| [9] | 1 | /* getgrent(), getgrgid(), getgrnam() - group 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 <grp.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 GROUP[]= "/etc/group"; /* The group file. */
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| 22 | static const char *grfile; /* Current group file. */
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| 23 |
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| 24 | static char buf[1024]; /* Read buffer. */
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| 25 | static char grline[512]; /* One line from the group file. */
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| 26 | static struct group entry; /* Entry to fill and return. */
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| 27 | static char *members[64]; /* Group members with the entry. */
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| 28 | static int grfd= -1; /* Filedescriptor to the file. */
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| 29 | static char *bufptr; /* Place in buf. */
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| 30 | static ssize_t buflen= 0; /* Remaining characters in buf. */
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| 31 | static char *lineptr; /* Place in the line. */
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| 32 |
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| 33 | void endgrent(void)
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| 34 | /* Close the group file. */
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| 35 | {
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| 36 | if (grfd >= 0) {
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| 37 | (void) close(grfd);
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| 38 | grfd= -1;
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| 39 | buflen= 0;
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| 40 | }
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| 41 | }
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| 42 |
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| 43 | int setgrent(void)
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| 44 | /* Open the group file. */
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| 45 | {
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| 46 | if (grfd >= 0) endgrent();
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| 47 |
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| 48 | if (grfile == nil) grfile= GROUP;
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| 49 |
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| 50 | if ((grfd= open(grfile, O_RDONLY)) < 0) return -1;
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| 51 | (void) fcntl(grfd, F_SETFD, fcntl(grfd, F_GETFD) | FD_CLOEXEC);
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| 52 | return 0;
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| 53 | }
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| 54 |
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| 55 | void setgrfile(const char *file)
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| 56 | /* Prepare for reading an alternate group file. */
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| 57 | {
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| 58 | endgrent();
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| 59 | grfile= file;
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| 60 | }
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| 61 |
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| 62 | static int getline(void)
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| 63 | /* Get one line from the group file, return 0 if bad or EOF. */
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| 64 | {
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| 65 | lineptr= grline;
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| 66 |
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| 67 | do {
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| 68 | if (buflen == 0) {
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| 69 | if ((buflen= read(grfd, buf, sizeof(buf))) <= 0)
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| 70 | return 0;
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| 71 | bufptr= buf;
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| 72 | }
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| 73 |
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| 74 | if (lineptr == arraylimit(grline)) return 0;
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| 75 | buflen--;
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| 76 | } while ((*lineptr++ = *bufptr++) != '\n');
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| 77 |
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| 78 | lineptr= grline;
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| 79 | return 1;
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| 80 | }
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| 81 |
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| 82 | static char *scan_punct(int punct)
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| 83 | /* Scan for a field separator in a line, return the start of the field. */
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| 84 | {
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| 85 | char *field= lineptr;
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| 86 | char *last;
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| 87 |
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| 88 | for (;;) {
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| 89 | last= lineptr;
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| 90 | if (*lineptr == 0) return nil;
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| 91 | if (*lineptr == '\n') break;
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| 92 | if (*lineptr++ == punct) break;
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| 93 | if (lineptr[-1] == ':') return nil; /* :::,,,:,,,? */
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| 94 | }
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| 95 | *last= 0;
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| 96 | return field;
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| 97 | }
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| 98 |
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| 99 | struct group *getgrent(void)
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| 100 | /* Read one entry from the group file. */
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| 101 | {
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| 102 | char *p;
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| 103 | char **mem;
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| 104 |
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| 105 | /* Open the file if not yet open. */
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| 106 | if (grfd < 0 && setgrent() < 0) return nil;
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| 107 |
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| 108 | /* Until a good line is read. */
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| 109 | for (;;) {
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| 110 | if (!getline()) return nil; /* EOF or corrupt. */
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| 111 |
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| 112 | if ((entry.gr_name= scan_punct(':')) == nil) continue;
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| 113 | if ((entry.gr_passwd= scan_punct(':')) == nil) continue;
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| 114 | if ((p= scan_punct(':')) == nil) continue;
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| 115 | entry.gr_gid= strtol(p, nil, 0);
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| 116 |
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| 117 | entry.gr_mem= mem= members;
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| 118 | if (*lineptr != '\n') {
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| 119 | do {
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| 120 | if ((*mem= scan_punct(',')) == nil) goto again;
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| 121 | if (mem < arraylimit(members) - 1) mem++;
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| 122 | } while (*lineptr != 0);
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| 123 | }
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| 124 | *mem= nil;
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| 125 | return &entry;
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| 126 | again:;
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| 127 | }
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| 128 | }
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| 129 |
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| 130 | struct group *getgrgid(_mnx_Gid_t gid)
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| 131 | /* Return the group file entry belonging to the user-id. */
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| 132 | {
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| 133 | struct group *gr;
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| 134 |
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| 135 | endgrent();
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| 136 | while ((gr= getgrent()) != nil && gr->gr_gid != gid) {}
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| 137 | endgrent();
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| 138 | return gr;
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| 139 | }
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| 140 |
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| 141 | struct group *getgrnam(const char *name)
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| 142 | /* Return the group file entry belonging to the user name. */
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| 143 | {
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| 144 | struct group *gr;
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| 145 |
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| 146 | endgrent();
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| 147 | while ((gr= getgrent()) != nil && strcmp(gr->gr_name, name) != 0) {}
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| 148 | endgrent();
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| 149 | return gr;
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| 150 | }
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