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1From 14adc898a36948267bfe5c63b399996879e94c98 Mon Sep 17 00:00:00 2001
2From: Andreas Gruenbacher <agruenba@redhat.com>
3Date: Fri, 17 Aug 2018 14:07:31 +0200
4Subject: Switch back to syscall()
5
6Switch back to syscall() for the *xattr system calls. The current
7mechanism of forwarding those calls to glibc breaks libraries like
8libfakeroot (fakeroot) and libasan (the gcc address sanitizer; gcc
9-fsanitize=address).
10
11Those libraries provide wrappers for functions defined in other shared
12libraries, usually glibc, do their own processing, and forward calls to
13the original symbols looke dup via dlsym(RTLD_NEXT, "symbol_name"). In
14our case, dlsym returns the libattr_*xattr wrappers. However, when our
15wrappers try calling glibc, they end up calling the libfakeroot /
16libasan wrappers instead because those override the original symbols =>
17recursion.
18
19The libattr_*xattr wrappers will only be used when symbols are looked up
20at runtime (dlopen / dlsym). Programs linking against libattr will
21directly use the glibc provided symbols. Therefore, the slightly worse
22performance of syscall() won't affect any of the "normal" users of
23libattr.
24---
25 libattr/syscalls.c | 26 ++++++++++++++------------
26 1 file changed, 14 insertions(+), 12 deletions(-)
27
28diff --git a/libattr/syscalls.c b/libattr/syscalls.c
29index 3013aa0..721ad7f 100644
30--- a/libattr/syscalls.c
31+++ b/libattr/syscalls.c
32@@ -22,6 +22,8 @@
33
34 #include "config.h"
35
36+#include <unistd.h>
37+#include <sys/syscall.h>
38 #include <sys/xattr.h>
39
40 #ifdef HAVE_VISIBILITY_ATTRIBUTE
41@@ -31,67 +33,67 @@
42 int libattr_setxattr(const char *path, const char *name,
43 void *value, size_t size, int flags)
44 {
45- return setxattr(path, name, value, size, flags);
46+ return syscall(__NR_setxattr, path, name, value, size, flags);
47 }
48
49 int libattr_lsetxattr(const char *path, const char *name,
50 void *value, size_t size, int flags)
51 {
52- return lsetxattr(path, name, value, size, flags);
53+ return syscall(__NR_lsetxattr, path, name, value, size, flags);
54 }
55
56 int libattr_fsetxattr(int filedes, const char *name,
57 void *value, size_t size, int flags)
58 {
59- return fsetxattr(filedes, name, value, size, flags);
60+ return syscall(__NR_fsetxattr, filedes, name, value, size, flags);
61 }
62
63 ssize_t libattr_getxattr(const char *path, const char *name,
64 void *value, size_t size)
65 {
66- return getxattr(path, name, value, size);
67+ return syscall(__NR_getxattr, path, name, value, size);
68 }
69
70 ssize_t libattr_lgetxattr(const char *path, const char *name,
71 void *value, size_t size)
72 {
73- return lgetxattr(path, name, value, size);
74+ return syscall(__NR_lgetxattr, path, name, value, size);
75 }
76
77 ssize_t libattr_fgetxattr(int filedes, const char *name,
78 void *value, size_t size)
79 {
80- return fgetxattr(filedes, name, value, size);
81+ return syscall(__NR_fgetxattr, filedes, name, value, size);
82 }
83
84 ssize_t libattr_listxattr(const char *path, char *list, size_t size)
85 {
86- return listxattr(path, list, size);
87+ return syscall(__NR_listxattr, path, list, size);
88 }
89
90 ssize_t libattr_llistxattr(const char *path, char *list, size_t size)
91 {
92- return llistxattr(path, list, size);
93+ return syscall(__NR_llistxattr, path, list, size);
94 }
95
96 ssize_t libattr_flistxattr(int filedes, char *list, size_t size)
97 {
98- return flistxattr(filedes, list, size);
99+ return syscall(__NR_flistxattr, filedes, list, size);
100 }
101
102 int libattr_removexattr(const char *path, const char *name)
103 {
104- return removexattr(path, name);
105+ return syscall(__NR_removexattr, path, name);
106 }
107
108 int libattr_lremovexattr(const char *path, const char *name)
109 {
110- return lremovexattr(path, name);
111+ return syscall(__NR_lremovexattr, path, name);
112 }
113
114 int libattr_fremovexattr(int filedes, const char *name)
115 {
116- return fremovexattr(filedes, name);
117+ return syscall(__NR_fremovexattr, filedes, name);
118 }
119
120 #ifdef HAVE_VISIBILITY_ATTRIBUTE