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wangbj@localhost ~/test $ ghci -v
1		wangbj@localhost ~/test $ ghci -v
2		GHCi, version 7.4.1: http://www.haskell.org/ghc/ :? for help
3		Glasgow Haskell Compiler, Version 7.4.1, stage 2 booted by GHC version 7.4.1
4		Using binary package database: /usr/lib64/ghc-7.4.1/package.conf.d/package.cache
5		hiding package time-1.4 to avoid conflict with later version time-1.4.0.1
6		wired-in package ghc-prim mapped to ghc-prim-0.2.0.0-c2ff696e5b8ec4d4b2bc2e42085fe471
7		wired-in package integer-gmp mapped to integer-gmp-0.4.0.0-3cccac07aef8e27023f605c1f45bdf74
8		wired-in package base mapped to base-4.5.0.0-40b99d05fae6a4eea95ea69e6e0c9702
9		wired-in package rts mapped to builtin_rts
10		wired-in package template-haskell mapped to template-haskell-2.7.0.0-8c8cd20e21666657195efabced685fe1
11		wired-in package dph-seq not found.
12		wired-in package dph-par not found.
13		Hsc static flags: -static
14		Loading package ghc-prim ... linking ... done.
15		*** gcc:
16		'gcc' '-fno-stack-protector' '-Wl,--hash-size=31' '-Wl,--reduce-memory-overheads' '-L/usr/lib64/ghc-7.4.1/integer-gmp-0.4.0.0' '--print-file-name' 'libgmp.so'
17		Loading package integer-gmp ... linking ... done.
18		Loading package base ... linking ... ghc: /usr/lib64/ghc-7.4.1/base-4.5.0.0/HSbase-4.5.0.0.o: unknown symbol `stat'
19		*** Deleting temp files:
20		Deleting:
21		*** Deleting temp dirs:
22		Deleting:
23		ghc: unable to load package `base'
24		wangbj@localhost ~/test $
25
26
27
28		I create a simple program for testing ``stat'':
29
30		$ cat ex98.c
31		#include <sys/types.h>
32		#include <sys/stat.h>
33
34		#include <stdio.h>
35
36		int main(int argc, char* argv[])
37		{
38		struct stat st;
39
40		stat (argv[0], &st);
41
42		return 0;
43		}
44
45
46		$ readelf -s ex98 \| grep stat
47		4: 0000000000000000 0 FUNC GLOBAL DEFAULT UND __xstat@GLIBC_2.2.5 (2)
48		39: 0000000000400670 16 FUNC GLOBAL HIDDEN 13 __stat
49		40: 0000000000400670 16 FUNC WEAK HIDDEN 13 stat
50		43: 0000000000000000 0 FUNC GLOBAL DEFAULT UND __xstat@@GLIBC_2.2.5
51
52		GLIBC (2.15) don't have symbol for function ``stat'' (or __stat):
53
54		wangbj@localhost ~/test $ readelf -s /lib64/libc.so.6 \| grep 'stat\>'
55		65: 0000000000077730 16 FUNC GLOBAL DEFAULT 12 _IO_file_stat@@GLIBC_2.2.5
56		452: 00000000000dc8d0 69 FUNC GLOBAL DEFAULT 12 __lxstat@@GLIBC_2.2.5
57		1466: 00000000000dc880 69 FUNC GLOBAL DEFAULT 12 __fxstat@@GLIBC_2.2.5
58		1513: 00000000000ea300 69 FUNC GLOBAL DEFAULT 12 ustat@@GLIBC_2.2.5
59		1929: 00000000000dc830 69 FUNC GLOBAL DEFAULT 12 __xstat@@GLIBC_2.2.5
60
61		If I objdump ex98:
62
63		0000000000400594 <main>:
64		400594: 55 push %rbp
65		400595: 48 89 e5 mov %rsp,%rbp
66		400598: 48 81 ec a0 00 00 00 sub $0xa0,%rsp
67		40059f: 89 bd 6c ff ff ff mov %edi,-0x94(%rbp)
68		4005a5: 48 89 b5 60 ff ff ff mov %rsi,-0xa0(%rbp)
69		4005ac: 48 8b 85 60 ff ff ff mov -0xa0(%rbp),%rax
70		4005b3: 48 8b 00 mov (%rax),%rax
71		4005b6: 48 8d 95 70 ff ff ff lea -0x90(%rbp),%rdx
72		4005bd: 48 89 d6 mov %rdx,%rsi
73		4005c0: 48 89 c7 mov %rax,%rdi
74		4005c3: e8 a8 00 00 00 callq 400670 <__stat>
75		4005c8: b8 00 00 00 00 mov $0x0,%eax
76		4005cd: c9 leaveq
77		4005ce: c3 retq
78		4005cf: 90 nop
79
80		...
81
82
83		0000000000400670 <__stat>:
84		400670: 48 89 f2 mov %rsi,%rdx
85		400673: 48 89 fe mov %rdi,%rsi
86		400676: bf 01 00 00 00 mov $0x1,%edi
87		40067b: e9 20 fe ff ff jmpq 4004a0 <__xstat@plt>
88		400680: 55 push %rbp
89		400681: 48 89 e5 mov %rsp,%rbp
90		400684: 53 push %rbx
91		400685: 48 83 ec 08 sub $0x8,%rsp
92		400689: 48 8b 05 58 07 20 00 mov 0x200758(%rip),%rax # 600de8 <__init_array_end+0x4>
93		400690: 48 83 f8 ff cmp $0xffffffffffffffff,%rax
94		400694: 74 19 je 4006af <__stat+0x3f>
95		400696: bb e8 0d 60 00 mov $0x600de8,%ebx
96		40069b: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
97		4006a0: 48 83 eb 08 sub $0x8,%rbx
98		4006a4: ff d0 callq *%rax
99		4006a6: 48 8b 03 mov (%rbx),%rax
100		4006a9: 48 83 f8 ff cmp $0xffffffffffffffff,%rax
101		4006ad: 75 f1 jne 4006a0 <__stat+0x30>
102		4006af: 48 83 c4 08 add $0x8,%rsp
103		4006b3: 5b pop %rbx
104		4006b4: c9 leaveq
105		4006b5: c3 retq
106		4006b6: 90 nop
107		4006b7: 90 nop
108
109
110	-	So it seems GCC will create its own stat, and will call __xstat@plt from glibc, not the plain ``stat''.
110	+	So it seems GCC will create its own stat, and will call __xstat@plt from glibc, not the plain ``stat''.
111
112		in /usr/include/sys/stat.h:
113
114		#if defined __GNUC__ && __GNUC__ >= 2 && defined __USE_EXTERN_INLINES
115		/* Inlined versions of the real stat and mknod functions. */
116
117		__extern_inline int
118		__NTH (stat (__const char __path, struct stat __statbuf))
119		{
120		return __xstat (_STAT_VER, __path, __statbuf);
121		}
122
123		So it should be an error that HSbase.o linked agaist ``stat'' directly?