shell.c

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#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
#include <sys/dirent.h>
#include <sys/wait.h>
#include <sys/syscall.h>
#include <unistd.h>
#include <syscall.h>
 
#define SHELL_MAX_ARGS 5
#define SHELL_MAX_LINE 256
 
void DispatchCommand(char *buf);
 
int
main(int argc, const char *argv[])
{
    char buf[256];
 
    printf("System Shell\n");
 
    while (1) {
        fputs("Shell> ", stdout);
        fgets(buf, sizeof(buf), stdin);
 
        DispatchCommand(buf);
    }
}
 
void
Cmd_Help(int argc, const char *argv[])
{
    printf("bkpt       Trigger a kernel breakpoint\n");
    printf("exit       Exit shell\n");
    printf("help       Display the list of commands\n");
}
 
void
Cmd_Exit(int argc, const char *argv[])
{
    int val = 0;
 
    if (argc != 1 && argc != 2) {
        printf("Invalid number of arguments\n");
        return;
    }
 
    if (argc == 2) {
        val = atoi(argv[1]);
    }
 
    exit(val);
}
 
const char *searchpath[] = {
    "",
    "/sbin/",
    "/bin/",
    "/tests/",
    NULL
};
 
void
Cmd_Run(int argc, const char *argv[])
{
    int i, status;
    char path[256];
    struct stat sb;
 
    if (argc == 0)
        return;
 
    i = 0;
    while (searchpath[i] != NULL) {
        strcpy(path, searchpath[i]);
        strcat(path, argv[0]);
 
        status = OSStat(path, &sb);
        if (status != 0) {
            i++;
            continue;
        }
 
        argv[argc] = NULL;
        status = spawn(path, &argv[0]);
        if (status > 100000) {
            printf("Spawn failed!\n");
        }
#if 0
        status = OSWait(status);
        printf("Process result: %d\n", status);
#endif
        return;
    }
 
    printf("Unknown command '%s'\n", argv[0]);
}
 
void
DispatchCommand(char *buf)
{
    int i;
    int argc;
    char *argv[SHELL_MAX_ARGS+1];
    char *nextArg;
 
    // Remove newline
    for (i = 0; buf[i] != 0; i++) {
        if (buf[i] == '\n') {
            buf[i] = '\0';
            break;
        }
    }
 
    // parse input
    nextArg = strtok(buf, " \t\r\n");
    for (argc = 0; argc < SHELL_MAX_ARGS; argc++) {
        if (nextArg == NULL)
            break;
 
        argv[argc] = nextArg;
        nextArg = strtok(NULL, " \t\r\n");
    }
 
    // execute command
    if (strcmp(argv[0], "help") == 0) {
        Cmd_Help(argc, (const char **)argv);
    } else if (strcmp(argv[0], "bkpt") == 0) {
        asm volatile("int3");
    } else if (strcmp(argv[0], "exit") == 0) {
        Cmd_Exit(argc, (const char **)argv);
    } else if (strcmp(argv[0], "#") == 0) {
        // Ignore comments
    } else if (buf[0] == '\0') {
        // Ignore empty lines
    } else {
        Cmd_Run(argc, (const char **)argv);
    }
}