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5776 vfork and getwd should not be exposed under XPG7
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--- old/usr/src/man/man2/vfork.2.man.txt
+++ new/usr/src/man/man2/vfork.2.man.txt
1 1 VFORK(2) System Calls VFORK(2)
2 2
3 -
4 -
5 3 NAME
6 - vfork, vforkx - spawn new process in a virtual memory efficient way
4 + vfork, vforkx spawn new process in a virtual memory efficient way
7 5
8 6 SYNOPSIS
9 - #include <unistd.h>
7 + #include <unistd.h>
10 8
11 - pid_t vfork(void);
9 + pid_t
10 + vfork(void);
12 11
12 + #include <sys/fork.h>
13 13
14 - #include <sys/fork.h>
14 + pid_t
15 + vforkx(int flags);
15 16
16 - pid_t vforkx(int flags);
17 -
18 -
19 17 DESCRIPTION
20 - The vfork() and vforkx() functions create a new process without fully
21 - copying the address space of the old process. These functions are
22 - useful in instances where the purpose of a fork(2) operation is to
23 - create a new system context for an execve() operation (see exec(2)).
18 + The vfork() and vforkx() functions create a new process without fully
19 + copying the address space of the old process. These functions are useful
20 + in instances where the purpose of a fork(2) operation is to create a new
21 + system context for an exec(2) operation.
24 22
23 + Unlike with the fork() function, the child process borrows the parent's
24 + memory and thread of control until a call to execve() or an exit (either
25 + abnormally or by a call to _exit(2)). Any modification made during this
26 + time to any part of memory in the child process is reflected in the
27 + parent process on return from vfork() or vforkx(). The parent process is
28 + suspended while the child is using its resources.
25 29
26 - Unlike with the fork() function, the child process borrows the parent's
27 - memory and thread of control until a call to execve() or an exit
28 - (either abnormally or by a call to _exit() (see exit(2)). Any
29 - modification made during this time to any part of memory in the child
30 - process is reflected in the parent process on return from vfork() or
31 - vforkx(). The parent process is suspended while the child is using its
32 - resources.
30 + In a multithreaded application, vfork() and vforkx() borrow only the
31 + thread of control that called vfork() or vforkx() in the parent; that is,
32 + the child contains only one thread. The use of vfork() or vforkx() in
33 + multithreaded applications, however, is unsafe due to race conditions
34 + that can cause the child process to become deadlocked and consequently
35 + block both the child and parent process from execution indefinitely.
33 36
37 + The vfork() and vforkx() functions can normally be used the same way as
38 + fork() and forkx(), respectively. The calling procedure, however, should
39 + not return while running in the child's context, since the eventual
40 + return from vfork() or vforkx() in the parent would be to a stack frame
41 + that no longer exists. The _exit() function should be used in favor of
42 + exit(3C) if unable to perform an execve() operation, since exit() will
43 + invoke all functions registered by atexit(3C) and will flush and close
44 + standard I/O channels, thereby corrupting the parent process's standard
45 + I/O data structures. Care must be taken in the child process not to
46 + modify any global or local data that affects the behavior of the parent
47 + process on return from vfork() or vforkx(), unless such an effect is
48 + intentional.
34 49
35 - In a multithreaded application, vfork() and vforkx() borrow only the
36 - thread of control that called vfork() or vforkx() in the parent; that
37 - is, the child contains only one thread. The use of vfork() or vforkx()
38 - in multithreaded applications, however, is unsafe due to race
39 - conditions that can cause the child process to become deadlocked and
40 - consequently block both the child and parent process from execution
41 - indefinitely.
50 + Unlike fork() and forkx(), fork handlers are not run when vfork() and
51 + vforkx() are called.
42 52
53 + The vfork() and vforkx() functions are deprecated. Their sole legitimate
54 + use as a prelude to an immediate call to a function from the exec(2)
55 + family can be achieved safely by posix_spawn(3C) or posix_spawnp(3C).
43 56
44 - The vfork() and vforkx() functions can normally be used the same way as
45 - fork() and forkx(), respectively. The calling procedure, however,
46 - should not return while running in the child's context, since the
47 - eventual return from vfork() or vforkx() in the parent would be to a
48 - stack frame that no longer exists. The _exit() function should be used
49 - in favor of exit(3C) if unable to perform an execve() operation, since
50 - exit() will invoke all functions registered by atexit(3C) and will
51 - flush and close standard I/O channels, thereby corrupting the parent
52 - process's standard I/O data structures. Care must be taken in the child
53 - process not to modify any global or local data that affects the
54 - behavior of the parent process on return from vfork() or vforkx(),
55 - unless such an effect is intentional.
56 -
57 -
58 - Unlike fork() and forkx(), fork handlers are not run when vfork() and
59 - vforkx() are called.
60 -
61 -
62 - The vfork() and vforkx() functions are deprecated. Their sole
63 - legitimate use as a prelude to an immediate call to a function from the
64 - exec family can be achieved safely by posix_spawn(3C) or
65 - posix_spawnp(3C).
66 -
67 57 Fork Extensions
68 - The vforkx() function accepts a flags argument consisting of a bitwise
69 - inclusive-OR of zero or more of the following flags, which are defined
70 - in the header <sys/fork.h>:
71 - FORK_NOSIGCHLD
72 - FORK_WAITPID
58 + The vforkx() function accepts a flags argument consisting of a bitwise
59 + inclusive-OR of zero or more of the following flags, which are defined in
60 + the header <sys/fork.h>:
73 61
62 + FORK_NOSIGCHLD
63 + FORK_WAITPID
74 64
75 - See fork(2) for descriptions of these flags. If the flags argument is
76 - 0, vforkx() is identical to vfork().
65 + See fork(2) for descriptions of these flags. If the flags argument is 0,
66 + vforkx() is identical to vfork().
77 67
78 68 RETURN VALUES
79 - Upon successful completion, vfork() and vforkx() return 0 to the child
80 - process and returns the process ID of the child process to the parent
81 - process. Otherwise,1 is returned to the parent process, no child
82 - process is created, and errno is set to indicate the error.
69 + Upon successful completion, vfork() and vforkx() return 0 to the child
70 + process and return the process ID of the child process to the parent
71 + process. Otherwise, 1 is returned to the parent process, no child process
72 + is created, and errno is set to indicate the error.
83 73
84 74 ERRORS
85 - The vfork() and vforkx() functions will fail if:
75 + The vfork() and vforkx() functions will fail if:
86 76
87 - EAGAIN
88 - The system-imposed limit on the total number of processes
89 - under execution (either system-quality or by a single user)
90 - would be exceeded. This limit is determined when the system
91 - is generated.
77 + EAGAIN The system-imposed limit on the total number of
78 + processes under execution (either system-quality or by
79 + a single user) would be exceeded. This limit is
80 + determined when the system is generated.
92 81
82 + ENOMEM There is insufficient swap space for the new process.
93 83
94 - ENOMEM
95 - There is insufficient swap space for the new process.
84 + The vforkx() function will fail if:
96 85
86 + EINVAL The flags argument is invalid.
97 87
88 +INTERFACE STABILITY
89 + The vfork() function is Obsolete Standard.
98 90
99 - The vforkx() function will fail if:
91 + The vforkx() function is Obsolete Uncommitted.
100 92
101 - EINVAL
102 - The flags argument is invalid.
93 +MT-LEVEL
94 + Unsafe.
103 95
104 -
105 -ATTRIBUTES
106 - See attributes(5) for descriptions of the following attributes:
107 -
108 -
109 -
110 -
111 - +--------------------+-----------------+
112 - | ATTRIBUTE TYPE | ATTRIBUTE VALUE |
113 - +--------------------+-----------------+
114 - |Interface Stability | Obsolete |
115 - +--------------------+-----------------+
116 - |MT-Level | Unsafe |
117 - +--------------------+-----------------+
118 -
119 96 SEE ALSO
120 - exec(2), exit(2), fork(2), ioctl(2), atexit(3C), exit(3C),
121 - posix_spawn(3C), posix_spawnp(3C), signal.h(3HEAD), wait(3C),
122 - attributes(5), standards(5)
97 + exec(2), exit(2), fork(2), ioctl(2), atexit(3C), exit(3C),
98 + posix_spawn(3C), posix_spawnp(3C), signal.h(3HEAD), wait(3C),
99 + standards(5)
123 100
124 101 NOTES
125 - To avoid a possible deadlock situation, processes that are children in
126 - the middle of a vfork() or vforkx() are never sent SIGTTOU or SIGTTIN
127 - signals; rather, output or ioctls are allowed and input attempts result
128 - in an EOF indication.
102 + To avoid a possible deadlock situation, processes that are children in
103 + the middle of a vfork() or vforkx() are never sent SIGTTOU or SIGTTIN
104 + signals; rather, output or ioctls are allowed and input attempts result
105 + in an EOF indication.
129 106
107 + To forestall parent memory corruption due to race conditions with signal
108 + handling, vfork() and vforkx() treat signal handlers in the child process
109 + in the same manner as the exec(2) functions: signals set to be caught by
110 + the parent process are set to the default action (SIG_DFL) in the child
111 + process (see signal.h(3HEAD)). Any attempt to set a signal handler in
112 + the child before execve() to anything other than SIG_DFL or SIG_IGN is
113 + disallowed and results in setting the handler to SIG_DFL.
130 114
131 - To forestall parent memory corruption due to race conditions with
132 - signal handling, vfork() and vforkx() treat signal handlers in the
133 - child process in the same manner as the exec(2) functions: signals set
134 - to be caught by the parent process are set to the default action
135 - (SIG_DFL) in the child process (see signal.h(3HEAD)). Any attempt to
136 - set a signal handler in the child before execve() to anything other
137 - than SIG_DFL or SIG_IGN is disallowed and results in setting the
138 - handler to SIG_DFL.
115 + On some systems, the implementation of vfork() and vforkx() cause the
116 + parent to inherit register values from the child. This can create
117 + problems for certain optimizing compilers if <unistd.h> is not included
118 + in the source calling vfork() or if <sys/fork.h> is not included in the
119 + source calling vforkx().
139 120
121 +STANDARDS
122 + The vfork() function is available in the following compilation
123 + environments. See standards(5).
140 124
141 - On some systems, the implementation of vfork() and vforkx() cause the
142 - parent to inherit register values from the child. This can create
143 - problems for certain optimizing compilers if <unistd.h> is not included
144 - in the source calling vfork() or if <sys/fork.h> is not included in the
145 - source calling vforkx().
125 + X/Open Portability Guide Issue4, Version2 (XPG4.2)
126 + Version2 of the Single UNIX Specification (SUSv2)
127 + Version3 of the Single UNIX Specification (SUSv3)
146 128
129 + It was marked obsolete in Version3 of the Single UNIX Specification
130 + (SUSv3) and removed from IEEE Std 1003.1-2008 (POSIX.1).
147 131
132 + The vforkx() function is a local extension and not available in any
133 + strictly standards-compliant compilation environment.
148 134
149 - December 13, 2006 VFORK(2)
135 +illumos August 20, 2014 illumos
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