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util, pasta: Add do_clone() wrapper around __clone2() and clone()
Spotted in Debian's buildd logs: on ia64, clone(2) is not available: the glibc wrapper is named __clone2() and it takes, additionally, the size of the stack area passed by the caller. Add a do_clone() wrapper handling the different cases, and also taking care of pointing the child's stack in the middle of the allocated area: on PA-RISC (hppa), handled by clone(), the stack grows up, and on ia64 the stack grows down, but the register backing store grows up -- and I think it might be actually used here. Suggested-by: David Gibson <david@gibson.dropbear.id.au> Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
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parent
7d8c2fb916
commit
ab6f825889
10
pasta.c
10
pasta.c
@ -226,11 +226,11 @@ void pasta_start_ns(struct ctx *c, uid_t uid, gid_t gid,
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arg.argv = sh_argv;
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}
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pasta_child_pid = clone(pasta_spawn_cmd,
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ns_fn_stack + sizeof(ns_fn_stack) / 2,
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CLONE_NEWIPC | CLONE_NEWPID | CLONE_NEWNET |
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CLONE_NEWUTS,
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(void *)&arg);
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pasta_child_pid = do_clone(pasta_spawn_cmd, ns_fn_stack,
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sizeof(ns_fn_stack),
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CLONE_NEWIPC | CLONE_NEWPID | CLONE_NEWNET |
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CLONE_NEWUTS,
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(void *)&arg);
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if (pasta_child_pid == -1) {
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perror("clone");
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21
util.c
21
util.c
@ -482,3 +482,24 @@ int write_file(const char *path, const char *buf)
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close(fd);
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return len == 0 ? 0 : -1;
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}
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/**
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* do_clone() - Wrapper of __clone2() for ia64, clone() for other architectures
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* @fn: Entry point for child
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* @stack_area: Stack area for child: we'll point callees to the middle of it
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* @stack_size: Total size of stack area, passed to callee divided by two
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* @flags: clone() system call flags
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* @arg: Argument to @fn
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*
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* Return: thread ID of child, -1 on failure
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*/
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int do_clone(int (*fn)(void *), char *stack_area, size_t stack_size, int flags,
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void *arg)
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{
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#ifdef __ia64__
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return __clone2(fn, stack_area + stack_size / 2, stack_size / 2,
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flags, arg);
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#else
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return clone(fn, stack_area + stack_size / 2, flags, arg);
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#endif
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}
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8
util.h
8
util.h
@ -81,13 +81,15 @@
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(((struct in_addr *)(a))->s_addr == ((struct in_addr *)b)->s_addr)
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#define NS_FN_STACK_SIZE (RLIMIT_STACK_VAL * 1024 / 8)
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int do_clone(int (*fn)(void *), char *stack_area, size_t stack_size, int flags,
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void *arg);
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#define NS_CALL(fn, arg) \
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do { \
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char ns_fn_stack[NS_FN_STACK_SIZE]; \
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\
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clone((fn), ns_fn_stack + sizeof(ns_fn_stack) / 2, \
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CLONE_VM | CLONE_VFORK | CLONE_FILES | SIGCHLD, \
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(void *)(arg)); \
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do_clone((fn), ns_fn_stack, sizeof(ns_fn_stack), \
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CLONE_VM | CLONE_VFORK | CLONE_FILES | SIGCHLD,\
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(void *)(arg)); \
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} while (0)
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#if __BYTE_ORDER == __BIG_ENDIAN
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