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5798 fexecve() needed per POSIX 2008
@@ -1,371 +1,329 @@
EXEC(2) System Calls EXEC(2)
-
-
NAME
- exec, execl, execle, execlp, execv, execve, execvp - execute a file
+ exec, execl, execle, execlp, execv, execve, execvp, fexecve execute a
+ file
SYNOPSIS
#include <unistd.h>
- int execl(const char *path, const char *arg0, ...
- /* const char *argn, (char *)0 */);
+ int
+ execl(const char *path, const char *arg0, ... /* const char *argn, (char *)0 */);
+ int
+ execv(const char *path, char *const argv[]);
- int execv(const char *path, char *const argv[]);
+ int
+ execle(const char *path, const char *arg0,
+ ... /* const char *argn, (char *)0, char *const envp[] */);
+ int
+ execve(const char *path, char *const argv[], char *const envp[]);
- int execle(const char *path, const char *arg0, ...
- /* const char *argn, (char *)0,char *const envp[]*/);
+ int
+ execlp(const char *file, const char *arg0, ... /* const char *argn, (char *)0 */);
+ int
+ execvp(const char *file, char *const argv[]);
- int execve(const char *path, char *const argv[],
- char *const envp[]);
+ int
+ fexecve(int fd, char *const argv[], char *const envp[]);
-
- int execlp(const char *file, const char *arg0, ...
- /* const char *argn, (char *)0 */);
-
-
- int execvp(const char *file, char *const argv[]);
-
-
DESCRIPTION
Each of the functions in the exec family replaces the current process
image with a new process image. The new image is constructed from a
- regular, executable file called the new process image file. This file
- is either an executable object file or a file of data for an
- interpreter. There is no return from a successful call to one of these
- functions because the calling process image is overlaid by the new
- process image.
+ regular, executable file called the new process image file. This file is
+ either an executable object file or a file of data for an interpreter.
+ There is no return from a successful call to one of these functions
+ because the calling process image is overlaid by the new process image.
-
An interpreter file begins with a line of the form
#! pathname [arg]
-
-
where pathname is the path of the interpreter, and arg is an optional
argument. When an interpreter file is executed, the system invokes the
- specified interpreter. The pathname specified in the interpreter file
- is passed as arg0 to the interpreter. If arg was specified in the
- interpreter file, it is passed as arg1 to the interpreter. The
- remaining arguments to the interpreter are arg0 through argn of the
- originally exec'd file. The interpreter named by pathname must not be
- an interpreter file.
+ specified interpreter. The pathname specified in the interpreter file is
+ passed as arg0 to the interpreter. If arg was specified in the
+ interpreter file, it is passed as arg1 to the interpreter. The remaining
+ arguments to the interpreter are arg0 through argn of the originally
+ exec'd file. The interpreter named by pathname must not be an
+ interpreter file.
-
When a C-language program is executed as a result of this call, it is
entered as a C-language function call as follows:
- int main (int argc, char *argv[]);
+ int main(int argc, char *argv[])
-
-
where argc is the argument count and argv is an array of character
pointers to the arguments themselves. In addition, the following
variable:
extern char **environ;
-
-
is initialized as a pointer to an array of character pointers to the
environment strings. The argv and environ arrays are each terminated by
a null pointer. The null pointer terminating the argv array is not
counted in argc.
-
The value of argc is non-negative, and if greater than 0, argv[0] points
to a string containing the name of the file. If argc is 0, argv[0] is a
- null pointer, in which case there are no arguments. Applications
- should verify that argc is greater than 0 or that argv[0] is not a null
- pointer before dereferencing argv[0].
+ null pointer, in which case there are no arguments. Applications should
+ verify that argc is greater than 0 or that argv[0] is not a null pointer
+ before dereferencing argv[0].
-
The arguments specified by a program with one of the exec functions are
- passed on to the new process image in the main() arguments.
+ passed on to the new process image in the Fn main arguments.
-
The path argument points to a path name that identifies the new process
image file.
+ The file argument is used to construct a pathname that identifies the new
+ process image file. If the file argument contains a slash character, it
+ is used as the pathname for this file. Otherwise, the path prefix for
+ this file is obtained by a search of the directories passed in the PATH
+ environment variable. See environ(5). The environment is supplied
+ typically by the shell. If the process image file is not a valid
+ executable object file, execlp() and execvp() use the contents of that
+ file as standard input to the shell. In this case, the shell becomes the
+ new process image. The standard to which the caller conforms determines
+ which shell is used. See standards(5).
- The file argument is used to construct a pathname that identifies the
- new process image file. If the file argument contains a slash
- character, it is used as the pathname for this file. Otherwise, the
- path prefix for this file is obtained by a search of the directories
- passed in the PATH environment variable (see environ(5)). The
- environment is supplied typically by the shell. If the process image
- file is not a valid executable object file, execlp() and execvp() use
- the contents of that file as standard input to the shell. In this case,
- the shell becomes the new process image. The standard to which the
- caller conforms determines which shell is used. See standards(5).
+ The fexecve() function is equivalent to execve(), except that instead of
+ using a named file, the file referenced by the file descriptor fd is
+ used. Note that this file descriptor must reference a regular file and
+ must have been opened for execute (with Dv O_EXEC , defined in
+ <fcntl.h>.) The image is loaded from offset zero of the file, regardless
+ of the offset of fd.
-
The arguments represented by arg0... are pointers to null-terminated
character strings. These strings constitute the argument list available
- to the new process image. The list is terminated by a null pointer.
- The arg0 argument should point to a filename that is associated with
- the process being started by one of the exec functions.
+ to the new process image. The list is terminated by a null pointer. The
+ arg0 argument should point to a filename that is associated with the
+ process being started by one of the exec functions.
-
The argv argument is an array of character pointers to null-terminated
strings. The last member of this array must be a null pointer. These
- strings constitute the argument list available to the new process
- image. The value in argv[0] should point to a filename that is
- associated with the process being started by one of the exec functions.
+ strings constitute the argument list available to the new process image.
+ The value in argv[0] should point to a filename that is associated with
+ the process being started by one of the exec functions.
-
The envp argument is an array of character pointers to null-terminated
strings. These strings constitute the environment for the new process
image. The envp array is terminated by a null pointer. For execl(),
execv(), execvp(), and execlp(), the C-language run-time start-off routine
- places a pointer to the environment of the calling process in the
- global object extern char **environ, and it is used to pass the
- environment of the calling process to the new process image.
+ places a pointer to the environment of the calling process in the global
+ object environ, and it is used to pass the environment of the calling
+ process to the new process image.
+ The number of bytes available for the new process's combined argument and
+ environment lists is ARG_MAX. It is implementation-dependent whether null
+ terminators, pointers, and/or any alignment bytes are included in this
+ total.
- The number of bytes available for the new process's combined argument
- and environment lists is ARG_MAX. It is implementation-dependent whether
- null terminators, pointers, and/or any alignment bytes are included in
- this total.
-
-
- File descriptors open in the calling process image remain open in the
- new process image, except for those whose close-on-exec flag FD_CLOEXEC
- is set; see fcntl(2). For those file descriptors that remain open, all
+ File descriptors open in the calling process image remain open in the new
+ process image, except for those whose close-on-exec flag FD_CLOEXEC is set;
+ see fcntl(2). For those file descriptors that remain open, all
attributes of the open file description, including file locks, remain
unchanged.
+ The preferred hardware address translation size (see memcntl(2)) for the
+ stack and heap of the new process image are set to the default system
+ page size.
- The preferred hardware address translation size (see memcntl(2)) for
- the stack and heap of the new process image are set to the default
- system page size.
+ Directory streams open in the calling process image are closed in the new
+ process image.
+ The state of conversion descriptors and message catalogue descriptors in
+ the new process image is undefined. For the new process, the equivalent
+ of:
- Directory streams open in the calling process image are closed in the
- new process image.
+ setlocale(LC_ALL, "C");
-
- The state of conversion descriptors and message catalogue descriptors
- in the new process image is undefined. For the new process, the
- equivalent of:
-
- setlocale(LC_ALL, "C")
-
-
-
is executed at startup.
+ Signals set to the default action (BSIG_DFL) in the calling process image
+ are set to the default action in the new process image (see signal(3C)).
+ Signals set to be ignored (SIG_IGN) by the calling process image are set
+ to be ignored by the new process image. Signals set to be caught by the
+ calling process image are set to the default action in the new process
+ image (see signal.h(3HEAD)). After a successful call to any of the exec
+ functions, alternate signal stacks are not preserved and the SA_ONSTACK
+ flag is cleared for all signals.
- Signals set to the default action (SIG_DFL) in the calling process
- image are set to the default action in the new process image (see
- signal(3C)). Signals set to be ignored (SIG_IGN) by the calling
- process image are set to be ignored by the new process image. Signals
- set to be caught by the calling process image are set to the default
- action in the new process image (see signal.h(3HEAD)). After a
- successful call to any of the exec functions, alternate signal stacks
- are not preserved and the SA_ONSTACK flag is cleared for all signals.
-
-
After a successful call to any of the exec functions, any functions
previously registered by atexit(3C) are no longer registered.
-
The saved resource limits in the new process image are set to be a copy
of the process's corresponding hard and soft resource limits.
-
If the ST_NOSUID bit is set for the file system containing the new
- process image file, then the effective user ID and effective group ID
- are unchanged in the new process image. If the set-user-ID mode bit of
- the new process image file is set (see chmod(2)), the effective user ID
- of the new process image is set to the owner ID of the new process
- image file. Similarly, if the set-group-ID mode bit of the new process
- image file is set, the effective group ID of the new process image is
- set to the group ID of the new process image file. The real user ID and
- real group ID of the new process image remain the same as those of the
- calling process image. The effective user ID and effective group ID of
- the new process image are saved (as the saved set-user-ID and the saved
- set-group-ID for use by setuid(2).
+ process image file, then the effective user ID and effective group ID are
+ unchanged in the new process image. If the set-user-ID mode bit of the new
+ process image file is set (see chmod(2)), the effective user ID of the
+ new process image is set to the owner ID of the new process image file.
+ Similarly, if the set-group-ID mode bit of the new process image file is
+ set, the effective group ID of the new process image is set to the group
+ ID of the new process image file. The real user ID and real group ID of
+ the new process image remain the same as those of the calling process
+ image. The effective user ID and effective group ID of the new process
+ image are saved (as the saved set-user-ID and the saved set-group-ID for use
+ by setuid(2)).
-
The privilege sets are changed according to the following rules:
- 1. The inheritable set, I, is intersected with the limit set,
- L. This mechanism enforces the limit set for processes.
+ 1. The inheritable set, I, is intersected with the limit set, L. This
+ mechanism enforces the limit set for processes.
- 2. The effective set, E, and the permitted set, P, are made
- equal to the new inheritable set.
+ 2. The effective set, E, and the permitted set, P, are made equal to
+ the new inheritable set.
+ The system attempts to set the privilege-aware state to non-PA both before
+ performing any modifications to the process IDs and privilege sets as
+ well as after completing the transition to new UIDs and privilege sets,
+ following the rules outlined in privileges(5).
- The system attempts to set the privilege-aware state to non-PA both
- before performing any modifications to the process IDs and privilege
- sets as well as after completing the transition to new UIDs and
- privilege sets, following the rules outlined in privileges(5).
+ If the {PRIV_PROC_OWNER} privilege is asserted in the effective set, the
+ set-user-ID and set-group-ID bits will be honored when the process is being
+ controlled by ptrace(3C). Additional restrictions can apply when the
+ traced process has an effective UID of 0. See privileges(5).
+ Any shared memory segments attached to the calling process image will not
+ be attached to the new process image (see shmop(2)). Any mappings
+ established through mmap(2) are not preserved across an exec. Memory
+ mappings created in the process are unmapped before the address space is
+ rebuilt for the new process image. See mmap(2).
- If the {PRIV_PROC_OWNER} privilege is asserted in the effective set,
- the set-user-ID and set-group-ID bits will be honored when the process is
- being controlled by ptrace(3C). Additional restriction can apply when
- the traced process has an effective UID of 0. See privileges(5).
+ Memory locks established by the calling process via calls to mlockall(3C)
+ or mlock(3C) are removed. If locked pages in the address space of the
+ calling process are also mapped into the address spaces the locks
+ established by the other processes will be unaffected by the call by this
+ process to the exec function. If the exec function fails, the effect on
+ memory locks is unspecified.
-
- Any shared memory segments attached to the calling process image will
- not be attached to the new process image (see shmop(2)). Any mappings
- established through mmap() are not preserved across an exec. Memory
- mappings created in the process are unmapped before the address space
- is rebuilt for the new process image. See mmap(2).
-
-
- Memory locks established by the calling process via calls to
- mlockall(3C) or mlock(3C) are removed. If locked pages in the address
- space of the calling process are also mapped into the address spaces
- the locks established by the other processes will be unaffected by the
- call by this process to the exec function. If the exec function fails,
- the effect on memory locks is unspecified.
-
-
If _XOPEN_REALTIME is defined and has a value other than 1, any named
semaphores open in the calling process are closed as if by appropriate
- calls to sem_close(3C)
+ calls to sem_close(3C).
-
Profiling is disabled for the new process; see profil(2).
-
Timers created by the calling process with timer_create(3C) are deleted
before replacing the current process image with the new process image.
-
For the SCHED_FIFO and SCHED_RR scheduling policies, the policy and
priority settings are not changed by a call to an exec function.
+ All open message queue descriptors in the calling process are closed, as
+ described in mq_close(3C).
- All open message queue descriptors in the calling process are closed,
- as described in mq_close(3C).
-
-
Any outstanding asynchronous I/O operations may be cancelled. Those
- asynchronous I/O operations that are not canceled will complete as if
- the exec function had not yet occurred, but any associated signal
+ asynchronous I/O operations that are not canceled will complete as if the
+ exec function had not yet occurred, but any associated signal
notifications are suppressed. It is unspecified whether the exec
function itself blocks awaiting such I/O completion. In no event,
however, will the new process image created by the exec function be
affected by the presence of outstanding asynchronous I/O operations at
the time the exec function is called.
-
All active contract templates are cleared (see contract(4)).
-
The new process also inherits the following attributes from the calling
process:
- o controlling terminal
+ controlling terminal
- o current working directory
+ current working directory
- o file-locks (see fcntl(2) and lockf(3C))
+ file-locks (see fcntl(2) and lockf(3C))
- o file mode creation mask (see umask(2))
+ file mode creation mask (see umask(2))
- o file size limit (see ulimit(2))
+ file size limit (see ulimit(2))
- o limit privilege set
+ limit privilege set
- o nice value (see nice(2))
+ nice value (see nice(2))
- o parent process ID
+ parent process ID
- o pending signals (see sigpending(2))
+ pending signals (see sigpending(2))
- o privilege debugging flag (see privileges(5) and
- getpflags(2))
+ privilege debugging flag (see privileges(5) and getpflags(2))
- o process ID
+ process ID
- o process contract (see contract(4) and process(4))
+ process contract (see contract(4) and process(4))
- o process group ID
+ process group ID
- o process signal mask (see sigprocmask(2))
+ process signal mask (see sigprocmask(2))
- o processor bindings (see processor_bind(2))
+ processor bindings (see processor_bind(2))
- o processor set bindings (see pset_bind(2))
+ processor set bindings (see pset_bind(2))
- o project ID
+ project ID
- o real group ID
+ real group ID
- o real user ID
+ real user ID
- o resource limits (see getrlimit(2))
+ resource limits (see getrlimit(2))
- o root directory
+ root directory
- o scheduler class and priority (see priocntl(2))
+ scheduler class and priority (see priocntl(2))
- o semadj values (see semop(2))
+ semadj values (see semop(2))
- o session membership (see exit(2) and signal(3C))
+ session membership (see exit(2) and signal(3C))
- o supplementary group IDs
+ supplementary group IDs
- o task ID
+ task ID
- o time left until an alarm clock signal (see alarm(2))
+ time left until an alarm clock signal (see alarm(2))
- o tms_utime, tms_stime, tms_cutime, and tms_cstime (see
- times(2))
+ tms_utime, tms_stime, tms_cutime, and tms_cstime (see times(2))
- o trace flag (see ptrace(3C) request 0)
+ trace flag (see ptrace(3C) request 0)
-
A call to any exec function from a process with more than one thread
results in all threads being terminated and the new executable image
being loaded and executed. No destructor functions will be called.
-
Upon successful completion, each of the functions in the exec family
marks for update the st_atime field of the file. If an exec function
failed but was able to locate the process image file, whether the
st_atime field is marked for update is unspecified. Should the function
succeed, the process image file is considered to have been opened with
open(2). The corresponding close(2) is considered to occur at a time
- after this open, but before process termination or successful
- completion of a subsequent call to one of the exec functions. The
- argv[] and envp[] arrays of pointers and the strings to which those
- arrays point will not be modified by a call to one of the exec
- functions, except as a consequence of replacing the process image.
+ after this open, but before process termination or successful completion
+ of a subsequent call to one of the exec functions. The argv and envp
+ arrays of pointers and the strings to which those arrays point will not
+ be modified by a call to one of the exec functions, except as a
+ consequence of replacing the process image.
-
The saved resource limits in the new process image are set to be a copy
of the process's corresponding hard and soft limits.
RETURN VALUES
- If a function in the exec family returns to the calling process image,
- an error has occurred; the return value is1 and errno is set to
- indicate the error.
+ If a function in the exec family returns to the calling process image, an
+ error has occurred; the return value is1 and errno is set to indicate
+ the error.
ERRORS
The exec functions will fail if:
- E2BIG
- The number of bytes in the new process's argument list
+ [E2BIG] The number of bytes in the new process's argument list
is greater than the system-imposed limit of {ARG_MAX}
bytes. The argument list limit is sum of the size of
the argument list plus the size of the environment's
exported shell variables.
-
- EACCES
- Search permission is denied for a directory listed in
+ [EACCES] Search permission is denied for a directory listed in
the new process file's path prefix.
The new process file is not an ordinary file.
The new process file mode denies execute permission.
@@ -374,132 +332,111 @@
restriction on directory searches.
The {FILE_DAC_EXECUTE} privilege overrides the lack of
execute permission.
-
- EAGAIN
- Total amount of system memory available when reading
+ [EAGAIN] Total amount of system memory available when reading
using raw I/O is temporarily insufficient.
+ [EFAULT] An argument points to an illegal address.
- EFAULT
- An argument points to an illegal address.
-
-
- EINVAL
- The new process image file has the appropriate
+ [EINVAL] The new process image file has the appropriate
permission and has a recognized executable binary
format, but the system does not support execution of a
file with this format.
-
- EINTR
- A signal was caught during the execution of one of the
+ [EINTR] A signal was caught during the execution of one of the
functions in the exec family.
+ The exec functions except fexecve() will fail if:
- ELOOP
- Too many symbolic links were encountered in translating
- path or file.
+ [ELOOP] Too many symbolic links were encountered in
+ translating path or file.
-
- ENAMETOOLONG
- The length of the file or path argument exceeds
+ [ENAMETOOLONG] The length of the file or path argument exceeds
{PATH_MAX}, or the length of a file or path component
exceeds {NAME_MAX} while {_POSIX_NO_TRUNC} is in
effect.
-
- ENOENT
- One or more components of the new process path name of
+ [ENOENT] One or more components of the new process path name of
the file do not exist or is a null pathname.
-
- ENOLINK
- The path argument points to a remote machine and the
+ [ENOLINK] The path argument points to a remote machine and the
link to that machine is no longer active.
-
- ENOTDIR
- A component of the new process path of the file prefix
+ [ENOTDIR] A component of the new process path of the file prefix
is not a directory.
-
-
The exec functions, except for execlp() and execvp(), will fail if:
- ENOEXEC
- The new process image file has the appropriate access
+ [ENOEXEC] The new process image file has the appropriate access
permission but is not in the proper format.
+ The fexecve() function will fail if:
+ [EBADF] The fd argument is not a valid file descriptor opened
+ for execute.
- The exec functions may fail if:
- ENAMETOOLONG
- Pathname resolution of a symbolic link produced an
+ The exec functions except for fexecve() may fail if:
+
+ [ENAMETOOLONG] Pathname resolution of a symbolic link produced an
intermediate result whose length exceeds {PATH_MAX}.
-
- ENOMEM
- The new process image requires more memory than is
+ [ENOMEM] The new process image requires more memory than is
allowed by the hardware or system-imposed by memory
management constraints. See brk(2).
-
- ETXTBSY
- The new process image file is a pure procedure (shared
+ [ETXTBSY] The new process image file is a pure procedure (shared
text) file that is currently open for writing by some
process.
-
USAGE
- As the state of conversion descriptors and message catalogue
- descriptors in the new process image is undefined, portable
- applications should not rely on their use and should close them prior
- to calling one of the exec functions.
+ As the state of conversion descriptors and message catalogue descriptors
+ in the new process image is undefined, portable applications should not
+ rely on their use and should close them prior to calling one of the exec
+ functions.
+ Applications that require other than the default POSIX locale should call
+ setlocale(3C) with the appropriate parameters to establish the locale of
+ the new process.
- Applications that require other than the default POSIX locale should
- call setlocale(3C) with the appropriate parameters to establish the
- locale of thenew process.
-
-
The environ array should not be accessed directly by the application.
+ Instead, getenv(3C) should be used.
-ATTRIBUTES
- See attributes(5) for descriptions of the following attributes:
+SEE ALSO
+ ps(1), sh(1), alarm(2), brk(2), chmod(2), exit(2), fcntl(2), fork(2),
+ getpflags(2), getrlimit(2), memcntl(2), mmap(2), nice(2), open(2),
+ priocntl(2), profil(2), semop(2), shmop(2), sigpending(2),
+ sigprocmask(2), times(2), umask(2), lockf(3C), ptrace(3C), setlocale(3C),
+ signal(3C), system(3C), timer_create(3C), fcntl.h(3HEAD),
+ signal.h(3HEAD), unistd.h(3HEAD), a.out(4), contract(4), process(4),
+ environ(5), privileges(5), standards(5)
+INTERFACE STABILITY
+ Standard.
+MT-LEVEL
+ The execle(), execve(), fexecve() functions are Async-Signal-Safe.
+STANDARDS
+ These functions are available in the following compilation environments.
+ See standards(5).
- +--------------------+-------------------+
- | ATTRIBUTE TYPE | ATTRIBUTE VALUE |
- +--------------------+-------------------+
- |Interface Stability | Committed |
- +--------------------+-------------------+
- |MT-Level | See below. |
- +--------------------+-------------------+
- |Standard | See standards(5). |
- +--------------------+-------------------+
+ execl(), execle(), execlp(), execv(), execve(), execvp()
+ IEEE Std 1003.1-1990 (POSIX.1)
+ X/Open Portability Guide Issue3 (XPG3)
+ X/Open Portability Guide Issue4 (XPG4)
+ X/Open Portability Guide Issue4, Version2 (XPG4.2)
+ Version2 of the Single UNIX Specification (SUSv2)
+ Version3 of the Single UNIX Specification (SUSv3)
+ IEEE Std 1003.1-2008 (POSIX.1)
+ fexecve()
+ IEEE Std 1003.1-2008 (POSIX.1)
- The execle() and execve() fucntions are Async-Signal-Safe.
-
-SEE ALSO
- ksh(1), ps(1), sh(1), alarm(2), brk(2), chmod(2), exit(2), fcntl(2),
- fork(2), getpflags(2), getrlimit(2), memcntl(2), mmap(2), nice(2),
- priocntl(2), profil(2), semop(2), shmop(2), sigpending(2),
- sigprocmask(2), times(2), umask(2), lockf(3C), ptrace(3C),
- setlocale(3C), signal(3C), system(3C), timer_create(3C), a.out(4),
- contract(4), process(4), attributes(5), environ(5), privileges(5),
- standards(5)
-
WARNINGS
If a program is setuid to a user ID other than the superuser, and the
- program is executed when the real user ID is super-user, then the
- program has some of the powers of a super-user as well.
+ program is executed when the real user ID is super-user, then the program
+ has some of the powers of a super-user as well.
-
-
- June 16, 2008 EXEC(2)
+illumos September 19, 2014 illumos