#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*/ exit(int);
int /*<<< orphan*/ *fgets(char *, int, int /*<<< orphan*/ *);
int /*<<< orphan*/ pclose(int /*<<< orphan*/ *);
int /*<<< orphan*/ *popen(char *, char *);
int /*<<< orphan*/ printf(char *, ...);
int main() {
  FILE *fp;
  char *cmd = "ps -ef";
  char buff[1024] = {0};
  if ((fp = popen(cmd, "r")) == NULL) {
    printf("Popen error\n");
    exit(1);
  }
  while ((fgets(buff, 1024, fp)) != NULL) {
    printf("%s", buff);
  }
  pclose(fp);
  exit(0);
}


x86 assembly (clang, -O0):
<main>:
push   %rbp
mov    %rsp,%rbp
sub    $0x420,%rsp
movl   $0x0,-0x4(%rbp)
lea    0xe87(%rip),%rax
mov    %rax,-0x18(%rbp)
lea    -0x420(%rbp),%rdi
xor    %esi,%esi
mov    $0x400,%edx
call   1050 <memset@plt>
mov    -0x18(%rbp),%rdi
lea    0xe6c(%rip),%rsi
call   1070 <popen@plt>
mov    %rax,-0x10(%rbp)
cmp    $0x0,%rax
jne    11c6 <main+0x66>
lea    0xe54(%rip),%rdi
mov    $0x0,%al
call   1030 <printf@plt>
mov    $0x1,%edi
call   1080 <exit@plt>
jmp    11cb <main+0x6b>
lea    -0x420(%rbp),%rdi
mov    -0x10(%rbp),%rdx
mov    $0x400,%esi
call   1060 <fgets@plt>
cmp    $0x0,%rax
je     1204 <main+0xa4>
lea    -0x420(%rbp),%rsi
lea    0xe1e(%rip),%rdi
mov    $0x0,%al
call   1030 <printf@plt>
jmp    11cb <main+0x6b>
mov    -0x10(%rbp),%rdi
call   1040 <pclose@plt>
xor    %edi,%edi
call   1080 <exit@plt>

x86 assembly (clang, -O2):
<main>:
push   %r15
push   %r14
push   %rbx
sub    $0x400,%rsp
mov    %rsp,%rdi
mov    $0x400,%edx
xor    %esi,%esi
call   1060 <memset@plt>
lea    0xe6e(%rip),%rdi
lea    0xe7b(%rip),%rsi
call   1080 <popen@plt>
test   %rax,%rax
jne    11b9 <main+0x49>
lea    0xe60(%rip),%rdi
call   1030 <puts@plt>
mov    $0x1,%edi
call   1090 <exit@plt>
mov    %rax,%r15
mov    %rsp,%rdi
mov    $0x400,%esi
mov    %rax,%rdx
call   1070 <fgets@plt>
test   %rax,%rax
je     1202 <main+0x92>
lea    0xe2f(%rip),%r14
mov    %rsp,%rbx
nopl   0x0(%rax,%rax,1)
mov    %r14,%rdi
mov    %rbx,%rsi
xor    %eax,%eax
call   1040 <printf@plt>
mov    %rbx,%rdi
mov    $0x400,%esi
mov    %r15,%rdx
call   1070 <fgets@plt>
test   %rax,%rax
jne    11e0 <main+0x70>
mov    %r15,%rdi
call   1050 <pclose@plt>
xor    %edi,%edi
call   1090 <exit@plt>

LLVM IR (-O0):
@.str = [7 x i8] c"ps -ef\00"
@.str.1 = [2 x i8] c"r\00"
@.str.2 = [13 x i8] c"Popen error\0A\00"
@.str.3 = [3 x i8] c"%s\00"
define i32 @main() {
%1 = alloca i32
%2 = alloca i32*
%3 = alloca i8*
%4 = alloca [1024 x i8]
store i32 0, i32* %1
store i8* getelementptr inbounds ([7 x i8], [7 x i8]* @.str, i64 0, i64 0), i8** %3
%5 = bitcast [1024 x i8]* %4 to i8*
%6 = load i8*, i8** %3
%7 = call i32* @popen(i8* %6, i8* getelementptr inbounds ([2 x i8], [2 x i8]* @.str.1, i64 0, i64 0))
store i32* %7, i32** %2
%8 = icmp eq i32* %7, null
br i1 %8, label %9, label %12
9: ; preds = %0
%10 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([13 x i8], [13 x i8]* @.str.2, i64 0, i64 0))
%11 = call i32 @exit(i32 1)
unreachable
12: ; preds = %0
br label %13
13: ; preds = %18, %12
%14 = getelementptr inbounds [1024 x i8], [1024 x i8]* %4, i64 0, i64 0
%15 = load i32*, i32** %2
%16 = call i32* @fgets(i8* %14, i32 1024, i32* %15)
%17 = icmp ne i32* %16, null
br i1 %17, label %18, label %21
18: ; preds = %13
%19 = getelementptr inbounds [1024 x i8], [1024 x i8]* %4, i64 0, i64 0
%20 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([3 x i8], [3 x i8]* @.str.3, i64 0, i64 0), i8* %19)
br label %13
21: ; preds = %13
%22 = load i32*, i32** %2
%23 = call i32 @pclose(i32* %22)
%24 = call i32 @exit(i32 0)
unreachable
}

LLVM IR (-O2):
@.str = [7 x i8] c"ps -ef\00"
@.str.1 = [2 x i8] c"r\00"
@.str.3 = [3 x i8] c"%s\00"
@str = [12 x i8] c"Popen error\00"
define i32 @main() {
%1 = alloca [1024 x i8]
%2 = getelementptr inbounds [1024 x i8], [1024 x i8]* %1, i64 0, i64 0
%3 = tail call i32* @popen(i8* getelementptr inbounds ([7 x i8], [7 x i8]* @.str, i64 0, i64 0), i8* getelementptr inbounds ([2 x i8], [2 x i8]* @.str.1, i64 0, i64 0))
%4 = icmp eq i32* %3, null
br i1 %4, label %8, label %5
5: ; preds = %0
%6 = call i32* @fgets(i8* %2, i32 1024, i32* %3)
%7 = icmp eq i32* %6, null
br i1 %7, label %15, label %11
8: ; preds = %0
%9 = tail call i32 @puts(i8* dereferenceable(1) getelementptr inbounds ([12 x i8], [12 x i8]* @str, i64 0, i64 0))
%10 = tail call i32 @exit(i32 1)
unreachable
11: ; preds = %5, %11
%12 = call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([3 x i8], [3 x i8]* @.str.3, i64 0, i64 0), i8* %2)
%13 = call i32* @fgets(i8* %2, i32 1024, i32* %3)
%14 = icmp eq i32* %13, null
br i1 %14, label %15, label %11
15: ; preds = %11, %5
%16 = call i32 @pclose(i32* %3)
%17 = call i32 @exit(i32 0)
unreachable
}