introduce cngets, a method for kernel to read a string from console
This is intended as a replacement for libkern's gets and mostly borrows its implementation. It uses cngrab/cnungrab to delimit kernel's access to console input. Note: libkern's gets obviously doesn't share any bits of implementation iwth libc's gets. They also have different APIs and the former doesn't have the overflow problems of the latter. Inspired by: bde MFC after: 2 months
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=228633
@ -407,6 +407,55 @@ cncheckc(void)
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return (-1);
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}
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void
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cngets(char *cp, size_t size, int visible)
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{
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char *lp, *end;
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int c;
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cngrab();
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lp = cp;
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end = cp + size - 1;
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for (;;) {
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c = cngetc() & 0177;
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switch (c) {
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case '\n':
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case '\r':
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cnputc(c);
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*lp = '\0';
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cnungrab();
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return;
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case '\b':
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case '\177':
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if (lp > cp) {
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if (visible) {
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cnputc(c);
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cnputs(" \b");
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}
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lp--;
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}
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continue;
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case '\0':
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continue;
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default:
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if (lp < end) {
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switch (visible) {
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case GETS_NOECHO:
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break;
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case GETS_ECHOPASS:
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cnputc('*');
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break;
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default:
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cnputc(c);
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break;
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}
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*lp++ = c;
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}
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}
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}
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}
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void
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cnputc(int c)
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{
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@ -121,6 +121,7 @@ void cngrab(void);
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void cnungrab(void);
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int cncheckc(void);
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int cngetc(void);
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void cngets(char *, size_t, int);
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void cnputc(int);
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void cnputs(char *);
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int cnunavailable(void);
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