rework mechanism for posix_spawnp calling posix_spawn

previously, a common __posix_spawnx backend was used that accepted an
additional argument for the execve variant to call in the child. this
moderately bloated up the posix_spawn function, shuffling arguments
between stack and/or registers to call a 7-argument function from a
6-argument one.

instead, tuck the exec function pointer in an unused part of the
(large) pthread_spawnattr_t structure, and have posix_spawnp duplicate
the attributes and fill in a pointer to __execvpe. the net code size
change is minimal, but the weight is shifted to the "heavier" function
which already pulls in more dependencies.

as a bonus, we get rid of an external symbol (__posix_spawnx) that had
no really good place for a declaration because it shouldn't have
existed to begin with.

diff --git a/include/spawn.h b/include/spawn.h
index bba57ce4975613b73fff1c2819fd95f8af7c53ec..c9bd1939e05b108ea6c42ac5100f84a6b9dbb2bc 100644 (file)
--- a/include/spawn.h
+++ b/include/spawn.h
@@ -28,7 +28,9 @@ typedef struct {
        int __flags;
        pid_t __pgrp;
        sigset_t __def, __mask;
-       int __prio, __pol, __pad[16];
+       int __prio, __pol;
+       void *__fn;
+       char __pad[64-sizeof(void *)];
 } posix_spawnattr_t;
 
 typedef struct {

diff --git a/src/process/posix_spawn.c b/src/process/posix_spawn.c
index 93fb15553537f8e3f34500f6414a5d75bdcdb85a..16308fb70737d9b2330a78b2cb7cd1e86869ba31 100644 (file)
--- a/src/process/posix_spawn.c
+++ b/src/process/posix_spawn.c
@@ -14,7 +14,6 @@ struct args {
        int p[2];
        sigset_t oldmask;
        const char *path;
-       int (*exec)(const char *, char *const *, char *const *);
        const posix_spawn_file_actions_t *fa;
        const posix_spawnattr_t *restrict attr;
        char *const *argv, *const *envp;
@@ -138,7 +137,10 @@ static int child(void *args_vp)
        pthread_sigmask(SIG_SETMASK, (attr->__flags & POSIX_SPAWN_SETSIGMASK)
                ? &attr->__mask : &args->oldmask, 0);
 
-       args->exec(args->path, args->argv, args->envp);
+       int (*exec)(const char *, char *const *, char *const *) =
+               attr->__fn ? (int (*)())attr->__fn : execve;
+
+       exec(args->path, args->argv, args->envp);
        ret = -errno;
 
 fail:
@@ -149,8 +151,7 @@ fail:
 }
 
 
-int __posix_spawnx(pid_t *restrict res, const char *restrict path,
-       int (*exec)(const char *, char *const *, char *const *),
+int posix_spawn(pid_t *restrict res, const char *restrict path,
        const posix_spawn_file_actions_t *fa,
        const posix_spawnattr_t *restrict attr,
        char *const argv[restrict], char *const envp[restrict])
@@ -166,7 +167,6 @@ int __posix_spawnx(pid_t *restrict res, const char *restrict path,
        pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
 
        args.path = path;
-       args.exec = exec;
        args.fa = fa;
        args.attr = attr ? attr : &(const posix_spawnattr_t){0};
        args.argv = argv;
@@ -193,11 +193,3 @@ int __posix_spawnx(pid_t *restrict res, const char *restrict path,
 
        return ec;
 }
-
-int posix_spawn(pid_t *restrict res, const char *restrict path,
-       const posix_spawn_file_actions_t *fa,
-       const posix_spawnattr_t *restrict attr,
-       char *const argv[restrict], char *const envp[restrict])
-{
-       return __posix_spawnx(res, path, execve, fa, attr, argv, envp);
-}

diff --git a/src/process/posix_spawnp.c b/src/process/posix_spawnp.c
index 37360001d24bd9ce02ff615a775283a97fb56525..165be746b8f85c0d886303fd3f6cba15c99aee3c 100644 (file)
--- a/src/process/posix_spawnp.c
+++ b/src/process/posix_spawnp.c
@@ -3,15 +3,13 @@
 
 int __execvpe(const char *, char *const *, char *const *);
 
-int __posix_spawnx(pid_t *restrict, const char *restrict,
-       int (*)(const char *, char *const *, char *const *),
-       const posix_spawn_file_actions_t *,
-       const posix_spawnattr_t *restrict, char *const *restrict, char *const *restrict);
-
 int posix_spawnp(pid_t *restrict res, const char *restrict file,
        const posix_spawn_file_actions_t *fa,
        const posix_spawnattr_t *restrict attr,
        char *const argv[restrict], char *const envp[restrict])
 {
-       return __posix_spawnx(res, file, __execvpe, fa, attr, argv, envp);
+       posix_spawnattr_t spawnp_attr = { 0 };
+       if (attr) spawnp_attr = *attr;
+       spawnp_attr.__fn = (void *)__execvpe;   
+       return posix_spawn(res, file, fa, &spawnp_attr, argv, envp);
 }