ddstats.c

/* compilation: cc    -lnewt -o build/ddstats ddstats.c */
#include <assert.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <signal.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <poll.h>
#include <newt.h>

#define pabort(x)                               \
        do {                                    \
                perror(x);                      \
                abort();                        \
        } while (0);

#define fabort(fmt, args...)                            \
        do {                                            \
                fprintf(stderr, fmt "\n", ##args);      \
                abort();                                \
        } while (0);

int main(int argc, char **argv)
{
        pid_t child;
        int pipes[2];
        long unsigned filesize = 0;
        int i;

        for (i = 0; i < argc; i++)
                if (!strncmp("if=", argv[i], 3)) {
                        struct stat st;
                        char *eq = strchr(argv[i], '=');

                        if (!eq)
                                fabort("Can't find input file (if=*) on command line");

                        eq++;   /* forwards pointer to filename, after `=' */

                        if (stat(eq, &st))
                                pabort("stat");

                        if (S_ISLNK(st.st_mode)) {
                                int status;
                                char *tmp = strdup(eq);

                                eq = malloc(st.st_size);
                                readlink(tmp, eq, st.st_size); /* follow syslink */
                                free(tmp);
                                status = stat(eq, &st);
                                free(eq);
                                if (status)
                                        pabort("stat");
                                filesize = st.st_size;
                                break; /* get out loop */
                        } else if (S_ISREG(st.st_mode)) {
                                filesize = st.st_size;
                                break;
                        } else
                                fabort("%s is not a file or a symbolic link", eq);
                }

        assert(filesize > 0);

        if (pipe(pipes))
                pabort("pipe");

        child = fork();
        if (!child) {           /* child process */
                dup2(pipes[1], STDERR_FILENO);
                argv[0] = "dd";
                execvp(argv[0], argv);
        } else if (child == -1) {
                pabort("fork");
        } else {                  /* parent process */
                newtComponent form;
                newtComponent cancel;
                newtComponent progress;
                char line[64];
                FILE *fp = fdopen(pipes[0], "r");
                struct pollfd pfd = {
                        .fd = pipes[0],
                        .events = POLLIN,
                };

                memset(line, '\0', sizeof(line));
                sleep(1);       /* give dd time to install signal hanlder */

                newtInit();
                newtCls();
                newtCenteredWindow(64, 12, "DD PROGRESS");
                form = newtForm(NULL, NULL, 0);
                cancel = newtButton(28, 8, "cancel");
                progress = newtScale(4, 4, 56, filesize);
                newtFormAddComponent(form, progress);
                newtFormAddComponent(form, cancel);
                newtDrawForm(form);
                newtRefresh();

                while (!waitpid(child, NULL, WNOHANG)) { /* while child lives */

                        kill(child, SIGUSR1); /* send signal to write stats on stderr */

                        while (poll(&pfd, 1, 1000)) {
                                int status;
                                int bytes;

                                fgets(line, 64, fp);
                                if (!strstr(line, "bytes")) /* skip lines that doesn't match */
                                        continue;
                                status = sscanf(line, "%d bytes", &bytes);
                                if (status == 1)
                                        newtScaleSet(progress, bytes);
                                newtRefresh();
                        }
                }

                newtRunForm(form);
                newtFormDestroy(form);
                newtFinished();
        }

        return 0;
}