122 lines
2.9 KiB
C++
122 lines
2.9 KiB
C++
/*
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* \brief Simple fork test
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* \author Norman Feske
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* \date 2012-02-14
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*/
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#include <stdio.h>
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#include <unistd.h>
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#include <string.h>
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#include <stdlib.h>
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#include <errno.h>
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#include <sys/wait.h>
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enum { MAX_COUNT = 100 };
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int main(int, char **argv)
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{
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printf("--- test-fork started ---\n");
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enum { MSG_SIZE = 100 };
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static char message_in_rw_segment[MSG_SIZE];
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char const * const message_about_rw_segment = "message stored in rw segment";
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strncpy(message_in_rw_segment, message_about_rw_segment, MSG_SIZE);
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char * const message_on_heap = (char *)malloc(MSG_SIZE);
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char const * const message_about_heap = "message stored on the heap";
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strncpy(message_on_heap, message_about_heap, MSG_SIZE - 1);
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enum { ARGV0_SIZE = 100 };
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static char parent_argv0[ARGV0_SIZE];
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strncpy(parent_argv0, argv[0], ARGV0_SIZE - 1);
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pid_t fork_ret = fork();
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if (fork_ret < 0) {
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printf("Error: fork returned %d, errno=%d\n", fork_ret, errno);
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return -1;
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}
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printf("pid %d: fork returned %d\n", getpid(), fork_ret);
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/* child */
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if (fork_ret == 0) {
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printf("pid %d: child says hello\n", getpid());
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/*
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* Validate that the child's heap and RW segment correspond to the
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* the state of the parent.
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*/
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printf("RW segment: %s\n", message_in_rw_segment);
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if (strcmp(message_in_rw_segment, message_about_rw_segment)) {
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printf("Error: unexpected content of the child's RW segment\n");
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return -1;
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}
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printf("argv0: %s\n", argv[0]);
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if (!argv[0] || strcmp(argv[0], parent_argv0)) {
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printf("Error: unexpected content of the child's args buffer\n");
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return -1;
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}
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printf("heap: %s\n", message_on_heap);
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if (strcmp(message_on_heap, message_about_heap)) {
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printf("Error: unexpected content on the child's heap\n");
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return -1;
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}
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{
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char c = 0;
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if (read(3, &c, 1) == 1) {
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printf("read character '%c' from FD 3\n", c);
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if (c != '5') {
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printf("Error: read unexpected value from FD 3\n");
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return -1;
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}
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}
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}
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pid_t fork_ret = fork();
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if (fork_ret < 0) {
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printf("Error: fork returned %d, errno=%d\n", fork_ret, errno);
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return -1;
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}
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printf("pid %d: fork returned %d\n", getpid(), fork_ret);
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/* grand child */
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if (fork_ret == 0) {
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printf("pid %d: grand child says hello\n", getpid());
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for (int k = 0; k < MAX_COUNT; k++) {
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printf("pid %d: grand child k = %d\n", getpid(), k);
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}
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return 0;
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};
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for (int j = 0; j < MAX_COUNT; j++) {
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printf("pid %d: child j = %d\n", getpid(), j);
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}
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if (fork_ret != 0) {
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printf("pid %d: child waits for grand-child exit\n", getpid());
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waitpid(fork_ret, nullptr, 0);
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}
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return 0;
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}
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printf("pid %d: parent received child pid %d, starts counting...\n",
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getpid(), fork_ret);
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for (int i = 0; i < MAX_COUNT; ) {
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printf("pid %d: parent i = %d\n", getpid(), i++);
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}
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printf("pid %d: parent waits for child exit\n", getpid());
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waitpid(fork_ret, nullptr, 0);
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printf("--- parent done ---\n");
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return 0;
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}
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