X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=liblttng-ust-fork%2Fustfork.c;h=7840bc1dda540166db27e762266b929d8b002be5;hb=d32dbe6722a94a6a1cdc0be1335599ceedbaf855;hp=fc83d05c3d3797cd7d0811277525bc71b8f3ba1c;hpb=b115a3fc6eefd727eec5874fa3dc346045183189;p=lttng-ust.git

diff --git a/liblttng-ust-fork/ustfork.c b/liblttng-ust-fork/ustfork.c
index fc83d05c..7840bc1d 100644
--- a/liblttng-ust-fork/ustfork.c
+++ b/liblttng-ust-fork/ustfork.c
@@ -29,25 +29,30 @@
 
 #include <lttng/ust.h>
 
+#include <urcu/uatomic.h>
+
 pid_t fork(void)
 {
 	static pid_t (*plibc_func)(void) = NULL;
+	pid_t (*func)(void);
 	sigset_t sigset;
 	pid_t retval;
 	int saved_errno;
 
-	if (plibc_func == NULL) {
-		plibc_func = dlsym(RTLD_NEXT, "fork");
-		if (plibc_func == NULL) {
+	func = uatomic_read(plibc_func);
+	if (func == NULL) {
+		func = dlsym(RTLD_NEXT, "fork");
+		if (func == NULL) {
 			fprintf(stderr, "libustfork: unable to find \"fork\" symbol\n");
 			errno = ENOSYS;
 			return -1;
 		}
+		uatomic_set(&plibc_func, func);
 	}
 
 	ust_before_fork(&sigset);
 	/* Do the real fork */
-	retval = plibc_func();
+	retval = func();
 	saved_errno = errno;
 	if (retval == 0) {
 		/* child */
@@ -62,22 +67,25 @@ pid_t fork(void)
 int daemon(int nochdir, int noclose)
 {
 	static int (*plibc_func)(int nochdir, int noclose) = NULL;
+	int (*func)(int nochdir, int noclose);
 	sigset_t sigset;
 	int retval;
 	int saved_errno;
 
-	if (plibc_func == NULL) {
-		plibc_func = dlsym(RTLD_NEXT, "daemon");
-		if (plibc_func == NULL) {
+	func = uatomic_read(plibc_func);
+	if (func == NULL) {
+		func = dlsym(RTLD_NEXT, "daemon");
+		if (func == NULL) {
 			fprintf(stderr, "libustfork: unable to find \"daemon\" symbol\n");
 			errno = ENOSYS;
 			return -1;
 		}
+		uatomic_set(&plibc_func, func);
 	}
 
 	ust_before_fork(&sigset);
 	/* Do the real daemon call */
-	retval = plibc_func(nochdir, noclose);
+	retval = func(nochdir, noclose);
 	saved_errno = errno;
 	if (retval == 0) {
 		/* child, parent called _exit() directly */
@@ -93,20 +101,23 @@ int daemon(int nochdir, int noclose)
 int setuid(uid_t uid)
 {
 	static int (*plibc_func)(uid_t uid) = NULL;
+	int (*func)(uid_t uid);
 	int retval;
 	int saved_errno;
 
-	if (plibc_func == NULL) {
-		plibc_func = dlsym(RTLD_NEXT, "setuid");
-		if (plibc_func == NULL) {
+	func = uatomic_read(plibc_func);
+	if (func == NULL) {
+		func = dlsym(RTLD_NEXT, "setuid");
+		if (func == NULL) {
 			fprintf(stderr, "libustfork: unable to find \"setuid\" symbol\n");
 			errno = ENOSYS;
 			return -1;
 		}
+		uatomic_set(&plibc_func, func);
 	}
 
 	/* Do the real setuid */
-	retval = plibc_func(uid);
+	retval = func(uid);
 	saved_errno = errno;
 
 	ust_after_setuid();
@@ -118,20 +129,23 @@ int setuid(uid_t uid)
 int setgid(gid_t gid)
 {
 	static int (*plibc_func)(gid_t gid) = NULL;
+	int (*func)(gid_t gid);
 	int retval;
 	int saved_errno;
 
-	if (plibc_func == NULL) {
-		plibc_func = dlsym(RTLD_NEXT, "setgid");
-		if (plibc_func == NULL) {
+	func = uatomic_read(plibc_func);
+	if (func == NULL) {
+		func = dlsym(RTLD_NEXT, "setgid");
+		if (func == NULL) {
 			fprintf(stderr, "libustfork: unable to find \"setgid\" symbol\n");
 			errno = ENOSYS;
 			return -1;
 		}
+		uatomic_set(&plibc_func, func);
 	}
 
 	/* Do the real setgid */
-	retval = plibc_func(gid);
+	retval = func(gid);
 	saved_errno = errno;
 
 	ust_after_setgid();
@@ -143,20 +157,23 @@ int setgid(gid_t gid)
 int seteuid(uid_t euid)
 {
 	static int (*plibc_func)(uid_t euid) = NULL;
+	int (*func)(uid_t euid);
 	int retval;
 	int saved_errno;
 
-	if (plibc_func == NULL) {
-		plibc_func = dlsym(RTLD_NEXT, "seteuid");
-		if (plibc_func == NULL) {
+	func = uatomic_read(plibc_func);
+	if (func == NULL) {
+		func = dlsym(RTLD_NEXT, "seteuid");
+		if (func == NULL) {
 			fprintf(stderr, "libustfork: unable to find \"seteuid\" symbol\n");
 			errno = ENOSYS;
 			return -1;
 		}
+		uatomic_set(&plibc_func, func);
 	}
 
 	/* Do the real seteuid */
-	retval = plibc_func(euid);
+	retval = func(euid);
 	saved_errno = errno;
 
 	ust_after_seteuid();
@@ -168,20 +185,23 @@ int seteuid(uid_t euid)
 int setegid(gid_t egid)
 {
 	static int (*plibc_func)(gid_t egid) = NULL;
+	int (*func)(gid_t egid);
 	int retval;
 	int saved_errno;
 
-	if (plibc_func == NULL) {
-		plibc_func = dlsym(RTLD_NEXT, "setegid");
-		if (plibc_func == NULL) {
+	func = uatomic_read(plibc_func);
+	if (func == NULL) {
+		func = dlsym(RTLD_NEXT, "setegid");
+		if (func == NULL) {
 			fprintf(stderr, "libustfork: unable to find \"setegid\" symbol\n");
 			errno = ENOSYS;
 			return -1;
 		}
+		uatomic_set(&plibc_func, func);
 	}
 
 	/* Do the real setegid */
-	retval = plibc_func(egid);
+	retval = func(egid);
 	saved_errno = errno;
 
 	ust_after_setegid();
@@ -193,20 +213,23 @@ int setegid(gid_t egid)
 int setreuid(uid_t ruid, uid_t euid)
 {
 	static int (*plibc_func)(uid_t ruid, uid_t euid) = NULL;
+	int (*func)(uid_t ruid, uid_t euid);
 	int retval;
 	int saved_errno;
 
-	if (plibc_func == NULL) {
-		plibc_func = dlsym(RTLD_NEXT, "setreuid");
-		if (plibc_func == NULL) {
+	func = uatomic_read(plibc_func);
+	if (func == NULL) {
+		func = dlsym(RTLD_NEXT, "setreuid");
+		if (func == NULL) {
 			fprintf(stderr, "libustfork: unable to find \"setreuid\" symbol\n");
 			errno = ENOSYS;
 			return -1;
 		}
+		uatomic_set(&plibc_func, func);
 	}
 
 	/* Do the real setreuid */
-	retval = plibc_func(ruid, euid);
+	retval = func(ruid, euid);
 	saved_errno = errno;
 
 	ust_after_setreuid();
@@ -218,20 +241,23 @@ int setreuid(uid_t ruid, uid_t euid)
 int setregid(gid_t rgid, gid_t egid)
 {
 	static int (*plibc_func)(gid_t rgid, gid_t egid) = NULL;
+	int (*func)(gid_t rgid, gid_t egid);
 	int retval;
 	int saved_errno;
 
-	if (plibc_func == NULL) {
-		plibc_func = dlsym(RTLD_NEXT, "setregid");
-		if (plibc_func == NULL) {
+	func = uatomic_read(plibc_func);
+	if (func == NULL) {
+		func = dlsym(RTLD_NEXT, "setregid");
+		if (func == NULL) {
 			fprintf(stderr, "libustfork: unable to find \"setregid\" symbol\n");
 			errno = ENOSYS;
 			return -1;
 		}
+		uatomic_set(&plibc_func, func);
 	}
 
 	/* Do the real setregid */
-	retval = plibc_func(rgid, egid);
+	retval = func(rgid, egid);
 	saved_errno = errno;
 
 	ust_after_setregid();
@@ -264,6 +290,9 @@ int clone(int (*fn)(void *), void *child_stack, int flags, void *arg, ...)
 	static int (*plibc_func)(int (*fn)(void *), void *child_stack,
 			int flags, void *arg, pid_t *ptid,
 			struct user_desc *tls, pid_t *ctid) = NULL;
+	int (*func)(int (*fn)(void *), void *child_stack,
+			int flags, void *arg, pid_t *ptid,
+			struct user_desc *tls, pid_t *ctid);
 	/* var args */
 	pid_t *ptid;
 	struct user_desc *tls;
@@ -279,13 +308,15 @@ int clone(int (*fn)(void *), void *child_stack, int flags, void *arg, ...)
 	ctid = va_arg(ap, pid_t *);
 	va_end(ap);
 
-	if (plibc_func == NULL) {
-		plibc_func = dlsym(RTLD_NEXT, "clone");
-		if (plibc_func == NULL) {
+	func = uatomic_read(plibc_func);
+	if (func == NULL) {
+		func = dlsym(RTLD_NEXT, "clone");
+		if (func == NULL) {
 			fprintf(stderr, "libustfork: unable to find \"clone\" symbol.\n");
 			errno = ENOSYS;
 			return -1;
 		}
+		uatomic_set(&plibc_func, func);
 	}
 
 	if (flags & CLONE_VM) {
@@ -293,16 +324,16 @@ int clone(int (*fn)(void *), void *child_stack, int flags, void *arg, ...)
 		 * Creating a thread, no need to intervene, just pass on
 		 * the arguments.
 		 */
-		retval = plibc_func(fn, child_stack, flags, arg, ptid,
-				tls, ctid);
+		retval = func(fn, child_stack, flags, arg, ptid,
+			tls, ctid);
 		saved_errno = errno;
 	} else {
 		/* Creating a real process, we need to intervene. */
 		struct ustfork_clone_info info = { .fn = fn, .arg = arg };
 
 		ust_before_fork(&info.sigset);
-		retval = plibc_func(clone_fn, child_stack, flags, &info,
-				ptid, tls, ctid);
+		retval = func(clone_fn, child_stack, flags, &info,
+			ptid, tls, ctid);
 		saved_errno = errno;
 		/* The child doesn't get here. */
 		ust_after_fork_parent(&info.sigset);
@@ -314,20 +345,23 @@ int clone(int (*fn)(void *), void *child_stack, int flags, void *arg, ...)
 int setns(int fd, int nstype)
 {
 	static int (*plibc_func)(int fd, int nstype) = NULL;
+	int (*func)(int fd, int nstype);
 	int retval;
 	int saved_errno;
 
-	if (plibc_func == NULL) {
-		plibc_func = dlsym(RTLD_NEXT, "setns");
-		if (plibc_func == NULL) {
+	func = uatomic_read(plibc_func);
+	if (func == NULL) {
+		func = dlsym(RTLD_NEXT, "setns");
+		if (func == NULL) {
 			fprintf(stderr, "libustfork: unable to find \"setns\" symbol\n");
 			errno = ENOSYS;
 			return -1;
 		}
+		uatomic_set(&plibc_func, func);
 	}
 
 	/* Do the real setns */
-	retval = plibc_func(fd, nstype);
+	retval = func(fd, nstype);
 	saved_errno = errno;
 
 	ust_after_setns();
@@ -339,20 +373,23 @@ int setns(int fd, int nstype)
 int unshare(int flags)
 {
 	static int (*plibc_func)(int flags) = NULL;
+	int (*func)(int flags);
 	int retval;
 	int saved_errno;
 
-	if (plibc_func == NULL) {
-		plibc_func = dlsym(RTLD_NEXT, "unshare");
-		if (plibc_func == NULL) {
+	func = uatomic_read(plibc_func);
+	if (func == NULL) {
+		func = dlsym(RTLD_NEXT, "unshare");
+		if (func == NULL) {
 			fprintf(stderr, "libustfork: unable to find \"unshare\" symbol\n");
 			errno = ENOSYS;
 			return -1;
 		}
+		uatomic_set(&plibc_func, func);
 	}
 
 	/* Do the real setns */
-	retval = plibc_func(flags);
+	retval = func(flags);
 	saved_errno = errno;
 
 	ust_after_unshare();
@@ -364,20 +401,23 @@ int unshare(int flags)
 int setresuid(uid_t ruid, uid_t euid, uid_t suid)
 {
 	static int (*plibc_func)(uid_t ruid, uid_t euid, uid_t suid) = NULL;
+	int (*func)(uid_t ruid, uid_t euid, uid_t suid);
 	int retval;
 	int saved_errno;
 
-	if (plibc_func == NULL) {
-		plibc_func = dlsym(RTLD_NEXT, "setresuid");
-		if (plibc_func == NULL) {
+	func = uatomic_read(plibc_func);
+	if (func == NULL) {
+		func = dlsym(RTLD_NEXT, "setresuid");
+		if (func == NULL) {
 			fprintf(stderr, "libustfork: unable to find \"setresuid\" symbol\n");
 			errno = ENOSYS;
 			return -1;
 		}
+		uatomic_set(&plibc_func, func);
 	}
 
 	/* Do the real setresuid */
-	retval = plibc_func(ruid, euid, suid);
+	retval = func(ruid, euid, suid);
 	saved_errno = errno;
 
 	ust_after_setresuid();
@@ -389,20 +429,23 @@ int setresuid(uid_t ruid, uid_t euid, uid_t suid)
 int setresgid(gid_t rgid, gid_t egid, gid_t sgid)
 {
 	static int (*plibc_func)(gid_t rgid, gid_t egid, gid_t sgid) = NULL;
+	int (*func)(gid_t rgid, gid_t egid, gid_t sgid);
 	int retval;
 	int saved_errno;
 
-	if (plibc_func == NULL) {
-		plibc_func = dlsym(RTLD_NEXT, "setresgid");
-		if (plibc_func == NULL) {
+	func = uatomic_read(plibc_func);
+	if (func == NULL) {
+		func = dlsym(RTLD_NEXT, "setresgid");
+		if (func == NULL) {
 			fprintf(stderr, "libustfork: unable to find \"setresgid\" symbol\n");
 			errno = ENOSYS;
 			return -1;
 		}
+		uatomic_set(&plibc_func, func);
 	}
 
 	/* Do the real setresgid */
-	retval = plibc_func(rgid, egid, sgid);
+	retval = func(rgid, egid, sgid);
 	saved_errno = errno;
 
 	ust_after_setresgid();
@@ -416,22 +459,25 @@ int setresgid(gid_t rgid, gid_t egid, gid_t sgid)
 pid_t rfork(int flags)
 {
 	static pid_t (*plibc_func)(int flags) = NULL;
+	pid_t (*func)(int flags);
 	sigset_t sigset;
 	pid_t retval;
 	int saved_errno;
 
-	if (plibc_func == NULL) {
-		plibc_func = dlsym(RTLD_NEXT, "rfork");
-		if (plibc_func == NULL) {
+	func = uatomic_read(plibc_func);
+	if (func == NULL) {
+		func = dlsym(RTLD_NEXT, "rfork");
+		if (func == NULL) {
 			fprintf(stderr, "libustfork: unable to find \"rfork\" symbol\n");
 			errno = ENOSYS;
 			return -1;
 		}
+		uatomic_set(&plibc_func, func);
 	}
 
 	ust_before_fork(&sigset);
 	/* Do the real rfork */
-	retval = plibc_func(flags);
+	retval = func(flags);
 	saved_errno = errno;
 	if (retval == 0) {
 		/* child */