实现pmap [-x -X]功能

pmap命令用于查看进程的内存映射情况。它的-x选项可以显示内存映射的详细信息，包括保护标志、偏移地址、设备号和inode号等。而-X选项则可以显示共享库的详细信息。

要实现pmap [-x -X]功能，可以使用以下步骤：

1. 解析命令行参数，判断是否有-x或-X选项。
2. 获取当前进程的pid。
3. 打开/proc/[pid]/maps文件，读取其中的内容。
4. 对于每一行内容，解析出起始地址、结束地址、保护标志、偏移地址、设备号和inode号等信息。
5. 如果有-x选项，则显示所有信息；如果有-X选项，则根据inode号查找共享库文件的详细信息，并显示出来。

以下是一个简单的示例代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>

#define MAXLINE 1024

struct mem_info {
    unsigned long start_addr;
    unsigned long end_addr;
    char perm[5];
    unsigned long offset;
    unsigned int dev_major;
    unsigned int dev_minor;
    unsigned int inode;
    char name[MAXLINE];
};

void print_mem_info(struct mem_info *info, int show_all, int show_shared_libs)
{
    if (show_all) {
        printf("%08lx-%08lx %s %08lx %02x:%02x %u %s\n",
            info->start_addr, info->end_addr, info->perm, info->offset,
            info->dev_major, info->dev_minor, info->inode, info->name);
    } else if (show_shared_libs && info->name[0] == '/') {
        printf("%08lx-%08lx %s %08lx %02x:%02x %u %s\n",
            info->start_addr, info->end_addr, info->perm, info->offset,
            info->dev_major, info->dev_minor, info->inode, info->name);
    }
}

int main(int argc, char *argv[])
{
    int fd;
    char line[MAXLINE];
    char *p;
    int show_all = 0;
    int show_shared_libs = 0;
    pid_t pid = getpid();

    // Parse command-line options
    while ((argc > 1) && (argv[1][0] == '-')) {
        if (strcmp(argv[1], "-x") == 0) {
            show_all = 1;
        } else if (strcmp(argv[1], "-X") == 0) {
            show_shared_libs = 1;
        } else {
            printf("Usage: %s [-x|-X]\n", argv[0]);
            exit(1);
        }
        argc--;
        argv++;
    }

    // Open /proc/[pid]/maps file
    snprintf(line, sizeof(line), "/proc/%d/maps", pid);
    if ((fd = open(line, O_RDONLY)) < 0) {
        printf("Can't open %s\n", line);
        exit(1);
    }

    // Read and print memory maps
    while (fgets(line, sizeof(line), fd) != NULL) {
        struct mem_info info;
        memset(&info, 0, sizeof(info));

        // Parse memory map line
        p = strtok(line, " \t\n-");
        sscanf(p, "%lx", &info.start_addr);
        p = strtok(NULL, " \t\n");
        sscanf(p, "%lx", &info.end_addr);
        p = strtok(NULL, " \t\n");
        strncpy(info.perm, p, sizeof(info.perm));
        p = strtok(NULL, " \t\n");
        sscanf(p, "%lx", &info.offset);
        p = strtok(NULL, " \t\n:");
        sscanf(p, "%x", &info.dev_major);
        p = strtok(NULL, " \t\n");
        sscanf(p, "%x", &info.dev_minor);
        p = strtok(NULL, " \t\n");
        sscanf(p, "%u", &info.inode);
        p = strtok(NULL, " \t\n");
        strncpy(info.name, p, sizeof(info.name));

        // Print memory map information
        print_mem_info(&info, show_all, show_shared_libs);
    }

    // Close /proc/[pid]/maps file
    close(fd);

    return 0;
}