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-rw-r--r--src/libstddjb/cspawn.c220
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