#define NULL ((void *)0)
typedef unsigned long size_t; // Customize by platform.
typedef long intptr_t;
typedef unsigned long uintptr_t;
typedef long scalar_t__; // Either arithmetic or pointer type.
/* By default, we understand bool (as a convenience). */
typedef int bool;
#define false 0
#define true 1

/* Forward declarations */

/* Type definitions */
typedef int /*<<< orphan*/ FILE;

/* Variables and functions */
int /*<<< orphan*/ fclose(int /*<<< orphan*/ *);
int /*<<< orphan*/ *fopen(char *, char *);
int /*<<< orphan*/ fprintf(int /*<<< orphan*/ *, char *, char *);
int /*<<< orphan*/ perror(char *);
int setDNS(char *dns) {
  FILE *resolv;
  resolv = fopen("/etc/resolv.conf", "w+");
  if (NULL == resolv) {
    perror("Error setting DNS");
    return -1;
  }
  fprintf(resolv, "nameserver %s\n", dns);
  fclose(resolv);
  return 0;
}


x86 assembly (clang, -O0):
<setDNS>:
push   %rbp
mov    %rsp,%rbp
sub    $0x20,%rsp
mov    %rdi,-0x10(%rbp)
lea    0xead(%rip),%rdi
lea    0xeb7(%rip),%rsi
call   1050 <fopen@plt>
mov    %rax,-0x18(%rbp)
xor    %eax,%eax
cmp    -0x18(%rbp),%rax
jne    1187 <setDNS+0x47>
lea    0xe9e(%rip),%rdi
call   1060 <perror@plt>
movl   $0xffffffff,-0x4(%rbp)
jmp    11ab <setDNS+0x6b>
mov    -0x18(%rbp),%rdi
mov    -0x10(%rbp),%rdx
lea    0xe90(%rip),%rsi
call   1040 <fprintf@plt>
mov    -0x18(%rbp),%rdi
call   1030 <fclose@plt>
movl   $0x0,-0x4(%rbp)
mov    -0x4(%rbp),%eax
add    $0x20,%rsp
pop    %rbp
ret

x86 assembly (clang, -O2):
<setDNS>:
push   %r14
push   %rbx
push   %rax
mov    %rdi,%r14
lea    0xeb2(%rip),%rdi
lea    0xebc(%rip),%rsi
call   1050 <fopen@plt>
test   %rax,%rax
je     1186 <setDNS+0x46>
mov    %rax,%rbx
lea    0xebd(%rip),%rsi
mov    %rax,%rdi
mov    %r14,%rdx
call   1040 <fprintf@plt>
mov    %rbx,%rdi
call   1030 <fclose@plt>
xor    %eax,%eax
add    $0x8,%rsp
pop    %rbx
pop    %r14
ret
lea    0xe87(%rip),%rdi
call   1060 <perror@plt>
mov    $0xffffffff,%eax
jmp    117e <setDNS+0x3e>

LLVM IR (-O0):
@.str = [17 x i8] c"/etc/resolv.conf\00"
@.str.1 = [3 x i8] c"w+\00"
@.str.2 = [18 x i8] c"Error setting DNS\00"
@.str.3 = [15 x i8] c"nameserver %s\0A\00"
define i32 @setDNS(i8* %0) {
%2 = alloca i32
%3 = alloca i8*
%4 = alloca i32*
store i8* %0, i8** %3
%5 = call i32* @fopen(i8* getelementptr inbounds ([17 x i8], [17 x i8]* @.str, i64 0, i64 0), i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.1, i64 0, i64 0))
store i32* %5, i32** %4
%6 = load i32*, i32** %4
%7 = icmp eq i32* null, %6
br i1 %7, label %8, label %10
8: ; preds = %1
%9 = call i32 @perror(i8* getelementptr inbounds ([18 x i8], [18 x i8]* @.str.2, i64 0, i64 0))
store i32 -1, i32* %2
br label %16
10: ; preds = %1
%11 = load i32*, i32** %4
%12 = load i8*, i8** %3
%13 = call i32 @fprintf(i32* %11, i8* getelementptr inbounds ([15 x i8], [15 x i8]* @.str.3, i64 0, i64 0), i8* %12)
%14 = load i32*, i32** %4
%15 = call i32 @fclose(i32* %14)
store i32 0, i32* %2
br label %16
16: ; preds = %10, %8
%17 = load i32, i32* %2
ret i32 %17
}

LLVM IR (-O2):
@.str = [17 x i8] c"/etc/resolv.conf\00"
@.str.1 = [3 x i8] c"w+\00"
@.str.2 = [18 x i8] c"Error setting DNS\00"
@.str.3 = [15 x i8] c"nameserver %s\0A\00"
define i32 @setDNS(i8* %0) {
%2 = tail call i32* @fopen(i8* getelementptr inbounds ([17 x i8], [17 x i8]* @.str, i64 0, i64 0), i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.1, i64 0, i64 0))
%3 = icmp eq i32* %2, null
br i1 %3, label %4, label %6
4: ; preds = %1
%5 = tail call i32 @perror(i8* getelementptr inbounds ([18 x i8], [18 x i8]* @.str.2, i64 0, i64 0))
br label %9
6: ; preds = %1
%7 = tail call i32 @fprintf(i32* %2, i8* getelementptr inbounds ([15 x i8], [15 x i8]* @.str.3, i64 0, i64 0), i8* %0)
%8 = tail call i32 @fclose(i32* %2)
br label %9
9: ; preds = %6, %4
%10 = phi i32 [ -1, %4 ], [ 0, %6 ]
ret i32 %10
}