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102 lines
1.6 KiB
C
102 lines
1.6 KiB
C
#include <sys/wait.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stdarg.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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pid_t
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pipeto(const char *cmdline)
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{
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int pipe0[2]; // stdout -> stdin
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int pipe1[2]; // child errno -> parent
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pid_t pid;
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if (pipe(pipe0) < 0)
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return -1;
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if (pipe(pipe1) < 0)
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return -1;
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pid = fork();
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if (pid < 0) {
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return -1;
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} else if (pid == 0) { // in child
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close(pipe1[0]);
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// close errno pipe on successful exec
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fcntl(pipe1[1], F_SETFD, FD_CLOEXEC);
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if (dup2(pipe0[0], 0) < 0)
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exit(111);
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close(pipe0[0]);
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close(pipe0[1]);
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// split cmdline, just on spaces
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char *argv[16];
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int argc = 0;
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char *cp = strdup(cmdline);
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if (!cp)
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exit(111);
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while (argc < 16 && *cp) {
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argv[argc++] = cp;
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cp = strchr(cp, ' ');
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if (!cp)
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break;
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*cp++ = 0;
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while (*cp == ' ')
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cp++;
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}
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argv[argc] = 0;
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if (argv[0])
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execvp(argv[0], argv);
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else
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errno = EINVAL;
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// execvp failed, write errno to parent
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int e = errno;
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if (write(pipe1[1], &e, sizeof e) < 0)
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exit(111); // do a magic dance for gcc -Wunused-result
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exit(111);
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} else { // in parent
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close(pipe1[1]);
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int e;
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ssize_t n = read(pipe1[0], &e, sizeof e);
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if (n < 0)
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e = errno;
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close(pipe1[0]);
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if (n == 0) {
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// child executed successfully, redirect stdout to it
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if (dup2(pipe0[1], 1) < 0)
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return -1;
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close(pipe0[0]);
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close(pipe0[1]);
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return pid;
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} else {
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errno = e;
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return -1;
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}
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}
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// return pid;
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}
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int
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pipeclose(pid_t pid)
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{
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int s;
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fflush(0);
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close(1);
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waitpid(pid, &s, 0);
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return s;
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}
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