diff options
Diffstat (limited to 'src/libstddjb/cspawn.c')
| -rw-r--r-- | src/libstddjb/cspawn.c | 220 |
1 files changed, 220 insertions, 0 deletions
diff --git a/src/libstddjb/cspawn.c b/src/libstddjb/cspawn.c new file mode 100644 index 0000000..4db86e0 --- /dev/null +++ b/src/libstddjb/cspawn.c @@ -0,0 +1,220 @@ +/* ISC license. */ + +#include <skalibs/sysdeps.h> + +#include <errno.h> + +#include <skalibs/cspawn.h> + +#ifdef SKALIBS_HASPOSIXSPAWN + +#include <signal.h> +#include <stdlib.h> +#include <spawn.h> + +#include <skalibs/config.h> +#include <skalibs/djbunix.h> + +#ifdef SKALIBS_HASPOSIXSPAWNEARLYRETURN + +#include <sys/wait.h> + +#include <skalibs/allreadwrite.h> + +static inline pid_t cspawn_workaround (pid_t pid, int const *p) +{ + siginfo_t si ; + int e ; + ssize_t r ; + char c ; + + fd_close(p[1]) ; + r = fd_read(p[0], &c, 1) ; + fd_close(p[0]) ; + if (r == -1) return 0 ; + if (r) return (errno = EILSEQ, 0) ; /* child wrote, wtf */ + + do e = waitid(P_PID, pid, &si, WEXITED | WNOHANG | WNOWAIT) ; + while (e == -1 && errno == EINTR) ; + if (e == -1) return pid ; /* we're in trouble, but don't leak a child */ + if (!si.si_pid) return pid ; /* child is running */ + if (si.si_code != CLD_EXITED || si.si_status != 127) return pid ; /* child died after execve(), let caller handle it */ + /* + child exited 127, so either execve() failed, which is what we want to catch, + or it raced like a mofo, execve()d and then exited 127 on its own, in which + case, tough luck, it never existed. + */ + wait_pid(pid, 0) ; + return (errno = 0, 0) ; +} + +#endif + +pid_t cspawn (char const *prog, char const *const *argv, char const *const *envp, uint32_t flags, cspawn_fileaction const *fa, size_t n) +{ + pid_t pid ; + posix_spawnattr_t attr ; + posix_spawn_file_actions_t actions ; + int e ; + int nopath = !getenv("PATH") ; +#ifdef SKALIBS_HASPOSIXSPAWNEARLYRETURN + int p[2] ; + if (pipecoe(p) == -1) return 0 ; +#endif + + if (flags) + { + e = posix_spawnattr_init(&attr) ; + if (e) goto err ; + if (flags & 3) + { + sigset_t set ; + sigemptyset(&set) ; + e = posix_spawnattr_setsigmask(&attr, &set) ; + if (e) goto errattr ; + e = posix_spawnattr_setflags(&attr, POSIX_SPAWN_SETSIGMASK) ; + if (e) goto errattr ; + } + } + + if (n) + { + e = posix_spawn_file_actions_init(&actions) ; + if (e) goto errattr ; + for (size_t i = 0 ; i < n ; i++) + { + switch (fa[i].type) + { + case CSPAWN_FA_CLOSE : + e = posix_spawn_file_actions_addclose(&actions, fa[i].x.fd) ; + if (e) goto erractions ; + break ; + case CSPAWN_FA_COPY : + e = posix_spawn_file_actions_adddup2(&actions, fa[i].x.fd2[1], fa[i].x.fd2[0]) ; + if (e) goto erractions ; + break ; + case CSPAWN_FA_MOVE : + e = posix_spawn_file_actions_adddup2(&actions, fa[i].x.fd2[1], fa[i].x.fd2[0]) ; + if (e) goto erractions ; + if (fa[i].x.fd2[0] != fa[i].x.fd2[1]) + { + e = posix_spawn_file_actions_addclose(&actions, fa[i].x.fd2[1]) ; + if (e) goto erractions ; + } + break ; + case CSPAWN_FA_OPEN : + e = posix_spawn_file_actions_addopen(&actions, fa[i].x.openinfo.fd, fa[i].x.openinfo.file, fa[i].x.openinfo.oflag, fa[i].x.openinfo.mode) ; + if (e) goto erractions ; + break ; + default : + e = EINVAL ; + goto erractions ; + } + } + } + + if (nopath && (setenv("PATH", SKALIBS_DEFAULTPATH, 0) == -1)) { e = errno ; goto erractions ; } + e = posix_spawnp(&pid, prog, &actions, &attr, (char *const *)argv, (char *const *)envp) ; + if (nopath) unsetenv("PATH") ; + if (e) goto errattr ; + + if (n) posix_spawn_file_actions_destroy(&actions) ; + if (flags) posix_spawnattr_destroy(&attr) ; +#ifdef SKALIBS_HASPOSIXSPAWNEARLYRETURN + return cspawn_workaround(pid, p) ; +#else + return pid ; +#endif + + erractions: + if (n) posix_spawn_file_actions_destroy(&actions) ; + errattr: + if (flags) posix_spawnattr_destroy(&attr) ; + err: +#ifdef SKALIBS_HASPOSIXSPAWNEARLYRETURN + fd_close(p[1]) ; + fd_close(p[0]) ; +#endif + errno = e ; + return 0 ; +} + +#else + +#include <fcntl.h> +#include <unistd.h> + +#include <skalibs/allreadwrite.h> +#include <skalibs/sig.h> +#include <skalibs/selfpipe.h> +#include <skalibs/exec.h> + +static inline void cspawn_child_exec (char const *prog, char const *const *argv, char const *const *envp, uint32_t flags, cspawn_fileaction const *fa, size_t n) +{ + for (size_t i = 0 ; i < n ; i++) + { + switch (fa[i].type) + { + case CSPAWN_FA_CLOSE : fd_close(fa[i].x.fd) ; break ; + case CSPAWN_FA_COPY : + if (fd_copy(fa[i].x.fd2[0], fa[i].x.fd2[1]) == -1) return ; + break ; + case CSPAWN_FA_MOVE : + if (fd_move(fa[i].x.fd2[0], fa[i].x.fd2[1]) == -1) return ; + break ; + case CSPAWN_FA_OPEN : + { + int fd = open(fa[i].x.openinfo.file, fa[i].x.openinfo.oflag, fa[i].x.openinfo.mode) ; + if (fd == -1) return ; + if (fd_move(fa[i].x.openinfo.fd, fd) == -1) return ; + break ; + } + default : + errno = EINVAL ; return ; + } + } + + if (flags & CSPAWN_FLAGS_SELFPIPE_FINISH) selfpipe_finish() ; + if (flags & CSPAWN_FLAGS_SIGBLOCKNONE) sig_blocknone() ; +} + +pid_t cspawn (char const *prog, char const *const *argv, char const *const *envp, uint32_t flags, cspawn_fileaction const *fa, size_t n) +{ + pid_t pid ; + int p[2] ; + char c ; + + if (pipecoe(p) == -1) return 0 ; + pid = fork() ; + if (pid == -1) + { + fd_close(p[1]) ; + fd_close(p[0]) ; + return 0 ; + } + if (!pid) + { + cspawn_child_exec(prog, argv, envp, flags, fa, n) ; + c = errno ; + fd_write(p[1], &c, 1) ; + _exit(127) ; + } + + fd_close(p[1]) ; + p[1] = fd_read(p[0], &c, 1) ; + if (p[1] < 0) + { + fd_close(p[0]) ; + return 0 ; + } + fd_close(p[0]) ; + if (p[1]) + { + wait_pid(pid, &p[0]) ; + errno = (unsigned char)c ; + return 0 ; + } + return pid ; +} + +#endif |