#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <assert.h>

int
main(int argc, char *argv[])
{
    int fd = -1, ret = -1, len = 0;
    char *path = NULL,
         buf[128] =
             {
                 0,
             },
         *cmd = NULL;
    struct stat stbuf = {
        0,
    };
    int write_to_child[2] =
        {
            0,
        },
        write_to_parent[2] = {
            0,
        };

    path = argv[1];
    cmd = argv[2];

    assert(argc == 3);

    ret = pipe(write_to_child);
    if (ret < 0) {
        fprintf(stderr,
                "creation of write-to-child pipe failed "
                "(%s)\n",
                strerror(errno));
        goto out;
    }

    ret = pipe(write_to_parent);
    if (ret < 0) {
        fprintf(stderr,
                "creation of write-to-parent pipe failed "
                "(%s)\n",
                strerror(errno));
        goto out;
    }

    ret = fork();
    switch (ret) {
        case 0:
            close(write_to_child[1]);
            close(write_to_parent[0]);

            /* child, wait for instructions to execute command */
            ret = read(write_to_child[0], buf, 128);
            if (ret < 0) {
                fprintf(stderr, "child: read on pipe failed (%s)\n",
                        strerror(errno));
                goto out;
            }

            system(cmd);

            ret = write(write_to_parent[1], "1", 2);
            if (ret < 0) {
                fprintf(stderr, "child: write to pipe failed (%s)\n",
                        strerror(errno));
                goto out;
            }
            break;

        case -1:
            fprintf(stderr, "fork failed (%s)\n", strerror(errno));
            goto out;

        default:
            close(write_to_parent[1]);
            close(write_to_child[0]);

            fd = open(path, O_CREAT | O_RDWR | O_APPEND, S_IRWXU);
            if (fd < 0) {
                fprintf(stderr, "open failed (%s)\n", strerror(errno));
                goto out;
            }

            len = strlen("test-content") + 1;
            ret = write(fd, "test-content", len);

            if (ret < len) {
                fprintf(stderr, "write failed %d (%s)\n", ret, strerror(errno));
            }

            ret = pread(fd, buf, 128, 0);
            if ((ret == len) && (strcmp(buf, "test-content") == 0)) {
                fprintf(stderr,
                        "read should've failed as previous "
                        "write would've failed with EDQUOT, but its "
                        "successful");
                ret = -1;
                goto out;
            }

            ret = write(write_to_child[1], "1", 2);
            if (ret < 0) {
                fprintf(stderr, "parent: write to pipe failed (%s)\n",
                        strerror(errno));
                goto out;
            }

            ret = read(write_to_parent[0], buf, 128);
            if (ret < 0) {
                fprintf(stderr, "parent: read from pipe failed (%s)\n",
                        strerror(errno));
                goto out;
            }

            /* this will force a sync on cached-write and now that quota
               limit is increased, sync will be successful. ignore return
               value as fstat would fail with EDQUOT (picked up from
               cached-write because of previous sync failure.
            */
            fstat(fd, &stbuf);

            ret = pread(fd, buf, 128, 0);
            if (ret != len) {
                fprintf(stderr,
                        "post cmd read failed %d (data:%s) "
                        "(error:%s)\n",
                        ret, buf, strerror(errno));
                goto out;
            }

            if (strcmp(buf, "test-content")) {
                fprintf(stderr, "wrong data (%s)\n", buf);
                goto out;
            }
    }

    ret = 0;

out:
    return ret;
}