无法处理管道函数，其中一个进程将一个字符串消息发送到第二个进程的给管道，第二个进程反转消息中每个字符的大小写并将其发送回第一个进程。
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/wait.h>
#include <string.h>
#include <ctype.h>
#include <assert.h>
#include <stdbool.h>
// Parent: reads from P1_READ, writes on P1_WRITE
// Child: reads from P2_READ, writes on P2_WRITE
#define P1_READ 0
#define P2_WRITE 1
#define P2_READ 2
#define P1_WRITE 3
// the total number of pipe *pairs* we need
#define NUM_PIPES 2
/*
toggleString accepts an a pointer to char array, allocates size for the
string to be toggled,
copys the argument into a string, loops through the string and for every
uppercase character
we set it to its lower case counterpart and vice versa, returning the
toggled string
*/
char *toggleString(char *argv){
int i; /* Declare counter */
char *str = malloc(sizeof(argv[1])); /* Declare array sizeof input */
strcpy(str, argv); /* Copy String to char array */
for(i=0;str[i]!='\0';i++) { //Loop through length of string
if(str[i]>='A'&&str[i]<='Z'){ //if the array at i is uppercase
str[i]+=32; //Make it lower case
} else if (str[i]>='a'&&str[i]<='z') {// if the array at i is lowercase
str[i]-=32; //Make it uppercase
}
}
return str;
}
/*
int inputValidation accept and integer (number of arugments) and a
pointer to the cmd line input array
We check to see if the command line input contains the minimal number of
arugments and check to see
whether or not the user input contains at least one reversible haracter,
if all goes well we return 0
*/
int inputValidation(int argc, char *argv[]){
int i; //Declare counter variable
bool c = false; //Declare boolean flag using imported <stdbool.h>
char str[strlen(argv[1])]; //Declare str
strcpy(str, argv[1]); //copy argument into str
if (argc != 2) { // check to see if we have enough arguments to
continue
// Prompt user of correct usage
fprintf(stderr, "\nUsage: %s <string> or <'string 1, string 2', ...,
string n'> for multiple strings\n", argv[0]);
exit(EXIT_FAILURE); //Exit on improper input
} else {
//loop through our string
for(i=0;i<strlen(str);i++) {
//if any any char is a reversible character
if(isalpha((int) str[i])){
c = true; //set the flag to true
}
}
if(c == false){ //If flag is false input does not contain any
reversible charachters
printf("\nSorry, The string you entered did NOT contain any
Alphabetical Characters\nRun me again, with at least 1 Alphabetical
character\n\n");
exit(EXIT_FAILURE); //Exit on improper input
}
return (0);
}
}
/ *
Main从命令行获取输入，调用输入验证以确保
适当的输入，
然后创建我们将需要的管道和分叉子进程，父母
和孩子
执行它们各自的代码
* /
int main(int argc, char *argv[]) {
assert(argc>1);
int fd[2*NUM_PIPES]; //Declare int[] of file descriptors
int len, i; //Declare length and integer for count
pid_t pid; //Declare process id
char parent[strlen(argv[1])]; //Declare Parent array
char child[strlen(argv[1])]; //Declare Child array
if(inputValidation(argc, argv) == 0) /* Check for proper input */
strcpy(parent, argv[1]);
// create all the descriptor pairs we need
for (i=0; i<NUM_PIPES; ++i)
{
if (pipe(fd+(i*2)) < 0)
{
perror("Failed to allocate pipes");
exit(EXIT_FAILURE);
}
}
// fork() returns 0 for child process, child-pid for parent process.
if ((pid = fork()) < 0)
{
perror("Failed to fork process");
return EXIT_FAILURE;
}
//////////////////////////////Childs Code
BEGINS//////////////////////////////////
// if the pid is zero, this is the child process
if (pid == 0)
{
// Child. Start by closing descriptors we
// don't need in this process
close(fd[P1_READ]);
close(fd[P1_WRITE]);
// used for output
pid = getpid();
// wait for parent to send us a value
len = read(fd[P2_READ], &child, len);
if (len < 0)
{
perror("Child: Failed to read data from pipe");
exit(EXIT_FAILURE);
}
else if (len == 0)
{
// not an error, but certainly unexpected
fprintf(stderr, "Child: Read EOF from pipe");
}
else
{
// report pid to console
printf("Child(%d): Recieved Message\n\nChild(%d): Toggling Case and
Sending to Parent\n",pid, pid);
// send the message to toggleString and write it to pipe//
if (write(fd[P2_WRITE], toggleString(child), strlen(child)) < 0)
{
perror("Child: Failed to write response value");
exit(EXIT_FAILURE);
}
}
// finished. close remaining descriptors.
close(fd[P2_READ]);
close(fd[P2_WRITE]);
return EXIT_SUCCESS;
}
//child code ends///
//////////////////////////////Parent Code
BEGINS//////////////////////////////////
// Parent. close unneeded descriptors
close(fd[P2_READ]);
close(fd[P2_WRITE]);
// used for output
pid = getpid();
// send a value to the child
printf("\nParent(%d): Sending %s to Child\n\n", pid, argv[1]);
if (write(fd[P1_WRITE], argv[1], strlen(argv[1])) != strlen(argv[1]))
{
perror("Parent: Failed to send value to child ");
exit(EXIT_FAILURE);
}
// now wait for a response
len = read(fd[P1_READ], &parent, strlen(parent));
if (len < 0)
{
perror("Parent: failed to read value from pipe");
exit(EXIT_FAILURE);
}
else if (len == 0)
{
// not an error, but certainly unexpected
fprintf(stderr, "Parent(%d): Read EOF from pipe", pid);
}
else
{
// report what we received
printf("\nParent(%d): Received %s from Child\n\n", pid, parent);
}
// close down remaining descriptors
close(fd[P1_READ]);
close(fd[P1_WRITE]);
// wait for child termination
wait(NULL);
return EXIT_SUCCESS;
}
//////////////////////////////Parent Code
ENDS//////////////////////////////////
答案 0 :(得分：1)
这有效：
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/wait.h>
#include <string.h>
#include <ctype.h>
#include <assert.h>
#include <stdbool.h>
#define P1_READ 0
#define P2_WRITE 1
#define P2_READ 2
#define P1_WRITE 3
#define NUM_PIPES 2
static
char *toggleString(char *argv)
{
int i;
char *str = malloc(strlen(argv) + 1); /* Key Fix */
strcpy(str, argv);
for (i = 0; str[i] != '\0'; i++)
{
if (str[i] >= 'A' && str[i] <= 'Z')
{
str[i] += 32;
}
else if (str[i] >= 'a' && str[i] <= 'z')
{
str[i] -= 32;
}
}
return str;
}
static
int inputValidation(int argc, char *argv[])
{
bool c = false;
char str[strlen(argv[1])];
strcpy(str, argv[1]);
if (argc != 2)
{
fprintf(stderr, "\nUsage: %s <string> or <'string 1, string 2', ..., string n'> for multiple strings\n", argv[0]);
exit(EXIT_FAILURE);
}
else
{
for (size_t i = 0; i < strlen(str); i++)
{
if (isalpha((int)str[i]))
{
c = true;
}
}
if (c == false)
{
printf("\nSorry, The string you entered did NOT contain any"
" Alphabetical Characters\nRun me again, with at least 1 Alphabetical"
" character\n\n");
exit(EXIT_FAILURE);
}
return(0);
}
}
int main(int argc, char *argv[])
{
assert(argc > 1);
int fd[2 * NUM_PIPES];
int len, i;
pid_t pid;
char parent[strlen(argv[1])];
char child[strlen(argv[1])];
if (inputValidation(argc, argv) == 0)
strcpy(parent, argv[1]);
for (i = 0; i < NUM_PIPES; ++i)
{
if (pipe(fd + (i * 2)) < 0)
{
perror("Failed to allocate pipes");
exit(EXIT_FAILURE);
}
}
if ((pid = fork()) < 0)
{
perror("Failed to fork process");
exit(EXIT_FAILURE);
}
if (pid == 0)
{
close(fd[P1_READ]);
close(fd[P1_WRITE]);
pid = getpid();
len = read(fd[P2_READ], child, sizeof(child));
if (len < 0)
{
perror("Child: Failed to read data from pipe");
exit(EXIT_FAILURE);
}
else if (len == 0)
{
fprintf(stderr, "Child: Read EOF from pipe\n");
}
else
{
child[len] = '\0';
printf("Child(%d): Received Message [%s]\nChild(%d): Toggling Case and Sending to Parent\n", pid, child, pid);
char *toggled = toggleString(child);
printf("Child(%d): Sending [%s]\n", pid, toggled);
if (write(fd[P2_WRITE], toggled, len) < 0)
{
perror("Child: Failed to write response value");
exit(EXIT_FAILURE);
}
free(toggled);
}
close(fd[P2_READ]);
close(fd[P2_WRITE]);
return EXIT_SUCCESS;
}
close(fd[P2_READ]);
close(fd[P2_WRITE]);
pid = getpid();
printf("\nParent(%d): Sending [%s] to Child\n\n", pid, argv[1]);
len = strlen(argv[1]);
if (write(fd[P1_WRITE], argv[1], len) != len)
{
perror("Parent: Failed to send value to child");
exit(EXIT_FAILURE);
}
len = read(fd[P1_READ], parent, sizeof(parent));
if (len < 0)
{
perror("Parent: failed to read value from pipe");
exit(EXIT_FAILURE);
}
else if (len == 0)
{
fprintf(stderr, "Parent(%d): Read EOF from pipe\n", pid);
}
else
{
parent[len] = '\0';
printf("\nParent(%d): Received [%s] from Child\n\n", pid, parent);
}
close(fd[P1_READ]);
close(fd[P1_WRITE]);
wait(NULL);
return EXIT_SUCCESS;
}
从您的评论中提取代码，以及分割多个行字符串等等，这是很痛苦的。 toggleString()函数被破坏 - 分配1个字节，然后在其上复制一个字符串。其他代码对于空终止字符串并处理它们并不小心。这些基本上是评论中诊断出的问题。
示例运行：
$ pp53 'AbSoLuTeLy GlOrIoUs'
Parent(5209): Sending [AbSoLuTeLy GlOrIoUs] to Child
Child(5210): Received Message [AbSoLuTeLy GlOrIoUs]
Child(5210): Toggling Case and Sending to Parent
Child(5210): Sending [aBsOlUtElY gLoRiOuS]
Parent(5209): Received [aBsOlUtElY gLoRiOuS] from Child
$