132 lines
3 KiB
C
132 lines
3 KiB
C
/* _XOPEN_SOURCE unlocks <stdlib.h> pty/ptmx/pts declarations. */
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#define _XOPEN_SOURCE 600
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/* _GNU_SOURCE unlocks the ptsname_r declaration*/
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#define _GNU_SOURCE
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#include <fcntl.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <asm/termbits.h> /* TIOC* constants */
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#include <sys/ioctl.h>
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#ifdef PATH_MAX
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# define SNAME_MAX PATH_MAX
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#else
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# define SNAME_MAX 512
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#endif /* PATH_MAX */
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/* Allocate PTY master and slave file descriptors.
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* errno will have been set if newpty() fails.
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*
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* NOTE: This function is my alternative to GLibC's
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* openpty() function. It exists as a learning resource.
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* REF: glibc.git:/login/openpty.c
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*/
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int mkpty(int *fdmx, int *fds) {
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int _fdmx = -1, _fds = -1;
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char sname[SNAME_MAX];
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// Configure PTY master (file descriptor)
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_fdmx = posix_openpt(O_RDWR | O_NOCTTY);
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if (_fdmx == -1)
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return EXIT_FAILURE;
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if (grantpt(_fdmx))
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goto fail;
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if (unlockpt(_fdmx))
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goto fail;
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#ifdef TIOCGPTPEER
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/* Try to allocate slave fd solely based on PTMX fd first. */
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_fds = ioctl(_fdmx, TIOCGPTPEER, O_RDWR | O_NOCTTY);
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#endif
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if (_fds == -1) {
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/* Fallback to path-based slave fd allocation
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* (if the kernel doesn't support TIOCGPTPEER, ie Linux <4.13) */
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if(ptsname_r(_fdmx, sname, sizeof(sname)))
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goto fail;
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_fds = open(sname, O_RDWR | O_NOCTTY);
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if (_fds == -1)
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goto fail;
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}
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// Propagate file descriptors via parameters
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*fdmx = _fdmx;
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*fds = _fds;
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return EXIT_SUCCESS;
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fail:
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if (_fdmx == -1) {
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close(_fdmx);
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if (_fds == -1)
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close(_fds);
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}
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return EXIT_FAILURE;
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}
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/*
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*/
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pid_t forkmkpty() {
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int fdmx, fds;
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pid_t pid;
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if (mkpty(&fdmx, &fds))
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return EXIT_FAILURE;
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switch (pid = fork()) {
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case -1:
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close(fdmx);
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close(fds);
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return -1;
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case 0:
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/* Child Process */
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close(fdmx);
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break;
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default:
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/* Parent Process */
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close(fds);
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break;
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}
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/* Both Processes */
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return pid;
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}
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/* Set pseudoterminal slave's window size.
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* Returns 0 on success, and fails with -1 if the kernel doesn't
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* implement this, or 1 for general errors (errno will be set).
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* NOTE: Typically this is part of a glibc openpty() call.
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*/
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int setptsxy(const unsigned short rows, const unsigned short cols, const int fds) {
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#ifndef TIOCSWINSZ
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/* Fail if kernel doesn't support TIOCSWINSZ. */
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return -1;
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#else
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struct winsize win = {
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.ws_row = rows,
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.ws_col = cols,
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};
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if (ioctl(fds, TIOCSWINSZ, &win))
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return EXIT_FAILURE;
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return EXIT_SUCCESS;
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#endif /* TIOCSWINSZ */
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}
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/* Get pseudoterminal slave's window size.
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* Returns 0 on success, and fails with -1 if the kernel doesn't
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* implement this, or 1 for general errors (errno will be set).
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*/
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int getptsxy(unsigned short *rows, unsigned short *cols, const int fds) {
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#ifndef TIOCGWINSZ
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/* Fail if kernel doesn't support TIOCGWINSZ. */
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return -1;
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#else
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struct winsize win = (struct winsize){ 0 };
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if (ioctl(fds, TIOCGWINSZ, &win))
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return EXIT_FAILURE;
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*rows = win.ws_row;
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*cols = win.ws_col;
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return EXIT_SUCCESS;
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#endif /* TIOCGWINSZ */
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}
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