source: trunk/minix/commands/i386/mtools-3.9.7/expand.c@ 20

/*
 * Do filename expansion with the shell.
 */

#define EXPAND_BUF      2048

#include "sysincludes.h"
#include "mtools.h"


int safePopenOut(char **command, char *output, int len)
{
        int pipefd[2];
        pid_t pid;
        int status;
        int last;

        if(pipe(pipefd)) {
                return -2;
        }
        switch((pid=fork())){
                case -1:
                        return -2;
                case 0: /* the son */
                        close(pipefd[0]);
                        destroy_privs();
                        close(1);
                        close(2); /* avoid nasty error messages on stderr */
                        dup(pipefd[1]);
                        close(pipefd[1]);
                        execvp(command[0], command+1);
                        exit(1);
                default:
                        close(pipefd[1]);
                        break;
        }
        last=read(pipefd[0], output, len);
        kill(pid,9);
        wait(&status);
        if(last<0) {
                return -1;
        }
        return last;
}



const char *expand(const char *input, char *ans)
{
        int last;
        char buf[256];
        char *command[] = { "/bin/sh", "sh", "-c", 0, 0 };

        ans[EXPAND_BUF-1]='\0';

        if (input == NULL)
                return(NULL);
        if (*input == '\0')
                return("");
                                        /* any thing to expand? */
        if (!strpbrk(input, "$*(){}[]\\?`~")) {
                strncpy(ans, input, EXPAND_BUF-1);
                return(ans);
        }
                                        /* popen an echo */
#ifdef HAVE_SNPRINTF
        snprintf(buf, 255, "echo %s", input);
#else
        sprintf(buf, "echo %s", input);
#endif

        command[3]=buf;
        last=safePopenOut(command, ans, EXPAND_BUF-1);
        if(last<0) {
                perror("Pipe read error");
                exit(1);
        }
        if(last)
                ans[last-1] = '\0';
        else
                strncpy(ans, input, EXPAND_BUF-1);
        return ans;
}