| 1 | /* getttyent(3) - get a ttytab entry Author: Kees J. Bot
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| 2 | * 28 Oct 1995
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| 3 | */
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| 4 | #define nil 0
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| 5 | #define open _open
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| 6 | #define close _close
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| 7 | #define fcntl _fcntl
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| 8 | #define read _read
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| 9 | #include <string.h>
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| 10 | #include <sys/types.h>
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| 11 | #include <ttyent.h>
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| 12 | #include <unistd.h>
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| 13 | #include <fcntl.h>
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| 14 |
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| 15 | #define arraysize(a) (sizeof(a) / sizeof((a)[0]))
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| 16 | #define arraylimit(a) ((a) + arraysize(a))
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| 17 |
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| 18 | static char TTYTAB[]= "/etc/ttytab"; /* The table of terminal devices. */
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| 19 |
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| 20 | static char buf[512]; /* Read buffer. */
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| 21 | static char ttline[256]; /* One line from the ttytab file. */
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| 22 | static char *ttargv[32]; /* Compound arguments. */
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| 23 | static struct ttyent entry; /* Entry to fill and return. */
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| 24 | static int ttfd= -1; /* Filedescriptor to the file. */
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| 25 | static char *bufptr; /* Place in buf. */
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| 26 | static ssize_t buflen= 0; /* Remaining characters in buf. */
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| 27 | static char *lineptr; /* Place in the line. */
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| 28 | static char **argvptr; /* Place in word lists. */
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| 29 |
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| 30 | void endttyent(void)
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| 31 | /* Close the ttytab file. */
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| 32 | {
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| 33 | if (ttfd >= 0) {
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| 34 | (void) close(ttfd);
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| 35 | ttfd= -1;
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| 36 | buflen= 0;
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| 37 | }
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| 38 | }
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| 39 |
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| 40 | int setttyent(void)
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| 41 | /* Open the ttytab file. */
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| 42 | {
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| 43 | if (ttfd >= 0) endttyent();
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| 44 |
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| 45 | if ((ttfd= open(TTYTAB, O_RDONLY)) < 0) return -1;
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| 46 | (void) fcntl(ttfd, F_SETFD, fcntl(ttfd, F_GETFD) | FD_CLOEXEC);
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| 47 | return 0;
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| 48 | }
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| 49 |
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| 50 | static int getline(void)
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| 51 | /* Get one line from the ttytab file, return 0 if bad or EOF. */
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| 52 | {
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| 53 | lineptr= ttline;
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| 54 | argvptr= ttargv;
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| 55 |
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| 56 | do {
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| 57 | if (buflen == 0) {
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| 58 | if ((buflen= read(ttfd, buf, sizeof(buf))) <= 0)
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| 59 | return 0;
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| 60 | bufptr= buf;
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| 61 | }
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| 62 |
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| 63 | if (lineptr == arraylimit(ttline)) return 0;
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| 64 | buflen--;
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| 65 | } while ((*lineptr++ = *bufptr++) != '\n');
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| 66 |
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| 67 | lineptr= ttline;
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| 68 | return 1;
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| 69 | }
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| 70 |
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| 71 | static int white(int c)
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| 72 | /* Whitespace? */
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| 73 | {
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| 74 | return c == ' ' || c == '\t';
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| 75 | }
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| 76 |
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| 77 | static char *scan_white(int quoted)
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| 78 | /* Scan for a field separator in a line, return the start of the field.
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| 79 | * "quoted" is set if we have to watch out for double quotes.
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| 80 | */
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| 81 | {
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| 82 | char *field, *last;
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| 83 |
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| 84 | while (white(*lineptr)) lineptr++;
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| 85 | if (!quoted && *lineptr == '#') return nil;
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| 86 |
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| 87 | field= lineptr;
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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 (quoted && *lineptr == '"') return field;
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| 93 | if (white(*lineptr++)) break;
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| 94 | }
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| 95 | *last= 0;
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| 96 | return *field == 0 ? nil : field;
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| 97 | }
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| 98 |
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| 99 | static char **scan_quoted(void)
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| 100 | /* Read a field that may be a quoted list of words. */
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| 101 | {
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| 102 | char *p, **field= argvptr;
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| 103 |
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| 104 | while (white(*lineptr)) lineptr++;
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| 105 |
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| 106 | if (*lineptr == '"') {
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| 107 | /* Quoted list of words. */
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| 108 | lineptr++;
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| 109 | while ((p= scan_white(1)) != nil && *p != '"') {
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| 110 | if (argvptr == arraylimit(ttargv)) return nil;
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| 111 | *argvptr++= p;
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| 112 | }
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| 113 | if (*lineptr == '"') *lineptr++= 0;
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| 114 | } else {
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| 115 | /* Just one word. */
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| 116 | if ((p= scan_white(0)) == nil) return nil;
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| 117 | if (argvptr == arraylimit(ttargv)) return nil;
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| 118 | *argvptr++= p;
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| 119 | }
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| 120 | if (argvptr == arraylimit(ttargv)) return nil;
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| 121 | *argvptr++= nil;
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| 122 | return field;
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| 123 | }
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| 124 |
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| 125 | struct ttyent *getttyent(void)
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| 126 | /* Read one entry from the ttytab file. */
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| 127 | {
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| 128 | /* Open the file if not yet open. */
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| 129 | if (ttfd < 0 && setttyent() < 0) return nil;
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| 130 |
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| 131 | /* Look for a line with something on it. */
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| 132 | for (;;) {
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| 133 | if (!getline()) return nil; /* EOF or corrupt. */
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| 134 |
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| 135 | if ((entry.ty_name= scan_white(0)) == nil) continue;
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| 136 | entry.ty_type= scan_white(0);
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| 137 | entry.ty_getty= scan_quoted();
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| 138 | entry.ty_init= scan_quoted();
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| 139 |
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| 140 | return &entry;
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| 141 | }
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| 142 | }
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| 143 |
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| 144 | struct ttyent *getttynam(const char *name)
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| 145 | /* Return the ttytab file entry for a given tty. */
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| 146 | {
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| 147 | struct ttyent *tty;
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| 148 |
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| 149 | endttyent();
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| 150 | while ((tty= getttyent()) != nil && strcmp(tty->ty_name, name) != 0) {}
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| 151 | endttyent();
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| 152 | return tty;
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| 153 | }
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