23 |
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24 | static char buf[1024]; /* Read buffer. */
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25 | static char pwline[256]; /* One line from the password file. */
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26 | static struct passwd entry; /* Entry to fill and return. */
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27 | static int pwfd= -1; /* Filedescriptor to the file. */
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28 | static char *bufptr; /* Place in buf. */
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29 | static ssize_t buflen= 0; /* Remaining characters in buf. */
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30 | static char *lineptr; /* Place in the line. */
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31 |
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32 | void endpwent(void)
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33 | /* Close the password file. */
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34 | {
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35 | if (pwfd >= 0) {
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36 | (void) close(pwfd);
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37 | pwfd= -1;
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38 | buflen= 0;
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39 | }
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40 | }
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41 |
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42 | int setpwent(void)
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43 | /* Open the password file. */
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44 | {
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45 | if (pwfd >= 0) endpwent();
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46 |
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47 | if (pwfile == nil) pwfile= PASSWD;
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48 |
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49 | if ((pwfd= open(pwfile, O_RDONLY)) < 0) return -1;
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50 | (void) fcntl(pwfd, F_SETFD, fcntl(pwfd, F_GETFD) | FD_CLOEXEC);
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51 | return 0;
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52 | }
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53 |
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54 | void setpwfile(const char *file)
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55 | /* Prepare for reading an alternate password file. */
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56 | {
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57 | endpwent();
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58 | pwfile= file;
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59 | }
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60 |
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61 | static int getline(void)
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62 | /* Get one line from the password file, return 0 if bad or EOF. */
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63 | {
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64 | lineptr= pwline;
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65 |
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66 | do {
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67 | if (buflen == 0) {
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68 | if ((buflen= read(pwfd, buf, sizeof(buf))) <= 0)
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69 | return 0;
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70 | bufptr= buf;
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71 | }
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72 |
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73 | if (lineptr == arraylimit(pwline)) return 0;
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74 | buflen--;
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75 | } while ((*lineptr++ = *bufptr++) != '\n');
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76 |
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77 | lineptr= pwline;
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78 | return 1;
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79 | }
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80 |
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81 | static char *scan_colon(void)
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82 | /* Scan for a field separator in a line, return the start of the field. */
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83 | {
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84 | char *field= lineptr;
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85 | char *last;
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86 |
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87 | for (;;) {
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88 | last= lineptr;
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89 | if (*lineptr == 0) return nil;
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90 | if (*lineptr == '\n') break;
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91 | if (*lineptr++ == ':') break;
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92 | }
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93 | *last= 0;
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94 | return field;
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95 | }
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96 |
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97 | struct passwd *getpwent(void)
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98 | /* Read one entry from the password file. */
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99 | {
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100 | char *p;
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101 |
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102 | /* Open the file if not yet open. */
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103 | if (pwfd < 0 && setpwent() < 0) return nil;
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104 |
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105 | /* Until a good line is read. */
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106 | for (;;) {
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107 | if (!getline()) return nil; /* EOF or corrupt. */
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108 |
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109 | if ((entry.pw_name= scan_colon()) == nil) continue;
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110 | if ((entry.pw_passwd= scan_colon()) == nil) continue;
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111 | if ((p= scan_colon()) == nil) continue;
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112 | entry.pw_uid= strtol(p, nil, 0);
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113 | if ((p= scan_colon()) == nil) continue;
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114 | entry.pw_gid= strtol(p, nil, 0);
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115 | if ((entry.pw_gecos= scan_colon()) == nil) continue;
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116 | if ((entry.pw_dir= scan_colon()) == nil) continue;
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117 | if ((entry.pw_shell= scan_colon()) == nil) continue;
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118 |
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119 | if (*lineptr == 0) return &entry;
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120 | }
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121 | }
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122 |
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123 | struct passwd *getpwuid(_mnx_Uid_t uid)
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124 | /* Return the password file entry belonging to the user-id. */
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125 | {
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126 | struct passwd *pw;
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127 |
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128 | endpwent();
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129 | while ((pw= getpwent()) != nil && pw->pw_uid != uid) {}
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130 | endpwent();
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131 | return pw;
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132 | }
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133 |
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134 | struct passwd *getpwnam(const char *name)
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135 | /* Return the password file entry belonging to the user name. */
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136 | {
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137 | struct passwd *pw;
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138 |
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139 | endpwent();
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140 | while ((pw= getpwent()) != nil && strcmp(pw->pw_name, name) != 0) {}
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141 | endpwent();
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142 | return pw;
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143 | }
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