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Commit 6919a43

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author
Margo
committed
Add in-class code for 11/8
1 parent cfd5d34 commit 6919a43

9 files changed

+309
-0
lines changed

‎shell2/GNUmakefile

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ALLPROG=parent child waiting-parent noisy-parent badchild waiting-parent2 waiting-parent3 util
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all: $(ALLPROG)
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O ?= -O2
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include ../common/rules.mk
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%: %.o $(BUILDSTAMP)
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$(CC) $(LDFLAGS) -o $@ $<
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%.o: %.c $(BUILDSTAMP)
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$(CC) $(CPPFLAGS) $(CFLAGS) $(DEPCFLAGS) $(O) -o $@ -c $<
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clean:
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rm -f $(ALLPROG) *.o
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rm -rf $(DEPSDIR) *.dSYM
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.PHONY: all clean

‎shell2/badchild.c

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#include <sys/types.h>
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#include <errno.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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// Sample program that we will exec from parent; just print out its argv.
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// And then, bad child that it is, it will loop forever!
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int main(int argc, char *argv[]) {
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pid_t mypid = getpid();
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printf("Hello from process %d\n", mypid);
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printf("My argument list is: ");
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for (int i = 0; i < argc; i++)
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printf("%s ", argv[i]);
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printf("\n");
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while (1) {
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printf("Child looping\n");
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sleep(1);
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}
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}

‎shell2/child.c

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#include <sys/types.h>
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#include <errno.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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// Sample program that we will exec from parent; just print out its argv.
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//
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int main(int argc, char *argv[]) {
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pid_t mypid = getpid();
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printf("Hello from process %d\n", mypid);
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printf("My argument list is: ");
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for (int i = 0; i < argc; i++)
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printf("%s ", argv[i]);
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printf("\n");
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exit(42);
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}

‎shell2/noisy-parent.c

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#include <sys/types.h>
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#include <errno.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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// Sample program that will take another program on the command line
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// and call execvp on it.
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// So, argv[0] = this process's name
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// argv[1] = the program we want to exec
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// argv[2-end] = the arguments to the program we want to exec
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//
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int main(int argc, char *argv[]) {
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(void)argc;
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pid_t parent_pid = getpid();
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printf("Hello from parent pid %d\n", parent_pid);
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pid_t child = fork();
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if (child == 0) {
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printf("Hi! I'm the child pid %d\n", getpid());
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if (execvp(argv[1], argv+1) == -1) {
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printf("The exec failed: %s\n", strerror(errno));
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exit(1);
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}
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printf("The exec succeeded! Here is pid %d\n", getpid());
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} else if (child > 0) {
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printf("Hi! I'm the parent pid %d\n", getpid());
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} else {
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printf("Fork failed!\n");
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}
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// Annoying parent is going to clutter up the console
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for (int i = 0; i < 100; i++)
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printf("Yak yak yak\n");
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}

‎shell2/parent.c

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#include <sys/types.h>
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#include <errno.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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// Sample program that will take another program on the command line
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// and call execvp on it.
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// So, argv[0] = this process's name
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// argv[1] = the program we want to exec
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// argv[2-end] = the arguments to the program we want to exec
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//
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int main(int argc, char *argv[]) {
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(void)argc;
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pid_t parent_pid = getpid();
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printf("Hello from parent pid %d\n", parent_pid);
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pid_t child = fork();
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if (child == 0) {
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printf("Hi! I'm the child pid %d\n", getpid());
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if (execvp(argv[1], argv+1) == -1) {
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printf("The exec failed: %s\n", strerror(errno));
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exit(1);
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}
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printf("The exec succeeded! Here is pid %d\n", getpid());
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} else if (child > 0) {
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printf("Hi! I'm the parent pid %d\n", getpid());
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} else {
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printf("Fork failed!\n");
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}
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}

‎shell2/util.c

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#include <sys/types.h>
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#include <sys/stat.h>
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#include <assert.h>
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#include <fcntl.h>
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#include <unistd.h>
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int
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main(void)
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{
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char c;
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int fd, n = 0;
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assert((fd = open("/dev/null", O_RDONLY)) > 0);
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while (1)
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n += read(fd, &c, 1);
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return (0);
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}

‎shell2/waiting-parent.c

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#include <sys/types.h>
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#include <sys/wait.h>
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#include <errno.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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// Sample program that will take another program on the command line
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// and call execvp on it.
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// So, argv[0] = this process's name
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// argv[1] = the program we want to exec
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// argv[2-end] = the arguments to the program we want to exec
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//
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int main(int argc, char *argv[]) {
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(void)argc;
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pid_t parent_pid = getpid();
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printf("Hello from parent pid %d\n", parent_pid);
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pid_t child = fork();
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if (child == 0) {
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printf("Hi! I'm the child pid %d\n", getpid());
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if (execvp(argv[1], argv+1) == -1) {
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printf("The exec failed: %s\n", strerror(errno));
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exit(1);
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}
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printf("The exec succeeded! Here is pid %d\n", getpid());
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} else if (child > 0) {
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printf("Hi! I'm the parent pid %d\n", getpid());
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} else {
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printf("Fork failed!\n");
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}
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// Wait for the child to exit
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int exit_status;
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pid_t exit_pid = waitpid(child, &exit_status, 0);
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printf("Child %d exited with status: %d\n",
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exit_pid, WEXITSTATUS(exit_status));
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}

‎shell2/waiting-parent2.c

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#include <sys/types.h>
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#include <sys/wait.h>
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#include <errno.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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// Sample program that will take another program on the command line
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// and call execvp on it.
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// So, argv[0] = this process's name
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// argv[1] = the program we want to exec
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// argv[2-end] = the arguments to the program we want to exec
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//
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int main(int argc, char *argv[]) {
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(void)argc;
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pid_t parent_pid = getpid();
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printf("Hello from parent pid %d\n", parent_pid);
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pid_t child = fork();
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if (child == 0) {
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printf("Hi! I'm the child pid %d\n", getpid());
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if (execvp(argv[1], argv+1) == -1) {
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printf("The exec failed: %s\n", strerror(errno));
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exit(1);
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}
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printf("The exec succeeded! Here is pid %d\n", getpid());
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} else if (child > 0) {
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printf("Hi! I'm the parent pid %d\n", getpid());
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} else {
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printf("Fork failed!\n");
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}
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// Wait for the child to exit
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int exit_status;
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pid_t exit_pid;
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while (1) {
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exit_pid = waitpid(child, &exit_status, WNOHANG);
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if (exit_pid == 0)
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printf("Child is running with no state change\n");
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else if (WIFEXITED(exit_status)) {
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break;
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}
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// If we got here, we still have a child - sleep a bit and
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// wait.
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sleep(1);
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}
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printf("Child %d exited with status: %d\n",
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exit_pid, WEXITSTATUS(exit_status));
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}

‎shell2/waiting-parent3.c

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#include <sys/types.h>
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#include <sys/wait.h>
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#include <errno.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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// Sample program that will take another program on the command line
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// and call execvp on it.
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// So, argv[0] = this process's name
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// argv[1] = the program we want to exec
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// argv[2-end] = the arguments to the program we want to exec
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//
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int main(int argc, char *argv[]) {
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(void)argc;
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pid_t parent_pid = getpid();
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printf("Hello from parent pid %d\n", parent_pid);
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pid_t child = fork();
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if (child == 0) {
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printf("Hi! I'm the child pid %d\n", getpid());
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if (execvp(argv[1], argv+1) == -1) {
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printf("The exec failed: %s\n", strerror(errno));
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exit(1);
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}
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printf("The exec succeeded! Here is pid %d\n", getpid());
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} else if (child > 0) {
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printf("Hi! I'm the parent pid %d\n", getpid());
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} else {
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printf("Fork failed!\n");
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}
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// Wait for the child to exit
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int exit_status;
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pid_t exit_pid;
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while (1) {
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exit_pid = waitpid(child, &exit_status, WUNTRACED | WCONTINUED);
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if (WIFEXITED(exit_status))
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break;
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else if (WIFSIGNALED(exit_status)) {
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printf("Child received a signal\n");
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break;
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} else if (WIFSTOPPED(exit_status)) {
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printf("Child process is stopped; keep waiting\n");
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}
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// If we got here, we still have a child - sleep a bit and
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// wait.
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sleep(1);
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}
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printf("Child %d exited with status: %d\n",
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exit_pid, WEXITSTATUS(exit_status));
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}

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