From: Carlos Santos <unixmania(a)gmail.com>
The return type of syscall() is long so __syscall_error, which is jumped
to by syscall handlers to stash an error number into errno, must return
long too otherwhise it returs 4294967295L instead of -1L. For example,
syscall for x86_64 is defined in libc/sysdeps/linux/x86_64/syscall.S as
syscall:
movq %rdi, %rax /* Syscall number -> rax. */
movq %rsi, %rdi /* shift arg1 - arg5. */
movq %rdx, %rsi
movq %rcx, %rdx
movq %r8, %r10
movq %r9, %r8
movq 8(%rsp),%r9 /* arg6 is on the stack. */
syscall /* Do the system call. */
cmpq $-4095, %rax /* Check %rax for error. */
jae __syscall_error /* Branch forward if it failed. */
ret /* Return to caller. */
In libc/sysdeps/linux/x86_64/__syscall_error.c, __syscall_error is
defined as
int __syscall_error(void) attribute_hidden;
int __syscall_error(void)
{
register int err_no __asm__ ("%rcx");
__asm__ ("mov %rax, %rcx\n\t"
"neg %rcx");
__set_errno(err_no);
return -1;
}
So __syscall_error returns -1 as a 32-bit int in a 64-bit register, %rax
(0x00000000ffffffff, whose decimal value is decimal 4294967295) and a
test like this always returns false:
if (syscall(number, ...) == -1)
foo();
Fix the error by making __syscall_error return a long, like syscall().
The problem can be circumvented by the caller by coercing the returned
value to int before comparing it to -1:
if ((int) syscall(number, ...) == -1)
foo();
The same problem probably occurs on other 64-bit systems but so far only
x86_64 was tested, so this change must be considered experimental.
Signed-off-by: Carlos Santos <unixmania(a)gmail.com>
---
libc/sysdeps/linux/aarch64/__syscall_error.c | 4 ++--
libc/sysdeps/linux/alpha/__syscall_error.c | 2 +-
libc/sysdeps/linux/arc/__syscall_error.c | 2 +-
libc/sysdeps/linux/arm/__syscall_error.c | 4 ++--
libc/sysdeps/linux/csky/__syscall_error.c | 2 +-
libc/sysdeps/linux/csky/clone.c | 2 +-
libc/sysdeps/linux/frv/sysdep.c | 2 +-
libc/sysdeps/linux/hppa/__syscall_error.c | 4 ++--
libc/sysdeps/linux/i386/__syscall_error.c | 4 ++--
libc/sysdeps/linux/ia64/__syscall_error.c | 4 ++--
libc/sysdeps/linux/m68k/__syscall_error.c | 4 ++--
libc/sysdeps/linux/metag/__syscall_error.c | 4 ++--
libc/sysdeps/linux/microblaze/__syscall_error.c | 4 ++--
libc/sysdeps/linux/mips/__syscall_error.c | 4 ++--
libc/sysdeps/linux/nds32/__syscall_error.c | 4 ++--
libc/sysdeps/linux/nios2/__syscall_error.c | 4 ++--
libc/sysdeps/linux/or1k/__syscall_error.c | 4 ++--
libc/sysdeps/linux/powerpc/__syscall_error.c | 4 ++--
libc/sysdeps/linux/riscv64/__syscall_error.c | 4 ++--
libc/sysdeps/linux/sparc/__syscall_error.c | 4 ++--
libc/sysdeps/linux/sparc64/__syscall_error.c | 4 ++--
libc/sysdeps/linux/tile/__syscall_error.c | 2 +-
libc/sysdeps/linux/x86_64/__syscall_error.c | 4 ++--
libc/sysdeps/linux/xtensa/__syscall_error.c | 4 ++--
libpthread/nptl/sysdeps/unix/sysv/linux/__syscall_error.c | 4 ++--
25 files changed, 44 insertions(+), 44 deletions(-)
diff --git a/libc/sysdeps/linux/aarch64/__syscall_error.c b/libc/sysdeps/linux/aarch64/__syscall_error.c
index 2b642e816..c682aae49 100644
--- a/libc/sysdeps/linux/aarch64/__syscall_error.c
+++ b/libc/sysdeps/linux/aarch64/__syscall_error.c
@@ -10,8 +10,8 @@
/* This routine is jumped to by all the syscall handlers, to stash
* an error number into errno. */
-int __syscall_error(int err_no) attribute_hidden;
-int __syscall_error(int err_no)
+long __syscall_error(int err_no) attribute_hidden;
+long __syscall_error(int err_no)
{
__set_errno(-err_no);
return -1;
diff --git a/libc/sysdeps/linux/alpha/__syscall_error.c b/libc/sysdeps/linux/alpha/__syscall_error.c
index 7c081f3b5..c986e484d 100644
--- a/libc/sysdeps/linux/alpha/__syscall_error.c
+++ b/libc/sysdeps/linux/alpha/__syscall_error.c
@@ -8,7 +8,7 @@
/* This routine is jumped to by all the syscall handlers, to stash
an error number into errno. */
-int attribute_hidden __syscall_error (void)
+long attribute_hidden __syscall_error (void)
{
register int err_no __asm__("$0");
__set_errno (err_no);
diff --git a/libc/sysdeps/linux/arc/__syscall_error.c b/libc/sysdeps/linux/arc/__syscall_error.c
index 962d743e4..7f30485a8 100644
--- a/libc/sysdeps/linux/arc/__syscall_error.c
+++ b/libc/sysdeps/linux/arc/__syscall_error.c
@@ -8,7 +8,7 @@
#include <errno.h>
#include <sys/syscall.h>
-int __syscall_error(int err_no)
+long __syscall_error(int err_no)
{
__set_errno(-err_no);
return -1;
diff --git a/libc/sysdeps/linux/arm/__syscall_error.c b/libc/sysdeps/linux/arm/__syscall_error.c
index 2b642e816..c682aae49 100644
--- a/libc/sysdeps/linux/arm/__syscall_error.c
+++ b/libc/sysdeps/linux/arm/__syscall_error.c
@@ -10,8 +10,8 @@
/* This routine is jumped to by all the syscall handlers, to stash
* an error number into errno. */
-int __syscall_error(int err_no) attribute_hidden;
-int __syscall_error(int err_no)
+long __syscall_error(int err_no) attribute_hidden;
+long __syscall_error(int err_no)
{
__set_errno(-err_no);
return -1;
diff --git a/libc/sysdeps/linux/csky/__syscall_error.c b/libc/sysdeps/linux/csky/__syscall_error.c
index cc1fb5977..c6a4a14eb 100644
--- a/libc/sysdeps/linux/csky/__syscall_error.c
+++ b/libc/sysdeps/linux/csky/__syscall_error.c
@@ -8,7 +8,7 @@
#include <errno.h>
#include <features.h>
-int __syscall_error(int err_no)
+long __syscall_error(int err_no)
{
__set_errno(-err_no);
return -1;
diff --git a/libc/sysdeps/linux/csky/clone.c b/libc/sysdeps/linux/csky/clone.c
index 991cb8962..f0fcc257b 100644
--- a/libc/sysdeps/linux/csky/clone.c
+++ b/libc/sysdeps/linux/csky/clone.c
@@ -9,7 +9,7 @@
#include <sysdep.h>
#include <unistd.h>
-extern int __syscall_error(int err_no);
+extern long __syscall_error(int err_no);
extern int __csky_clone (
int flags,
diff --git a/libc/sysdeps/linux/frv/sysdep.c b/libc/sysdeps/linux/frv/sysdep.c
index bfae12100..28beb418f 100644
--- a/libc/sysdeps/linux/frv/sysdep.c
+++ b/libc/sysdeps/linux/frv/sysdep.c
@@ -19,7 +19,7 @@
/* This routine is jumped to by all the syscall handlers, to stash
an error number into errno. */
-int __syscall_error (int err_no)
+long __syscall_error (int err_no)
{
__set_errno (-err_no);
return -1;
diff --git a/libc/sysdeps/linux/hppa/__syscall_error.c b/libc/sysdeps/linux/hppa/__syscall_error.c
index 5e109a83b..af26cf6ab 100644
--- a/libc/sysdeps/linux/hppa/__syscall_error.c
+++ b/libc/sysdeps/linux/hppa/__syscall_error.c
@@ -10,8 +10,8 @@
/* This routine is jumped to by all the syscall handlers, to stash
* an error number into errno. */
-int __syscall_error(int err_no) attribute_hidden;
-int __syscall_error(int err_no)
+long __syscall_error(int err_no) attribute_hidden;
+long __syscall_error(int err_no)
{
__set_errno(err_no);
return -1;
diff --git a/libc/sysdeps/linux/i386/__syscall_error.c b/libc/sysdeps/linux/i386/__syscall_error.c
index 36946bc6d..102ebbedb 100644
--- a/libc/sysdeps/linux/i386/__syscall_error.c
+++ b/libc/sysdeps/linux/i386/__syscall_error.c
@@ -25,8 +25,8 @@
#include <errno.h>
#include <features.h>
-int __syscall_error(void) attribute_hidden;
-int __syscall_error(void)
+long __syscall_error(void) attribute_hidden;
+long __syscall_error(void)
{
register int eax __asm__ ("%eax");
int _errno = -eax;
diff --git a/libc/sysdeps/linux/ia64/__syscall_error.c b/libc/sysdeps/linux/ia64/__syscall_error.c
index 0727b2b53..cc2b13450 100644
--- a/libc/sysdeps/linux/ia64/__syscall_error.c
+++ b/libc/sysdeps/linux/ia64/__syscall_error.c
@@ -10,8 +10,8 @@
/* This routine is jumped to by all the syscall handlers, to stash
* an error number into errno. */
-int __syscall_error(void) attribute_hidden;
-int __syscall_error(void)
+long __syscall_error(void) attribute_hidden;
+long __syscall_error(void)
{
register int err_no __asm__("%r8");
__set_errno(err_no);
diff --git a/libc/sysdeps/linux/m68k/__syscall_error.c b/libc/sysdeps/linux/m68k/__syscall_error.c
index a29f6ffd6..2d2677521 100644
--- a/libc/sysdeps/linux/m68k/__syscall_error.c
+++ b/libc/sysdeps/linux/m68k/__syscall_error.c
@@ -10,8 +10,8 @@
/* This routine is jumped to by all the syscall handlers, to stash
* an error number into errno. */
-int __syscall_error(void) attribute_hidden;
-int __syscall_error(void)
+long __syscall_error(void) attribute_hidden;
+long __syscall_error(void)
{
register int err_no __asm__("%d0");
__set_errno(-err_no);
diff --git a/libc/sysdeps/linux/metag/__syscall_error.c b/libc/sysdeps/linux/metag/__syscall_error.c
index f97cd0126..3e82abe0d 100644
--- a/libc/sysdeps/linux/metag/__syscall_error.c
+++ b/libc/sysdeps/linux/metag/__syscall_error.c
@@ -10,8 +10,8 @@
/* This routine is jumped to by all the syscall handlers, to stash
* an error number into errno. */
-int __syscall_error(int err_no) attribute_hidden;
-int __syscall_error(int err_no)
+long __syscall_error(int err_no) attribute_hidden;
+long __syscall_error(int err_no)
{
__set_errno(-err_no);
return -1;
diff --git a/libc/sysdeps/linux/microblaze/__syscall_error.c b/libc/sysdeps/linux/microblaze/__syscall_error.c
index 2b642e816..c682aae49 100644
--- a/libc/sysdeps/linux/microblaze/__syscall_error.c
+++ b/libc/sysdeps/linux/microblaze/__syscall_error.c
@@ -10,8 +10,8 @@
/* This routine is jumped to by all the syscall handlers, to stash
* an error number into errno. */
-int __syscall_error(int err_no) attribute_hidden;
-int __syscall_error(int err_no)
+long __syscall_error(int err_no) attribute_hidden;
+long __syscall_error(int err_no)
{
__set_errno(-err_no);
return -1;
diff --git a/libc/sysdeps/linux/mips/__syscall_error.c b/libc/sysdeps/linux/mips/__syscall_error.c
index 5e109a83b..af26cf6ab 100644
--- a/libc/sysdeps/linux/mips/__syscall_error.c
+++ b/libc/sysdeps/linux/mips/__syscall_error.c
@@ -10,8 +10,8 @@
/* This routine is jumped to by all the syscall handlers, to stash
* an error number into errno. */
-int __syscall_error(int err_no) attribute_hidden;
-int __syscall_error(int err_no)
+long __syscall_error(int err_no) attribute_hidden;
+long __syscall_error(int err_no)
{
__set_errno(err_no);
return -1;
diff --git a/libc/sysdeps/linux/nds32/__syscall_error.c b/libc/sysdeps/linux/nds32/__syscall_error.c
index 2aa6903e2..c8e6044a7 100644
--- a/libc/sysdeps/linux/nds32/__syscall_error.c
+++ b/libc/sysdeps/linux/nds32/__syscall_error.c
@@ -8,8 +8,8 @@
/* This routine is jumped to by all the syscall handlers, to stash
* an error number into errno. */
-int __syscall_error(int err_no) attribute_hidden;
-int __syscall_error(int err_no)
+long __syscall_error(int err_no) attribute_hidden;
+long __syscall_error(int err_no)
{
__set_errno(err_no);
return -1;
diff --git a/libc/sysdeps/linux/nios2/__syscall_error.c b/libc/sysdeps/linux/nios2/__syscall_error.c
index 2b642e816..c682aae49 100644
--- a/libc/sysdeps/linux/nios2/__syscall_error.c
+++ b/libc/sysdeps/linux/nios2/__syscall_error.c
@@ -10,8 +10,8 @@
/* This routine is jumped to by all the syscall handlers, to stash
* an error number into errno. */
-int __syscall_error(int err_no) attribute_hidden;
-int __syscall_error(int err_no)
+long __syscall_error(int err_no) attribute_hidden;
+long __syscall_error(int err_no)
{
__set_errno(-err_no);
return -1;
diff --git a/libc/sysdeps/linux/or1k/__syscall_error.c b/libc/sysdeps/linux/or1k/__syscall_error.c
index 1b7e8a394..7d1e09d91 100644
--- a/libc/sysdeps/linux/or1k/__syscall_error.c
+++ b/libc/sysdeps/linux/or1k/__syscall_error.c
@@ -17,11 +17,11 @@
#include <errno.h>
-int __syscall_error (int err_no);
+long __syscall_error (int err_no);
/* This routine is jumped to by all the syscall handlers, to stash
* an error number into errno. */
-int __syscall_error (int err_no)
+long __syscall_error (int err_no)
{
__set_errno (err_no);
return -1;
diff --git a/libc/sysdeps/linux/powerpc/__syscall_error.c b/libc/sysdeps/linux/powerpc/__syscall_error.c
index 5e109a83b..af26cf6ab 100644
--- a/libc/sysdeps/linux/powerpc/__syscall_error.c
+++ b/libc/sysdeps/linux/powerpc/__syscall_error.c
@@ -10,8 +10,8 @@
/* This routine is jumped to by all the syscall handlers, to stash
* an error number into errno. */
-int __syscall_error(int err_no) attribute_hidden;
-int __syscall_error(int err_no)
+long __syscall_error(int err_no) attribute_hidden;
+long __syscall_error(int err_no)
{
__set_errno(err_no);
return -1;
diff --git a/libc/sysdeps/linux/riscv64/__syscall_error.c b/libc/sysdeps/linux/riscv64/__syscall_error.c
index 2b642e816..c682aae49 100644
--- a/libc/sysdeps/linux/riscv64/__syscall_error.c
+++ b/libc/sysdeps/linux/riscv64/__syscall_error.c
@@ -10,8 +10,8 @@
/* This routine is jumped to by all the syscall handlers, to stash
* an error number into errno. */
-int __syscall_error(int err_no) attribute_hidden;
-int __syscall_error(int err_no)
+long __syscall_error(int err_no) attribute_hidden;
+long __syscall_error(int err_no)
{
__set_errno(-err_no);
return -1;
diff --git a/libc/sysdeps/linux/sparc/__syscall_error.c b/libc/sysdeps/linux/sparc/__syscall_error.c
index 5e109a83b..af26cf6ab 100644
--- a/libc/sysdeps/linux/sparc/__syscall_error.c
+++ b/libc/sysdeps/linux/sparc/__syscall_error.c
@@ -10,8 +10,8 @@
/* This routine is jumped to by all the syscall handlers, to stash
* an error number into errno. */
-int __syscall_error(int err_no) attribute_hidden;
-int __syscall_error(int err_no)
+long __syscall_error(int err_no) attribute_hidden;
+long __syscall_error(int err_no)
{
__set_errno(err_no);
return -1;
diff --git a/libc/sysdeps/linux/sparc64/__syscall_error.c b/libc/sysdeps/linux/sparc64/__syscall_error.c
index 5e109a83b..af26cf6ab 100644
--- a/libc/sysdeps/linux/sparc64/__syscall_error.c
+++ b/libc/sysdeps/linux/sparc64/__syscall_error.c
@@ -10,8 +10,8 @@
/* This routine is jumped to by all the syscall handlers, to stash
* an error number into errno. */
-int __syscall_error(int err_no) attribute_hidden;
-int __syscall_error(int err_no)
+long __syscall_error(int err_no) attribute_hidden;
+long __syscall_error(int err_no)
{
__set_errno(err_no);
return -1;
diff --git a/libc/sysdeps/linux/tile/__syscall_error.c b/libc/sysdeps/linux/tile/__syscall_error.c
index a91fdff3a..31cab3799 100644
--- a/libc/sysdeps/linux/tile/__syscall_error.c
+++ b/libc/sysdeps/linux/tile/__syscall_error.c
@@ -6,7 +6,7 @@
#include <errno.h>
#include <features.h>
-int __syscall_error(int err_no)
+long __syscall_error(int err_no)
{
__set_errno(-err_no);
return -1;
diff --git a/libc/sysdeps/linux/x86_64/__syscall_error.c b/libc/sysdeps/linux/x86_64/__syscall_error.c
index 448f50983..7f0f388c4 100644
--- a/libc/sysdeps/linux/x86_64/__syscall_error.c
+++ b/libc/sysdeps/linux/x86_64/__syscall_error.c
@@ -10,8 +10,8 @@
/* This routine is jumped to by all the syscall handlers, to stash
* an error number into errno. */
-int __syscall_error(void) attribute_hidden;
-int __syscall_error(void)
+long __syscall_error(void) attribute_hidden;
+long __syscall_error(void)
{
register int err_no __asm__ ("%rcx");
__asm__ ("mov %rax, %rcx\n\t"
diff --git a/libc/sysdeps/linux/xtensa/__syscall_error.c b/libc/sysdeps/linux/xtensa/__syscall_error.c
index 2b642e816..c682aae49 100644
--- a/libc/sysdeps/linux/xtensa/__syscall_error.c
+++ b/libc/sysdeps/linux/xtensa/__syscall_error.c
@@ -10,8 +10,8 @@
/* This routine is jumped to by all the syscall handlers, to stash
* an error number into errno. */
-int __syscall_error(int err_no) attribute_hidden;
-int __syscall_error(int err_no)
+long __syscall_error(int err_no) attribute_hidden;
+long __syscall_error(int err_no)
{
__set_errno(-err_no);
return -1;
diff --git a/libpthread/nptl/sysdeps/unix/sysv/linux/__syscall_error.c b/libpthread/nptl/sysdeps/unix/sysv/linux/__syscall_error.c
index 5e109a83b..af26cf6ab 100644
--- a/libpthread/nptl/sysdeps/unix/sysv/linux/__syscall_error.c
+++ b/libpthread/nptl/sysdeps/unix/sysv/linux/__syscall_error.c
@@ -10,8 +10,8 @@
/* This routine is jumped to by all the syscall handlers, to stash
* an error number into errno. */
-int __syscall_error(int err_no) attribute_hidden;
-int __syscall_error(int err_no)
+long __syscall_error(int err_no) attribute_hidden;
+long __syscall_error(int err_no)
{
__set_errno(err_no);
return -1;
--
2.18.1
