+#ifndef lint
+static char sccsid[] = "@(#)termcap.c 4.1 (Berkeley) %G%";
+#endif
+
+#define BUFSIZ 1024
+#define MAXHOP 32 /* max number of tc= indirections */
+#define E_TERMCAP "/etc/termcap"
+
+#include <ctype.h>
+/*
+ * termcap - routines for dealing with the terminal capability data base
+ *
+ * BUG: Should use a "last" pointer in tbuf, so that searching
+ * for capabilities alphabetically would not be a n**2/2
+ * process when large numbers of capabilities are given.
+ * Note: If we add a last pointer now we will screw up the
+ * tc capability. We really should compile termcap.
+ *
+ * Essentially all the work here is scanning and decoding escapes
+ * in string capabilities. We don't use stdio because the editor
+ * doesn't, and because living w/o it is not hard.
+ */
+
+static char *tbuf;
+static int hopcount; /* detect infinite loops in termcap, init 0 */
+char *tskip();
+char *tgetstr();
+char *tdecode();
+char *getenv();
+
+/*
+ * Get an entry for terminal name in buffer bp,
+ * from the termcap file. Parse is very rudimentary;
+ * we just notice escaped newlines.
+ */
+tgetent(bp, name)
+ char *bp, *name;
+{
+ register char *cp;
+ register int c;
+ register int i = 0, cnt = 0;
+ char ibuf[BUFSIZ];
+ char *cp2;
+ int tf;
+
+ tbuf = bp;
+ tf = 0;
+#ifndef V6
+ cp = getenv("TERMCAP");
+ /*
+ * TERMCAP can have one of two things in it. It can be the
+ * name of a file to use instead of /etc/termcap. In this
+ * case it better start with a "/". Or it can be an entry to
+ * use so we don't have to read the file. In this case it
+ * has to already have the newlines crunched out.
+ */
+ if (cp && *cp) {
+ if (*cp!='/') {
+ cp2 = getenv("TERM");
+ if (cp2==(char *) 0 || strcmp(name,cp2)==0) {
+ strcpy(bp,cp);
+ return(tnchktc());
+ } else {
+ tf = open(E_TERMCAP, 0);
+ }
+ } else
+ tf = open(cp, 0);
+ }
+ if (tf==0)
+ tf = open(E_TERMCAP, 0);
+#else
+ tf = open(E_TERMCAP, 0);
+#endif
+ if (tf < 0)
+ return (-1);
+ for (;;) {
+ cp = bp;
+ for (;;) {
+ if (i == cnt) {
+ cnt = read(tf, ibuf, BUFSIZ);
+ if (cnt <= 0) {
+ close(tf);
+ return (0);
+ }
+ i = 0;
+ }
+ c = ibuf[i++];
+ if (c == '\n') {
+ if (cp > bp && cp[-1] == '\\'){
+ cp--;
+ continue;
+ }
+ break;
+ }
+ if (cp >= bp+BUFSIZ) {
+ write(2,"Termcap entry too long\n", 23);
+ break;
+ } else
+ *cp++ = c;
+ }
+ *cp = 0;
+
+ /*
+ * The real work for the match.
+ */
+ if (tnamatch(name)) {
+ close(tf);
+ return(tnchktc());
+ }
+ }
+}
+
+/*
+ * tnchktc: check the last entry, see if it's tc=xxx. If so,
+ * recursively find xxx and append that entry (minus the names)
+ * to take the place of the tc=xxx entry. This allows termcap
+ * entries to say "like an HP2621 but doesn't turn on the labels".
+ * Note that this works because of the left to right scan.
+ */
+tnchktc()
+{
+ register char *p, *q;
+ char tcname[16]; /* name of similar terminal */
+ char tcbuf[BUFSIZ];
+ char *holdtbuf = tbuf;
+ int l;
+
+ p = tbuf + strlen(tbuf) - 2; /* before the last colon */
+ while (*--p != ':')
+ if (p<tbuf) {
+ write(2, "Bad termcap entry\n", 18);
+ return (0);
+ }
+ p++;
+ /* p now points to beginning of last field */
+ if (p[0] != 't' || p[1] != 'c')
+ return(1);
+ strcpy(tcname,p+3);
+ q = tcname;
+ while (q && *q != ':')
+ q++;
+ *q = 0;
+ if (++hopcount > MAXHOP) {
+ write(2, "Infinite tc= loop\n", 18);
+ return (0);
+ }
+ if (tgetent(tcbuf, tcname) != 1)
+ return(0);
+ for (q=tcbuf; *q != ':'; q++)
+ ;
+ l = p - holdtbuf + strlen(q);
+ if (l > BUFSIZ) {
+ write(2, "Termcap entry too long\n", 23);
+ q[BUFSIZ - (p-tbuf)] = 0;
+ }
+ strcpy(p, q+1);
+ tbuf = holdtbuf;
+ return(1);
+}
+
+/*
+ * Tnamatch deals with name matching. The first field of the termcap
+ * entry is a sequence of names separated by |'s, so we compare
+ * against each such name. The normal : terminator after the last
+ * name (before the first field) stops us.
+ */
+tnamatch(np)
+ char *np;
+{
+ register char *Np, *Bp;
+
+ Bp = tbuf;
+ if (*Bp == '#')
+ return(0);
+ for (;;) {
+ for (Np = np; *Np && *Bp == *Np; Bp++, Np++)
+ continue;
+ if (*Np == 0 && (*Bp == '|' || *Bp == ':' || *Bp == 0))
+ return (1);
+ while (*Bp && *Bp != ':' && *Bp != '|')
+ Bp++;
+ if (*Bp == 0 || *Bp == ':')
+ return (0);
+ Bp++;
+ }
+}
+
+/*
+ * Skip to the next field. Notice that this is very dumb, not
+ * knowing about \: escapes or any such. If necessary, :'s can be put
+ * into the termcap file in octal.
+ */
+static char *
+tskip(bp)
+ register char *bp;
+{
+
+ while (*bp && *bp != ':')
+ bp++;
+ if (*bp == ':')
+ bp++;
+ return (bp);
+}
+
+/*
+ * Return the (numeric) option id.
+ * Numeric options look like
+ * li#80
+ * i.e. the option string is separated from the numeric value by
+ * a # character. If the option is not found we return -1.
+ * Note that we handle octal numbers beginning with 0.
+ */
+tgetnum(id)
+ char *id;
+{
+ register int i, base;
+ register char *bp = tbuf;
+
+ for (;;) {
+ bp = tskip(bp);
+ if (*bp == 0)
+ return (-1);
+ if (*bp++ != id[0] || *bp == 0 || *bp++ != id[1])
+ continue;
+ if (*bp == '@')
+ return(-1);
+ if (*bp != '#')
+ continue;
+ bp++;
+ base = 10;
+ if (*bp == '0')
+ base = 8;
+ i = 0;
+ while (isdigit(*bp))
+ i *= base, i += *bp++ - '0';
+ return (i);
+ }
+}
+
+/*
+ * Handle a flag option.
+ * Flag options are given "naked", i.e. followed by a : or the end
+ * of the buffer. Return 1 if we find the option, or 0 if it is
+ * not given.
+ */
+tgetflag(id)
+ char *id;
+{
+ register char *bp = tbuf;
+
+ for (;;) {
+ bp = tskip(bp);
+ if (!*bp)
+ return (0);
+ if (*bp++ == id[0] && *bp != 0 && *bp++ == id[1]) {
+ if (!*bp || *bp == ':')
+ return (1);
+ else if (*bp == '@')
+ return(0);
+ }
+ }
+}
+
+/*
+ * Get a string valued option.
+ * These are given as
+ * cl=^Z
+ * Much decoding is done on the strings, and the strings are
+ * placed in area, which is a ref parameter which is updated.
+ * No checking on area overflow.
+ */
+char *
+tgetstr(id, area)
+ char *id, **area;
+{
+ register char *bp = tbuf;
+
+ for (;;) {
+ bp = tskip(bp);
+ if (!*bp)
+ return (0);
+ if (*bp++ != id[0] || *bp == 0 || *bp++ != id[1])
+ continue;
+ if (*bp == '@')
+ return(0);
+ if (*bp != '=')
+ continue;
+ bp++;
+ return (tdecode(bp, area));
+ }
+}
+
+/*
+ * Tdecode does the grung work to decode the
+ * string capability escapes.
+ */
+static char *
+tdecode(str, area)
+ register char *str;
+ char **area;
+{
+ register char *cp;
+ register int c;
+ register char *dp;
+ int i;
+
+ cp = *area;
+ while ((c = *str++) && c != ':') {
+ switch (c) {
+
+ case '^':
+ c = *str++ & 037;
+ break;
+
+ case '\\':
+ dp = "E\033^^\\\\::n\nr\rt\tb\bf\f";
+ c = *str++;
+nextc:
+ if (*dp++ == c) {
+ c = *dp++;
+ break;
+ }
+ dp++;
+ if (*dp)
+ goto nextc;
+ if (isdigit(c)) {
+ c -= '0', i = 2;
+ do
+ c <<= 3, c |= *str++ - '0';
+ while (--i && isdigit(*str));
+ }
+ break;
+ }
+ *cp++ = c;
+ }
+ *cp++ = 0;
+ str = *area;
+ *area = cp;
+ return (str);
+}
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