Damien Guard nerd sniped me and and other folks wanted more proof that it is now cheap, easy and possible to cheaply rewrite software or clone existing “source available” businesses (see bottom of the post).
So, let’s get cracking by creating a toy application by sending this prompt to the LLM.
Create a sales tax calculator in C
Food is taxed at 10%
Personal Hygine is at 0%
Everything else 25%
Which creates
#include
#include
#include
// Tax rates
#define FOOD_TAX 0.10
#define HYGIENE_TAX 0.00
#define DEFAULT_TAX 0.25
// Item categories
#define FOOD 1
#define HYGIENE 2
#define OTHER 3
int getCategory() {
char choice;
printf("Enter item category (F for Food, H for Hygiene, O for Other): ");
scanf(" %c", &choice);
choice = toupper(choice);
switch(choice) {
case 'F': return FOOD;
case 'H': return HYGIENE;
case 'O': return OTHER;
default:
printf("Invalid category. Defaulting to Other.n");
return OTHER;
}
}
double calculateTax(double price, int category) {
switch(category) {
case FOOD: return price * FOOD_TAX;
case HYGIENE: return price * HYGIENE_TAX;
case OTHER: return price * DEFAULT_TAX;
default: return price * DEFAULT_TAX;
}
}
int main() {
double price;
int category;
char another = 'Y';
while (toupper(another) == 'Y') {
printf("Enter item price: $");
scanf("%lf", &price);
category = getCategory();
double tax = calculateTax(price, category);
double total = price + tax;
printf("Price: $%.2fn", price);
printf("Tax: $%.2fn", tax);
printf("Total: $%.2fnn", total);
printf("Calculate another item? (Y/N): ");
scanf(" %c", &another);
}
return 0;
} Now let’s compile it via gcc calc.c -o calc then objdump -d calc > calc.asm to convert it to assembly which results in the following
calc: file format elf64-x86-64
Disassembly of section .init:
0000000000001000 <_init>:
1000: f3 0f 1e fa endbr64
1004: 48 83 ec 08 sub $0x8,%rsp
1008: 48 8b 05 d9 2f 00 00 mov 0x2fd9(%rip),%rax # 3fe8 <__gmon_start__@Base>
100f: 48 85 c0 test %rax,%rax
1012: 74 02 je 1016 <_init+0x16>
1014: ff d0 call *%rax
1016: 48 83 c4 08 add $0x8,%rsp
101a: c3 ret
Disassembly of section .plt:
0000000000001020 <.plt>:
1020: ff 35 7a 2f 00 00 push 0x2f7a(%rip) # 3fa0 <_GLOBAL_OFFSET_TABLE_+0x8>
1026: f2 ff 25 7b 2f 00 00 bnd jmp *0x2f7b(%rip) # 3fa8 <_GLOBAL_OFFSET_TABLE_+0x10>
102d: 0f 1f 00 nopl (%rax)
1030: f3 0f 1e fa endbr64
1034: 68 00 00 00 00 push $0x0
1039: f2 e9 e1 ff ff ff bnd jmp 1020 <_init+0x20>
103f: 90 nop
1040: f3 0f 1e fa endbr64
1044: 68 01 00 00 00 push $0x1
1049: f2 e9 d1 ff ff ff bnd jmp 1020 <_init+0x20>
104f: 90 nop
1050: f3 0f 1e fa endbr64
1054: 68 02 00 00 00 push $0x2
1059: f2 e9 c1 ff ff ff bnd jmp 1020 <_init+0x20>
105f: 90 nop
1060: f3 0f 1e fa endbr64
1064: 68 03 00 00 00 push $0x3
1069: f2 e9 b1 ff ff ff bnd jmp 1020 <_init+0x20>
106f: 90 nop
1070: f3 0f 1e fa endbr64
1074: 68 04 00 00 00 push $0x4
1079: f2 e9 a1 ff ff ff bnd jmp 1020 <_init+0x20>
107f: 90 nop
Disassembly of section .plt.got:
0000000000001080 <__cxa_finalize@plt>:
1080: f3 0f 1e fa endbr64
1084: f2 ff 25 6d 2f 00 00 bnd jmp *0x2f6d(%rip) # 3ff8 <__cxa_finalize@GLIBC_2.2.5>
108b: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
Disassembly of section .plt.sec:
0000000000001090 :
1090: f3 0f 1e fa endbr64
1094: f2 ff 25 15 2f 00 00 bnd jmp *0x2f15(%rip) # 3fb0
109b: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
00000000000010a0 :
10a0: f3 0f 1e fa endbr64
10a4: f2 ff 25 0d 2f 00 00 bnd jmp *0x2f0d(%rip) # 3fb8
10ab: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
00000000000010b0 <__stack_chk_fail@plt>:
10b0: f3 0f 1e fa endbr64
10b4: f2 ff 25 05 2f 00 00 bnd jmp *0x2f05(%rip) # 3fc0 <__stack_chk_fail@GLIBC_2.4>
10bb: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
00000000000010c0 :
10c0: f3 0f 1e fa endbr64
10c4: f2 ff 25 fd 2e 00 00 bnd jmp *0x2efd(%rip) # 3fc8
10cb: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
00000000000010d0 <__isoc99_scanf@plt>:
10d0: f3 0f 1e fa endbr64
10d4: f2 ff 25 f5 2e 00 00 bnd jmp *0x2ef5(%rip) # 3fd0 <__isoc99_scanf@GLIBC_2.7>
10db: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
Disassembly of section .text:
00000000000010e0 <_start>:
10e0: f3 0f 1e fa endbr64
10e4: 31 ed xor %ebp,%ebp
10e6: 49 89 d1 mov %rdx,%r9
10e9: 5e pop %rsi
10ea: 48 89 e2 mov %rsp,%rdx
10ed: 48 83 e4 f0 and $0xfffffffffffffff0,%rsp
10f1: 50 push %rax
10f2: 54 push %rsp
10f3: 45 31 c0 xor %r8d,%r8d
10f6: 31 c9 xor %ecx,%ecx
10f8: 48 8d 3d fd 01 00 00 lea 0x1fd(%rip),%rdi # 12fc
10ff: ff 15 d3 2e 00 00 call *0x2ed3(%rip) # 3fd8 <__libc_start_main@GLIBC_2.34>
1105: f4 hlt
1106: 66 2e 0f 1f 84 00 00 cs nopw 0x0(%rax,%rax,1)
110d: 00 00 00
0000000000001110 :
1110: 48 8d 3d f9 2e 00 00 lea 0x2ef9(%rip),%rdi # 4010 <__tmc_end__>
1117: 48 8d 05 f2 2e 00 00 lea 0x2ef2(%rip),%rax # 4010 <__tmc_end__>
111e: 48 39 f8 cmp %rdi,%rax
1121: 74 15 je 1138
1123: 48 8b 05 b6 2e 00 00 mov 0x2eb6(%rip),%rax # 3fe0 <_ITM_deregisterTMCloneTable@Base>
112a: 48 85 c0 test %rax,%rax
112d: 74 09 je 1138
112f: ff e0 jmp *%rax
1131: 0f 1f 80 00 00 00 00 nopl 0x0(%rax)
1138: c3 ret
1139: 0f 1f 80 00 00 00 00 nopl 0x0(%rax)
0000000000001140 :
1140: 48 8d 3d c9 2e 00 00 lea 0x2ec9(%rip),%rdi # 4010 <__tmc_end__>
1147: 48 8d 35 c2 2e 00 00 lea 0x2ec2(%rip),%rsi # 4010 <__tmc_end__>
114e: 48 29 fe sub %rdi,%rsi
1151: 48 89 f0 mov %rsi,%rax
1154: 48 c1 ee 3f shr $0x3f,%rsi
1158: 48 c1 f8 03 sar $0x3,%rax
115c: 48 01 c6 add %rax,%rsi
115f: 48 d1 fe sar %rsi
1162: 74 14 je 1178
1164: 48 8b 05 85 2e 00 00 mov 0x2e85(%rip),%rax # 3ff0 <_ITM_registerTMCloneTable@Base>
116b: 48 85 c0 test %rax,%rax
116e: 74 08 je 1178
1170: ff e0 jmp *%rax
1172: 66 0f 1f 44 00 00 nopw 0x0(%rax,%rax,1)
1178: c3 ret
1179: 0f 1f 80 00 00 00 00 nopl 0x0(%rax)
0000000000001180 <__do_global_dtors_aux>:
1180: f3 0f 1e fa endbr64
1184: 80 3d 85 2e 00 00 00 cmpb $0x0,0x2e85(%rip) # 4010 <__tmc_end__>
118b: 75 2b jne 11b8 <__do_global_dtors_aux+0x38>
118d: 55 push %rbp
118e: 48 83 3d 62 2e 00 00 cmpq $0x0,0x2e62(%rip) # 3ff8 <__cxa_finalize@GLIBC_2.2.5>
1195: 00
1196: 48 89 e5 mov %rsp,%rbp
1199: 74 0c je 11a7 <__do_global_dtors_aux+0x27>
119b: 48 8b 3d 66 2e 00 00 mov 0x2e66(%rip),%rdi # 4008 <__dso_handle>
11a2: e8 d9 fe ff ff call 1080 <__cxa_finalize@plt>
11a7: e8 64 ff ff ff call 1110
11ac: c6 05 5d 2e 00 00 01 movb $0x1,0x2e5d(%rip) # 4010 <__tmc_end__>
11b3: 5d pop %rbp
11b4: c3 ret
11b5: 0f 1f 00 nopl (%rax)
11b8: c3 ret
11b9: 0f 1f 80 00 00 00 00 nopl 0x0(%rax)
00000000000011c0 :
11c0: f3 0f 1e fa endbr64
11c4: e9 77 ff ff ff jmp 1140
00000000000011c9 :
11c9: f3 0f 1e fa endbr64
11cd: 55 push %rbp
11ce: 48 89 e5 mov %rsp,%rbp
11d1: 48 83 ec 10 sub $0x10,%rsp
11d5: 64 48 8b 04 25 28 00 mov %fs:0x28,%rax
11dc: 00 00
11de: 48 89 45 f8 mov %rax,-0x8(%rbp)
11e2: 31 c0 xor %eax,%eax
11e4: 48 8d 05 1d 0e 00 00 lea 0xe1d(%rip),%rax # 2008 <_IO_stdin_used+0x8>
11eb: 48 89 c7 mov %rax,%rdi
11ee: b8 00 00 00 00 mov $0x0,%eax
11f3: e8 c8 fe ff ff call 10c0
11f8: 48 8d 45 f7 lea -0x9(%rbp),%rax
11fc: 48 89 c6 mov %rax,%rsi
11ff: 48 8d 05 41 0e 00 00 lea 0xe41(%rip),%rax # 2047 <_IO_stdin_used+0x47>
1206: 48 89 c7 mov %rax,%rdi
1209: b8 00 00 00 00 mov $0x0,%eax
120e: e8 bd fe ff ff call 10d0 <__isoc99_scanf@plt>
1213: 0f b6 45 f7 movzbl -0x9(%rbp),%eax
1217: 0f be c0 movsbl %al,%eax
121a: 89 c7 mov %eax,%edi
121c: e8 6f fe ff ff call 1090
1221: 88 45 f7 mov %al,-0x9(%rbp)
1224: 0f b6 45 f7 movzbl -0x9(%rbp),%eax
1228: 0f be c0 movsbl %al,%eax
122b: 83 f8 4f cmp $0x4f,%eax
122e: 74 1f je 124f
1230: 83 f8 4f cmp $0x4f,%eax
1233: 7f 21 jg 1256
1235: 83 f8 46 cmp $0x46,%eax
1238: 74 07 je 1241
123a: 83 f8 48 cmp $0x48,%eax
123d: 74 09 je 1248
123f: eb 15 jmp 1256
1241: b8 01 00 00 00 mov $0x1,%eax
1246: eb 22 jmp 126a
1248: b8 02 00 00 00 mov $0x2,%eax
124d: eb 1b jmp 126a
124f: b8 03 00 00 00 mov $0x3,%eax
1254: eb 14 jmp 126a
1256: 48 8d 05 f3 0d 00 00 lea 0xdf3(%rip),%rax # 2050 <_IO_stdin_used+0x50>
125d: 48 89 c7 mov %rax,%rdi
1260: e8 3b fe ff ff call 10a0
1265: b8 03 00 00 00 mov $0x3,%eax
126a: 48 8b 55 f8 mov -0x8(%rbp),%rdx
126e: 64 48 2b 14 25 28 00 sub %fs:0x28,%rdx
1275: 00 00
1277: 74 05 je 127e
1279: e8 32 fe ff ff call 10b0 <__stack_chk_fail@plt>
127e: c9 leave
127f: c3 ret
0000000000001280 :
1280: f3 0f 1e fa endbr64
1284: 55 push %rbp
1285: 48 89 e5 mov %rsp,%rbp
1288: f2 0f 11 45 f8 movsd %xmm0,-0x8(%rbp)
128d: 89 7d f4 mov %edi,-0xc(%rbp)
1290: 83 7d f4 03 cmpl $0x3,-0xc(%rbp)
1294: 74 36 je 12cc
1296: 83 7d f4 03 cmpl $0x3,-0xc(%rbp)
129a: 7f 43 jg 12df
129c: 83 7d f4 01 cmpl $0x1,-0xc(%rbp)
12a0: 74 08 je 12aa
12a2: 83 7d f4 02 cmpl $0x2,-0xc(%rbp)
12a6: 74 15 je 12bd
12a8: eb 35 jmp 12df
12aa: f2 0f 10 4d f8 movsd -0x8(%rbp),%xmm1
12af: f2 0f 10 05 21 0e 00 movsd 0xe21(%rip),%xmm0 # 20d8 <_IO_stdin_used+0xd8>
12b6: 00
12b7: f2 0f 59 c1 mulsd %xmm1,%xmm0
12bb: eb 33 jmp 12f0
12bd: f2 0f 10 4d f8 movsd -0x8(%rbp),%xmm1
12c2: 66 0f ef c0 pxor %xmm0,%xmm0
12c6: f2 0f 59 c1 mulsd %xmm1,%xmm0
