s3:smbd: change user_struct->vuid to uint64_t

[Samba/gebeck_regimport.git] / lib / ccan / failtest / failtest.c

/* Licensed under LGPL - see LICENSE file for details */
#include <ccan/failtest/failtest.h>
#include <stdarg.h>
#include <string.h>
#include <stdio.h>
#include <stdarg.h>
#include <ctype.h>
#include <err.h>
#include <unistd.h>
#include <poll.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/mman.h>
#include <sys/resource.h>
#include <signal.h>
#include <assert.h>
#include <ccan/time/time.h>
#include <ccan/read_write_all/read_write_all.h>
#include <ccan/failtest/failtest_proto.h>
#include <ccan/build_assert/build_assert.h>
#include <ccan/hash/hash.h>
#include <ccan/htable/htable_type.h>
#include <ccan/str/str.h>
#include <ccan/compiler/compiler.h>

enum failtest_result (*failtest_hook)(struct tlist_calls *);

static FILE *tracef = NULL, *warnf;
static int traceindent = 0;

unsigned int failtest_timeout_ms = 20000;

const char *failpath;
const char *debugpath;

enum info_type {
        WRITE,
        RELEASE_LOCKS,
        FAILURE,
        SUCCESS,
        UNEXPECTED
};

struct lock_info {
        int fd;
        /* end is inclusive: you can't have a 0-byte lock. */
        off_t start, end;
        int type;
};

/* We hash the call location together with its backtrace. */
static size_t hash_call(const struct failtest_call *call)
{
        return hash(call->file, strlen(call->file),
                    hash(&call->line, 1,
                         hash(call->backtrace, call->backtrace_num,
                              call->type)));
}

static bool call_eq(const struct failtest_call *call1,
                    const struct failtest_call *call2)
{
        unsigned int i;

        if (strcmp(call1->file, call2->file) != 0
            || call1->line != call2->line
            || call1->type != call2->type
            || call1->backtrace_num != call2->backtrace_num)
                return false;

        for (i = 0; i < call1->backtrace_num; i++)
                if (call1->backtrace[i] != call2->backtrace[i])
                        return false;

        return true;
}

/* Defines struct failtable. */
HTABLE_DEFINE_TYPE(struct failtest_call, (struct failtest_call *), hash_call,
                   call_eq, failtable);

bool (*failtest_exit_check)(struct tlist_calls *history);

/* The entire history of all calls. */
static struct tlist_calls history = TLIST_INIT(history);
/* If we're a child, the fd two write control info to the parent. */
static int control_fd = -1;
/* If we're a child, this is the first call we did ourselves. */
static struct failtest_call *our_history_start = NULL;
/* For printing runtime with --trace. */
static struct timeval start;
/* Set when failtest_hook returns FAIL_PROBE */
static bool probing = false;
/* Table to track duplicates. */
static struct failtable failtable;

/* Array of writes which our child did.  We report them on failure. */
static struct write_call *child_writes = NULL;
static unsigned int child_writes_num = 0;

/* fcntl locking info. */
static pid_t lock_owner;
static struct lock_info *locks = NULL;
static unsigned int lock_num = 0;

/* Our original pid, which we return to anyone who asks. */
static pid_t orig_pid;

/* Mapping from failtest_type to char. */
static const char info_to_arg[] = "mceoxprwfal";

/* Dummy call used for failtest_undo wrappers. */
static struct failtest_call unrecorded_call;

struct contents_saved {
        size_t count;
        off_t off;
        off_t old_len;
        char contents[1];
};

/* File contents, saved in this child only. */
struct saved_mmapped_file {
        struct saved_mmapped_file *next;
        struct failtest_call *opener;
        struct contents_saved *s;
};

static struct saved_mmapped_file *saved_mmapped_files;

#if HAVE_BACKTRACE
#include <execinfo.h>

static void **get_backtrace(unsigned int *num)
{
        static unsigned int max_back = 100;
        void **ret;

again:
        ret = malloc(max_back * sizeof(void *));
        *num = backtrace(ret, max_back);
        if (*num == max_back) {
                free(ret);
                max_back *= 2;
                goto again;
        }
        return ret;
}
#else
/* This will test slightly less, since will consider all of the same
 * calls as identical.  But, it's slightly faster! */
static void **get_backtrace(unsigned int *num)
{
        *num = 0;
        return NULL;
}
#endif /* HAVE_BACKTRACE */

static struct failtest_call *add_history_(enum failtest_call_type type,
                                          bool can_leak,
                                          const char *file,
                                          unsigned int line,
                                          const void *elem,
                                          size_t elem_size)
{
        struct failtest_call *call;

        /* NULL file is how we suppress failure. */
        if (!file)
                return &unrecorded_call;

        call = malloc(sizeof *call);
        call->type = type;
        call->can_leak = can_leak;
        call->file = file;
        call->line = line;
        call->cleanup = NULL;
        call->backtrace = get_backtrace(&call->backtrace_num);
        memcpy(&call->u, elem, elem_size);
        tlist_add_tail(&history, call, list);
        return call;
}

#define add_history(type, can_leak, file, line, elem)           \
        add_history_((type), (can_leak), (file), (line), (elem), sizeof(*(elem)))

/* We do a fake call inside a sizeof(), to check types. */
#define set_cleanup(call, clean, type)                  \
        (call)->cleanup = (void *)((void)sizeof(clean((type *)NULL, false),1), (clean))

/* Dup the fd to a high value (out of the way I hope!), and close the old fd. */
static int move_fd_to_high(int fd)
{
        int i;
        struct rlimit lim;
        int max;

        if (getrlimit(RLIMIT_NOFILE, &lim) == 0) {
                max = lim.rlim_cur;
                printf("Max is %i\n", max);
        } else
                max = FD_SETSIZE;

        for (i = max - 1; i > fd; i--) {
                if (fcntl(i, F_GETFL) == -1 && errno == EBADF) {
                        if (dup2(fd, i) == -1) {
                                warn("Failed to dup fd %i to %i", fd, i);
                                continue;
                        }
                        close(fd);
                        return i;
                }
        }
        /* Nothing?  Really?  Er... ok? */
        return fd;
}

static bool read_write_info(int fd)
{
        struct write_call *w;
        char *buf;

        /* We don't need all of this, but it's simple. */
        child_writes = realloc(child_writes,
                               (child_writes_num+1) * sizeof(child_writes[0]));
        w = &child_writes[child_writes_num];
        if (!read_all(fd, w, sizeof(*w)))
                return false;

        w->buf = buf = malloc(w->count);
        if (!read_all(fd, buf, w->count))
                return false;

        child_writes_num++;
        return true;
}

static char *failpath_string(void)
{
        struct failtest_call *i;
        char *ret = strdup("");
        unsigned len = 0;

        /* Inefficient, but who cares? */
        tlist_for_each(&history, i, list) {
                ret = realloc(ret, len + 2);
                ret[len] = info_to_arg[i->type];
                if (i->fail)
                        ret[len] = toupper(ret[len]);
                ret[++len] = '\0';
        }
        return ret;
}

static void do_warn(int e, const char *fmt, va_list ap)
{
        char *p = failpath_string();

        vfprintf(warnf, fmt, ap);
        if (e != -1)
                fprintf(warnf, ": %s", strerror(e));
        fprintf(warnf, " [%s]\n", p);
        free(p);
}

static void fwarn(const char *fmt, ...)
{
        va_list ap;
        int e = errno;

        va_start(ap, fmt);
        do_warn(e, fmt, ap);
        va_end(ap);
}


static void fwarnx(const char *fmt, ...)
{
        va_list ap;

        va_start(ap, fmt);
        do_warn(-1, fmt, ap);
        va_end(ap);
}

static void tell_parent(enum info_type type)
{
        if (control_fd != -1)
                write_all(control_fd, &type, sizeof(type));
}

static void child_fail(const char *out, size_t outlen, const char *fmt, ...)
{
        va_list ap;
        char *path = failpath_string();

        va_start(ap, fmt);
        vfprintf(stderr, fmt, ap);
        va_end(ap);

        fprintf(stderr, "%.*s", (int)outlen, out);
        printf("To reproduce: --failpath=%s\n", path);
        free(path);
        tell_parent(FAILURE);
        exit(1);
}

static void PRINTF_FMT(1, 2) trace(const char *fmt, ...)
{
        va_list ap;
        unsigned int i;
        char *p;
        static int idx;

        if (!tracef)
                return;

        for (i = 0; i < traceindent; i++)
                fprintf(tracef, "  ");

        p = failpath_string();
        fprintf(tracef, "%i: %u: %s ", idx++, getpid(), p);
        va_start(ap, fmt);
        vfprintf(tracef, fmt, ap);
        va_end(ap);
        free(p);
}

static pid_t child;

static void hand_down(int signum)
{
        kill(child, signum);
}

static void release_locks(void)
{
        /* Locks were never acquired/reacquired? */
        if (lock_owner == 0)
                return;

        /* We own them?  Release them all. */
        if (lock_owner == getpid()) {
                unsigned int i;
                struct flock fl;
                fl.l_type = F_UNLCK;
                fl.l_whence = SEEK_SET;
                fl.l_start = 0;
                fl.l_len = 0;

                trace("Releasing %u locks\n", lock_num);
                for (i = 0; i < lock_num; i++)
                        fcntl(locks[i].fd, F_SETLK, &fl);
        } else {
                /* Our parent must have them; pass request up. */
                enum info_type type = RELEASE_LOCKS;
                assert(control_fd != -1);
                write_all(control_fd, &type, sizeof(type));
        }
        lock_owner = 0;
}

/* off_t is a signed type.  Getting its max is non-trivial. */
static off_t off_max(void)
{
        BUILD_ASSERT(sizeof(off_t) == 4 || sizeof(off_t) == 8);
        if (sizeof(off_t) == 4)
                return (off_t)0x7FFFFFF;
        else
                return (off_t)0x7FFFFFFFFFFFFFFULL;
}

static void get_locks(void)
{
        unsigned int i;
        struct flock fl;

        if (lock_owner == getpid())
                return;

        if (lock_owner != 0) {
                enum info_type type = RELEASE_LOCKS;
                assert(control_fd != -1);
                trace("Asking parent to release locks\n");
                write_all(control_fd, &type, sizeof(type));
        }

        fl.l_whence = SEEK_SET;

        for (i = 0; i < lock_num; i++) {
                fl.l_type = locks[i].type;
                fl.l_start = locks[i].start;
                if (locks[i].end == off_max())
                        fl.l_len = 0;
                else
                        fl.l_len = locks[i].end - locks[i].start + 1;

                if (fcntl(locks[i].fd, F_SETLKW, &fl) != 0)
                        abort();
        }
        trace("Acquired %u locks\n", lock_num);
        lock_owner = getpid();
}


static struct contents_saved *save_contents(const char *filename,
                                            int fd, size_t count, off_t off,
                                            const char *why)
{
        struct contents_saved *s = malloc(sizeof(*s) + count);
        ssize_t ret;

        s->off = off;

        ret = pread(fd, s->contents, count, off);
        if (ret < 0) {
                fwarn("failtest_write: failed to save old contents!");
                s->count = 0;
        } else
                s->count = ret;

        /* Use lseek to get the size of file, but we have to restore
         * file offset */
        off = lseek(fd, 0, SEEK_CUR);
        s->old_len = lseek(fd, 0, SEEK_END);
        lseek(fd, off, SEEK_SET);

        trace("Saving %p %s %zu@%llu after %s (filelength %llu) via fd %i\n",
              s, filename, s->count, (long long)s->off, why,
              (long long)s->old_len, fd);
        return s;
}

static void restore_contents(struct failtest_call *opener,
                             struct contents_saved *s,
                             bool restore_offset,
                             const char *caller)
{
        int fd;

        /* The top parent doesn't need to restore. */
        if (control_fd == -1)
                return;

        /* Has the fd been closed? */
        if (opener->u.open.closed) {
                /* Reopen, replace fd, close silently as we clean up. */
                fd = open(opener->u.open.pathname, O_RDWR);
                if (fd < 0) {
                        fwarn("failtest: could not reopen %s to clean up %s!",
                              opener->u.open.pathname, caller);
                        return;
                }
                /* Make it clearly distinguisable from a "normal" fd. */
                fd = move_fd_to_high(fd);
                trace("Reopening %s to restore it (was fd %i, now %i)\n",
                      opener->u.open.pathname, opener->u.open.ret, fd);
                opener->u.open.ret = fd;
                opener->u.open.closed = false;
        }
        fd = opener->u.open.ret;

        trace("Restoring %p %s %zu@%llu after %s (filelength %llu) via fd %i\n",
              s, opener->u.open.pathname, s->count, (long long)s->off, caller,
              (long long)s->old_len, fd);
        if (pwrite(fd, s->contents, s->count, s->off) != s->count) {
                fwarn("failtest: write failed cleaning up %s for %s!",
                      opener->u.open.pathname, caller);
        }

        if (ftruncate(fd, s->old_len) != 0) {
                fwarn("failtest_write: truncate failed cleaning up %s for %s!",
                      opener->u.open.pathname, caller);
        }

        if (restore_offset) {
                trace("Restoring offset of fd %i to %llu\n",
                      fd, (long long)s->off);
                lseek(fd, s->off, SEEK_SET);
        }
}

/* We save/restore most things on demand, but always do mmaped files. */
static void save_mmapped_files(void)
{
        struct failtest_call *i;
        trace("Saving mmapped files in child\n");

        tlist_for_each_rev(&history, i, list) {
                struct mmap_call *m = &i->u.mmap;
                struct saved_mmapped_file *s;

                if (i->type != FAILTEST_MMAP)
                        continue;

                /* FIXME: We only handle mmapped files where fd is still open. */
                if (m->opener->u.open.closed)
                        continue;

                s = malloc(sizeof *s);
                s->s = save_contents(m->opener->u.open.pathname,
                                     m->fd, m->length, m->offset,
                                     "mmapped file before fork");
                s->opener = m->opener;
                s->next = saved_mmapped_files;
                saved_mmapped_files = s;
        }
}

static void free_mmapped_files(bool restore)
{
        trace("%s mmapped files in child\n",
              restore ? "Restoring" : "Discarding");
        while (saved_mmapped_files) {
                struct saved_mmapped_file *next = saved_mmapped_files->next;
                if (restore)
                        restore_contents(saved_mmapped_files->opener,
                                         saved_mmapped_files->s, false,
                                         "saved mmap");
                free(saved_mmapped_files->s);
                free(saved_mmapped_files);
                saved_mmapped_files = next;
        }
}

/* Returns a FAILTEST_OPEN, FAILTEST_PIPE or NULL. */
static struct failtest_call *opener_of(int fd)
{
        struct failtest_call *i;

        /* Don't get confused and match genuinely failed opens. */
        if (fd < 0)
                return NULL;

        /* Figure out the set of live fds. */
        tlist_for_each_rev(&history, i, list) {
                if (i->fail)
                        continue;
                switch (i->type) {
                case FAILTEST_CLOSE:
                        if (i->u.close.fd == fd) {
                                return NULL;
                        }
                        break;
                case FAILTEST_OPEN:
                        if (i->u.open.ret == fd) {
                                if (i->u.open.closed)
                                        return NULL;
                                return i;
                        }
                        break;
                case FAILTEST_PIPE:
                        if (i->u.pipe.fds[0] == fd || i->u.pipe.fds[1] == fd) {
                                return i;
                        }
                        break;
                default:
                        break;
                }
        }

        /* FIXME: socket, dup, etc are untracked! */
        return NULL;
}

static void free_call(struct failtest_call *call)
{
        /* We don't do this in cleanup: needed even for failed opens. */
        if (call->type == FAILTEST_OPEN)
                free((char *)call->u.open.pathname);
        free(call->backtrace);
        tlist_del_from(&history, call, list);
        free(call);
}

/* Free up memory, so valgrind doesn't report leaks. */
static void free_everything(void)
{
        struct failtest_call *i;

        while ((i = tlist_top(&history, list)) != NULL)
                free_call(i);

        failtable_clear(&failtable);
}

static NORETURN void failtest_cleanup(bool forced_cleanup, int status)
{
        struct failtest_call *i;
        bool restore = true;

        /* For children, we don't care if they "failed" the testing. */
        if (control_fd != -1)
                status = 0;
        else
                /* We don't restore contents for original parent. */
                restore = false;

        /* Cleanup everything, in reverse order. */
        tlist_for_each_rev(&history, i, list) {
                /* Don't restore things our parent did. */
                if (i == our_history_start)
                        restore = false;

                if (i->fail)
                        continue;

                if (i->cleanup)
                        i->cleanup(&i->u, restore);

                /* But their program shouldn't leak, even on failure. */
                if (!forced_cleanup && i->can_leak) {
                        printf("Leak at %s:%u: --failpath=%s\n",
                               i->file, i->line, failpath_string());
                        status = 1;
                }
        }

        /* Put back mmaped files the way our parent (if any) expects. */
        free_mmapped_files(true);

        free_everything();
        if (status == 0)
                tell_parent(SUCCESS);
        else
                tell_parent(FAILURE);
        exit(status);
}

static bool following_path(void)
{
        if (!failpath)
                return false;
        /* + means continue after end, like normal. */
        if (*failpath == '+') {
                failpath = NULL;
                return false;
        }
        return true;
}

static bool follow_path(struct failtest_call *call)
{
        if (*failpath == '\0') {
                /* Continue, but don't inject errors. */
                return call->fail = false;
        }

        if (tolower((unsigned char)*failpath) != info_to_arg[call->type])
                errx(1, "Failpath expected '%s' got '%c'\n",
                     failpath, info_to_arg[call->type]);
        call->fail = cisupper(*(failpath++));
                        if (call->fail)
                                call->can_leak = false;
        return call->fail;
}

static bool should_fail(struct failtest_call *call)
{
        int status;
        int control[2], output[2];
        enum info_type type = UNEXPECTED;
        char *out = NULL;
        size_t outlen = 0;
        struct failtest_call *dup;

        if (call == &unrecorded_call)
                return false;

        if (following_path())
                return follow_path(call);

        /* Attach debugger if they asked for it. */
        if (debugpath) {
                char *path;

                /* Pretend this last call matches whatever path wanted:
                 * keeps valgrind happy. */
                call->fail = cisupper(debugpath[strlen(debugpath)-1]);
                path = failpath_string();

                if (streq(path, debugpath)) {
                        char str[80];

                        /* Don't timeout. */
                        signal(SIGUSR1, SIG_IGN);
                        sprintf(str, "xterm -e gdb /proc/%d/exe %d &",
                                getpid(), getpid());
                        if (system(str) == 0)
                                sleep(5);
                } else {
                        /* Ignore last character: could be upper or lower. */
                        path[strlen(path)-1] = '\0';
                        if (!strstarts(debugpath, path)) {
                                fprintf(stderr,
                                        "--debugpath not followed: %s\n", path);
                                debugpath = NULL;
                        }
                }
                free(path);
        }

        /* Are we probing?  If so, we never fail twice. */
        if (probing) {
                trace("Not failing %c due to FAIL_PROBE return\n",
                      info_to_arg[call->type]);
                return call->fail = false;
        }

        /* Don't fail more than once in the same place. */
        dup = failtable_get(&failtable, call);
        if (dup) {
                trace("Not failing %c due to duplicate\n",
                      info_to_arg[call->type]);
                return call->fail = false;
        }

        if (failtest_hook) {
                switch (failtest_hook(&history)) {
                case FAIL_OK:
                        break;
                case FAIL_PROBE:
                        probing = true;
                        break;
                case FAIL_DONT_FAIL:
                        trace("Not failing %c due to failhook return\n",
                              info_to_arg[call->type]);
                        call->fail = false;
                        return false;
                default:
                        abort();
                }
        }

        /* Add it to our table of calls. */
        failtable_add(&failtable, call);

        /* We're going to fail in the child. */
        call->fail = true;
        if (pipe(control) != 0 || pipe(output) != 0)
                err(1, "opening pipe");

        /* Move out the way, to high fds. */
        control[0] = move_fd_to_high(control[0]);
        control[1] = move_fd_to_high(control[1]);
        output[0] = move_fd_to_high(output[0]);
        output[1] = move_fd_to_high(output[1]);

        /* Prevent double-printing (in child and parent) */
        fflush(stdout);
        fflush(warnf);
        if (tracef)
                fflush(tracef);
        child = fork();
        if (child == -1)
                err(1, "forking failed");

        if (child == 0) {
                traceindent++;
                if (tracef) {
                        struct timeval diff;
                        const char *p;
                        char *failpath;
                        struct failtest_call *c;

                        c = tlist_tail(&history, list);
                        diff = time_sub(time_now(), start);
                        failpath = failpath_string();
                        p = strrchr(c->file, '/');
                        if (p)
                                p++;
                        else
                                p = c->file;
                        trace("%u->%u (%u.%02u): %s (%s:%u)\n",
                              getppid(), getpid(),
                              (int)diff.tv_sec, (int)diff.tv_usec / 10000,
                              failpath, p, c->line);
                        free(failpath);
                }
                /* From here on, we have to clean up! */
                our_history_start = tlist_tail(&history, list);
                close(control[0]);
                close(output[0]);
                /* Don't swallow stderr if we're tracing. */
                if (!tracef) {
                        dup2(output[1], STDOUT_FILENO);
                        dup2(output[1], STDERR_FILENO);
                        if (output[1] != STDOUT_FILENO
                            && output[1] != STDERR_FILENO)
                                close(output[1]);
                }
                control_fd = move_fd_to_high(control[1]);

                /* Forget any of our parent's saved files. */
                free_mmapped_files(false);

                /* Now, save any files we need to. */
                save_mmapped_files();

                /* Failed calls can't leak. */
                call->can_leak = false;

                return true;
        }

        signal(SIGUSR1, hand_down);

        close(control[1]);
        close(output[1]);

        /* We grab output so we can display it; we grab writes so we
         * can compare. */
        do {
                struct pollfd pfd[2];
                int ret;

                pfd[0].fd = output[0];
                pfd[0].events = POLLIN|POLLHUP;
                pfd[1].fd = control[0];
                pfd[1].events = POLLIN|POLLHUP;

                if (type == SUCCESS)
                        ret = poll(pfd, 1, failtest_timeout_ms);
                else
                        ret = poll(pfd, 2, failtest_timeout_ms);

                if (ret == 0)
                        hand_down(SIGUSR1);
                if (ret < 0) {
                        if (errno == EINTR)
                                continue;
                        err(1, "Poll returned %i", ret);
                }

                if (pfd[0].revents & POLLIN) {
                        ssize_t len;

                        out = realloc(out, outlen + 8192);
                        len = read(output[0], out + outlen, 8192);
                        outlen += len;
                } else if (type != SUCCESS && (pfd[1].revents & POLLIN)) {
                        if (read_all(control[0], &type, sizeof(type))) {
                                if (type == WRITE) {
                                        if (!read_write_info(control[0]))
                                                break;
                                } else if (type == RELEASE_LOCKS) {
                                        release_locks();
                                        /* FIXME: Tell them we're done... */
                                }
                        }
                } else if (pfd[0].revents & POLLHUP) {
                        break;
                }
        } while (type != FAILURE);

        close(output[0]);
        close(control[0]);
        waitpid(child, &status, 0);
        if (!WIFEXITED(status)) {
                if (WTERMSIG(status) == SIGUSR1)
                        child_fail(out, outlen, "Timed out");
                else
                        child_fail(out, outlen, "Killed by signal %u: ",
                                   WTERMSIG(status));
        }
        /* Child printed failure already, just pass up exit code. */
        if (type == FAILURE) {
                fprintf(stderr, "%.*s", (int)outlen, out);
                tell_parent(type);
                exit(WEXITSTATUS(status) ? WEXITSTATUS(status) : 1);
        }
        if (WEXITSTATUS(status) != 0)
                child_fail(out, outlen, "Exited with status %i: ",
                           WEXITSTATUS(status));

        free(out);
        signal(SIGUSR1, SIG_DFL);

        /* Only child does probe. */
        probing = false;

        /* We continue onwards without failing. */
        call->fail = false;
        return false;
}

static void cleanup_calloc(struct calloc_call *call, bool restore)
{
        trace("undoing calloc %p\n", call->ret);
        free(call->ret);
}

void *failtest_calloc(size_t nmemb, size_t size,
                      const char *file, unsigned line)
{
        struct failtest_call *p;
        struct calloc_call call;
        call.nmemb = nmemb;
        call.size = size;
        p = add_history(FAILTEST_CALLOC, true, file, line, &call);

        if (should_fail(p)) {
                p->u.calloc.ret = NULL;
                p->error = ENOMEM;
        } else {
                p->u.calloc.ret = calloc(nmemb, size);
                set_cleanup(p, cleanup_calloc, struct calloc_call);
        }
        trace("calloc %zu x %zu %s:%u -> %p\n",
              nmemb, size, file, line, p->u.calloc.ret);
        errno = p->error;
        return p->u.calloc.ret;
}

static void cleanup_malloc(struct malloc_call *call, bool restore)
{
        trace("undoing malloc %p\n", call->ret);
        free(call->ret);
}

void *failtest_malloc(size_t size, const char *file, unsigned line)
{
        struct failtest_call *p;
        struct malloc_call call;
        call.size = size;

        p = add_history(FAILTEST_MALLOC, true, file, line, &call);
        if (should_fail(p)) {
                p->u.malloc.ret = NULL;
                p->error = ENOMEM;
        } else {
                p->u.malloc.ret = malloc(size);
                set_cleanup(p, cleanup_malloc, struct malloc_call);
        }
        trace("malloc %zu %s:%u -> %p\n",
              size, file, line, p->u.malloc.ret);
        errno = p->error;
        return p->u.malloc.ret;
}

static void cleanup_realloc(struct realloc_call *call, bool restore)
{
        trace("undoing realloc %p\n", call->ret);
        free(call->ret);
}

/* Walk back and find out if we got this ptr from a previous routine. */
static void fixup_ptr_history(void *ptr, const char *why)
{
        struct failtest_call *i;

        /* Start at end of history, work back. */
        tlist_for_each_rev(&history, i, list) {
                switch (i->type) {
                case FAILTEST_REALLOC:
                        if (i->u.realloc.ret == ptr) {
                                trace("found realloc %p %s:%u matching %s\n",
                                      ptr, i->file, i->line, why);
                                i->cleanup = NULL;
                                i->can_leak = false;
                                return;
                        }
                        break;
                case FAILTEST_MALLOC:
                        if (i->u.malloc.ret == ptr) {
                                trace("found malloc %p %s:%u matching %s\n",
                                      ptr, i->file, i->line, why);
                                i->cleanup = NULL;
                                i->can_leak = false;
                                return;
                        }
                        break;
                case FAILTEST_CALLOC:
                        if (i->u.calloc.ret == ptr) {
                                trace("found calloc %p %s:%u matching %s\n",
                                      ptr, i->file, i->line, why);
                                i->cleanup = NULL;
                                i->can_leak = false;
                                return;
                        }
                        break;
                default:
                        break;
                }
        }
        trace("Did not find %p matching %s\n", ptr, why);
}

void *failtest_realloc(void *ptr, size_t size, const char *file, unsigned line)
{
        struct failtest_call *p;
        struct realloc_call call;
        call.size = size;
        p = add_history(FAILTEST_REALLOC, true, file, line, &call);

        /* FIXME: Try one child moving allocation, one not. */
        if (should_fail(p)) {
                p->u.realloc.ret = NULL;
                p->error = ENOMEM;
        } else {
                /* Don't catch this one in the history fixup... */
                p->u.realloc.ret = NULL;
                fixup_ptr_history(ptr, "realloc");
                p->u.realloc.ret = realloc(ptr, size);
                set_cleanup(p, cleanup_realloc, struct realloc_call);
        }
        trace("realloc %p %s:%u -> %p\n",
              ptr, file, line, p->u.realloc.ret);
        errno = p->error;
        return p->u.realloc.ret;
}

/* FIXME: Record free, so we can terminate fixup_ptr_history correctly.
 * If there's an alloc we don't see, it could get confusing if it matches
 * a previous allocation we did see. */
void failtest_free(void *ptr)
{
        fixup_ptr_history(ptr, "free");
        trace("free %p\n", ptr);
        free(ptr);
}


static struct contents_saved *save_file(const char *pathname)
{
        int fd;
        struct contents_saved *s;

        fd = open(pathname, O_RDONLY);
        if (fd < 0)
                return NULL;

        s = save_contents(pathname, fd, lseek(fd, 0, SEEK_END), 0,
                          "open with O_TRUNC");
        close(fd);
        return s;
}

/* Optimization: don't create a child for an open which *we know*
 * would fail anyway. */
static bool open_would_fail(const char *pathname, int flags)
{
        if ((flags & O_ACCMODE) == O_RDONLY)
                return access(pathname, R_OK) != 0;
        if (!(flags & O_CREAT)) {
                if ((flags & O_ACCMODE) == O_WRONLY)
                        return access(pathname, W_OK) != 0;
                if ((flags & O_ACCMODE) == O_RDWR)
                        return access(pathname, W_OK) != 0
                                || access(pathname, R_OK) != 0;
        }
        /* FIXME: We could check if it exists, for O_CREAT|O_EXCL */
        return false;
}

static void cleanup_open(struct open_call *call, bool restore)
{
        if (restore && call->saved)
                restore_contents(container_of(call, struct failtest_call,
                                              u.open),
                                 call->saved, false, "open with O_TRUNC");
        if (!call->closed) {
                trace("Cleaning up open %s by closing fd %i\n",
                      call->pathname, call->ret);
                close(call->ret);
                call->closed = true;
        }
        free(call->saved);
}

int failtest_open(const char *pathname,
                  const char *file, unsigned line, ...)
{
        struct failtest_call *p;
        struct open_call call;
        va_list ap;

        call.pathname = strdup(pathname);
        va_start(ap, line);
        call.flags = va_arg(ap, int);
        call.always_save = false;
        call.closed = false;
        if (call.flags & O_CREAT) {
                call.mode = va_arg(ap, int);
                va_end(ap);
        }
        p = add_history(FAILTEST_OPEN, true, file, line, &call);
        /* Avoid memory leak! */
        if (p == &unrecorded_call)
                free((char *)call.pathname);

        if (should_fail(p)) {
                /* Don't bother inserting failures that would happen anyway. */
                if (open_would_fail(pathname, call.flags)) {
                        trace("Open would have failed anyway: stopping\n");
                        failtest_cleanup(true, 0);
                }
                p->u.open.ret = -1;
                /* FIXME: Play with error codes? */
                p->error = EACCES;
        } else {
                /* Save the old version if they're truncating it. */
                if (call.flags & O_TRUNC)
                        p->u.open.saved = save_file(pathname);
                else
                        p->u.open.saved = NULL;
                p->u.open.ret = open(pathname, call.flags, call.mode);
                if (p->u.open.ret == -1) {
                        p->u.open.closed = true;
                        p->can_leak = false;
                } else {
                        set_cleanup(p, cleanup_open, struct open_call);
                }
        }
        trace("open %s %s:%u -> %i (opener %p)\n",
              pathname, file, line, p->u.open.ret, &p->u.open);
        errno = p->error;
        return p->u.open.ret;
}

static void cleanup_mmap(struct mmap_call *mmap, bool restore)
{
        trace("cleaning up mmap @%p (opener %p)\n",
              mmap->ret, mmap->opener);
        if (restore)
                restore_contents(mmap->opener, mmap->saved, false, "mmap");
        free(mmap->saved);
}

void *failtest_mmap(void *addr, size_t length, int prot, int flags,
                    int fd, off_t offset, const char *file, unsigned line)
{
        struct failtest_call *p;
        struct mmap_call call;

        call.addr = addr;
        call.length = length;
        call.prot = prot;
        call.flags = flags;
        call.offset = offset;
        call.fd = fd;
        call.opener = opener_of(fd);

        /* If we don't know what file it was, don't fail. */
        if (!call.opener) {
                if (fd != -1) {
                        fwarnx("failtest_mmap: couldn't figure out source for"
                               " fd %i at %s:%u", fd, file, line);
                }
                addr = mmap(addr, length, prot, flags, fd, offset);
                trace("mmap of fd %i -> %p (opener = NULL)\n", fd, addr);
                return addr;
        }

        p = add_history(FAILTEST_MMAP, false, file, line, &call);
        if (should_fail(p)) {
                p->u.mmap.ret = MAP_FAILED;
                p->error = ENOMEM;
        } else {
                p->u.mmap.ret = mmap(addr, length, prot, flags, fd, offset);
                /* Save contents if we're writing to a normal file */
                if (p->u.mmap.ret != MAP_FAILED
                    && (prot & PROT_WRITE)
                    && call.opener->type == FAILTEST_OPEN) {
                        const char *fname = call.opener->u.open.pathname;
                        p->u.mmap.saved = save_contents(fname, fd, length,
                                                        offset, "being mmapped");
                        set_cleanup(p, cleanup_mmap, struct mmap_call);
                }
        }
        trace("mmap of fd %i %s:%u -> %p (opener = %p)\n",
              fd, file, line, addr, call.opener);
        errno = p->error;
        return p->u.mmap.ret;
}

/* Since OpenBSD can't handle adding args, we use this file and line.
 * This will make all mmaps look the same, reducing coverage. */
void *failtest_mmap_noloc(void *addr, size_t length, int prot, int flags,
                          int fd, off_t offset)
{
        return failtest_mmap(addr, length, prot, flags, fd, offset,
                             __FILE__, __LINE__);
}

static void cleanup_pipe(struct pipe_call *call, bool restore)
{
        trace("cleaning up pipe fd=%i%s,%i%s\n",
              call->fds[0], call->closed[0] ? "(already closed)" : "",
              call->fds[1], call->closed[1] ? "(already closed)" : "");
        if (!call->closed[0])
                close(call->fds[0]);
        if (!call->closed[1])
                close(call->fds[1]);
}

int failtest_pipe(int pipefd[2], const char *file, unsigned line)
{
        struct failtest_call *p;
        struct pipe_call call;

        p = add_history(FAILTEST_PIPE, true, file, line, &call);
        if (should_fail(p)) {
                p->u.open.ret = -1;
                /* FIXME: Play with error codes? */
                p->error = EMFILE;
        } else {
                p->u.pipe.ret = pipe(p->u.pipe.fds);
                p->u.pipe.closed[0] = p->u.pipe.closed[1] = false;
                set_cleanup(p, cleanup_pipe, struct pipe_call);
        }

        trace("pipe %s:%u -> %i,%i\n", file, line,
              p->u.pipe.ret ? -1 : p->u.pipe.fds[0],
              p->u.pipe.ret ? -1 : p->u.pipe.fds[1]);

        /* This causes valgrind to notice if they use pipefd[] after failure */
        memcpy(pipefd, p->u.pipe.fds, sizeof(p->u.pipe.fds));
        errno = p->error;
        return p->u.pipe.ret;
}

static void cleanup_read(struct read_call *call, bool restore)
{
        if (restore) {
                trace("cleaning up read on fd %i: seeking to %llu\n",
                      call->fd, (long long)call->off);

                /* Read (not readv!) moves file offset! */
                if (lseek(call->fd, call->off, SEEK_SET) != call->off) {
                        fwarn("Restoring lseek pointer failed (read)");
                }
        }
}

static ssize_t failtest_add_read(int fd, void *buf, size_t count, off_t off,
                                 bool is_pread, const char *file, unsigned line)
{
        struct failtest_call *p;
        struct read_call call;
        call.fd = fd;
        call.buf = buf;
        call.count = count;
        call.off = off;
        p = add_history(FAILTEST_READ, false, file, line, &call);

        /* FIXME: Try partial read returns. */
        if (should_fail(p)) {
                p->u.read.ret = -1;
                p->error = EIO;
        } else {
                if (is_pread)
                        p->u.read.ret = pread(fd, buf, count, off);
                else {
                        p->u.read.ret = read(fd, buf, count);
                        if (p->u.read.ret != -1)
                                set_cleanup(p, cleanup_read, struct read_call);
                }
        }
        trace("%sread %s:%u fd %i %zu@%llu -> %i\n",
              is_pread ? "p" : "", file, line, fd, count, (long long)off,
              p->u.read.ret);
        errno = p->error;
        return p->u.read.ret;
}

static void cleanup_write(struct write_call *write, bool restore)
{
        trace("cleaning up write on %s\n", write->opener->u.open.pathname);
        if (restore)
                restore_contents(write->opener, write->saved, !write->is_pwrite,
                                 "write");
        free(write->saved);
}

static ssize_t failtest_add_write(int fd, const void *buf,
                                  size_t count, off_t off,
                                  bool is_pwrite,
                                  const char *file, unsigned line)
{
        struct failtest_call *p;
        struct write_call call;

        call.fd = fd;
        call.buf = buf;
        call.count = count;
        call.off = off;
        call.is_pwrite = is_pwrite;
        call.opener = opener_of(fd);
        p = add_history(FAILTEST_WRITE, false, file, line, &call);

        /* If we're a child, we need to make sure we write the same thing
         * to non-files as the parent does, so tell it. */
        if (control_fd != -1 && off == (off_t)-1) {
                enum info_type type = WRITE;

                write_all(control_fd, &type, sizeof(type));
                write_all(control_fd, &p->u.write, sizeof(p->u.write));
                write_all(control_fd, buf, count);
        }

        /* FIXME: Try partial write returns. */
        if (should_fail(p)) {
                p->u.write.ret = -1;
                p->error = EIO;
        } else {
                bool is_file;
                assert(call.opener == p->u.write.opener);

                if (p->u.write.opener) {
                        is_file = (p->u.write.opener->type == FAILTEST_OPEN);
                } else {
                        /* We can't unwind it, so at least check same
                         * in parent and child. */
                        is_file = false;
                }

                /* FIXME: We assume same write order in parent and child */
                if (!is_file && child_writes_num != 0) {
                        if (child_writes[0].fd != fd)
                                errx(1, "Child wrote to fd %u, not %u?",
                                     child_writes[0].fd, fd);
                        if (child_writes[0].off != p->u.write.off)
                                errx(1, "Child wrote to offset %zu, not %zu?",
                                     (size_t)child_writes[0].off,
                                     (size_t)p->u.write.off);
                        if (child_writes[0].count != count)
                                errx(1, "Child wrote length %zu, not %zu?",
                                     child_writes[0].count, count);
                        if (memcmp(child_writes[0].buf, buf, count)) {
                                child_fail(NULL, 0,
                                           "Child wrote differently to"
                                           " fd %u than we did!\n", fd);
                        }
                        free((char *)child_writes[0].buf);
                        child_writes_num--;
                        memmove(&child_writes[0], &child_writes[1],
                                sizeof(child_writes[0]) * child_writes_num);

                        /* Child wrote it already. */
                        trace("write %s:%i on fd %i already done by child\n",
                              file, line, fd);
                        p->u.write.ret = count;
                        errno = p->error;
                        return p->u.write.ret;
                }

                if (is_file) {
                        p->u.write.saved = save_contents(call.opener->u.open.pathname,
                                                         fd, count, off,
                                                         "being overwritten");
                        set_cleanup(p, cleanup_write, struct write_call);
                }

                /* Though off is current seek ptr for write case, we need to
                 * move it.  write() does that for us. */
                if (p->u.write.is_pwrite)
                        p->u.write.ret = pwrite(fd, buf, count, off);
                else
                        p->u.write.ret = write(fd, buf, count);
        }
        trace("%swrite %s:%i %zu@%llu on fd %i -> %i\n",
              p->u.write.is_pwrite ? "p" : "",
              file, line, count, (long long)off, fd, p->u.write.ret);
        errno = p->error;
        return p->u.write.ret;
}

ssize_t failtest_pwrite(int fd, const void *buf, size_t count, off_t offset,
                        const char *file, unsigned line)
{
        return failtest_add_write(fd, buf, count, offset, true, file, line);
}

ssize_t failtest_write(int fd, const void *buf, size_t count,
                       const char *file, unsigned line)
{
        return failtest_add_write(fd, buf, count, lseek(fd, 0, SEEK_CUR), false,
                                  file, line);
}

ssize_t failtest_pread(int fd, void *buf, size_t count, off_t off,
                       const char *file, unsigned line)
{
        return failtest_add_read(fd, buf, count, off, true, file, line);
}

ssize_t failtest_read(int fd, void *buf, size_t count,
                      const char *file, unsigned line)
{
        return failtest_add_read(fd, buf, count, lseek(fd, 0, SEEK_CUR), false,
                                 file, line);
}

static struct lock_info *WARN_UNUSED_RESULT
add_lock(struct lock_info *locks, int fd, off_t start, off_t end, int type)
{
        unsigned int i;
        struct lock_info *l;

        for (i = 0; i < lock_num; i++) {
                l = &locks[i];

                if (l->fd != fd)
                        continue;
                /* Four cases we care about:
                 * Start overlap:
                 *      l =    |      |
                 *      new = |   |
                 * Mid overlap:
                 *      l =    |      |
                 *      new =    |  |
                 * End overlap:
                 *      l =    |      |
                 *      new =      |    |
                 * Total overlap:
                 *      l =    |      |
                 *      new = |         |
                 */
                if (start > l->start && end < l->end) {
                        /* Mid overlap: trim entry, add new one. */
                        off_t new_start, new_end;
                        new_start = end + 1;
                        new_end = l->end;
                        trace("splitting lock on fd %i from %llu-%llu"
                              " to %llu-%llu\n",
                              fd, (long long)l->start, (long long)l->end,
                              (long long)l->start, (long long)start - 1);
                        l->end = start - 1;
                        locks = add_lock(locks,
                                         fd, new_start, new_end, l->type);
                        l = &locks[i];
                } else if (start <= l->start && end >= l->end) {
                        /* Total overlap: eliminate entry. */
                        trace("erasing lock on fd %i %llu-%llu\n",
                              fd, (long long)l->start, (long long)l->end);
                        l->end = 0;
                        l->start = 1;
                } else if (end >= l->start && end < l->end) {
                        trace("trimming lock on fd %i from %llu-%llu"
                              " to %llu-%llu\n",
                              fd, (long long)l->start, (long long)l->end,
                              (long long)end + 1, (long long)l->end);
                        /* Start overlap: trim entry. */
                        l->start = end + 1;
                } else if (start > l->start && start <= l->end) {
                        trace("trimming lock on fd %i from %llu-%llu"
                              " to %llu-%llu\n",
                              fd, (long long)l->start, (long long)l->end,
                              (long long)l->start, (long long)start - 1);
                        /* End overlap: trim entry. */
                        l->end = start-1;
                }
                /* Nothing left?  Remove it. */
                if (l->end < l->start) {
                        trace("forgetting lock on fd %i\n", fd);
                        memmove(l, l + 1, (--lock_num - i) * sizeof(l[0]));
                        i--;
                }
        }

        if (type != F_UNLCK) {
                locks = realloc(locks, (lock_num + 1) * sizeof(*locks));
                l = &locks[lock_num++];
                l->fd = fd;
                l->start = start;
                l->end = end;
                l->type = type;
                trace("new lock on fd %i %llu-%llu\n",
                      fd, (long long)l->start, (long long)l->end);
        }
        return locks;
}

/* We trap this so we can record it: we don't fail it. */
int failtest_close(int fd, const char *file, unsigned line)
{
        struct close_call call;
        struct failtest_call *p, *opener;

        /* Do this before we add ourselves to history! */
        opener = opener_of(fd);

        call.fd = fd;
        p = add_history(FAILTEST_CLOSE, false, file, line, &call);
        p->fail = false;

        /* Consume close from failpath (shouldn't tell us to fail). */
        if (following_path()) {
                if (follow_path(p))
                        abort();
        }

        trace("close on fd %i\n", fd);
        if (fd < 0)
                return close(fd);

        /* Mark opener as not leaking, remove its cleanup function. */
        if (opener) {
                trace("close on fd %i found opener %p\n", fd, opener);
                if (opener->type == FAILTEST_PIPE) {
                        /* From a pipe? */
                        if (opener->u.pipe.fds[0] == fd) {
                                assert(!opener->u.pipe.closed[0]);
                                opener->u.pipe.closed[0] = true;
                        } else if (opener->u.pipe.fds[1] == fd) {
                                assert(!opener->u.pipe.closed[1]);
                                opener->u.pipe.closed[1] = true;
                        } else
                                abort();
                        opener->can_leak = (!opener->u.pipe.closed[0]
                                            || !opener->u.pipe.closed[1]);
                } else if (opener->type == FAILTEST_OPEN) {
                        opener->u.open.closed = true;
                        opener->can_leak = false;
                } else
                        abort();
        }

        /* Restore offset now, in case parent shared (can't do after close!). */
        if (control_fd != -1) {
                struct failtest_call *i;

                tlist_for_each_rev(&history, i, list) {
                        if (i == our_history_start)
                                break;
                        if (i == opener)
                                break;
                        if (i->type == FAILTEST_LSEEK && i->u.lseek.fd == fd) {
                                trace("close on fd %i undoes lseek\n", fd);
                                /* This seeks back. */
                                i->cleanup(&i->u, true);
                                i->cleanup = NULL;
                        } else if (i->type == FAILTEST_WRITE
                                   && i->u.write.fd == fd
                                   && !i->u.write.is_pwrite) {
                                trace("close on fd %i undoes write"
                                      " offset change\n", fd);
                                /* Write (not pwrite!) moves file offset! */
                                if (lseek(fd, i->u.write.off, SEEK_SET)
                                    != i->u.write.off) {
                                        fwarn("Restoring lseek pointer failed (write)");
                                }
                        } else if (i->type == FAILTEST_READ
                                   && i->u.read.fd == fd) {
                                /* preads don't *have* cleanups */
                                if (i->cleanup) {
                                        trace("close on fd %i undoes read"
                                              " offset change\n", fd);
                                        /* This seeks back. */
                                        i->cleanup(&i->u, true);
                                        i->cleanup = NULL;
                                }
                        }
                }
        }

        /* Close unlocks everything. */
        locks = add_lock(locks, fd, 0, off_max(), F_UNLCK);
        return close(fd);
}

/* Zero length means "to end of file" */
static off_t end_of(off_t start, off_t len)
{
        if (len == 0)
                return off_max();
        return start + len - 1;
}

/* FIXME: This only handles locks, really. */
int failtest_fcntl(int fd, const char *file, unsigned line, int cmd, ...)
{
        struct failtest_call *p;
        struct fcntl_call call;
        va_list ap;

        call.fd = fd;
        call.cmd = cmd;

        /* Argument extraction. */
        switch (cmd) {
        case F_SETFL:
        case F_SETFD:
                va_start(ap, cmd);
                call.arg.l = va_arg(ap, long);
                va_end(ap);
                trace("fcntl on fd %i F_SETFL/F_SETFD\n", fd);
                return fcntl(fd, cmd, call.arg.l);
        case F_GETFD:
        case F_GETFL:
                trace("fcntl on fd %i F_GETFL/F_GETFD\n", fd);
                return fcntl(fd, cmd);
        case F_GETLK:
                trace("fcntl on fd %i F_GETLK\n", fd);
                get_locks();
                va_start(ap, cmd);
                call.arg.fl = *va_arg(ap, struct flock *);
                va_end(ap);
                return fcntl(fd, cmd, &call.arg.fl);
        case F_SETLK:
        case F_SETLKW:
                trace("fcntl on fd %i F_SETLK%s\n",
                      fd, cmd == F_SETLKW ? "W" : "");
                va_start(ap, cmd);
                call.arg.fl = *va_arg(ap, struct flock *);
                va_end(ap);
                break;
        default:
                /* This means you need to implement it here. */
                err(1, "failtest: unknown fcntl %u", cmd);
        }

        p = add_history(FAILTEST_FCNTL, false, file, line, &call);

        if (should_fail(p)) {
                p->u.fcntl.ret = -1;
                if (p->u.fcntl.cmd == F_SETLK)
                        p->error = EAGAIN;
                else
                        p->error = EDEADLK;
        } else {
                get_locks();
                p->u.fcntl.ret = fcntl(p->u.fcntl.fd, p->u.fcntl.cmd,
                                       &p->u.fcntl.arg.fl);
                if (p->u.fcntl.ret == -1)
                        p->error = errno;
                else {
                        /* We don't handle anything else yet. */
                        assert(p->u.fcntl.arg.fl.l_whence == SEEK_SET);
                        locks = add_lock(locks,
                                         p->u.fcntl.fd,
                                         p->u.fcntl.arg.fl.l_start,
                                         end_of(p->u.fcntl.arg.fl.l_start,
                                                p->u.fcntl.arg.fl.l_len),
                                         p->u.fcntl.arg.fl.l_type);
                }
        }
        trace("fcntl on fd %i -> %i\n", fd, p->u.fcntl.ret);
        errno = p->error;
        return p->u.fcntl.ret;
}

static void cleanup_lseek(struct lseek_call *call, bool restore)
{
        if (restore) {
                trace("cleaning up lseek on fd %i -> %llu\n",
                      call->fd, (long long)call->old_off);
                if (lseek(call->fd, call->old_off, SEEK_SET) != call->old_off)
                        fwarn("Restoring lseek pointer failed");
        }
}

/* We trap this so we can undo it: we don't fail it. */
off_t failtest_lseek(int fd, off_t offset, int whence, const char *file,
                     unsigned int line)
{
        struct failtest_call *p;
        struct lseek_call call;
        call.fd = fd;
        call.offset = offset;
        call.whence = whence;
        call.old_off = lseek(fd, 0, SEEK_CUR);

        p = add_history(FAILTEST_LSEEK, false, file, line, &call);
        p->fail = false;

        /* Consume lseek from failpath. */
        if (failpath)
                if (should_fail(p))
                        abort();

        p->u.lseek.ret = lseek(fd, offset, whence);

        if (p->u.lseek.ret != (off_t)-1)
                set_cleanup(p, cleanup_lseek, struct lseek_call);

        trace("lseek %s:%u on fd %i from %llu to %llu%s\n",
              file, line, fd, (long long)call.old_off, (long long)offset,
              whence == SEEK_CUR ? " (from current off)" :
              whence == SEEK_END ? " (from end)" :
              whence == SEEK_SET ? "" : " (invalid whence)");
        return p->u.lseek.ret;
}


pid_t failtest_getpid(const char *file, unsigned line)
{
        /* You must call failtest_init first! */
        assert(orig_pid);
        return orig_pid;
}

void failtest_init(int argc, char *argv[])
{
        unsigned int i;

        orig_pid = getpid();

        warnf = fdopen(move_fd_to_high(dup(STDERR_FILENO)), "w");
        for (i = 1; i < argc; i++) {
                if (!strncmp(argv[i], "--failpath=", strlen("--failpath="))) {
                        failpath = argv[i] + strlen("--failpath=");
                } else if (strcmp(argv[i], "--trace") == 0) {
                        tracef = warnf;
                        failtest_timeout_ms = -1;
                } else if (!strncmp(argv[i], "--debugpath=",
                                    strlen("--debugpath="))) {
                        debugpath = argv[i] + strlen("--debugpath=");
                }
        }
        failtable_init(&failtable);
        start = time_now();
}

bool failtest_has_failed(void)
{
        return control_fd != -1;
}

void failtest_exit(int status)
{
        trace("failtest_exit with status %i\n", status);
        if (failtest_exit_check) {
                if (!failtest_exit_check(&history))
                        child_fail(NULL, 0, "failtest_exit_check failed\n");
        }

        failtest_cleanup(false, status);
}