diff options
Diffstat (limited to 'nq.c')
-rw-r--r-- | nq.c | 175 |
1 files changed, 175 insertions, 0 deletions
diff --git a/nq.c b/nq.c new file mode 100644 index 0000000..ab2e1ee --- /dev/null +++ b/nq.c @@ -0,0 +1,175 @@ +/* +##% gcc -Wall -g -o $STEM $FILE +*/ + +#include <sys/file.h> +#include <sys/stat.h> +#include <sys/types.h> +#include <sys/wait.h> + +#include <dirent.h> +#include <errno.h> +#include <fcntl.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <time.h> +#include <unistd.h> + +static void +quit(int sig) +{ + exit(0); +} + +#include <sys/time.h> +/* +char * +timestamp() { + struct timeval tv; + gettimeofday(&tv, NULL); + static char buf[10]; + + int64_t ms = tv.tv_sec * 1000 + tv.tv_usec / 1000; + + buf[9] = 0; + int i; + for (i = 8; i >= 0; i--) { + buf[i] = 'a' + (ms % 26); + ms /= 26; + } + + return buf; +} +*/ + +int +main(int argc, char *argv[]) +{ + pid_t child; + int lockfd; + char lockfile[128]; + int dirfd; + + struct timeval tv; + gettimeofday(&tv, NULL); + int64_t ms = tv.tv_sec * 1000 + tv.tv_usec / 1000; + + char *path = getenv("NQDIR"); + if (!path) + path = "."; + + dirfd = open(path, O_RDONLY); + if (dirfd < 0) { + perror("dir open"); + exit(111); + } + + child = fork(); + if (child == -1) { + perror("fork"); + exit(111); + } + + if (child > 0) { + // background + signal(SIGINT, quit); + pause(); + exit(0); + } + + child = fork(); + if (child == -1) { + perror("fork"); + exit(111); + } + if (child > 0) { + int status; + sprintf(lockfile, ",%lx.%d", ms, child); + + puts(lockfile); + + // signal parent to exit + kill(getppid(), SIGINT); + + wait(&status); + int fd; + fd = openat(dirfd, lockfile, O_RDWR | O_APPEND); + fchmod(fd, 0600); + if (WIFEXITED(status)) + dprintf(fd, "\n[exited with status %d.]\n", WEXITSTATUS(status)); + else + dprintf(fd, "\n[killed by signal %d.]\n", WTERMSIG(status)); + + exit(0); + } + + sprintf(lockfile, ".,%lx.%d", ms, getpid()); + lockfd = openat(dirfd, lockfile, O_CREAT | O_EXCL | O_RDWR | O_APPEND, 0600); + + if (lockfd < 0) { + perror("open"); + exit(222); + } + + flock(lockfd, LOCK_EX); + + // drop leading . + renameat(dirfd, lockfile, dirfd, lockfile+1); + + write(lockfd, "exec", 4); + int i; + for (i = 0; i < argc; i++) { + int j, l = strlen(argv[i]); + write(lockfd, " '", 2); + for (j = 0; j < l; j++) { + if (argv[i][j] == '\'') + write(lockfd, "'\\''", 4); + else + write(lockfd, argv[i]+j, 1); + } + write(lockfd, "'", 1); + } + + DIR *dir = fdopendir(dirfd); + if (!dir) { + perror("fdopendir"); + exit(111); + } + + struct dirent *ent; + +again: + while ((ent = readdir(dir))) { + if (ent->d_name[0] == ',' && strcmp(ent->d_name, lockfile+1) < 0) { + int f = openat(dirfd, ent->d_name, O_RDWR); + + if (flock(f, LOCK_EX | LOCK_NB) == -1 && errno == EWOULDBLOCK) { + flock(f, LOCK_EX); // sit it out + + rewinddir(dir); + goto again; + } + + fchmod(f, 0600); + close(f); + } + } + + closedir(dir); + + // ready to run + + write(lockfd, "\n", 1); + + fchmod(lockfd, 0700); + + dup2(lockfd, 2); + dup2(lockfd, 1); + close(lockfd); + close(dirfd); + + execvp(argv[1], argv+1); + + return 111; +} |